The BMW boxer twins bible

Othe<g,.al booll1 !romVeloc•-
www.veloce.co.uk
INTRODUCTION
&
ACKNOWLEDGEMENTS
S
ince the release of the A32 in 1923, the.
boxer twin engine design and the BMW
motorcycle have become synonymous
Other manufacturers have emulated, even copied,
the design, and BMW has considered replacing
the boxer with an alternative engine layout, but
the boxer has endured. Max Friz chose the boxer
layout because he felt 11 was ideally suited for a
motorcycle application, and this remains relevant
today. The two cylinders were out in the air stream
for optimum cooling, the engine provided a low
centre of gravity, was suited to shaft drive. and
could be kept oil- tight. Later designs expanded
these features. emphasising reliab1hty and ease
of service. BMW's boxer twin always setting the
standardlorall-roundusab1hty
When the time came to replace the ageing
and expensive /2·series 11 was no surprise that
BMW continued its adherence to the boxer layout
While thenewType246wasundoubtedlycheaper
to produce than the /2, 1t continued to provide
unparalleledquahtyandreliab1hty.Gradually,the
Type246 evolved 1ntothesporting R90Sand sport
touring R100RS-bothlandmarkmotorcycles. The
R90S also provided BMW with racing success
that had eluded it for decades Although BMW
planned to replace the venerable air-coo led boxer
twin during the 1980s. consistent demand saw
11 remain in production until the m1d-1990s. As
BMW moved into a world of high technology, the
uncomplicated air-cooled twins re1used to die
- providing pleasure to thousands of enthusiasts
around the world_ These owners value ease of
maintenance and long-term rehab1hty w1th1n
an accessible technological framework The
air-cooled BMW boxer may no longer be at the
cutting edge of high performance. but 11 remains
relevant in a modern world with rts open road speed
l1m1tsand traffic congestion. Because 1t possesses
a unique character and provides unparalleled
competence over a wide variety of cond1t1ons.
the air-cooled BMW boxer twin has, just1f1ably,
earned a loyal following_ This book endeavours
to document the myriad developmental changes
to these motorcycles during their long production
run. The material 1s organised by model year.
and only the larger capacity street boxers are
included
The preparation of this manuscript has
only been possible with the assistance and
enthusiasm of many friends and en thusiasts
Photographs were supplied by the BMW press
department. Jeremy Bowdler, editor of Two
Wheels magazine. Hans Crabbe, Helmut Dahne.
Jet! Dean. Nico Georgeoglou. lvar de Gier, Udo
Gietl, Eric Heilveil, Mac Kirkpatrick. JeffWh1tlock
and Nolan Woodbury. I must also thank my family,
my wi fe M1nam and sons Ben and Trm. for their
continued support of my ded1cat1on to such tome
consuming projects
Ian Falloon
Melbourne, Australia
CHAPTER I
HISTORIC AL BACKGRO UND
T
he story of BMW motorcycles began dunng
World War I. growing out of t wo struggling
aircraft and aero-engine companies near
Obe1w1esenfeld airport , m the north - eastern
outskirts of Munich . On e was th e Bayer1sche
Flugzeug-Werke(BavananA1rcraft Works). founded
by Gustav Otto m 1910. The other, only a few
hundred meters away. was Karl Rapp's Rapp Motor
Works. a manufacturer of aircra ft engines. By
1917. Bayer1sche Flugzeug-Werke was produc ing
200 aircraf t a month. unti l a fire destroyed the
factoryandthecompanywasreduced tobuild1ng
furnoture. Things were little better for the Rapp
Motor Works. Following a series ot business
disasters, 11 became a public company and. in
1917. the Bavarian Motor Works was established
The two companies continued to coexist until
1922 when a merger saw BMW move mto the BFW
premises a\ NeulerchenfelderStreet. laterknown
as Lerchenauer Street. Th1s1sstdl the s11eofthe
mam BMW works
In 1917, Rapp'sBMWgamedanewleaseofl1fe
whenMaxFnz1oinedthecompany. Friz
redes1gnedoneofRapp'sproblemat1c
six-cylinderaero-engines.result1ngin
theBMWllla_Th1sneweng1neallowed
German flying ace. Ernst Udet to down
30enemyaircraft mh1sFokkerDVll
dunngthelinaldaysofWorldWarl
Unfortunately for BMW. the
1919 Treaty ol Versailles forbode any
German company to be involved 1n
aircraft manufacture. This provided
the impetus for both BMW and the
neighbouring BFWto seek salvation
in other fields of manufacturing
endeavour. BMW managed to survive
after its director. Franz-Josef Popp,
secured an order to produce railway
pneumatic brakes. BFW decided
to produce motorcycles. and its
first effort was the Fhnk of 1920
with a 143cc Hanfland two-stroke
eng1ne.Co1nc1dentally.BMWwasalso
1nterested1nmotorcyclesandin1920
HI ST OR I CAL BACKGROUND
its foreman, Martin Stolle. stripped down his 1914
Douglas 500cc flat twin_ Friz set about copying it,
with a few mod1ficat1ons. and the BMW M2 B15
engine was born. This engine was then sold to
severalmotorcyclemanufacturersasaproprietary
motor. including BFW for its Helios early 1n 1922
When BMW and BFW merged in June 1922. BMW
inherited the Hellos production line and some
unsold stock. This encouraged Popp to engage
Friz in motorcycle design, and Friz embarked on
desigmngthefirstBMWmotorcycle.
The R32 was first launched in Berlin
in September 1923, heralding a long line of
A-series BMW motorcycles. Although the
engine spec1ficat1on was unremarkable, the R32
offered a new level of refinement compared to its
contemporaries. Emphasising reliab ility with low
maintenance, the R32 pioneered a formula that
would dist1ngu1sh all BMW motorcycles. While
not revolutionary, Friz was the first to combine
the features of a horizontal-transverse twin with
shaft final-drive.
The R32's engine was based on the M2 815.
retaining the same 68x68mm bore and stroke,
and one-piece, cast-iron. side-valve cylinder and
head layout. W1tha5.0: 1 compression and single,
srnall 22mm BMW special carburettor, the power
was only 8.5 horsepower at 3200rpm. The clutch
was a dry single disc type, and with the hand
operated. three-speed. grease-filled gearbox.
the R32 was years ahead of its time when it came
to user-friendliness. The
flat tw in engine was
housedinaclosed-duplex
tubular-steel frame.w ith
a rigid rear end and
short-swinging front fork
On early models, there
was no front brake, and
the block rear brake
was an old-fashioned
type. heel operated
with a dummy-belt rim
The 122kg (2661b) R32
was capable of around
90km/h {56mph). and
the second series o f
1925 included a small
(150mm) lront drum
brake. Although greeted
with scepticism. the
transverse-horizontal
twin-cylinder engine
layout proved ideally
suited to a motorcycle
The two cylinders were
adequately cooled by the air stream. and
the design provided a low centre of gravity,
contributing to agile handling. Although the
R32 was an expensive. premium quality, luxury
product, it was a success and 11 paved thewaylor
a succession of more sophisticated models
By 1924, Friz was again working on
aero-engines and motorcycle development was
entrusted to Rudolf Schleicher. Schleicher was
not only a fine engineer, but an outstanding
motorcyclist. riding a prototype overhead-valve
R32 to victory in the 1924 AOAC Winter Rally in
Garmisch-Partenkirchen. This was BMW's first
sporting success. and the overhead-valve R32
eventually became the R37. Although only 16
horsepower at 4000rpm. the R37 won nearly 100
races in Germany dunng 1925. Schleicher also
took an R37 to England for the Six-Day race .
winning a gold medal.
During 1926. the R32 evolved into the A42.
The engine was still a side-valve 500, but with
new detachable light alloy cylinder heads and
circumferential cylinder cooling fins. The power
was now 12 horsepower at 3400rpm, the engine
located further rearwards to improve handling.
and the braking updated with the introduction of
a driveshaft rear brake with narrow brake shoes
mounted on the gearbo~ case. Although only
produced for two years, the R42 was the most
popular BMW motorcycle of the 1920s and more
than 6500 were sold
By 1926 the R32 evolved
intc the side· valve R42, one
of BMVV's mos1 SI.JC( sf,I/
rnotorcycJesofthe 19.:
THE B MW B oxER T w1Ns B1eLE
While BMW was earning a reputation for
producing sohd and reliable side-valve touring
machines like the R32 and R42. 11 continued to
develop the SOOcc overhead ·vatvesl)Ortmg model
In 1927. the R47 replaced the R37 and, while sllll
an expensive spor!ing model. 11 shared the R42
chassis 10 keep costs down. The power was now
18 horsepower at 4000rpm
Four new boxer twins were unveiled lor 1928.
including two 750cc models The side-valve R52
and R62 shared a longer(78rnm) stroke. while the
overhead-valve R57 and R63 retained the 68mrn
stroke Producing 24 horsepower at 4000rpm,
al'ld capable of 120km/h (75mph). the R63 was
one of the fastest and most powerful motorcycles
of its day. It also formed the basis of the next
generation of racing machines, providing BMW
w1th91 v1ctoriesthrou9hun1111930
Problemsw1ththelramescrack1ngwhef1l11ted
with a s1decar led to the replacemen1 of the R62
and R63w1th two new 750ccmodels1n 1929. These
These new austere machines weren't pan1cularly
exc1t1ng. but the R11 round favour with them1htary
and helped sustain the company through the
d1tflcult period of the early 1930s
Germany was hit particularly hard by the 1929
world depression and. in thewakeotfa\hng sales.
BMW decided to concentrate on world speed
records instead of racing. l\s first successful
attempt was in September 1929, when Ernst Henne
set a world record of 134.68mph (216.9km/h) on
a short-s1roke 750. Henne would set many more
records over the next decade. culminating 1n
November 1937 when he ache1ved 173.69mph
(279. 503kmlh)on a supercharged 500. This record
stood for fourteen years
BMW's fortunes had improved by 1934,
leading to the release of two new 750cc models
for 1935. These were the side-valve R12, and
overhead-valve R17, replacing the All and R16
The R12 proved even more popular with the
m ilitary than the R11, and 36.000 were produced
until 1942. Although 1\ shared the ut1t1tarian R12
chassis. the 33 horsepower R\7 was sold as a
high performance sporting machine. and was
considerably more expensive
HI STOR ICAL BACKGROUND
Tne RI<!
9
w
c111ie6r:;tmc'~
h1~a1.-~
Both the A12 and R17 were an amalgam
of conservatism and radicalism. The engine
and drivetrain were similar to those of their
predecessors. as was the old-fashioned
pressed-steel frame with a rigid rear end. But
the front suspension was via a set of rudimentary
011-damped telescopic forks - the first hydraulic
forks to appear on a production motorcycle. While
theR12foundareadymarket,during193StheSOO
Kompressor established itself in the racing world
and the time was right for a new sporting flagship
BMW responded with the AS, an all-time classic.
and the most advanced motorcycle of its day
Although the arc-welded tubular-steel frame
and telescopic forks were similar to those of the
racing Kompressor. the RS's engine was all-new,
sharing little with the racer or earlier production
models. Central to the design was the one-piece,
tunnel-type. aluminium crankcase that would
leatu1e on all air-cooled twins through until 1996
Instead of a single camshaft. th e AS had t wo
chain-driven camshafts above thecrankshalt . the
long t1m1ng chain also driving the Bosch generator
on top of the crankcase. The four-speed gearbox
was now foot operated. and. while the power
(24 horsepower at SBOOrpm) was less than that of
the A17, the 16Skg (3631b) AS was a much more
sporting motorcycle_ Despite the rigid frame .
handling rivalled that of the best British singles.
and a 600cc side-valve A61oined 11 1n 1937 The
A6 featured a completely new engine design with
a single gear-driven camshaft, but lasted 1ust
one year because the military still favoured the
pressed-steel frame R12 for s1decar use
The racing Kompressor gained
rear-suspension for the 1937 season. and
demonstrated its superiority by winning four Grand
Prix races that year. In the wake of this success.
rear suspension was added to four new production
models for 1936. The RS1 and A61 replaced the
)p
yie
le
fr
~'
11 1 "I<.
THE BMW BOXER TwtNS B1sLE
men
,f
a~
Wrr t
R
t
nd -ig
1l6
AS and A6, while the side-valve 750cc R71 was
111troduced as another replacement for the R12
This time 1t was more successful. and the R71.
BMW'sf111als1de-valvetw111.lastedunt111941. But
the most exciting new motorcycle for 1938 was
thetop-oHhe-rangesportingA66.Combinmgthe
overhead-valve cylinder heads of the A51. with
the superior s111gle gear-dnven camshaft setup
of the R6. A61, and R71. the 70x78mm 600cc
twin produced an 1mpress1ve 30 horsepower at
5300rpm. Thiswasenoughtoprov1deatopspeed
10
of 90mph (145km/h), an impressive speed for a
product1onmotorcycle1n 1938. BMW also offered
rac1ngvers1onsoltheR5andR51towellconnected
privateers. An R5SS and sprung frame A51SS
appeared during 1937. but the most effective of
these hm1ted ed1t1on production racers was the
R51RS(Rennsport).Although1tretainedpushrod
operated overhead -valves, this was the closest
production model to the works Kompressor. The
single camshaft engine was based on the R66.
and the power was 36 horsepower.
H I S T OR I CAL BACKGROUND
,._
?go.
~(
'11.l)IOl'l
Ko na c,Hu R. ·q::
1rrq
lnrh t>veJf~War
'sorg Meler won le
Seruo nattl)(! 1e >I Mm
on the 8M'N Korn~
/Go.utesylvarkJGJer!
11
THE B MW B OXER T wrNS B IBLE
-
12
BMW continued to develop the racing
Kompressor, with Georg "Schorsch" Meier
winning the 1938 European Champ1onsh1p
This was a magnificent achievement. but
his finest moment came at the Isle of Man
in June 1939. Meier won the Semor TI.
the first foreigner on a foreign machine.
travelling an average speed of 89.36mph
{143.BKm/h). Jock. West came second but
BMW's victory was marred by the death of
its other worKs rider. Karl Gall. alter a crash
during practice. Following the outbreak. of
World War II. military production assumed
priority. including the venerable R12 and a
new military motorcycle, the R75
Although BMW's Mumch-M1lbertsholen
plant was extensively bombed. by 1948 BMW
was again producing motorcycles. lmt1ally,
this was restricted to 250cc and the first
post-warmotorcyclewasthesinglecylinder
R24. based on the pre-war R23. Capacity
restrictions were lifted during 1949 but, with
little money available for development, the
1938 R51 was resurrected as the R51/2. An
updated R5113 was introduced for 1951
Although similar to the R51/2, powering the
R51 / 3 was a new engine with a gear-driven
single camshaft above the crank.shaft. This
was 1oined soon afterwards by the 600cc
R67 and higher performance R68. The R68
was marKeted as an expensive lifestyle
accessory, but was also one of the leading
sporting motorcycles. ava1lable1n 1952. With
35 horsepower at 7000rpm.
the claimed top speed was
160Km/h(100mph)
BMW's continued
success 1n the early 1950s
prompted a return to racing.
and the creation of the
RS54 Aennsport. With a
bevel-gear-driven double
overhead camshaft engine
derived from the pre-war
Kompressor. the RS54
formed the basis of au
factory racers for the rest
of the decade. Fitted with
an Earleslead1ng-hnK front
fork.. the limited production
R$54 was not particularly
successful as a solo racer
but, the engine subsequently
powered s1decar world
champ1onsh1p machines
unt1lthem1d-1970s
HI STORICAL BACKGROUND
The RS54 racers had an
Eanes front fork but we.--e
not as successful a Sot!
race.-- as en vis.aged.
wi t h four new models being
released in 1961
Heading the new hneup were
two sporting models, the R50S
and R69S, alongside new versions
of the R50 and R60: the R50/2 and
R60/2. The /2s looked outwardly
similar to their predecessors but
underneath there were a number
of developments. pr1man!y aimed
at improving rel1abil1 ty. The
RSOS was short-hved due to its
unrehab1l1ty. but the R69S would
become one of BMW's most
su ccesslultwms Now producmg
42 horsepower at 7000rpm. the
top speed was a claimed 109mph
(175km/h).
Replacing the R51/3 and R68 1n 1g55 were
two new twins, the R50and R69. These featured
!ront and rear swmgarm suspension patterned
on the RS54 racer. The driveshaft was now
enclosed in the right-side of the swingarm, with
the universal jomt moved to the gearboK end. The
neK\ year saw a touring R60, but this coincided
with a serious slump in motorcycle sales. During
1957, several German manufacturers (mcludmg
Adler, DKW and HoreK) disappeared, while
BMW's motorcycle production slumped to less
than 5500. There was virtually no motorcycle
development for live years, and BMW laced
bankruptcy in 1959. A rally of shareholders
saw the company survive and, during 1960, the
motorcycle range was developed and improved
Sldec<lrs powered by !he
Rennsport engrne wern
much more svcces:;ful
Klaus Enders and Raif
Englehart won four WOfla'
Chamf)IOflsh•ps between
1969 and 1974
The produCtlOf'I RSO of 1955
also had an Earles front fOfk
Altho"gh ''°""'"o" '"""9 lhe 1960• ,.,.,
managed to replicate the boom years o! the early
1950s, the /2 twins sold solidly unto! 1967. As sales
tapered, particularly 1n the US. specific US models
were developed with a te!escop1c fork. replacing
the 1d1osyncrat•c Earles fork By this stage,
car production was eJtpand1n.g and becoming
increasingly profitable. and as a remnant of an
earlier era. the /2 was e:w.:pens1ve to produce. The
/2 was built with lavish attention to deta•I and
finish. and the engine - with its pressed together
rollerbeanngcrankshaftandgearcamshaltdnve
- didn't lend itself to mass production. Even
components such as the throttle control and !he
rear brake linkage were unne<::essanly complex
As sales dwindled to around 5000 in 1968. 11 was
lI
CHAPTER II
THE /5-SERIES (TYPE
246)
T
1mes were tough for European motorcycle
manufacturers during the 1960s. The
Japanese already dominated the smaller
capacity market but they gradually expanded their
horizons. This threatened the survival of the British
and European manufacturers that concentrated
on motorcycles over 250cc. Built with up-to-date
machinery, these new mass-produced Japanese
motorcycles offered class-leading performance
and were cheap and reliable. Atthough motorcycle
sales sustained BMW early in the 1960s, by 1963
BMW's new range of cars was more successful
and profitable The increase in demand for cars
was coupled with a reduction for motorcycles
In spite ol a threat to stop motorcycle
production altogether, technical director Helmut
Werner BOnsch remained firmly committed to
motorcycles. Facing opposition during 1963,
B6nschmanagedtopersuadeBMW'sdirectors to
sanction a pilot scheme, to develop a replacement
forthe/2 with an internal des1gnat1on of Type 246.
Under the superv1s1on of Claus von RUcker a new
chassis was fabricated for the R69S. Von RUcker
came from Porsche in 1964, bringing with him
Hans-Gunther van der Marw11z to head the Test
Department Ha1hng from a d1stingu1shed family,
vonderMarwttz was born in 1927 (he died in 2002),
and had also worked with Kreidler and Henkel
Like Friz and Schleicher before him. he was an
avid mo1orcycl1st, used to racing around on an AJS
7R_ He was dismayed at the handling of the Earles
lork R69S and wanted the new BMW to handle
as well n a Manx Nonon. It was no coincidence
that the prototype frame !or the new bo•er twin
me rmpetus behtnd the 15
design was Hans-Gunther
von der Marv.1L::
was a full cradle duplex type, that bore more than
a passing resemblance to the Re• McCandless
Man• Norton ' featherbed.'
Replacing the Earles fork of the/2 on the 246
prototype was a set of telescopic forks_ Initially,
thesewereratherrud1mentaryw1thsmalldiameter
fork tubes, but already included a leading a•le
mount to reduce the trail. The first version was
15
TttE BMW B oxER Tw1NS B10LE
fhe
1e
built m oil-road guise, with a h1gh-r1se single
muffler exhaust on the right and m1mmal street
equipment Its debut was at an off-road event m
Eschwege, in April 1964
During 196<1, the 2<16 protolypeevotved into
a s1ree\ model As a test nder. von der Marw1ti:
had a strong influence on the design. ensuring
the new bike handled well. There was no longer
a requirement lor s1decar capability and the
prototype was considerably lighter than the
R69S. A 19-inch front wheel and strooger front
fork were fitted. and the styling of the !uel tank
and seat began to assume !he propor tions of the
eventual production version. The telescopic front
fork soon found 11s way on the US/2, wh1lechass1s
development ol the 2d6 continued throughout
1965 and 1966. A new engine was required 11
overall development was to proceed further
By 1965. the spec1hcat1ons for a more
modern boxer twin were being considered by
Engine Development head Alex von Falkenhausen
and Ferdinand Jardin. To improve rehab1ht y and
reduce costs they decided to introduce many
features ot the recenlly developed, smaller
capacity BMW automob1les. in parhcular, a
plain-bearing crankshaft. While the !our-speed
gearbox. single-plate dry clutch and dnveshaft
through the swmgarm was s1m1lar to the 12. a
Bosch electric start and three-phase generator
were new add1t1ons. By 1967, the prototype was
close to the eventual production version
Despite a recession 1n Germany during 1967,
demand for BMW's new range of compact cars
from 1500 to 2000cc continued unabated_ It
was decided to move motorcycle p<oduct1on to
Berlin to provide add1t1onal capacity m Mumch
BMW already owned a repair and machine work
factorymtheWestBerlmsuburbofSpandau. and
THE /5-SERIES (TYPE 246)
during 1967. this was converted into a motorcycle
production facility. Originally set up as an aircraft
engine factory by Siemens & Halske in 1928, in
1936 it became Brandenburg1sche Motorenwerke
{Bramo). Bramo merged with BMW to become
BMW Flugmotoren-Gesellschaft in 1939, and
after World War II. the works became BMW
Maschinenfabrik Spandau. It initially produced
scythe and sickle hand tools for agricultural use.
and from 1958, was involved in the manufacture
of vehicle components. While the motorcycle
development and administration remained in
Munich, the first motorcycles left the Spandau
factory in 1967. Gradually. the plant was prepared
for the release of the 15 for the 1970 model
year, and when 1t was released at Hockenheim
on August 28, 1969, even the sceptics were
impressed.
R75/5, R60/5, R50/5 1970
model year
Although a small number of all types were
built for press and dealer evaluation in August
1969. production of the R60/5 commenced in
September 1969, the R75J5 in October, and the
R50f5 in November. The A75/5 was also the
first off1c1al 750cc twin since the military R75
of 1942-44, but even as the 750 was first rolling
off the production hne. BMW was testing 900cc
versions. 1970 model year frame numbers for the
A50/5 began a\2900001. through to 2901810. The
R60/5 lrame numbers began at 2930001 , finishing
at 2932774, while the R75J5 began at 2970001,
ending at 2973761. Each model received a new
code from BMW, R75/5 (0260), R60/5 (0250), and
R50/5(0240).
/5 engine
The air-cooled boxer engine in the /5-senes and
subsequent developments was known as the
M04'. The design differed s19mhcant1y in detail
and execution to the 12. Aeliab1hty rather than
outright power was emphasised in the design.
and the crankshaft now a one-piece forged
type running in plain main bearings. The single
camshaft was also located below the crankshaft,
as originally proposed by Leonhard lsch1nger in
the prototype M205-M208 500-800cc twins of
1932. These extremely advanced designs also
featured a one-piece tunnel crankcase and forged
crankshaft with plain bearings. but never reached
the production hne
As the camshaft was now underneath the
crankshaft , the pushrods were also below the
cylinders, tidying the look of the engine. The
pushrod tubes also provided an oil return to the
crankcase. Unlike the /2 engine that featured a
gear c am shaft drive. the camshaft was driven
by a duplex chain. Also 1mprov1ng the engine
aesthetics. was the extension of the crankcase to
the fuel tank. with aluminium covers for the new
electric start and air filter on top of the engine
Considerable effort was spent in m1mm1sing
weight and, instead of the earlier pressed steel
sump. the /5 had a cast aluminium sump cover
The 15 camshdft was
cha!n-dnven and siluared
belowthecranAsflilft
17
THE
BMW BoxER Tw1NS BIBLE
Ostensibly the three 15 variants were identical,
sharing the same stroke but with different bores
With carburet1ors and 011, but without 1gn1hon
coils and an induction system. the R50/5 engine
we1ghed58.5kg. theR60/6eng1ne63.5kg, and the
R7515 engine 64.9kg. Typical ol BMW's methodical
development, the basic engine design was so
sound that 11 survived through until 1996 with only
m inimal updates
As on all boxer twins since the A5. the /5
engine housing was a one-piece tunnel type,
however. because 11 incorporated an electric
starter motor and air filter above the crankcase.
1t was bulkier than its predecessor. Internal
gussets reinforced the cast aluminium housing,
and the engine number was located on the engine
block. on the left, above the 011 filler_ There was
also a BMW logo stamped after the seven-d1911
number. The very earliest crankcase housing
(July 1969) featured 'BMW' lettering. cast above
the cylinder like on the /2 series (and carried a
d11!erent part number), although, duflng 1970 , the
crankcase was standardised. The three models
were d1f ferent1ated through 1dent1fication plates
on either side o! the upper crankcase. the earliest
plates without a black background . Instead of the
12·s pressed-steel sump cover, the /5 had a cast
alum1mum cover, retained by 14instead of 12 bolts
Thealuminiumhous1ng for thet1ming
chain was t wo- piec e and
cast, without
18
While ma1nta1mng a design without a centre
main bearing tom1mmiseollset.thecrankshaft
was now a one-piece drop-forged stetil type
R1g1d1ty was achieved by increasing the mam
bearing 1ournal diameter to 60mm (from 35mm
on the R69S), with three-layer (b1onze. tin. and
1nd1um) plain bearings shared with the newly
developed six-cylinder M06° 2500cc BMW car
engine. These bearings were pressed into a
die-forged alloy bear mg bush inserted in the front
and rear of the crankcase. Also increased. was
the b ig-end journal diameter (to 48mm), while the
die-forged steel conrods were two-piece (with a
22mmolf-centregudgeon pm)_ The conrods. also
shared with the Mos· six-cylinder car engine. ran
mthree-layerplainbearmgs,wh1lethegudgeon
pins ran in bronze bushes. With an eye-to-eye
length of 135mm the stroke to conrod length
ratio was 1.91:1, close to lhe optimum 2:1_ An
automotive-t ype llywheel was bolted onto 1he
end of the crankshaft and included a ring gear
fortheetectricstart
Three-ring convex , rising oval, forged
aluminium pistons were fitted to the /5. These
were almost flat topped, with very little valve
cutaway. The top piston ring (compression) was
hard chrome-plated and quite Ihm to avoid flutter
and loss of compression at highenpm. The second
ring was an L-shaped Dykes pattern compression
nng, with a third, oil-scraper ring. There was also
a higher compression compet1t1on piston available
fortheR7515
Unlike the R69S that had cast-iron cylinders,
the /5cyhnderswerealummiumwithbonded
cast-iron sleeves. The sleeves were
molecularly bonded to the cylinders.
through a process known as
Al-Fin. and provided the benefits
of less weight and improved heat
dissipation. Because of the more
uniform expansion rates between
the piston and cylinder, closer
tolerances were specified
(O 0035· 0.0045mm). Two
pushrod tubes were pressed
into the bottom of the cylinder.
also prov1dmg an oil return to the
crankcase. The 0.5mm cylinder
base gasket was aluminium fibre.
with the cylinder head gasket
being metal-asbestos
Therewasanewcylinder
head design for the /5, with
the two overhead-valves set
at a shallower. 65-degreemcluded
angle. The finned cylinder head was constructed
THE / 5-SERIES (TYPE 246)
of aluminium alloy, with shrunk-in valve seats,
fine pearlit1c grey iron for the intake, and high
alloy grey iron for the e)(haust. Each version of
the 15 came with different valves. the R75/5 with
42mm intake and 38mm e)(haust (both 98.Bmm
long}. On the R60f5, the valves were 38mm intake
{98.5mm long) and 34mm exhaust (97.5mm long).
with the R50/5 receiving 34mm and 32mm valves
(103mm and 102.5mm long). All valve stems were
hard chrome-plated and 8mm in diameter, while
the e)(haust valves had a heat conductive ferrite
stem, and an austenit1c head. The valves were
actuated through 22mm hardened followers.
pushrods. and rocker arms, with the pushrod
having a similar coefficient ol e)(pansion to the
cylinder to maintain a consistent valve c learance
The valve springs were a single coil-type, and the
valve guides 54mm long
The threaded intake manifold was 26mm 1n
diameter for the R50/5 and R60/5, and 36mm in
diameter !or 1he R75/5. The R75/5 manilold was
30mm long. though this was later reduced to
25mm. Von der Marw11z insisted on longer and
&turdoer cylinder bolls and. for the first time on
a BMW motorcycle engine. the cylinders and
cylinder head were retained by four long studs
(10)(275mm). Two additional bolts (10)(30mm
and 10x50mm) connected the cylinder head with
the cylinder. Rocker arm blocks were attached
to these through-bolts. with the rocker arms
pivoting on 18mm floating bronze bushings
The rocker arm ratio was 1:1-39. Soon after
production commenced, sealing of the top end
locating dowels was improved. with 15)(2)(3mm
0-nngs and spacers (from RS0/52900602. R60f5
2930965, and R75/5 2970980)
The case-hardened die-cast camshaft ran
d irectly into the crankcase at the rear, and into a
flanged a!um1mum bearing support at the front. 11
was phosphated forlowerfnction, and ano1I pump
rotor for the Eaton 011 pump was incorporated at
the rear. Located on the front of the camshaft were
the 1gmtion advance unit and the tachome1erdnve
gear While the RS0/5 and R60/5 shared the same
camshaft. the R75/5 used a sporting camshaft
with greater overlap and a 110-degree lobe centre
(compared to the 90-degree lobe centre for the
RSO and R60/5). The R75/5 camshaft also provided
ft1' ;ylinderheadde ign
wa. new wr/11 a narrowet"
.nc 'u<Jed valve angle An
ai'temMor was .iiso fiitl!d to
the front , )/ the engrne
19
THE BMW BoxER Tw1NS BIBLE
6.756mm ol valve hit. compared to 6.198mm for
theR50/SandR60/S
The duplex chain camshaft drive was s1m1lar
to tha t on the overhead camsha ft BMW car
engines. The 50-hnk doubleroller3J8x7/321ncha1n
incorporated an automatic leaf spring tensioner,
and the lower sprocket ran m a 3Sx62x9mm
bearing in the housing_ A Sx6.5mm woodruff key
located the sprocket on the camshaft
The plain bearings inside the engine required
copious amoun ts ol l1ltered high pressure oil, and
this was supphed by an Eaton hypo trocho1dal
pump-essentially a four-bladed impeller revolving
1ns1de a five-chamfered housing. 1t was capable
of dehvermg 1400 hires per hour at 6000rpm_ On
the early /5 a very small 2.Sx3.7mm woodruff key
connec ted the inner rotor to the camshaft_ The
011 pump sucked 011 from the 011 pan through a
suction bell with a perforated screen. pumped 11
through the main lubricating passages and into
the automotive type disposable full flow 011 filter
This was retained by a plain cover on the /5
Oil was then pressure fed to passages in the
camshaft bearing flange and the main bearing
cover. through thelelt-s1deof the crankcase to the
rear main bearing. II then went upward, through
the two upper through-bolt holes in thecyhnder. to
the tappet bearing blocks and shafts. lubricating
20
the valve mechanism. The connecting rods
werelub11catedthroughholesinthecrankshah
receiving their 011 from the annular groove of th~
Iron! or rear main bearing sleeve, with the rear
camshaft bearing lubricated directly by the oil
pump. The t1m1ng chain was splash lubricated
from the sump and a venting dome on top of the
crankcase separated the oil mist from crankcase
pressure, through a check ball valve_ This was
then led back into the intake_ Undoubtedly, the
efficiency of the lubrication system contributed
to the outstanding reltab1hty of the M04' engine
throughout its long produc11on lifespan.
A new air intake system was designed for
the /5. Instead of the air filter being situated 1n
a separate housing above the transmission. 11
was now incorporated 1ns1de the engine cases.
also at the rear above the gearbox. At the top
of the housing, underneath the fuel tank, was a
rear facing air intake grill. As the air intake laced
rearward there was no ram air effect but the air
filter volume was 60 percent larger than that of
the R69S. A small amount of air went to cool
the electrical components on the front of the
engine. before the filtered air entered a common
chamber. under the large 'Micro Star' disposable
dry paper air filter element. A1rthen proceeded to
two ind1v1dual carburettor ducts and, while this
THE /5-Semes (TYPE 246)
convoluted mtake system didn't contribute to
horsepower, 1t successfully quelledintake noise as
well as prov1dmg e1<.cellent air filtration_ To prevent
oil from the engme breather contammaling the
air filter. an improved engme breather tube was
fitted after R50/5 2901704. R60/5 2932473, and
R75/52973142
After considering Japanese Keihin
carburettors, the Nuremburg company Bing
eventually gained the contract to supply
the /5. Two types of carburettor were fitted.
The R50/5 and R60/5 received Bing 26mm
concentric carburettors, and the R75/5 receNed
a new vacuum type Bmg 32mm carburettor. The
vacuum carburettors were initially built 1n the
BMW development shop to very fme tolerances
Unfortunately, the first batch of Bing vacuum
carburettorssufferedfrom1nadequatetolerances.
delaying the introduction of the R75/5 until after
the two smaller versions. The R75 carburettors
were also attached to the cylinder heads through
short rubber steeves and 52mm diameter clamps
to 1solatethemfromv1bralion. There was no choke
provided on the concentric carburettor, only an
enriching float plunger, while an accelerator pump
supplied additional fuel. The plastic intake tubes
were silver on 1970 models. After A50/5 number
2900441, a 135 main 1et replaced the 145 mam
1et and the needle position was changed from
2 to 3. A kit to improve the accelerator pump
action was also installed on the R60/5, from
number 2930530. Eventually, BMW provided an
updated carburettor for the R75/5. from number
2972061, the carburettor receiving a reinforced
0.4mm diaphragm and a 'C' on the top of the
carburettor body
All /5s shared the chrome-plated steel
38x1.5mm exhaust headers and d1st1nct1ve
100mmdiameterc1gar-shaped muffler. This large
capacity exhaust system mcluded a crossover
pipe in front of the engine and was designed to
m1nim1se backpressure over a wide rpm range.
accentuating quietness over performance
The /5 received an up-to-date 12 volt
electrical system, including an automotive-type
three-phase alternator positioned on the end of
the crankshaft. Designed by BMW and built by
Bosch, this Gl 14V 13A19 alternator provided
180 watts and a maximum current strength of 13
amps. There was a diode plate mounted above
the alternator and a Bosch AD 1114V regulator
controlled the voltage. AsmallVarta 15Ah battery
completed the electrical system. and the first
mod1ficallon to the /5 was dunng the autumn of
1970, when a new. more fle1<.1ble battery cable
was installed (from number R50/5 2900921.
R60/5 2931336. and R75/5 2971545) to m1mm1se
damage from vibrallon. At about the same time.
there was an improved alternator rotor (RS0/5
2901772, R60/5 2932606, and R75/5 2973649).
claimed to be more stable and with a blue or
wh1temarkmg
The battery and points
1gmt1on system included a single
contact breaker opened by a cam
mcorporated on the end of the
camshaft. Common to all three /5
models was the Bosch centnfugal
ignition advance umt s11t1ng on
the end of the camshaft. Ignition
advance began at 800rpm. ending at
appro1<.1mately 2500rpm. The dwell
angle for 1970 was 110 degrees
or 61 per cent. Right at the end
of the 1970 model year, in July
(R7515) and August (RS0/5, R60/5),
a new centrifugal advance umt was
fitted (from R50/5 2901787, R60/5
2932689 and R75/5 9273307). It
provided maximum advance at
3000rpm with 43 per cent dwell.
butcanrea!tybeconsidereda 1971
model year update. Twin Bosch 6 ThQR5Ql5andR60/5
volt coils were mounted m series and ret,fln9d the oorfJer Bing
theh1ghtens1on leadswere550mm. shde-type c..Jff)(Jrottor w1rh
with metal shrouded (with resistor) plunger ennchmenl for cold
starting
Bosch or Beru sparkp!ug caps
21
THE
n
BMW BoxER TWINS B1BLE
spailq;lug lPS m the
were met II shrouded
BoS<_h HBeru
hAd higher
m
Eur1(J'
22
Hidden underneath a removable alloy cover
and located above the crankcase was a Bosch OF
12V 0_5-horsepower series wound D.C. electric
start motor and transistor-controlled relay. The
electncstartwasstandard on the R75/5 and R60/5,
and optional on the RS0/5. Although the /5 was the
first BMW motorcycle to feature an electric start.
there was still the trad1t1onal kick start incorporated
at the back of the gearbox and connected to the
input shaft_ Starling was generally reliable.
although. despite the small battery.
the penalty was we ight because the
electncstartassemblywe1ghedmore
than 20kg There was some
solenoid problems
onearlyexamples.w1ththestarter
inadvertently engaged while the
engine was running
A180mmsinglediscdryclutch
connec tedthecrankshaflandthe
transmission input shaft. with a
diaphragm spring compressing a
pressureplateandbondedlriction
lin1ngclutchplate.TheR50/5and
R60/5spnng was2.4mm thick and
17.5mm high, while the stronger
R75/5springwas2.6mmthickand
19.0mm high. A diaphragm was
spot-welded to the pressure plate.
betweenthellywheelandpressure
ring, allowing the pressure plate
to move axially and to transmit
some engine torque. The 6mm
clu tch plate was mounted on the
splines of the transmission input
shaft and was disengaged by a
pushrod inside the input shaft.
activated by a lever.
Designed by Development Team member
Ri.Jd1ger Gutsche, the gearbox was similar to
thatofthe/2butwithw1dergears,andal1ghter,
stronger housing. Gutsche was not only an
engineer, he was a leading compet1t1on nder. He
would later achieve notable success in the ISDT
on his specially-developed R75/5 and, after a
few years. would be respons•ble for the
R80 G/S. Gutsche was instructed to
THE /5·5ERIES (TYPE 246)
countershaft. and output shaft _The countershaft
and output shafts incorporated four gears. each
in constant mesh. with a spring and cam-type
shock absorber also on the output shaft _ The
transmission shafts were supported in ball
bearings and. although the gearbox shifted more
smoothly than earlier BMW twins, 1t still wasn't
flawless_ There were to be many modif1cat1ons to
the shifting mechanism over the next few years
A close-rat1ocompeht1on gearbox was an option
Drive from the gearbox was through an
enclosed dnveshalt running in an ml bath on the
right-side of the sw1ngarm There was a needle
bearing universal joint at the gearbox end, bolted
tc a drive nange mounted to the taper of the
transmission output shaft. with a hypoid gear
coupling at the input end. To facilitate ease of
wheel removal. an internally-splined 1:6 coupling
was at the rear of the driveshaft. Rear drive was
through a set of Khngelnberg Pallo1d helical-tooth
spiral bevel-gears. already well proven on the 12
senes.Toprov1detheopt1mumperformance.each
version of the /5 received a different set of final
drive ratios After number 2973204. 1n July 1970.
to improve acceleration the R75/5 final d rive ratio
was lowered to 1:3.2 (10:32). The final drive ratios
for the RS0/5 and R60/5 were unchanged
essentially unchanged through until 1996. Unlike
earlier 12 twms with a removable aluminium VIN
plate attached to the steering head. the /5 came
with a paper VIN 1dent1hcat1on. The frame number
was stamped to the nght of the steering head
The Sachs-manufac tured (!o BMW
spec1ficahon) telescopic fork first appeared on the
RSO. R60.and R69USof 1968. With long travel and
progressive spnngs they weighed 11. 7kg (down
from the 14.Skg Earles fork) with a 57 per cent
reduction in the moment of inertia. Unlike earlier
US models with ball steering head bearings. on
the /5 they were supported by two tapered roller
beanngsm lhesteenng head. The upper fork triple
clamp was steel and the lower triple clamp forged
aluminium. With 36mm hard-chromed fork tubes.
/5 chassis
The two-piece frame of the /5 was constructed
of variable section conical tubing that included
changes in taper and ovahty in accordance
with the an11c1pated stress Unlike the Norton
featherbed· frame that inspired 11, the /5 had a
single backbone tube instead of two. This 45x3mm
diameter dual-walled backbone was attached to
double loops that varied from 28x1 .5mm diameter
to 32x3mm. Weighing 13kg (4.5kg less than the
12) the frame was argon-welded and weighed
13kg. 4mm gussets allowed longitudinal elast1c1ty
without affecting torsional rig1d1ty while bracing
the forged one-piece 46x4.5mm diameter steering
head.Ontheveryf lrstframes thesegussetswere
butt-welded. The tunnel for the fuel tank was very
shallow. the engine located with two bolts, and
the light triangular rear subframe bolted to the
main frame with four 8mm bolts. The swingarm
pivoted in the frame on ad1ustable tapered roller
bearings, but the short swingarm favoured by von
der Ma1w1tz was cn1tc1sed for 1mped1ng slab1l1ty
Some of these del1c1enc1es were overcome
through htt1ng tyres with increased lateral stiffness
1n the tyre s1dewall construction. Von der Marw1tz
believed too much frame stiffness was detrimental
for a street motorcycle and. although the strength
or the struc1ure was q uestioned, 1t remained
23
THE BMW BoxER Tw1Ns BIBLE
A 13-rib rubber gaiter protected the fork
tubes from stone damage. and a tubular-steel
brace provided additional ng1d1ty. There was a
friction steering damper, with a knob ad1uster on
top ol the upper triple clamp, but a more eftect1ve
!:!;:;<i~Miiiiiilllllll&ll :~d~~~:~nst~;~n;:r~ym:~::~~~~:b;~o~
n
In
"°"""
,,bf: e wasa
"""'
st1ct1on caused by the one-piece bush held
bya snap ring inside the fork lubes. The soft
fork springs also dived under braking. and
there was an option of a stiffer fork spring
and damping ring
Twin 316mm Boge shock absorbers
were fitted on the rear. providing 125mm of
spring travel. There was an alloy cover over
the top of the spring, and spring pre-load
ad1ustment was made through a lever
incorporated at the bottom ol the shock
absorber The springs were black, and
the shock absorber pressure was 240-310
Kilo-Pascal
High quality aluminium wheel rims
graced the /5. a 1.85Bx19in on the front
and 1.85Bx 18m on the rear. These included
40x4mmstra1ghtpullspokesoneachwheel,
and were a new design compared to the
/2 that sometimes failed as a result of the
spoke head breaking off. Instead of a rim
lock to prevent the tyre bead leaving the rim
1f the tyre deflated. BMW wheel rims were
stamped with hve dents oppas1te the valve
stem This prevented the tyre bead from
moving into the cent re well allowing the other side
to climb off the rim. The wheel bearings were a
sealed taper roller type, and the front axle was
14mm. Because of problems with stability on
early /5 models, certain Contmental or Metzeler
tyres were spec1hed: a rib 3.25x19in on the front
and 4.00x18in Universal on the rear Metzeler
introduced the Block 66
Touring Spe<:1al rear tyre
spec1f1callyforthe/5
BMW
had
no
~~~1~~~r:;~I~~ :~a~~= ll•aiillllll
"'""' lo<ged
"14'lll.m "' lflfrnger
1ndenl·
"
/5 had drum brakes
Although there was some
exper1mentat1on with a
rad1allyvented,fourleading
shoe brake, ultimately,
the double leading shoe
remained Compared to
the /2. the brake drums
offered increased ng1d1ty
with deep st1fternng and
cooling ridges 1n the alloy
housing. The front brake was a 200x30mm
Duplex {double leading shoe), with a 200x30mm
Simplex (single leading shoe) on the rear_ The
left plates were chrome-plated. Although
narrower than those ol the 12, the brakes were
considerably more effective due to the new
bonded brake linings developed for Porsche
cars earherin the 1960s. Instead of an ad1ustable
rod between the two front brake pivot arms.
with both arms pulling 1n the same direction,
the single brake cab!e attached d irectly to the
arms, moving them together when the front
brake lever was pulled. The system worked well
and, when properly adiusted. the front brake
was perfectly adequate. Rear brake actuation
was by a rod, and both brakes also featured
chrome-plated covers on the left side. Dunng
1970 (from R50/5 2900689, R60/5 2931055
and R75/5 2971013) a new brake light switch
was fitted to the rear foot lever. This featured
improved insulation between !he plastic and
metal case.
Two types of chrome-plated tubular-steel
handlebar were 1rnt1ally available for the /5: a
600mmand optional h1gher680mm handlebar
The handlebars attached to the top fork crown
with two-piece aluminium risers. similar to
those of the 1968-69 US telescopic forks
R50. R60, and R69. The handlebar controls
were also similar to the final 12. Magura-forged
aluminium levers with finger indentations. Each
lever had Teflon bushings at the pivots, with
spring washers between the lever and body
to ensure a smooth action. The throttle control
incorporated a cam and chain, s1m1tarmdesign
to the previous R50/R60/R69-type but prov1d1ng
a quicker and more progressive action. Unlike
theearhertwins, therewasarubberboot where
the cables entered the throttle.
THE /5-SERIES {TYPE 246)
"P~"0iiiiiiii~~~~-·
pinst-~:~ck
Generally, only one handlebar-mounted
rear vision mirror was filled to the 15. the
chrome-plated round mirror screwing mto
threaded holes in the lever mounts. There were
mirror mounts on both lever assemblies. and
both short- and long-stemmed mirrors were
specrf1ed The short-stemmed were intended for
the higher hand lebars, bul there wascons1derable
inconsistency as lo which type was fitted. Neither
type of mirror was very satisfactory. especially
above 125km/h
Rudiger Gutsche was entrusted to design
the distinctive large fuel tank . The shape would
become representative of the 15-senes. and
th" first tanks were 24-litres, rubber mounted
at the front with a single rubber pad. and two
rubber blocks at the rear. The tank was retained
by two wing nuts at the rear. The paint quality
was extremely high, with fast1d1ously accurate
hand-painted pinstripes. The tank incorporated
rubber knee pads on each side. but the early
tanks didn't includ e ribs to retain the rubbers.
The shape at the rear was also slig htly d ifferent
on earlier tanks. There were the trad1t1onal fired
clo1sonne enamel BMW emblems with rubber
washers. screwed mto the tank with two 4x8mm
oval-headed screws.
but not always, and this
inconsistency accentuated
the hand-crafted aspect
of the /5. A fuel tank that
incorporated a lockable
tool box m the top. s1m1lar
t o that of some earlier
BMW motorcycles. was an
option
The fue! filler cap was not lockable although
a locking filler cap was an option, and initially
opened towards the rider. The fuel cap was
alum1nium.Asthefueltankwasconstructedintwo
sections to clear the frame backbone there were
two fuel petcocks. These screwed directly into the
tank, and the one-piece metal Everbest pet cocks
were carried over from the 12. The Everbest
petcocks weren't easily rebuilt. and featured cork
seals that could block the fuel llow. Initially only
black with wh•te pinstripes (086/590). metallic
ThedualDenfeldseat,
without model 1dent1ficat1on
badge on the rear. hinged
from the right to reveal
a storage tray. The seat
was lockable, utilising the
same Neiman key as the
steermg lock, whi le on
each s ide was a chrome
passenger grab ra1L A solo
seat wit h lockable rear
compartmentwasanopt1on
The round footpeg rubbers
were also Denfeld. and both
a centre and side stand
were fitted - the side stand
was manually re1ractable
on 1970 versions. A chrome-plated hftrng handle
was pos1honed near the seat lock, and a factory
engine protection bar was available as an o ption
Other options included a luggage rack , leather
saddlebags, hard plastic bag s, and a black rear
mudtlap with a BMW logo
Each /5 came with a specific handbook
encased m a plastic envelope and the usual
comprehensive 22-piece BMW tool k1t: with
embroidered towel, tyre repair kit. and tyre pump
The tyre pump was located under the seat, on
silver with blue
(559) and white with
pinstripes (084/ 584) / 5 s
were produced. All versions
(R50/5,R60/5, and R75/5)
were available m these three
colours
Von der Marw1tz was
determined to reduce weight,
and eventually persuaded the
Construction Department
(after some re luc t ance)
to incorporate f ibreglass
mudguards. These we re
painted to match the fuel
tank (with p i nst ripes)
Generally, thepinstnpecolour
matched that of the luel tank
,;;;::s~
T1'lf. Evetbestf'""3ipe'' ICI<,
were camOO over from me
12
-
The large fueJ lank
incorporated rubber I.nee
pads and screwed-Ofl
25
TH E / 5 · S ERIES (TYPE 24 6)
a spec1!1c tail hght tens that differed lrom
the left of the rear subframe. An even more receiving
versions 1n lhat there was no circle in
comprehensive 33-piece toolkit was available European
The rectangular turn signal indicators
as an option until 1984 One of von der Marwitz' the centre.
bodies. and US models (for 1970
1nnovat1ons was to include a removable plastic had aluminium
and 1971) included reflectors on !he front and
tool tray. a very useful and practical feature
On the left handlebar was a three-way Hella rear turn signals
horn/high beam and head
hghtflashersw1tch,w 1ththe
1'
is~ riguishing features 1970 model year
turns1gnalsandstartersw1tch
Seat without rear badge
' BMW'
on the right. The hard robber Early crankcase housing included
Four warning lights in speedometer
letteringcastabove thecylinder
handgrips were Magura.
From R50/5 290137g, R60/5 2g32142 and
and the plunger 1gnit1on Plaino1lfiltercover
R75/5 2972388 indicator hght in the
and
angle
dwell
switchintheheadlig htwas 61 per cent 1gnit1on
head light shell
maJCimum advance at 2500rpm
the universal type, as on
R75/5 higher final drive ratio until July 1970
thP /2. This also operated Top end locating dowels with 0-nngs
{2973203)
and spacers (from R50/5 2900602, R60/5
the lights. The plunger was
After R50/5 2900441 main jet changed to 135
2930965 and R75/5 2970980)
not really an ignition key,
and needle to position 3
Improved engine breather tube fitted after
more of a kill switch m
Accelerator pump carb kit from R6015
R50/5 2901704, R60/5 2932473 and
reverse. but it did have some
2930530
R75/52973142
advantages as 1t could be
From R50/5 2900689. R60/5 2931055 and
Butt-welded steering head gussets without
operated with groves and
R75/5 2971013 new brake hght switch with
outer welds
easily snapped into position
improved insulation
The plunger receptacle had Early fuel tanks 24-htres without ribs to retain
R75/5 from number 2972061 carburettor with
the knee rubbers
a spring-loaded cover that
0.4mm diaphragm and ·c· marking
provided effective water Fuel cap opened in the opposite d1rect1on
New alternator rotor from R50/5 2901772.
protection. A Bosch 0320 Everbest fuel petcocks
R60/5 2932606 and R75/5 2973649)
Seat with two side grab rails
123013 horn was fitted
on 1970 models. with an
optional heavy-dutylow tone
horn available.
R75/S, R60/5, RS0/5 1971
The /5 instrument cluster was incorporated
model year
into the headlamp_ A single 3 in glass contained
the mechanical speedometer and tachometer.
and was
along with four warning lights. These were for As/5 development lasted nearly s1JC years
e. there were few updates for
pressure
oil
eJCtremelyeJChaushv
(green),
neutral
high beam (blue),
to
(orange), and alternator (red)_ An odometer the 1971 model year_ Visually, there was little
Frame
was included but there was no room for a trip distinguish the 1971 modelyearfrom 1g10.
meter. The MotoMeter instruments featured numbers for the 1971 model year R50/5 were
white numbers on a black background, but the 2901811-2903660, the R60/5 2932775-2938932
numbers were quite small and difficult to read. and the R75/5 2973762-2982998
Gradually. BMW ironed out the few small
The speedometer read from 10-120mph or
20-200km/h, the tachometer to 8000rpm and a problems that afflicted the earliest bikes. Early
redlineat6800rpm. Not all tachometers included in the model year. on the R75/5 from number
a redline and the instroments differed between 2977321, new32mm B1ng64/32/9 and 64/32/10
the various /5 models. as the speedometer drive vacuum carburettors were fitted. Despite
was from the gearboJC and the speedometer was a mod1ficat1on during 1970 the first series
remained troublesome. and the new carburettors
matched to a specific final drive ratio.
The Bosch 0 303 550 002 headlamp was featured a revised throttle slide with a greater
a 160mm 45140 watt unit, encased in a metal wall clearance, a different needle Jet. stronger
option
an
was
neoprene diaphragm and a domed carburettor
shell - a H4 headlamp conversion
From A50/5 2901379. A60/5 2932142 and R75/5 cover_ The result was an improved idle. and
2972386, the head hght shell incorporated a wllh the new carburettors came a new Magura
single turn signal indicator hght This 111\h warning choke leverassembtyw1th stronger cables. Other
light. on the left of the 1gni11on switch, was mostly updatesmtroducedd ur1ng 19711ncludedslighUy
green. but orange on some e)(amples. The tail reshaped e)(haust silencers and an optional
light was a rectangular Hella, with us models close-ratio gearbo)(
27
THE
BMW B OX ER T WINS B IBLE
The R60!5 was little
-hanged for 1971
1971 model year bikes featured the new
centrifugal advance unit, with maximum
advance at 3000rpm and 43 per cent dwell.
The gremlin in the starter-solenoid circuit that
sometimes allowed the starter to engage whilst
the engine was running was sorted out. The
R7515 now included a lower final drive ratio and
the plastic and rubber components improved to
resist premature ageing. Toalleviatecnt1cism of
head shaking and wobbles, updates included
more careful assembly of the long travel front
fork. with closer tolerances so 11 would react to
bumps more 1mmed1ately. To further improve
stability, the steering head angle was extended
to 28 degrees. In the spring of 1971 {from
R50J5 2902093. R60/5 2933525 and R75/5
2975253), the battery carrier was modified to
include five rubber buffers. The fuel tank was
slightly reshaped. the tank cap opened 1n the
opposite d1rect1on and it now held 22-litres.
From R50!5290300B. R60!5 2937402 and R75/5
2981006 there was a new leak-free 011 pump
cover, without a releasing slot. Other updates
included a shim on the tachometer dnve to
reduce Oil leakage (from R50/5 2903617. R60/5
2938592 and R75/5 2982663). Just before the
end of the 1971 model year. the side stand
was changed to be self-retracting (from R50!5
2903624. R60/5 2938705 and R75/5 2982738)
- this feature continued for 1972. The choice ol
three colours for the /5 range was unchanged
for the 1971 model year
28
R75/5 included a lower final drive ratio (10·
R75/5 new Magura choke lever assembly
stronger cables
New centrifugal advance unit. maximum
advance at 3000rpm and 43 per cent
dwell
New silencers
Steering head angle 28 degrees to further
improve stability
Fuel tank reshaped and held 22-litres, cap
opened in opposite direction
From R50/5 2902093, RS0/5 2933525 and
R75/5 2975253 battery carrier included
five rubber buffers
From R50/5 2903008. R60/5 2937402 and
R75/5 2981006 new 011 pump cover
From R50J5 2903617. R60/5 2938592 and
R75/5 2982663 shim on tacho dnve
From R50/5 2903624. R60/5 2938705 and
R75/5 2982738 side stand seff·retractinl
R75/5, R60/5, RS0/5 1972
model year
The/5rece1vedmanymoreupdatesforthe1972
model year and most were st~listic. With the
T HE /5-SERIES (TYPE 246)
intention of making the /5 more appealing for
the US market. the fuel tank was downsized with
chromes1depanelsandaccomparnedbymatch1ng
chrome-plated side battery covers. It soon earned
thernckname'Toaster'tankbecauseof1tss1milarity
1n appearance to the kitchen appliance The
previous22-litretankwasst1llava1lableasan opt1on
Frame numbers for the 1g72 model year were
RS0/5 2903661-2905718. R60/5 2938933-2945721
and R75/5 2982999-2984790
Bob Lut2 /Olned BM'W ITT
1972, and was 1nfluent.al
1n the subsequent
de11elopment of f/le /5 and
16 (Covrtesv Two Wht..>e!SJ
29
THE BMW BOXER TWINS BIBLE
Engine (1972)
in
Updatestothe/Senginew ereminomaltorlhe 1972
model year. but improvements were gradually
implemented when necessary. Early m the model
year. in September 1971 (from RS0/5 2903693.
R60/5 2938962 and R7515 2982820). a 2mm
thrust washer and new bush were added to the
gearbox output shaft. A s!ronger crankshaft with
new bearing shells was installed during February
1972(lromA50/52904190,
R60/52940740andA75/5
2985208).Thecrankshaf t
material was changed
fromCK45 to41 CR4VBO.
andthecrankpin to crank
web radius enlarged from
1.6mmto22mm
The engine housing
was also modified. and
th is would run through
until the 16 (1976 model
year). Complaints about
excessive noise meant
new slotted rocker shaft
supporting brackets and
hardened steel shims
were htted from March
1972 (R50/5 2904721,
R60/52942632andR75/ 5
2989472). One update the
R75/5 (from 2993256 m
June 1972) received that
the smaller models didn't - until a few months
later - was new cylinder heads with cast dowels.
eliminating the 0-rings and spacers introduced
m1970
The R75/5 from 2992320 (June 1972) also
received vacuum ports on the carburettors. Some
later 1972 model year R75/5s featured black
carburettor a1r intakes instead ol silver. These
black intakes were a precursor for the 1973 model
year. providing more legroom. but only a few
1972 R75/5s had them. The model 1dentoficatmn
badges on the engine cases were now on a black
background. and the exhaust header pipes were
slightly thinner {38x lmm). Some US examples
featured add1toonal vented heat shields over the
header pipes
Chassis (1972)
The most notoceable styling teatures for 1972
were the 1nclus1on of a smaller 17-Mre fuel
tank. chrome-plated side panels. and matching
chrome-plated battery covers. Nicknamed the
Toaster' because ol 1ts s1m1lanly to thos household
electrical apploance, the tank incorporated three
30
painted stripes. and the soae panels four stnp&e
Another feature Of the ·roaster' lank was that t
unders1dewas alreadydes1gnedlortheompend1
/6 under tank front brake master cylinder. but
optoonallargertankwasnotmod1f1edunt11m•d-19
Nol all markets greeted the "Toaster' fuel tank
unequivocal acclaim: 1n Australia lhe /5 was
with the earlier-style larger tank as standard
BMW (GB) followed suit later in the year
A w1derselect1on of colours was also available
lor 1972. Alongside the ex1shng black, silver or
white were metallic blue with white pinstripes
(033/533}andmetalliccu rrygoldw1thblackstnpes
(029/529). Black. blue. or silver bikes came woth
black or blue stripes on the chromed panels. but
therewassome1ncons1s tencyinthecolourof these
stripes although they were obviously intended to
match the tank. Along with the smaller fuel tank.
there was a new seat with a single handrail running
across and behind the passenger. Thosincluded a
model-type black highlighted emblem on the rear
a white bead following the line of the handrail and
longitudinal pleating on the upholstery
Along with slightly wider 650mm handlebars
some 1972 /Ss had two mirrors. An extra mirror on
the right was sometomes fitted to balance the left
handlebar and alleviate weaving. US models had
a 680mm handlebar, and thos was also blamed for
high speed weaving. especially when combined
with the US propensity for strappmg luggage to a
rear rack . US and European /Ss shared the same
alumin1um-bod1ed turn signal indicators. with the
large, round US-required reflectors located on
the head light brackets at the front and license
plate bracket at the rear. There were new head
light brackets for 1972, and many 1972 models
had a Hella 831 horn This large round horn had
a chrome-plated grill. as did the equivalent Bosch
horn. Ooo small practical improvement was the
rerouting of the cables. allowing easier reading
of the small tachometer
One ol the more s1gmf1cant updates during
1972 was to the front fork To further improve fork
action. from AS0/5 2g04276. A60/5 2941811 and
R7515 2987432. a three-piece lloating damper
noule replaced the one-piece bush held by a snap
ring msode the fork tubes. The aluminium centre
damper ring was now supported by two outer
thieaded rings that allowed the piston to move
more freely, also altenng the rebound damping
shghUy From AS0/52904276, R60/52940990and
A75/5 2g0sago, three types of fork springs weie
available: 538x4mm. 567x4mm and 543x4 Smm
A thrrd fork mod1hcat1on occurred at the very end
ot the 1972 model year (R5015 2905654. R6015
2945479 and R7515 2994494). when a copper
asbestos sealing ring was fitted at the bottom of
the front fork. The Boge shock absorbers also
gamed heav1erdampmg and the springs were now
chrome-plated. Although the tyre sizes remained
unchanged. from October 1971 all /Ss received a
woderWM32.15Bx181n rear wheel nm (trom R50i5
2903756. R6015 2939:?07 and R7515 2983280)
During 1972. BMW expanded 1he range ol
luggage and accessones available In add1t1on to
the larger fuel tank. tradotoonal leather panniers
were first offered, followed by plastic cases
produced1mtiallybyClausW1lckeandlater"G1gr
Krauser (a Munich dealer)
31
THE BMW B OXER T W I NS BIBLE
/ 5 distinguishing features 1972 model year
From R50/5 2903693. R60/5
2938962 and R75/5 2982820,
2mm thrust washer and new
bush was added to the gearbox
output shaft
From R5015 2904190. R60/5
2940740 and R75/5 2985208.
stronger crankshaft
Mod1hed engine housing
From R50/5 2904721. R60/5
2942632 and R7515 2989472,
new rocker shaft supporting
brackets
R7515 (from 2993256) cylinder
heads with cast dowels
From June 1972, R75/5 featured
carburettor vacuum ports
Later in the 1972 model year.
R75/5sleaturedblack
carburettor air intakes
Engine case model 1dent1f1cat1on
badgesw1thablackbackground
Thinner exhaust header pipes
{38xlmm)
17-litre fuel tank. with chrome side
panels and chrome battery
New seat with a single rear handrail
and ident1ficat1on badge
Slightly wider, 650mm handlebars,
some with two mirrors
New head light brackets
Some with Hella 631 horn
From AS0/5 2904276. R60/S
2941811 and R75/5 2987432, fork
included a three-piece floating
damper noule
From RS0/5 2904276, R60/5
2940990 and R75/5 2985890.
three types of fork springs were
available
From R50/S 2905654, R60/5
2945479 and R75/5 2994494, a
copper asbestos sealing ring
fitted to the bottom of the front
fork
Shock absorbers with more
damping and chrome-plated
springs
From October 1971, a wider WM3
2.15Bx18m rear wheel rim filled
R75/5, R60/5, R50/5 1973
model year
Market resistance to the gaudy 'Toaster' tank
m Europe led to BMW returning to their more
trad1t1onal. conservative styling during 1973. The
22-litre tank was standard and 17-htre tank was
optional, both with rubber knee pads The chrome
'Toas!er' tank was still fitted to many US models
Frame numbers for the 1973 model year were
RS0/5 2905719-2907865, R60/5 2945722-2952721
and R75/5 m three series. 2984791-3000000
4000001-4008371 (from January 1973) and
4009001-4010000 (the final series m August 1973)
There was some overlap between model years
with the fitting of the 'Toaster' tank. evenlorEurope,
the 'Toaster' fimshmg at RSOJS 2906304, R60/5
2947966, and R75/5 2997986
In response to continua! complaints regarding
the high speed stability, a longer swingarm was
fitted from January 1973. This lengthened the
wheelbase and also allowed for a larger battery
and longer seat. Two longer wheelbase R75/5s
were selected at random from the production line.
by the West German Motorcycling Federation, and
shipped m sealed cases to the Isle of Man m May
1973. In an attempt to wm the coveted Maudes
Trophy, awarded to manufacturers for extremely
commendable performance and run under strict
ACU control. fourteen riders rode the two R75/Ss
continuously for a week. Despite heavy rain and
two crashes, the machines covered 16.658 miles
(26,808.5km)andwonthe Trophy. Towards theend
ol 1973. in add1t1on to the normal US spec1frcat1on
machines imported by Buller and Smith , a
number of European spec1f1cat1on / 5s from the
Italian distributor ended up rn the US These bik es
had different reflectors. with the rear ones glued
to the lender because the license plate bracket
wasllat
Engine (1973)
Engine updates were ffilllOf tor 1973. The R50/5
(from 2905756) and R60/5 (from 2946787) received
the new cylinder heads with cast dowals. A new
inner rotor for the 011 pump included a larger 3x5mm
Wood1uff key coonect1n91t to the camshaft As the
c am sha!t drive sprocket woodruff key was also
reduced to the same 3x5mm. the camshaft was
new. Another centrifugal advance unit was fi tted
from November 1972(1rom RS0/52905857. R6015
2946096 and R75/5 2996220) Ignition advance
now commenced at 1550rpm. with lull 3dvance
at 3000rpm
Chassis (1973)
While the tanks with rubbe1 kneepads made a
return during 1973. the earlier b<l1tery covers
were optional These were now painted black
or blue but man y were also c hrome-plated as
before. US examples with 'Toaster' tanks also
had chrome battery covers. From October 1972
{RS0/5 2905828 . R60/5 294 6037 and R7515
2995073). the steering head bearing adiuster was
33
THE BMW BOXER TWINS BIBLE
changed from the round indented nut to a large
hexagonal nut 1g731ss also received a new top
throttle cam cover. and US examples a new Hella
ta1lhghtlens. During 1973.theearherEverbestfuel
petcocks were replaced by Karcoma or Germa.
depending on supply at the time of manufacture
Eight colours were available for the IS for 1973
In add1t1on to the five ex1st1ng colours, were red
with white stripes (023/S23), green metallic with
white stnpes (074/S74) and metallic silver with
bluestripes(SS9)
Tofurther1mprovestab1l1ty.alongersw1n9arm
was fitted after R50/S 2906304. R6015 2947966
and R7515 2997986. The splined coupling ratio
was now 1 7 (instead of 1-6). The new sw1ngarm
lengthened the wheelbase SOmm, and was also
c!a1med to provide increased clearance between
the riders' sh1nsarxl the carburettors. The foot pegs
were actually 1n the same pos1hon. and the
improved clearance was achieved through the new
shape of the black intakes. These were 36mm in
d iameter. and 25mm long On the first examples
of long wheelbase /Ss. the extra swing arm length
was rather crudely achieved through an inserted
welded sleeve wrth a temporary mudguard mount
Eventually, a specific, longer swmgarm appeared.
fitted on most final /Ss and st1ll 1nclud1ng a welded
seam. but also a larger diameter transverse tube
to increase stiffness. From June 1973. the R75/5
also incorporated a 10Smm spacer tube at the
rear crankcase mount - this continuing on all later
models from the /6 onwards. Accompanying the
longer sw1ngarm were a longer seat. longer rear
subframe. longer rear brake rod and longer rear
mudguard mounting bolts. A breathing hole was
also included 1n the gearbox cover to prevent the
rubber gaiter 1nl!at1ng. The rear axle 011 capacity
was also increased to l SOcc (from 100cc) of SAE
90 hypo1d gearo•I. The long wheelbase s1gn1flcantly
improved the stra1ghHine stability of the IS.
TH E / 5 - S EAIES (T YPE 246)
ast/l ~rialy8all
191
th P J bu~ or. shown h
f
•)µfionar
w
reducing wobbles, and also enhancing
cornering ab1l1ty through better weight
d1stnbut1on. It also allowed more room in
the frame for a larger 16Ah battery
To overcome problems with the
spoke heads disintegrating on the rear
wheel. from September 1972 the rear
wheel spokes were moved 1.5mm to the
left to provide more swingarm clearance,
and there was a new spoke type. This
featured from A50/5 2905646. R60/5
2945366 and R75/5 2994445. The spoke
now had a small shoulder that kept 11 from
sp1nn1ng 1f the tension was correct. From
R50!52905828. RS0/52946097 and A75/5
2995037. the high US handlebar was
reshaped for improved ergonomics
Over its four-year lllespan the
~~~iiii!!~:::::::::'.!i1~--::!!
up to its
than lived
15-senes more With
nearly 69,000 "
expectations
35
T HE BMW B OXER T WIN S BI BLE
/5 distinguishing features 1973 model year
New camshaft, inner 011 pump rotor
andcen tnfugaladvanceumt
R50J5 (from 2905756) and R60/5
(from 2946787) with the new
cy linderheadsandcastdowels
Fuel tan ks with rubber kneepads
(17-or22-htres)dunng 1973
Battery cO\lers optional
US bikes retained the ·toaster' tank
and chrome battery covers
From R50/5 2905828, R60/5
2946037 and R75/5 2995073.
steering head bearing adjuster
changed to a large hexagonal nut
New top throttle cam cover
US models with a new Hella tail light
lens
During 1973. the Everbest fuel
petcocks replaced by Karcoma
orGerma
Longer sw1ngarm with welded seam
was htted after R50/5 2906304.
R60/529479ti6and R75/5
2997986
Splined coupling ratio 1:7 with
longer swingarm
With the longer swingarm were a
longer seat, longer rear
subframe, longer rear brake rod
and longer rear mudguard
mounting bolts
With longer swingarm breathing
hole included in the gearbox
cover
From A50/5 2905646, R60/5
2945366 and R75/5 2994445.
the rear wheel spokes were
moved 1.5 mm to the left
From A50J5 2905828. R60/5
2946097 and R75/5 2995037, US
handlebar reshaped
.........
A50/5
2900001-2go1810
2901811 -2903660
A75/5
-- --
/5 frame numbers
Type
R60/5
produced, the 15 almost matched the entire
production run of the R50, A60and12-senes from
1955. through until 1969. It continued the BMW
motorcycle tradition of offering unparalleled
touring comfort ~nd reliability, whilst (particularly
the R75/5) prov1d1ng acceptable performance
But 1n some respects the /5 was outdated. By
1973, the single face combined speedometer and
tachometer and the p lunger ignition switch was
old fash ioned. The era of the disc brake had also
arrived, as had c loser ratio five-speed gearbo~es
On July 28th 1973. only three days after the
500.000" BMW motorcycle (an R75/5) came off
the production hne. the last 15 left Spandau. The
end of the /5 also saw the demise of the 500cc
boxer twin. 1mt1ated with the R32 back in 1923
By 1973. the demand for a 32 horsepower 205kg
motorcycle was virtually nonexistent
1970
11/69-08/70
1971
09/70-08171
09/71-08/72
2903661-2905718
1972
2905719-2907865
1973
09/72-07173
2930001-2932774
1970
09/69-08170
2932775-2938932
1971
09/70-08/71
2938933-2945721
1972
09/71-08/72
2945722-2952721
1973
09/72-08/73
2970001-2973761
1970
10/69-08170
2973762-2982998
1971
09/70-08/71
2982999-2984790
1972
09/71-08/72
I
2984791-3000000
1973
09/72-01173
r
4000001-4008371
1973
01173-07173
4009001-4010000
1973
08/73
36
CHAPTER Ill
THE /6-SERIES (TYPE
A
Ithough !he /5 can be credited with saving
:~e~~tww:~~O:,~~:;r~m1 ~~~n~~~o~;rvk:~
for motorcycles was changing. During the /5
production run a new wave of 'superbikes' evolved·
from Honda's 750 Four to the Kawasaki Z1 900
and Laverda's 1000cc tnp!e. Motorcyclists now
demanded more performance, and this inevitably
meant an increase 1n engine capacity.
BMW was reluctant to follow this trend. While
Dr Helmut BOnsch encouraged the development of
the R75/5, he declared that 11 would be unfortunate
ii BMW foltowed the path of producing larger and
more powerful motorcycles. BOnsch retired in
1972. but even after that there was an unw1llrngness
to embrace a displacement increase to 900cc
As a result, the development of the /6-senes
initially proceeded along similar lines to the /5
The team responsible included Rudolf Graf von
der Schulenburg (tater to head the motorcycle
department) and Ferdinand Jardin, in charge
of engine deve!opment. Jardin was assisted by
Gard Wirth and Wolfgang Wurst {engine testing)
HardyMUllerwasinchargeofmotorcyclestrategy,
Gi.Jnther von der Marw11z coordinated the overall
design while AUd1ger Gutsche was responsible for
the updated chassis and live-speed gearboJ<
Without the intervention ol Bob Lutz, is 11
unlikely the /6 would ever have evolved into 900cc
or the A90S. Lutz joined BMW as eJ<ecut1ve vice
pres1dentofBMWSa!esduring 1972. The American
educatadbutSw1ss-bornLutzcameto6MW from
General Motors in Europe, and was a member of
theBMWBoard.AneJ<·USMarinellgliterpilot and
247)
motorcycle enlhusiast. Lutz was troubled by the
state of the motorcycle division when he arrived
at BMW. Lutz grew up with Hondas and told the
author: "I had just arrived at the company. had
to sell my almost-new Honda CB 750 Four. and
was dismayed at what I found . There was no 'bike
d1v1s1on.'Therewasasymbolic.smallb1kegroupi n
each of the main departments-sales. engineering.
design. etc - but they all reported to their various
functional bosses. Nobody was 1n charge of the
overall motorcycle business.~ Soon after arriving
at BMW Lutz ordered a special A75/5, but he
saw the future in high performance motorcycles.
saying in 1972, -1 adm11 that what attracted me
to the big Honda was brute power and the seJ<
appeal of four cylinders. The growth market is in
big b ikes and that 1s why we are taking a look at a
motorcycle which might be more eJ<Citing for the
high performance man. A bigger BMW would be
another harmonious synthesis of all things or we
won't build1t."
Lutz approached BMW's CEO. Von Kuenhe1m,
about contributing to motorcycle development
and, at a meeting of the motorcycle department, 1t
was agreed to increase the engine displacement to
900cc. This 1mtialfy went against the wishes of the
engineering department and von der Marw1tz, who
was happy with a 750. Vonder Marwitz envisaged
an S variant of the R75/5. believing an increase
to 900cc would compromise BMW's trad1t1onal
reliability. Von der Marw1tz thought 50 horsepower
was enough for the average rider but Lutz wanted
to match the 67-horsepower of the Honda 750
In the end Lutz was more influential, but, while
37
THE BMW BOXER TWINS BIBLE
he was the chief protagonist for more capacity.
Rudiger Gutsche had already successfully bu1l1
his own 900 in 1970. boring an R75/5 to 90mm
Celebratingthe50'.. anniversaryoftheBMWboxer
twin. the/6-seneswasreleasedforlhe 1974 model
year. The R60/6 was now the base mode!. with
the R90S the spearhead. The /6s (including US
versions) also received new production codes.
now changed with each new model year
~/J
hastnetargerfl.JI.
' rubber knee pads
uS
R90S, R90/6, R75/6, R60/6
16 engine
Creating a Superb1ke out of the R75/5 was not
an easy propos1t1on but, from experience gamed
with Helmut Oiihne's racing R75/5, BMW knew a
well-balanced machine with a wide power band
was extremely effective on road circuits such as
the Isle of Man. Knowing a twin-cylinder motor
could never match a lour-cylinder for outright
horsepower. BMW chose to emphasise all-round
performance instead o! pursuing high revs and high
horsepower Although the R90S would spearhead
the BMW range for 1974_ the /6 included many
important updates. notably a live-speed gearbox.
disc front brake {except the R60/6), and revised
instrument panel. Numbers for the 1974 model
year were R60/6 (code 0251) 2910001-2911677
Considering the performance differential
between the four models, the s1m1larity 1n engine
spec1ficat1on was striking and an example of clever
model rationalisation_ The quoted weight of the
16 engines (including starter and carburettors
but without ignition) was also sim ilar. The R90/6
engine weighed the same as the A90S (62.Skg),
while the A75/6 was the heaviest, at 64 9kg. The
R60/6 engine weighed 63.Skg
Designated the Type 247, the essential
tunnel-style engine housing was carried over
from the final series A75/5. bul was strengthened
around the front crankcase aperture_ The front
crankshaft bearing was now in a closed seat and
there was a new outer alternator and ignition cover
This included three air vents and vertical ribbing
instead of the eartier smooth cast type, and was
1974 model year
Burto ;if/]fl'dr ·brake.
91~R7 6w
very
S/fl
t theR15-5 Thi
US versions received a specific number sequence
for the first time: 4900001-4900827 (code 0253)
R75/6 (code 0261) '1010001-4012831 and
versions '1910001-4911097 (code 0263)_ The
R90/6 for 1974 (code 0271) were numbered
'10'10001-404'1971, the US versions (code 0273)
4930001-4932218, the R90S (code 0272) were
4070001-4075054 and the US versions (code
0274)4950001-4951005
THE '?·SERIES (T YPE 247)
sloghtly different for the R90S
lnsidelheengmetherewere only
minor updates. the Eaton type 011
pump including a new inner ro!or
and the engine brealher check
valve was mod1f1ed slightly to
accommodate the larger piston
pulses from the 180-degree twin.
At the time. 90mm pistons were
1
amongst the largest d1ameterf1tted
to a product1on motorcycle, and
the R90/6 check valve was m the
~~~ r::~'·f~~ ~~~~! z~~h~~;,~s. I\i~•JI. ._
The drop-forged. threebeanng crankshaft wrth 70.Gmm
stroke was similar 1n all the /6s.
although for the high performance
R90$ with 9.5:1 pistons. 90 per
cent tungsten plugs were inserted
1n the crank webs. This was to
reduce the crank web diameter to
130mm because the strengthened
front crankcase tunnel aperture
was too small to allow a large. fully
counterweighted crankshaft to
pass through. Evenw1th the smaller
crank weights and tungsten plugs.
the crankshaft was a very tight
fit through the front crankcase
opening and required 11ltmg for
c 01J
':t
~e~~:~~:;~~:~!~!:~;~;a~;:;:~~I: r:'.""~-;...____
f'l'!l.V/(lr /11f!R9(}:;.
through the smaller aperture of l~:lii2~gi:~~~ilj
the new crankcase. As the R75/6 t.
crankshaft was 1dent1ca1 to that
of the R90/6 (and R90S). 11 was a relat1..-ely easy constructed of a high tensile N1monrc steel alloy
operation to convert an R75/6 to 898cc. The The valves were manufactured m two pieces. with
forged I-section connectmg rods lor the 900cc the head fusion-welded to the stem. R90S valve
models were also constructed of a higher tensile guides (48mm) were shorter than the /6 (54mm).
steel, while the conrod bearings were now and the rocker arms on all /6s pivoted m needle
roller bearings mstead ol bronze bushes. with new.
four-layer mstead of three-layer as on the 750
The automotive-like eight-pound flywheel was wider. rocker support blocks. The R90S also had
bolted to the crankshaft with the same five small larger(38mm)intakemanrfold s.butthe308-degree
10x1mm bolts as the /5. Some of the early R90 camshaft was shared with the R90/6 and R75/6
engmes vibrated e•cessively, particularly between The cam hit was 6.756mm and a more sporting
336-degree camshaft was available as an option
4100 and 4500rpm
Along with the capacity, the cylinder heads The R60/6reta1ned the284-degreecamshaft. While
of all models varied. The R60/6 cylinder head was the pistons for the R60/6 and R75/6 were 1dent1cal
identical to that ol the R60/5. and the R75/6 the to those on the 15. lhe 90mm R90/6 pistons had
same as the R7515. The R60/6 retained the 38mm a flatter dome than the A90S. and a lower 9.0 1
and 34mm valves (98.5mm and 97.5mm long) and compression ratio. The cylinders on 16s were plain
the R7516 the 42mm and 38mm valves (98.Bmm aluminium. and pamled black on the R90S
All models featured a Micro Star dry a1rf1lter.
long) The R90/6 valves were the same 42mm and
40mm as for the R90S. The val\/0 lengths were but the carburehon differed. Like the AS0/5 and
98.Smm. W•th an Bmm stem, and the valves were R60/5, the A60/6 11lCluded t wo slide-type Bmg
1or-191.:
•\
hel<.fCJ<.
.cartleverwas taJne:!
JUrt•' yJen
Wh' XKIMar. Klrl<.patnd<.
39
THE BMW BOXER TWINS BIBLE
26mm carburettors, with accelerator pumps.
in1!1ally without a choke_ From number 2911378
and US 4900617, a choke was incorporated with
the usual Maguro choke lever a\lached to the air
filter housing_ Theearhest R90/6 lealured constant
vacuum Bing carburettors(64/32/13-14), identical to
those on the R75/5except for a 150 ma1n1et. 2.68
needle iet. and needle in the first pos1t1on
Although some R90S prototypes were fitted
with Bing carburettors. the production R90S
received a pair of Italian 38mm Det!'Orto PHM
38BS and BO concentric carburettors. The PHM
Dell'Orto was relatively new in 1973, incorporating
an accelerator pump. and hence was nicknamed
'pumper.' Every time the throttle was wound open
0.4cc of fuel squirted into !he cylinder. On the
first R90S the carburettor bodies were smooth
cast PHM 38AS and AD. without any provision
for a choke attachment. Starting enrichment
was by a float depressor. but these carburettors
were fitted to only the very earliest examples.
Most production models incorporated a choke,
with the Magura lever 1n the usual pos1t1on on
the left-side of the aluminium air filter cover. The
early Dell'Orto carburettors featured polished
aluminium float bowls. alum1mum ban10 fittings
and a 14mm float bowl nut. The alum1mum cable
guide at the carburettor top was also sharply
bent {almost 90 degrees). There were a number of
variations to the carburettors during 1974, some
early examples coming without a plugged hole for
connecting a vacuum gauge. The 1ncons1stency
in Dell'Orto specification was typical of Italian
manufacture, especially during this period. and
there were also variations in the choke setup on
the carburettor bodies
Theintakemamfoldswere26mmindiameter
on theR6016. and 36mm (25mm lor.g)onthe R90/6
and R75/6_ While the R90S featured a new air
filter housing with larger intakes suitable for the
larger carburettors. the R60/6. R75/6, and R90/6
aluminium housing was shared with the /5 series.
The /6 exhaust system included double radius
38x 1.5mm exhaust headers coupled with 87mm
(3.391n) diameter mufflers.The R90/6 was also
offered a specific US muffler (Cahforma. Florida.
and Oregon}
16 gearbox
In add1t1on to the earlier /5 gearbox, Rudiger
Gutsche was responsible for the /6 11Ye-speed
gearbox on the Type 247. The die-cast housing
was new, lighter and smaller than the previous fourspeed unit, while the three-shall design included
an input shaft {supported by caged ball bearings)
in constant mesh with a helical-gear driven gear
on the loy shaft. Also included on the input sha~
was a kick start engagement gear and spring
loaded shock absorber cam to provide a cushion
between the engine and final drive. Sh1ft1ng waa
achieved with two cam plates rotating. one sliding
two shift forks and two gears on the main shaft
with the other slid ing one sh11t1ng fork and gear~
the lay shaft. Wh1lesh1ftingwas1mproved over the
15. there was still room for improvement and t
1974 transm1ss1ons were problematic_ A design
fault led to pawl spring breakage - resulting in ro
shifting - while the kick start pinion gears were
very soft. Sometimes loose metal destroyed the
bearings, while neutral was often difficult to find
on early models. The R90S clutch featured a new
forged pressure ring, with ribbed supports, and
a stronger (2.8mm) diaphragm spring. The clutch
throw out bearing was now a needle instead of ball
type, and the c lutch cable lined to improve clutch
action_ While the driveshaft was the longer type
introduced on the final /5, there was a new type of
DNTP bearrng for the ring gear. The R90/6shared
the 2.8mm clutch diaphragm spring of the R90S,
but both the R7516 and R60/6 used the 2.6 mm
R75/5 clutch spring. As with the 15. each model
of the 16 had a different final drive ratio, with the
R90S having the highest final dnve ratio of the
range and the option of an even higher (1:2.91).
/6 electrical system
All /6 models received an updated electncal
system, with a larger 25-Ah battery and G1
14V 20A 21/280W (14 volt, 20 amp) three-phase
Bosch alternator !or the R60/6, R75/6 and R90/6
The R90S featured a 240 watt (14 volt. 17 amp)
alternatorwithasmallerd1ame1ertop rov1demore
clearance at higher rpm, when crankshaft whip
was more evident. Anothere1ectncal improvement
was the colour-coded wmng system which
included a Bosch printed circuit diode board in
the head light shell. The head light was a 180mm
Bosch 60/55 watt H4 quartz iodine and the head
light shell also housed a new key-type ignition on
the left mounting bracket, with five positions on the
1974 models to also combine the head light low
beam switch. Three ignition keys were supplied
a flat metal key, a hinged key with a plastic upper
and a barrel-shaped. plastic key
1974 modet year /6 retained the older style
/5 Hella handlebar switches, the left switch
operating the head light high beam. flash0!' and
horn. The right switch operated turn signals and
starter. There was no engine stop switch. and the
1974 /6 included alum1mum-bod1ed turn signals
New for the R90S and R90/6 was an updated
1gnit1on advance. with the dwell angle increased
T HE / 6 - S ER I ES (TYPE 247)
overcome some high
speed 1nstab1llty,
caused by the
handlebar-mounted
cockpit fairing
The boll-on rear
subframe on all /6s
was new, but the
strength of the entire
structure remained
questionable due to
littleng1dityprov1ded
by tnangulat1on
The F1chtel & Sachs
leading axle 36mm
telescopic fork was
internally 1dent1ca l
to 110 degrees. The 1grnt1on advance umt for the
R60/6 and R75/6 was the same as the /5. The
sparkp!ug caps were still metal shrouded Beru,
and the starter motor a Bosch 0.5-horsepower.
16 chassis
The Type 247 frame was a development based
the Type 246 (15). With 34mm outer diameter
steel tubing. and an internal cylindrical tube on
the R90S, there were some add1t1onal gussets
around the steering head. The R90S received the
add1t1onal frame strengthening m an attempt to
"""'"""'""'"""' to that of the A75/5,
w1thsoftspnngsand
generous wheel travel, but the R60/6 fork !egs
were new and specific for that model. The forged
aluminium lower triple clamp on all /6s and the
R90S was also new. but the /5 steel upper triple
clamp remained. The R90S had a specific upper
triple clamp. and the forks d1stingu1shed by fork
cups instead of the trad1t1onal ribbed gaiters
Inside the fork cups were 011-soaked felt rings to
maintain a smooth action_ Like the /5 there was
only a single axle pinch bolt (on the right). this
changing to twopmch boltssomet1medurmg 1974
The front axle was still 14mm 1n diameter for 1974
The 1974 ~and 16
retained the eamer He/la
handleb.Jr swirches The
instrumem face~ had white
rdes, and the tum signal
bodleS were alumm urn
JUTl<..>sy Jeff Wh 1OCl<J
Mc K1rl<.patnck1
An earty publieity phor, )f
the 1974 R9016 TheSilX
Ner decals are missing
and the fuel rank badges
lre sti the screw-on type
There are no rubber 1<.nee
pads on me tanks and early
exampleslil<.eth1shadrea.r
vl€W mirrors w th curved
Sl~S
THE
BMW BOXER Tw1Ns BIBLE
The 16 fork springs were 1mt1ally shorter than those
of the R90S. at 538mm _Aller R6016 29t0998. R75/6
4012043and R90/6404461. the fork springs were
changed to the longer (567x4mm) R90S type. A
shorter and stronger sect.on (543x4.25mm) fork
spring was available when the bike was fitted
with a full fairing. On early /6s the fork spring
locator bush was too wide at 16mm. and was
subsequently reduced to 15.Smm to prevent fork
spring breakage
As on the 15. the /6 sw1ngarm pivoted 1n
taper-roller bearings, and the earliest examples
had a welded seam. The 316mm Boge shock
absorbers were new for the R90S and 16 series
Although some early publicity photos showed /6
rear shock absorbers without aluminium spring
covers, production shock absorbers had covers
The cahper was black anodized (for improved heat
d1spers1on), and piston size was 38mm. The caliper
was mounted on the left behind the fork leg to
m1rnm1se angular momentum in turning. Brake pad
ad1ustmentwasbyaneccenlncp1nunderneaththe
fork leg. and the ATE master cylinder was located
undemeaththefue!tank-crudelyattachedtothe
top frame tube with a hose clamp on the earliest
versions. A Bowden cable connected the master
cylinder to the handlebar-mounted brake lever and.
while this seemed excessively complicated. the
front brakes worked adequately 1f set up correctly
The master cylinder size was 14 29mm. with the
dual disc A90S receiving a larger 15.87mm master
cylinder. The master cylinder location was again,
one of pract1cal1ty, under the fuel tank where 11 was
well protected in the event of an accident
~~o;;d:~sa ~~~h1 ~~~~~ 1t=~ r-----~-:
,,
from road irregularity but the
soft suspension and extra
long travel did compromise
ultimate sporting abthly
Acknowledging that high
speed stab1l1ty wasn't
perfect. BMW fitted
a three-way adjustable
double-acting Stab1lus
hydraulic steering damper
under the steering head
The steering damper knob
turned a shall 1ns1de the
steering head tube, moving
the damper away from the
steering head axis. This
provided a very effectwe
damping ad1ustment.
although the damper umt
was prone to 011 leakage
One of the /6's maon
updates was to the braking
system. the R90S. R90/6
and R75/6 all receiving a
front disc brake. The R60/6
retained the earlier Ouplex
drum front brake. s1m1lar to
the previous 15 umt. but with
a new ribbed casting and no
chromecover lncooperat1on
with Alfred Tewes GmbH
(ATE) of Frankfurt. BMW
developed a floating piston
brake cahper. The lloa\ing
p1stonmeant!hefrontwheel
could then be removed
without unbolting the cal1per
THE / 6 - S ERIES (TYPE 247)
The solid stainless steel brake disc was
260mm, the R90S rece1v1ng dual front discs
The rod-operated rear brake was the 200x30mm
Simplex of the/5, but with a stronger hub casting
and US DOT-required inspection wmdows to
check brake lining wear without removing the
wheel. The wheels included Weinmann light alloy
wheel rims (185Bx19in and 2.15Bx18m) and the
fmned front hub featured 40 stainless steel straight
pull spokes, to provide maximum strength fo r the
frontwheelw1thd1scbrakes
The /6 instrument layout with a separate
85mm MotoMeter speedometer and tachometer
and fi ve warning lights was shared with the
R90S. but each speedometer was geared for a
specific fmal drive. The new mstruments featured
black faces with white numbers. and the 1974
speedometer also included a tri p meter for the
l 1rst time on a BMW The speedometer read to
140mph or 220km/h. and the 8500rpm tachometer
was red lined at 7000rpm (or 6750rpm 1n early
brochures). Some early A90Ss were madvert ently
fitted with an R90/6 speedometer designed for
a lower final drive ratio . resultmg 1n opt1m1s t1c
speedometer and odo meter readings
The R90Salso recei ved a clock and voltmeter.
mounted in the small Muth- designed fai ri ng. In
1974. a clock as standard was revolu tionary- the
first as standard equipment on a motorcycle since
the wmd -up eight- day cloc k o n the Ariel Square
Four. thirty years earlier. The black anodized
alum1mum Magura handlebar levers incorporated
finger grooves, and the c am and c ham throttle
assembly was matched to the Bing ca rburettors
On the R90S the thrott le was very slow acting
THE BMW BOXER TWINS BIBLE
At.WI ~,,.,
C'
1 r''"'fl
•, m
The standard /6s had a smaller (18-litre) fuel
tank and a larger 22-litre tank was optional Only
the larger tank now featured rubber kneepads
Most tanks for 1974mcludedglued thin metal BMW
badges. but some 16s and R90Ss received the
older-style enamelled (clolsonne) gas tank badges
Some early /6 badges were screwed, as on the
/5. but on the R90S even the enamelled badges
were glued. There was a range of s111 colours for
the /6: Black with White pinstripes (086/590):
White with Black pinstripes
{084/584): Metallic Bluew1th
White pinstripes {0331533):
Red with White p1nstnpes
(026J526J: Metall1cCurrywith
Black pinstripes (029/529)
and Green Metallic w ith
White p1nslnpes (0771577)
The hallcl-pamted pinstripes
~ fully encircled the side of
the smaller tank. A22-htre
police spec1f1cat1on fuel
tank. with lockable built 1n
toolboio;. was available as
an ophon_ Some early f6s
and R90Ss had the older
style Everbest petcocks
but these were gradually
replaced by Karcoma or
Germa during 1974
On the /6 the dual
Denleld seat was s1m1lar to
the 1973/5, with longrtudmal
pleats on the upholstery,
a white plashc bead and
a single chrome-p lated
handrail at the rear The
seat a!so had a black model
emblem on the tail and a
shorter solo seat was an
opt1onthroughunt11 the1976
model year. The /6 libreglass
front mudguard wasn·1
shaped as deeply as that of
the R90S but a deeper police
mudguard was an option
In add1hon to the pressed
steel brace between the
fork legs. /6s also included
a chrome-plated tubular stay
that connected the rear of
the mudguard to the lower
forkteg. The fibreglass side
coverswerepa1ntedtoma!ch
the tank and fenders . Some
early brochures showed side
covers without decals. but
production models came
with a decal 1nd1cating the
capacity. '900cc'. '750cc'
or"600cc'
THE /6-SERIES (TYPE 247J
TheR90S :Iii! w
d fferent 10 :hat of the 16
Forl974.fhe:-;eat ~
wassmoorher
(Courtesy Jeff Wh 110 -w
M- -Kirl<patnc~)
Unhk.e the /6 that featured a fuel tank. and
seat similar to the/5. the R90S had a new shape
24-litre tank. and seat with fibreglass base. In a
ground-break.ing move for motorcycle design.
BMW enlisted the services of an industrial
designer and stylist, Hans A Muth. Educated as
a toolmak.er, Muth went on to study design and
graphics in Wuppertal. in the Ruhr valley. before
becoming a freelance automot1vedes1gner. From
1965 he work.ed at Ford. moving to BMW in 1971
as the chief designer of car interiors Muth was a
motorcycle enthusiast. riding an MV Agusta 750
at that time. and approached von der Marw1tz
regarding motorcycle design_ The /6 and R90S
was his first motorcycle project. and he had to fit
11 in with his automotive work.
Hans Muth w, respons ble
for the design of the R90S.
;;m(i BISO rhe ldltff R IOORS
45
THE BMW BoxER Tw1Ns BIBLE
As mony European sporting mo torcycles
were beginning to incorporate standard famngs,
1n 1g72 11 was decided 1h1s should also feature on
the R90S. The production l1breglass fairing was
beautifully hmshed. and many early e)(amples
featured two holes underneath the head light
Muth's styling makeover not only included the
fairing , but e)(tended to the steel 24 -litre fuel tank
and Denfeld saddle.
T he saddle had
a fibreglass base
and incorporated a
sporting rear cowling
Undernea t h were
two storage trays ,
one removable and
slightly different to
that of the /6. The
seat pad was thinner
than the other /6s,
with denser foam ,
but was iust as
comfortable. The
1974 seat covering
was without pleats
andthetankcapwas
aluminium
Only one colour was available on the R90S
for 1974, Silver Smoke with Gold pinstripes
(561). The Silver Smoke was hand painted and
air brushed. with a clear lacquer over the paint
The paint was supplied by Herbol of Wurzburg
and the dual colours had to be applied within 20
minutes of each other. Muth felt the R90S needed
a special colou r scheme that wasn't shared with
other BMW motorcycles. The p1nstr1ping was
1mt1allybygoldtape1nstead
of the usual hand-painting
because a suitable paint
prov1d1ng a uniform fini sh
wasn'tava1lable1n 1974 .The
luel tank was also located
by wing nuts tor 1974. The
fibreglass front mudguard ol
theA90Sd1fferedtothe/6as
11 didn't incorporate a lower
stay. Front mudguards had
pinstripes. but not the rear
mudguard of the R90S. The
1974 R90S front mudguard
had a longer cen tre sec tion
than later front guards.
where 1\ angled in to clear
the 1ork Completing the
spec1l1cation of the /6 and
R90S was an eKlremely
46
comprehensive toolk1t, including a BMW towel
tyre patches and tyre pump
·
While the A90S was envisaged as a sporting
model, BMW didn't follow the strict cate racer
route. the low 600mm handlebar providing a
semi-sport ing riding pos1t10n. The other /6s
included new head light support brackets and a
new tubular-steel handlebar: a standard 600mm
and a broader 680mm fo rt he US. The handlebars
we re con nected to the top triple clamp with
polished aluminium clamps and the t w in round
mirrors were chrome-plated, rather than black as
on the R90S. While all R90S had black m irrors
the mirror stalks on the 1974s (and some earl;
1975s) were curved, and not straight as on later
models. BMW also rnstalled reflectors on the sides
oftheforksandattherearoneachs1defor those
markets that required them. in particular the US.
Most fibreglass components were coded fo r the
yearofmanu facture.mclud1ng thefainng,battery
side covers and mudguards
16 options included the R90S lairing, with
voltmeter and clock.. or a touring fairing with
high w1ndsh1eld provided by Avon in England
The voltmeter and clock. were also available as
accessory pods mounted on top of the forks. In
add1t1on, there was the usual lockable fuel filler
cap, engmeprotect1on bars. soft and hard luggage
and additional driving lights.
The R90S was sold as an e)(pensive lu)(ury
model and eKceeded BMW's e)(pectations. Bob
Lutz said: "We made more o ut of each R90S
than a 1600cc car." Apart from the ad ditional
horsepower, e)(tra front disc brake. larger tank.
cock.pit fairing and special Silver Smoke pain t,
a number of detail touches set the R90 S apart.
T HE /6-SERIES _(_Tv
Besides the lower output alternator and Dell'Orto
carburettors. the A90S also received black painted
cyhnders for improved heat d1ss1pat1on. The
handlebars on the A90S were clamped with black
h19hllghted aluminium brackets to the black top
tnple clamp and many bolts (including the shock
absorber bolts) were chrome-plated. There were
special R90S emblems on !he motor and seat, and
only the R90S recerved 16 supplemental breather
holes in the back of the arr filter housing to assist
induction at h1ghereng1ne speeds. The high price
ensured the A90S earned celebnty status. finding
a place in the garages of racing car champions
Emerson F1tt1pald1 and Hans Joachim Stuck. and
motorcycle enthusiast King Hussein ot Jordan
All BMW motorcycles of this period were
characterized by superb quahty control. Each
bike was assembled by one tecl1111c1an and 66
inspectors checked various components and
t11e motorcycles before t11ey left t11e factory in
Spandau. Many inspectors stamped t11eir 111111als
in an inconspicuous place and 26 paint spots
througnout tne machine indicated bolts had been
correctly torqued. Every engine and 1ransm1ss1on
was run for 15 minutes on a dyno. before its final
assembly and a road test
247)
THE BMW BoxEA Tw1NS B1BLE
16 distinguishing features
1974 model year
Stronger crankcases with closed seat front
crankshaft bearing
Alternator and 1gmt1on covef with three air
ventsandvert1calr1bbing
New inner oil pump rotor and the engine
breather check valve
Five-speed gearbox with new die-cast
housing
Larger 25-Ah battery and 280 Watt
three-phase Bosch alternator
180mm Bosch 60/55-Watt H4 quartz iodine
head light incorporating five pos1ttons
igmt1onkey
No engine stop switch
Older style /5 Halla handlebar switches
retained
R90S and Rg0/6 with updated ignition
advance. the dwell angle increased to
110degrees
Alum1mum-boched turn signals
Frame received add1t1onal steering head
gussets and new bolt-on rear subframe
New forged aluminium lower tnple clamp
Early fork with single axle pinch bolt with two
bo!tsduring 1974
Early /6 fork springs shorter at 538mm
New Boge shock absorbers
Adjustable Stabilus hydraulic steering
damper
Solid 260mm single disc brake with 38mm
floating piston ATE cahper for R90/6 and
R75/6
14.29mm master cylinder underneath fuel
tank
Stronger rear hub casting with brake lining
inspection window
Finned front hub with 40 stainless steel
straight pull spokes
Separate speedometer and tachometer with
five warning lights and white outer ring
Black Magura handlebar levers incorporated
finger grooves
18-litre fuel tank standard without rubber
kneepads, most with glued thin metal
badges
New head light support brackets. and a new
tubular-steel handlebar
Handlebars clamped with polished aluminium
clamps
Twin round mirrors chrome-plated with
curved stalks
48
-.........1974--
Tungsten plug& lnaerted In the crank webt
Cylinders painted black
Dell'Orto PHM 388S Md BO concentrie
carburettors, the earNnt 38As without
chokes. Sharply bent aluminlum cable
guide
Air fiher housing with larger intakes and 16
breather holes
Clutch with a 2.8mm diaphragm spring
Smaller diameter 240 wan alternator
Specific upper tnple clamp, the fOl'ks without
ribbed gaiters
Top frame tube with additional reinforcing
,,.,.
Dual 260mm discs wrth 15.87mm master
cylinder
Clock and voltmeter mounted in fairing
Only colour was Silver Smoke
Gold pinstripes 1mt1ally by gold tape
24-litre fuel tank with aluminium fuel cap
located at the rear with wing nuts
Early examples with Everbest fuel taps
Seat with fibreglass base and seat covering
unpleated
Front fibreglass mudguard not as deeply
shaped as /6 and didn't include lower
stay. 1974 front mudguard with longer
centre section
Rear mudguard without pmstripes
Black mirrors with curved stalks
Handlebars clamps black highlighted
alumimum brackets
Many bolts (including the shock absorber
bolts) chrome-plated
Chrome acorn-shaped nut on the nght lower
shock mount
A90S emblems on the motor and seat
First A90Ss with a different instrumeot
support bracket
R90S, R90/6, R75/6, R60/6
1975 model year
BMW continued its policy of gradual evolut10
of the R90S and /6 during 1974, and, in Jun
and July that year. several 1975 model ye<i
pre-production examples of the R90S and /I.
were prepared. There were new production code
and a new number seQuence for 1975: R90:
(0276) 4080001-4084675. US examples (027S
4980001-4981738; A90/6(0275) 4050001-4053311
us (0277) 4960001- 4963602; A75/5 (0265
4020001-4023688, us (0267) 4940001-4942087;
R60/6 (0255) 2920001-2923868, US (0257)
4920001-4921103
There was some overlap with the end of
the 1974 series, but general 1975 model year
production commenced in September after the
summer holiday break, as was customary. The
early 1975 model year bikes were essentially
similar to the final 1974 bikes. except for
updated cosmetic and electrical equipment
As was evident during 1974, there was no
definitive date for the implementation of all
the 1975 model year updates. The R90S and
16 continued to evolve through the production
cycle
EvolutlOfl or the R9QJ6 1w
anumberolupd<.il<>Slor
1915. though lhegen<x.
style was unchang1.!d
49
THE BMW BoxER Tw1Ns BlBLE
Engine
The basic engine for 1975 was carried over !rom
1974. but BMW installed new Jet production
equipment that provided smoother alloy engine
castings. and while the rear gearbox cover still
provided for a ktck start . this was now optional
Several updates were incorporated gradually,
after: R90S 408 0438 and US version 4980305:
R90/6 40501 87 and US 4960791: R7 5/6 40 20453
and US 4940407: R60/6 2921611 and US 4920663
The motor was updated with a new c rankshaft.
front main bearing, fly wheel and stronger
(11x1.5mm) flywheel retaining bolts. These bolts
replaced the previo us M 10x1mm ones that were
known to fail on the larger engines . Th e ignition
advance unit also received new springs to eliminate
the shudder that existed at around 2800rpm , the
smaller R60/6 and R75/6
now shared the centrifugal
1gmt1on unrt with the 900cc
models. The ignition t1mmg
was also reduced from
9/34degrees to6/22degrees
tosu1t lower oc tane fuel
There were new 15mm
41CR4 cylinder head nuts
after numbers: R90S
4081381 and US version
4980678. R90/6 4050895
and US 4961838; R75/6
4021199 and US 4940956;
R60/ 6 2921572 and US
4920637.Ataroundthesame
time.theflywheeloilsealwas
updated: R90S4081381 and
US version 4980678: R90/6
4050895 and US 4961958,
R75/6 4021205 and US
4940987; R60/6 2921627
and US 4920738. Now made
o! silicon. this included a
strongersealin9hp
The
weakest
component. the 5-speed
transmission. also came in
for some updates with new
l 'and2''gearsh1 ftmgforks
starter motor was fitted This increased the
shortc1rcu1t starting currant to 320 amps(from
290 amps). ensuring reliable starting in even the
most adverse conditions. A change in the starter
ratio !rom 8.93 to 9.111 further improved starting
efficiency. The R90S regulator was also fitted to
the rest of the /6 range for 1g75, While ostensibly
thecarburettorswereunchanged,therewerenew
mixture chambers for the Bing constant vacuum
carburettors on the R90/6 and R75/6 this yea r
900cc models also received updated cylinder
head centnng during 1975. From A90$ 4081080
and R90/£ 4050544 the clamping dowels and
countersunk nuts were d1scont1nued. These wera
accompanied by new cylinder base gaskets. The
sharply angled Dell'Orto carburettor cable guide~
on the R90S were discontinued during 1975
~:r~i~~94~~~~~~~;~;~~~/~ ((,}:1111111••!!!!@!
4050991. US 4961904. A li..o
hell. k 111
n
1tie ~ « md 16
,,.,
191
yJeff
Wh1//oc1t./MJc Kirk(.'.Jl Hnck)
50
~:2:~-n~!~ 7 ~11~~e:k~ 11 1~:~ . ..,~. .!"ii!~iiiiiml;
the gearsh1!t lever. As the
kick start was now optional.
a slightly more powerful
Bosch 0 6-horsepower
TH E /6·SEAIES (TYPE 247)
Chassis
For 1g75, the frame on !he touring /6 models
rece1vedthere1nforced topframetubeoftheR90S
All 1975modefsre<:e1vedne wforklegs,anewfront
hub and a larger diameter (17mm} a Kie to tighten
the handling . The front fork included pinch bolts
on both fork legs. as on the final 1974 model year
bikes. There were some gradual updates during
the production cycle: From R90S 4081154 (US
4980521 ). and as an option for the R90/6 4050984
(US 4960803); R75/6 4020748 (US 4940641): and
R60/6 2921589 (US 4920637) there were new
fork damping tubes, and a stronger damping
ring Primarily to accommodate the double disc
front brake. these new dampers provided more
compression damping They not only stiffened
the suspension. but reduced the fork travel to
200mm. While the brake cahpers and under tank
master cylinder were unchanged. the stainless
steel disc rotors were now drilled (100 holes in
each). Although unsprung weight was reduced
slightly, the primary reason for the holes was to
improve wet weather braking performance - the
perforations aiding the d1ss1pat1on ol water more
quickly_ The R60/6 retained the drum front brake,
bul with new front brake plate
The 16 atso received
updated handlebar
controls. with black dogleg
Magura levers and new
Hella handlebar switches
The new clutch lever
provided an improved ratio
for clutch actuation and
was JOined by an improved
throttle assembly. The
R90S throttle included a
taster action 40-stroke
bevel-gear and chain
spec1flcally for the larger
Dell'Orto carburet tors
The other /6s retained the
33-stroke throttle. The
throttle cam provided a
more progressive action,
shortening the thro!tle
throw to a quarter of a
turn, improving throttle response
During the year, the R90S Dell'Orto
carburettors received ports for
vacuum balancing. There was
also an add1t1onal cable adjuster
incorporated at the top of the
carburettor. facilitating carburettor
Thfc lrOflt d1
f•<Jnl 1915
Whllock/M
were d
.ourrcsy
K1rl<patnc1<
''°'"'°"'""0"
The integrated Hella handlebar ~
~:;:~~=~I~~~~~=~ .t~~t~~~g~~: !It~~:
andturns1gnalsontheri ght. As the ,.:;; •
1gmt1on key no longer sw11ched on
the head light, thlS now included
only three pos1t1ons. On US models
the l•ghts were always on w•th the
ignition. Other running updates.
some installed gradually throughout the model
~
:--.1'!::"'"'"":::::'3"'C::::""'.'-;'-:,,..,...;::"O~'.!'.'!lij;ii.i ~~~:~~:n~~p~~~f:~!~
1ncludedstraightstalksf or
the black mirrors on the
R90S.andachrome-plate d
steel fuel filler cap. By now,
all the fuel petcocks were
Karcoma The MotoMeter
and
speedometer
tachometer had smaller
graduation marks and no
white outer ring. with the
tachometer including a
The "'"'trumefl'
1nd
.w11cht>,<; 1\-et"e ni:w for
1g7., 1Court•tsy.Jeff
W111t.'ock/M - K1t"-PJ!1
51
THE
BMW B OXER T WI NS BIBL E
An add1/l()(J,1J colour kx the
19:5 R90S was Dayton.1
O"ange (Courtesy Jeff
Wh1t/ocll; Mac K1r!<putnck)
larger red line band and high beam light. The Hella
turn signal indicators now featured low reflective
black plastic bodies ra1her than aluminium.
The R90S received a new seat cover for 1975,
with transverse grooves rather than smooth. This
was introduced in response to complaints that
the earlier smooth seat allowed the rider to slip
backwardsunderfull-throttleaccelerat1on.Alsonew
that year. was an add1t1onal colour to Silver Smoke:
OaytonaOrange (510). known in house as ·egg yolk
Oft1cially. colours were named after racetracks 1n
1975: Dayton a Orange (after Daytona Beach. Flonda)
Joining TT (Isle of Man Tourist Trophy) Silver Smoke
There are many stories in c1rculat1on regarding
how e)(actly the Daytona Orange colour came
about. which at the time seemed out of character
for such a conservative company as BMW One
1975 brochure describes the colour as 'Daytona
Orange-Safety Colour.· and this could make sense
w1th1n the conte)(t of BMW"s philosophy. Although
Sales Direc tor Bob Lutz.wasn't enamoured with the
br1ghtDaytonaOrange,dunngthe1980shecla1med
responsibility for the colour. saying the insp1rat1on
wasasunriseatDaytonaBeach
The pinstripes were now md1v1dually hand
painted. Red for the Daytona Orange (still without
a rear fender pinstripe) and Gold for the TT Silver
Smoke. The 1n1t1als of the pinstripe painter were
often under the seat, tank or to the right of the
fairing inside 11. Two piastre knobs. rather than wing
nuts, nowretainedthefuel tankandthecentreot
the horn went from chrome to black during 1975
There were also fewer chrome-plated nuts and
bolts, the lower right shock mount changing from
achromedacorntoaplainnut
A number of updates also flowed onto the /6
for 1975. Following the success of Helmut Dfihne
and Hans Otto Butenuth 1n production racing and
production-based racing in Europe. colours for
1975 were named after racetracks. Five colours
wereava1lableandmcluded: Monz.a Bluew1thWh1te
stripes (038/538): Nurburg Green metallic with White
stripes (077/577); Bol d"Or Red with White stripes
(0261526); lmola Silver with Black pinstripes (5591
and Avus Black with White stripes (590). There
was a new seat cover with transverse grooves for
the 1975 16. also without white beading. Instead
of a specific model emblem on the tail, there was
now a round BMW emblem. Other equipment was
shared with the R90S. including the MotoMeter
speedometer and tachometer. 1gnitron key and
handlebar switches. bu! the new twist-grip was a
33cam. In the same year. the/6 was offered w•th an
opt1onaltounng package that included aw1ndsh1eld
andthelargerfueltankOfatouringlu)(urypackage
- w1thth1scameafullrangeofaccessories
j'
16 distinguishing features 1975 model year
{some introduced gradually)
New crankshaft, front main bearing. flywheel and
fly wheel retaining bolts
New ign1t1on advance springs. all /6s sharing the
centrifugal1gnit1onunit
15mm cy linder head nuts fitted
Updated flywheel oil seal
New 1'' and 2"" gear sh1ft1ng forks for R90S and
R90f6
larger 26x7x16mm gearsh1ft lever oil seal
More Powerful Bosch 0.6-horsepower starter
motor
R90S reg·~:;i.tor fitted to all /6s
New mixture chambers for R90/6 and R75/6 Bing
New 900cc cylinder base gaskets and clamping
dowels discontinued
Frame on /6 models with R90S reinforced top
frame tube
New fork legs with twin pinch bolts, new front hub
anda17mmaxle
New fork damping tubes and stronger damping
ring
Stainless steel front disc rotor drilled (twin discs an
option)
R60/6 with new front brake plate
New handlebar controls with black dogleg
Maguralevers
New He11a handlebar switches
Three position 1gnit1on key
New clutch lever and 33-stroke throttle assembly
Speedometer and tachometer with smaller
graduations, no white outer ring, and larger
redhneband
Chrome-plated steel fuel filler cap
Hella turn signals with black plastic bodies
Fuel tank retained by two plastic knobs
Horn centre black instead of chrome
New seat cover with transverse grooves, no white
beading. and a rear round BMW emblem
As BMW prepared lor the introduction of the
1000cc boxer twin and the 17 series. man y
interim updates appeared on the R90S and
16 for 1976. There was another new number
sequence R90S (0284) 4090001 - 4093724
and US versions (0294) 4990001 -4991260;
R90/6 (0283) 4060001 - 4063018 and US
(0293) 4970001 - 4973316; R75/ 6 (0282)
4030001-4035306 and US (0292) 4945001 4947578: R60/6 (0281) 2960001 -2965122
and US {0291) 4925001 - 4925914 As usual.
there was some overlap between model years
and the introduction of all updates gradual,
as the parts supply for earlier versions was
exhausted
Thf. R90Sep'.fll ·~ 197
;tyle Th1s1sfromape; >d
advert1semem 1,.,, worn
ck.J!/llflQ
R90S distinguishing features
1975 model year
fasterachon40-strokethrottle
Dell'Orto carburettors received Ports for vacuum
balancing and an add1t1onal cable adjuster
Dell'Orto cable guides discontinued
Blackm1rrorshadstra1ghtstalks
New seat cover with transverse grooves rather
than smooth
Daytona Orange available alongside Silver Smoke
Fewer c hrome-plated nuts and bolts
53
THE
BMW BoxER Tw1Ns BIBLE
Engine (Type 247/76)
Altnough /116 1976 R90S
/ooll.edV91'}'.Sfflllar'O that
,, 975 1nSJde/he6'191ne
..,
54
a number of update:
While the 1976 R90S and /6s looked visually
s1m1larto 1975, there were many unseen updates.
particularly to the motor- most a precursor to the
new 17. The updates were officially incorporated
from February 1976. with the proviso 1hat these
"mod1hcat1ons were subiect to a11era11on without
notice." The Type 247176 engine included new
crankcases. cylinders. pistons and cylinder
heads. The reinforced crankcasesaccepted larger
cylinder sp1go1s and were strengthened around
the front main bearing. There was also a lOmm
deeper 011 sump pan
(and longer dip stick),
although theeng1neo11
capacity of 2.25·htres
was unchanged. The
new sump pan moved
the oil further from
the cranksha ft and
camsha ft to reduce
1nternalfnct1on,stab1l1ze
oil consumption, and
lower 011 temperature
In October 1975, a
59x3mm 0-ring was
inserted between
the crankshatt and
flywheel after numbers:
R90S 4090352 and
US 4990308: R90/6
4060267 and US
4970610: R75/6 4030398 and US 4945030; A60/6
2960660 and US 495289_ Also new for 1976, was
the timing chain case and inner and outer cover.
with larger bushes and 011 seals for the timing
advance mechanism. All /6s now shared the R90S
alternator cover
The cylinder heads were also new, with
mod1tied valve guide positions to provide a greater
clearance between the rocker and valve spring
plate. Allmodelssharedvalvegu1desw1thlheR90S
and the inlet valve guides were longer. al 54mm.
while the exhaust valve guide remained al 48mm
There were wider rocker arm support blocks and a
spacer was included 1n the cylinder head pushrod
supports_ These updates were aimed at reducing
valve clatter. The shorter rocker arms. centred m
the cylinder head with special fitted rings instead
of sleeves, were re-angled to increase stiffness
and striking angle efhc1ency. The rocker arm ratio
was unchanged. but incorporated selt·aligmng
needle bearings. This had a practical benefit in
that the valves didn't require read1ustment every
time the cylinder head was re- torqued. The
275mm push rods were 20 per cenl lighter, hollow
three-part alum1mum/steel/alumm1um. similar to
those used on the V8 automoblle engines. with
new lower rubber grommets. These pushrods
expanded more consistently with the aluminium
cylinders and provided quieter running from cold to
full operating temperature_ Instead of an aluminium
base gasket to seal the new cylinders, 'Hylomar'
sealing compound was used. with O·nng seals
on the cylinder studs. The Hy1omar compound
needed to be applied sparingly so as not to block
the small 0-rings. Thenewcylindersalsoincluded
newpushrod tubes
Although the camshaft valve lift and timing
were as before, the camshaft spindle d iameter
was increased from 12mm to 20mm. The larger
diameter spindle was intended to reduce camshaft
flex, with a reduction in 01t seal wear and improved
valve operation. The front cam beanng fiange was
cast-iron, instead of alumm1um. with a bronze
bush - resulting m closer tolerances and cam
timing accuracy. The reduced bearing play was
also claimed to reduce load on the sealing nng
which was now large!". Inside the 011 pump was a
new inner rotor and the clearance between the oil
pump rotor and pump housing. as well as the gap
between the inner and outer rotor, was tightened
The woodruff key locating the 011 pump rotor on the
camshaft was increased to 5.0x6.5mm, although
the sprocket key remained the same as before
During 1976. a new engine breather cover was
also introduced. TheR7S/6eng1nebreathercheck
valve was now 1n the same pos1t1on as that of the
R90/6, and all models were fitted with the same
front alternator cover as the R90S. The R60/6 and
R75/6alsorecewedtheR90/6automat1c 1gnit1on
advance umt
THE 16-SERIES (TYPE 247)
Gearbox updates 1ncl uded
strengthened transmission cases and a
'!;~~:;:~~===~:=~~j~~~~!~~;:;;i=~~=~
F
new gearsh1ft cam plate and detent spnng to
improve thegearsh1ft. The neutral Indicator
was also revised. with a redesigned spring·
loaded neutral 1nd1cator switch detent
plunger m the gearboK, and the recess m the
shift cam replaced by a raised pro1ect1on.
The other gearbox update was a new torsion
spring for the switch pawl, with five turns
instead of three. The US R60/6 and R75/6
received a lower final dnve to improve top
gear acceleratton, and featured revised
speedometers
Except for a new Bosch diode camer
and slightly higher rated Bosch alternator,
the electrical system was largely unchanged.
The maximum output was now 250 watts
with 18ampsofcurrent Thes1arterincluded
a wider chamfer on the starter gear ring,
and a modified starter pinion for easier
starting and pinion engagement_ Updates
to the Oell'Orto carburettors on the Rgos
saw the carburettor slides activating the
accelerator pumps earlier. to improve low
speed enginep1ckup
To improve the handhng there was less clearance
between the fork tube and fork leg (0 1mm instead
Chassis
There were also a number of chassis updates of 0 24mm). The brake cahper mounts were
for 1g75_ The swingarm was more convent•onal wider (72 Smm from 72.2mm) fort he larger brake
than before, and instead of the single transverse cahpers, and the rear shock absorbers had dual
bracing tube welded across the e)(treme closed rate springs_ Not all 1976 R90Ss and /6s were
end of the arm. BMW now adopted a pressed 1dent1cal, and some 1976e)(amples had a cut-away
out bo)( section, welded in place. and reinforcing for the rear subframe bolt 1n the nght side cover
the sw1ngarm so lhe bearing pivot couldn't twist The clutch lever featured a repos1t1oned pivot
torsionally as before. The cross strut on the centre point and. when combined with the reduction in
stand was repos1t1oned to provide clearance for clutch spring pressure, made for a lighter clutch
the deeper sump
pull and improved clutch engagement
The 1976 /6 and R90S looked similar to
There were also updates to the braking
system, with larger piston (40mm) ATE black the 1g75 eJ1amples as \he colour range was
anodized front brake calipers and new brake unchanged. By June 1976, production of the R90S
pads The cahpers were marked '40' to indicate and 16 was scaled down, as BMW prepared lor
their piston size Accompanying the larger cal1pers the /7, R100S. and R100RS. and some R90Ss
on the Rgos (and the twin disc option for the /6) appearedw1thnfeatures. Some of these features
was a new master cylinder with a larger (17.46mm) included•a/7-styteflushgascap;blackreargrab
piston, considerably reducing hand lever effort
rail and black left hit handle rns1ead of chrome;
The R7516 and R90/6 also featured a 40mm matte black f1msh on the rear mudguard and
brake caliper, along with a new master cylinder. side covers; and a matt black tyre pump The
but unlike the R90S, this wasn't correspondingly valve covers were also black and the cylinder fins
larger with the piston size remaining at 14.29mm
unpainted on some of the final R90Ss. To move
A coil clip replaced the hose clamp retaining the e~cess stock in the US. BMW also offered the
mastercyhnder to the lrame. and there was a new R90/6 L1m1ted Ed1t1on. This included a standard
Bowden brake cable connecting lhe handlebar clock and voltmeter rubber mounted on brackets
lever to master cylinder, with a larger {12mm from the top tnple clamp, four-way emergency
instead ot 10mm) cable nipple
!lasher and stiffer fork springs so the LE could
The suspension also included some updates
be fitted w1lh a fairing
upgrade f<Y 19,6
Cha
lflCluded bral\e C<lif)e(S w !I
f'
Y gl!rptS' ;)flS ,(;()1Jr1e Y
\Ml t:oclv'MacK,,kp._ilr<ek.
55
l
THE BMW BoxER Tw1Ns B1BLE
Nurburg Green {/6 verSIO<lS only)
The range of r Jlours
wai.Jble frx the R90S and
16 kY 1975 and 1976
TI Silver Smoke (R90S only)
Avus Black(/6versionsonty)
lmola Silver (16 wirs•ons only)
R90S and /6 distinguishing features 1976 model year
(some introduced gradually during the model year)
New crankcases. cylinders and pistons. and
cylinder heads
10mm deeper oil sump pan and longer dip
stick
0 -ring inserted between the crankshalt and
flywheel
New t1mmg chain case and inner and outer
cover shared with the R90S
Modified valve guide pos1hons, longer mlet
valve guides, wider rocker arm support
blocks, shorter rocker arms with special
rings and needle beanngs
Lighter pushrods with new lower rubber
grommets
Sealing compound on the cylinder base and
0-ringsonthecylinderstuds
Camshaft spindle 20mm
Cast-iron front cam bearing flange with a
bronze bush
New inner oil pump rotor
011 pump rotor Woodruff key on the camshaft
now5.0x6.Smm
New engine breather cover introduced
R75/6 engine breather check valve now the
same pos111on as A90/6
R60/6 and R75/6 with R90/6 automatic ignition
advance unit
Strengthened transmission cases, and new
gearsh1ft cam plate and detent spring
Revised neutral indicator
New torsion spring for the gearbox switch pawl
US R60/6 and A75/6 with lower Imai drive and
revised speedometers
New Bosch diode carrier and alternator
Modified starter pinion
New swingarm
Centre stand altered to provide clearance for
the deeper sump
Front brake caliper with 40mm piston and new
mastercyhnder
12mm brake cable nipple
New front fork with wider brake caliper mounts
Clutch lever pivot point repositioned
R90S Dell'Orto carburettor slides activated
accelerator pumps earlier
R90S 40mm brake calipers with larger
(17.46mm) master cylinder
Some final R90Ss with n-style flush gas cap
and miscellaneous /7 black parts
TH E / 6-SERIES (TYPE 2 47)
...
""°"'
:;;: R75/6
R90J6
- -/6 frame numbers
1974
07173-08174
2920001-2923868
1975
08174-08175
08175-06176
2960001-2965122
1976
4900001-4900827
1974(US)
01174-07174
4920001-4921103
1975(US)
08174-07175
4925001 -4925914
1976(US)
09175-05176
4010001-4012631
1974
09173-08174
4020001-4023688
1975
09174-08175
4030001-4035306
1976
09175-08176
4910001-4911097
1974(US)
09173-08174
4940001-4942087
1975(US)
09174-08175
4945001-4947578
1976 (US)
4040001-4044971
1974
09173-08fl4
1975
06174-08175
4060001-4063018
1976
08175-06176
4930001-4932218
1974(US)
01174-06/74
4960001-4964263
1975(US)
06174-08175
4050001-4053311
R90S
Productlond1tes
2910001-2911677
09175-08176
4970001-4973316
1976(US)
09175-06/76
4070001-4075054
1974
09173-08n4
4060001-4064675
1975
06/74-09175
4090001-4093408
1976
08175-06176
4950001-4951005
1974(US)
01174-07174
4980001-4981738
1975(US)
07174-08175
4990001-4991260
1976(US)
08/75-06/76
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57
CHAPTER IV
THE /7-SERIES (TYPE 247)
T
he success of the 16-senes. particularly
the R90S and R90f6 during 1974 and 1975.
resulted 1n the establishment of BMW
Motorrad GmbH in January 1976. Although engine
development was as before. the production and
sales of motorcycles were now separate from the
car d1vis1on_ Under the control of Hans Koch. with
Horst Spmtler in charge of sales. the development
team of von der Marw1tz. Muth. Or 01etnch Reister
TheRIOORS wi"ls lhe new
1ngeleador tor 1977.
d w.
a superb ndlng
m ;hine
and Gerd Wirth were encouraged to produce
an innovative design. more funct1onal than the
flawed R90S
Following the success of the R90S, Hans
Muth was asked to style a motorcycle emphas1s1ng
"--•"'!"llj
.,_ _ _
rider protection
and aerodynamic
function. Again he
was successful. and
the R100RS was
the first production
motorcycle to offer
a fully integrated
famng that not only
provided outstanding
weather protection.
but also contributed
to the stability of the
motorcycle. Sharing
the AS abbrev1at1on
with the legendary
bevel-gearracing500
of
1950s. instead
of the
Rennsport
RS,
now indicated a more
appropriate Reise Sport or Touring Sport. The new
lairing improved aerodynamics but, because the
frontal area was increased, the top speed was less
than that of the A90S. High speed handling was
superior though, as was rider comfort
Alongside the R100RS for 1977 was a
completely new range. the 17-series. Now
comprising five models, replacing the successful
four model range of the R90S and 16. displacement
1umped up to 980cc with the R100RS. The 900cc
models were discontinued. and the 750cc and
600cc versions were in1t1ally much as before. in
updated form. Although the R90S continued as
the RlOOS, this model was relegated down the
line-up as the RlOORS established itself as the
range leader. It was also an improved motorcycle.
even 1f 11 lacked the R90S mystique. Despite a
slightly lower power output, 11 was arguably the
strongest performer in the 1977 line-up. The other
17s also incorporated many of the improvements
introduced on the R100RS. As in the past, there
was a high degree of model uniformity and parts
interchangeab1l1ty, with all /7s sharing much with
the more expensive RlOORS
R1 OORS, R1 OOS, R100/7,
R75/7, R60/7 1977 model year
As usual, there was some overlap between the
final 1976andearly 1977modelyears.withall 1977
variants rece1v1ng a new frame number sequence
R100RS (code 0306) 6060001-6085159 and US
(Code 0316) 6180001-6181263; RlOOS (0305)
6060001-6063149andUS(0315)6160001-6161365:
THE /7-SERIES (TYPE 247)
R10017 (0304) 6040001-6043414 and US {0314)
6140001-6142451; R75/7 (0302)6020001-6024507
and US (0312) 6120001-6121474; R60/7
(0301) 6000001-6005517 and US {0311)
6100001-6100407
Engine (Type 247/76)
Despite the success of the /6-series, BMW's
board wouldn't agree to the development of a
new engine for the /7, so the engine remained
very s1m1!ar Many ol the engine updates for the
R100RS. and its /7-series
stable mates. were introduced
on the R90S and /6 for the
1976 model year. But while
the RlOORS engine earned
the same 247176 internal
engine designation, the new
engine type was known as
the M65'. The deeper 011
C: pan introduced during 1976
leaturedonall/7seKceptthe
A 100RS for Cahlorn1a. Florida
and Oregon. where 11 was
optional As was typical of
BMW, the engine continually
1 evolved. Although the s1lumin
crankcases were further
reinforced to withstand
the increased horsepower.
engine weight was 1dent1cal
to that of the earlier R90S at
62.Skg. The quoted weight
ol other /7 engines was also
1dent1ca1 to their respective
/6vanants
T he most noticeable
development for 1977wasthe
increase in capacity for the
A100RS. RlOOS and R100/7,
achieved with 94mm pistons
and cylinders. Constructed of
a new lightweoght aluminium
alloy by either Mahle or
Kolben Schmidt, the pistons
weighed the same as the
previous 90mm type. The
cylinders had thicker and
shorter cooling fins to reduce
noise, and no longer were
there any black-painted
cylmders (as on the R90S)
The p iston clearances were
also tighter on all /7s. with
a maK1mum wear limit of
0.08mm instead of 0.12mm
The crankcase ventilation
system was omproved and,
along with a small baffle
chamber cnst into the
crankcase starter cavity,
there was a new breather
An RICIO repJaced
the R90!6. 1/fhougfl tflil
style was SlfT)llar Thr.
e~ample has many op'-onat
acce. sone:::
The R7517 was short Wed
andontypn:Jducedlor-197
(CourtesyTwoW'hee-
59
I
~
THE BMW BoxER Tw1Ns BIBLE
housing that included a small rectangular top hat ser1esrepresenteda shghllyd1tferenlvariahonon
and new outlet. A longer hose and new intake bell the engine type 247176 theme. Inside, the eng•ne,
accompanied the housing. and 11 still ventilated of the R60/7 and the A7517 d•ffered very little !rom
into the right carburettor intake. The engine 1heir respective /6 variants, while the A100/7 was
breather system on the A75/7, Rl00/7 and RlOOS also similar to the A90/6. The AlOOS engine was
was the updated setup of the RlOORS, while the 1dent1ca11n spec1l1cat1on to the RlOORS. although
R60/7 retained the /6 engine breather housing
the power output was slightly less due to a more
Inside the gaocc cylinder head were larger restr1ct1veexhaustsystem
inlet valves. now 44mm (98.8mm
long)w1th48mmlnletande!thaust
valve guides. The R100Scylinder
head was 1dent1cal to the RtOORS.
while the RlOOn valves were the
42mm and 40mm of the Rg0/6.
Jns1de the cylinder head of the
R60/7, the 38mm and 34mm
valves were the same as the
R6016(and R60/5). The42mmand
38mm valves of the R7517 were
unchanged from the earlier 750
There were still only two
AJI 17s had new .Jngu/ar camshafts, the R60/7 rece1v1ng the
roc1<.ercovers afld Bing milder 284-degree camshaft and
carbureruxs The covers all other models the 308-degree
were black on /he RIOORS camshaft. The camshaft drive
!Counesy Two WheelS) system was also unchanged, but
longer (8!t45mm and 8!t55mm)
studs retained the camshaft drive housing.
Setting all the new engines apart from
Although lighter aluminium pushrods featured earlier versions were new angular rocker covers
on the 1976 R90Sand /6, 1twasn't until 1977 that Compared to the older round rocker covers
tighter valve clearances of 0. 10mm for the inlet that first appeared on the R68 of 1g52, the new
and 0.15mm for the exhaust were specified to covers were larger and heavier, increasing engine
reduce noise. The one-piece forged crankshaft width slightly. 'l' and 'A' marks were cast inside
was unchanged but the con rods exh1b1ted more the covers to represent left and right. Both the
resistance to cracking due to improved forging. AlOORS and AlOOS featured black anodized
Changes to the lubrication system included rocker covers with polished fins. The A100RS
a gasket for the 011 pump pick-up 1n the sump, special engine emblems were black with silver and
and a new 011 filter outer cover plate. The 011filter blue highlighting, while the RlOOS emblem was
included a steel shim and 0-ring and. as already highlighted in red to match the bodywork.
mentioned, the deeper oil pan from 1976featured
Rather than the concentric Dell'Orto
on all /7s except the R lOOAS where 1t was optional carburettors of the R90S, the AlOOAS and RlOOS
in some US states until 1979 (number 6183254).
both received Bing 40mm Type 94 constant
Towards the end of the 1977 model year. vacuum carburettors. With these carburettors
the rocker arms were strengthened by widening came 40mm intake manifolds, a new a1rbox and
the bridge between the hub and thread from a revised intake bell on the top of the air filter
7mm to 11mm. These were fitted from: R100RS box. With larger40x1.5mm exhaust header pipes.
6084553 and US 6181262: RlOOS 6062884 and new star exhaust pipe nuts and an 87mm muffler.
US 6161323: Al00/7 6043219 and US 6142340: the RlOOAS was the most powerful boxer twin
A75n 6024207 and US6121470: A60/7 6005190 to date. The larger exhausts came with 42mm
and US 6100407 At the very end of the model clamps, although the smaller 38mm exhaust
year. the AlOORS (from 6085018) received new header pipes (with 40mm clamps) were listed
Seeger pattern gudgeon c1rcJips and a redesigned as an option for 1977. All Ca11forma, Oregon and
piston c rown for improved combustion and 0 11 Flonda AlOORSs had the smaller header pipes and
debris reduction. These would feature on all 1978 a more restrictive muffler (through unlll number
model year engines.
6183254). The RlOOS, Rl00/7, R7517 and R60/7
As with the /6 series, each model of the /7 continued with 3Bx1.5mm exhaust headers. The
60
THE / 7- S EAIES (TYPE 247)
cart>uret1on on the R100/7, R75/7 and R60/7 was
essentially carried over from the previous models.
the R75f7 and Rt00/7 reta1mng 36x25mm intake
manifolds. The clutch on the RlOORS, RtOOS
and R100/7 was a s1m1lar 180mm single disc
unit to the R90S, also using a 2.8mm diaphragm
spnng, but with a heavier duty an ti-warp clutch
disc. There was a new flywheel. slightly thinner
than before, and the number of teet11 on the
flywheel increased to 94 The transmission case
received lengthwise external ribbing, and the
five-speed gearbox featured 6.Smm {up from
5.7mm) gear wheels. The selector fork guide
t11ickness was reduced by lmm and there was a
different riPutral light switch. To prevent jumping
out of gear, the square shift dogs on 3- 0 , 4"' and
5· gears incorporated window sections. There
were no longer sealing rings on the cam plate
bearing bolts and an alternative close-ratio
sporting, or competit ion, transmission was also
available.Thekickstartrema1nedanopt1on.and
the standard final drive ratio for the European
RtOORS was 1:3.00 (33:11), with a higher 1:2.91
(32: 11)fortheUS. Some early US RlOORSscame
with the European final dnve. All /7s featured
the revised clutch and flywheel with different
starter ratio but the R75/7 and R60/7 both had a
2.6mm clutch spring. A different final dnve ratio
for each version also distinguished the 17, with
the US R100/7 having a higher 1:3.0 ratio than
European versions.
The R100RS and R100S retained the 250
watt Bosch Gl 14V 18A 22/240W alternator of
\he R90S and. while the 0.6-horsepower Bosch
starter motor was also identical, the starter
transmission ratio was increased to aid starting
in colder temperatures. The other /7s featured
the Bosch Gl 14V 20A 211280W alternator of
the R90/6, R7516 and R60/6. Along with a new
Chassis (Type 247177)
Although the /7 frame and swmgarm was
essentially unchanged from the final 1976 version,
a second transverse tube was added between
the front double downtubes, and the frame
tubing was a thicker sechon_ There was also
add1t1onal gusset1ng around the steering head
and the chassis type designated 247177. The fork
legs were black to fit the A100RS's accentuated
black image and, because of the fairing, the
steering angle of the front fork was reduced to
35 degrees (from 42 degrees). US versions still
11ad tile rectangular reflectors but these were
absent on European models. The fork springs
were also shorter on the R100RS than other / 7s.
at 543mm. while modified front fork damping
provided the same 200mm of fork travel as the
1976 A90S. There was one less bleed hole m
each fork damper assembly
oil capacity was also reduced
250cc). This resulted in a
softer ride in the middle
The leading axle front fork
on the 17 was 1m1e changed
from mar of the 16. nor were
the spoked front wnooi Ind
Slflgiefrontd1 ·bfak
{with 31-degrees of advance) but there
were new sparkplug leads and caps,
and different Bosch W225 T30, Beru
230/14/JAor Champion N6Y spark~ugs
Very early in the model year, the 1gmt1on
timing mark on the flywheel was
reduced to 6 degrees before TDC
instead of 9 degrees. This was to
accommodate lower octane fuel and
was changed alterc R100RS 608036g
and US 6180040; R100S 60603g6 and
US 6160217; R100/7 6040680 and us
6140074, R75/7 6020327 and US 6120088;
R60/7 6000207 and US 6100055
61
THE BMW BOXER TWINS BIBLE
All / 7s. and the R100$, featured plain
aluminium fork legs. 567mm lork spnngs and
42 degrees of steering loc k on each side. The
R1 00S forks retained the more sporting. rnbber
fork cups. with gaiters s\111 featuring on other / 7s.
There was a new, pohshed steel upper triple
clamp, and blac k anodized handlebar clamps
All/7s. and most 1977 RlOORSs, had spoked
wheels with usual aluminium nms. cast hubs and
40 straight pull stainless steel spokes. These
wheels were the same s ize as the p revious /6
(1.65B)(191n on the front and 2.158)(16m on the
rear) and two blue pinstripes on each w heel nm
d 1st1ng uished the A 1OORS. Cast alloy 'snowflake'
McA 1977RIOORSshad
WITTJ-spol<.eclwheefs. 11Je
shocl<. absorbers no kJnger
had top spnng ~vers
pattern wheels w e re
listed as an optio n ($400)
for the R 100R S only
- the rear a 2.50)(18m.
Whilst these featured on
RlOORSs m brochures
and manyearly road tests,
they weren' t generally
ava1labledur1ng 1977due
to supply problems. and
were possibly fitted to
only three 1976 European
prototypes and lour
US prototypes - 11 the
chassis numbers fo r
early b ikes are any guid e
Muth always envisaged
the RlOORS with alloy
wheels, initially buil t
by BBS near Stuttgart
Nearly 3kg heavier than
the spoked type. they
were also prone to
cracking. and all wheels
manufactured prior to
the end of 1962 were
rec alled during 1964
The replacement wheels
62
looked s1m1lar, but included add1t1onal support
around the spokes. Tyres on the R\OORS were
Continental Twins (matched front and rear) 01
Metzeler Block C66 Touring, 1n 3 .25-H19 and
4.00-H16
All /7s (including the R60/7) had a front
disc brake this year with the R100$ and R100RS
receiving dual discs. The perforated dual front
discs were now quoted at 264mm, with 40mm
ATE single piston l!oat1ng calipers . The brake
calipers were black on the R100$ and /7, and
anodized blue on the R100RS. M uth originally
wanted red anodized cahpers, as on a Ferrari,
but couldn't find any company able to do that in
1976. The ATE (17.46mm on dual disc versions)
master cylinder still resided underneath the fuel
tankandthebrakelmeswereas1m1lar rubbertstee1
combination, but spaced to clear the fairing. The
rod-operated 200mm rear drum brake was as
before on spoked wheel models . The few cast
wheel RlOORSs inc orporated air scoops for
cooling the rear drum brake. with protective plastic
screens over the scoops.
A much narrower, almost clip-on style.
handlebar distinguished the A100RS from
other sporting BMWs. Short enough to lit
completely ins1dethefamng, the 548x22mm flat
handlebarprovided an aggressive riding position.
contributing to the AlOOAS's +mproved stab1l1ty
overthe R90S. The handlebar levers were black
Magura dogleg-type with the same Magura
handgrips as before. and the new rectangular
rear-view mirrors were also black
Standard on the /7 was a 600mm
chrome-plated tubular-steel handlebar. while US
17s had a broader 680mm handlebar. Because
the frame mod1hcat1ons improved stab1lrty there
was no lon')"f a standard steering damper on the
R100S and 17s. although the R100RS retained
the three-pos1t1on two-stage steering damper
as standard equipment this year. As on the 16.
the round mirrors were black on the R100S
and chrome-plated on other /7s. As there was
now an add1t1onal frame brace where the horn
had been located. the Bosch horn on the 17
and R100S was replaced with a new Italian
single Fiamm 410 Hertz horn on the left. The
RlOORS had twin Fiamm horns. the left as on
the /7 and a 410 Hertz on the right. Although
the layout of the Hella handlebar switches was
the same as before. the right indicator switch
now included a thumb extension wing for ease
of operation, as did the left high/low beam and
flashersw1\ch
While instruments and instrument layout on
were 1dent1cal to the final /6.
the R100S and
with the 1gni11on switch rema1mng on the left head
light bracket. the instrument layout of the A100AS
with warning lights was more integrated into the
fairing. The speedometer and tachometer were
still black with white numerals, mounted on the
top tnpleclamp. and an au1omot1ve-style plastic
cover concealed the handlebar. On the R100RS
the 1gmt1on key was more conveniently located.
between the voltmeter and electric clock_ The
180mm Bosch H4 head hght, Hella tail light in
polished black surround and Hella turn signal
indicators in black housings were unchanged
All /7s, including the R100RS. featured
the 24-htre steel fuel tank of the R90S. with
the black !lush-mounted lockable filler cap
that appeared on some linal A90Ss - the key
to the ignition was separate. The design of !he
tank cap wasn't perfect on early e~amples as
it could sometimes rotate without unlocking
Constructed 1n two halves as before. the tank
incorporated an internal eKpans1on chamber and
wasreta1r.edattherearb ytwoplast1cthreaded
knobs An update on the A60/7, from 6005190
n
63
THE BMW BOXER TWINS BIBLE
and US 6100407, saw the petrol tank cap fitted
with a lmm breather hole. All the fuel taps were
Karcoma Germa wtlh rubber seals and enlarged
internal passages
the fork legs. Three colours were specified for the
other /7s: Black Metallic with Gold stripes (532t,
Metallic Blue with White st11pes (533): Oran
Metallic with Gold stripes (0341534)
The 17s also featured the R90S-style
fibreglass front mudguard but without a lower
brace. although the fork leg casting Shll retained
the mount (even on the AS}. The rear mudguard
was painted to match theluel tank on / 7s. but black
on the R100RS and R100S. / 7 pmstripesenc1rcled
the side of the tank while lhe R100RS and R100S
pinstripes were more abbreviated. as on the R90S.
The handlebar-mounted fairing of the R100S was
1dent1ca1to that or the R90S. as was the dual seat
(but with a black grab handle). The left-side handle
was also black on the R100S, although chrome on
other /7s. The R100S had black side covers. with
gold '1000cc·decals.andfor 1977, the only colour
available was Metallic Red with Gold pinstripes
(566). The 1977 R100RS was only available in one
colour as well: flat Metallic Silver with clear lacquer
and Blue pinstripes (530). The insp1rat1on for thlS
colour came from the pre-war BMW 328 car,
and the fm1sh was developed in con1unct1on with
Herbol-BSF_ With the support of Bob Lut:i:, Muth
managed to persuade the accountants to agree to
produce the RlOORS m metallic paint with a clear
lacquer byonlyoffer1ngonecolour. The side panels
were flat black with blue ' 1000cc' decals, while
the !font mudguard was painted silver with blue
pmstnpes and incorporated a steel brace between
There was a choice of two seats for the
R100RS. a solo (almost one and a half) sport seat
andtheR90S-typedualseat. Bothseats1ncfudeda
roundBMWemblemonthe1rtailandwere lockable,
with the dual seat featunng a black grab rail. As
well as two helmet locks there was the usual hit out
plastic tool tray under the seat. with a useful rear
storage compartment that was quite large on the
solo seat version. Locks for 1977 included separate
keys for the ignition and fuel filler cap. There were
new rectangular Denleld loot peg rubbers for all
/7s this year, although on the solo seat R100RS
there were no passenger foot pegs
The R I00S continued the
style of the R90S. and had
Wlf9-Spol\ed wllee/S !ex
1977
Many 1971 RIOORSs had a
)Jo seat !Courri:sy
TwoWheel-V
64
had failed , (such as the Vin cent Black Prince and
Anel Leader) •t wa s a big ask The RlOORS lairing
was the first motorcycle component to benefit
from CAD (C omputer· A1ded Design) technology,
shared with the automotive department. and was
tested in a wind tunnel. Design commenced as
early as 1974 . w hile testing began during 1975
- initially at th e Technical Univers1 tyof Stuttgart and
subsequently at P1nmfar 1na in Italy. Although BMW
paid handsomely to use the Pininfanna facili ties
(£2500). by attachin g fabri c an d electrodes to the
bodywork. Muth was able to design a fa1rmg that
redu ced wind re sistance by 5.4 per cent. side
w ind yawing b y 60 per cen t and front wheel hit
by 17.4per cent
y, lh th
roolk.11
wo WI
he Pini I
sea t
HIOOfi
w
round BMW and spec1f1c decal model emblems
on the ta1L As in the past. the 26-piece toolk 1t
was extremely comprehensive <:1nd included a
spanner!or ad1usting thesteermg head bearings
and sw1ngarm. Along w ith the usual tyre repair kit
there was a tyre pump under the seat European
models also included a first aid kit that fitted under
was the in1ect1on-moulded fibreglass fairing
Despite the R90S's sales success. von der
Marw1tz was not enamoured w ith the high speed
•nstab1l 1ty created by the handlebar- mounted
la1r1ng - and although BMW offered aftermarket
Avon or Glaser fairings. these were sens1t1ve to
side winds. Von der Marw1tz asked Muth to design
a fairing that offered improved weather protection
and stab1hty, while continuing BMW's design
Philosophy. The !airing also had to be easy to
P•oduce and_ cons1der1ng other fu lly faired designs
65
THE BMW BoxER TWINS B1e1.e
n RTOOFI
I JEW
tt
11ounnq
anrJmetainnq~
bee '116abenehmJri<
Beautifully constructed. the 9.Skg famng
was in seven sections with a low w1ndsh1eld
The front upper sec11on included a
rubber head light shell and a Sekurit
safety glass cover that 1ocorporated
five orange Imes. These lines were
purelyastyhngadd1t1ontothedesign
of the w1ndsh•eld with no functional
was also a horizontal rectangular parking hght
abovetheheadhght. The front fa1nng sect1onwas
a grill that allowed air to reach the front of the
engine. whilethelowersect1onscould be removed
for ndmg m hot weather. These were one-p•ece
on 1977 models, requmng the e)(haust
pipes to be dropped for removal. Two
black-painted tubular- steel brackets.
incorporated into the bracket welded
to the headstock. rigidly located
the top of \he lamng and served
as mounts for the mirrors. Two
add1t1onal tubes bolted to the
sides. with a third set of pressed·
steel brac kets below the
cu ps encircling
the fork tubes.
while open- cell
foam filled the
space between
thefa1nngand
the front frame
down tubes.
theRIOOR.
'
~St
y
v
in 'Jl..blK;Jrypic· ns.
/he
whee:.:: Neri rare :>ri
pt'Od!J(,'·c~nxJels
66
T HE /7-S ERIES (T YPE 247)
Cylinders w•th lh•cker and shorter cooling
f>nS
Improved crankcase ventilation system
1ooocc models with 44mm inlet valves
Longer camshafl drive housing studs
Gasket for the oil pump pick-up and new oil
filteroutercoverp!ate
New angular rocker covers b!ack anodized
on the A100RS and RlOOS
RlOOAS ior>ri RlOOS with Bing 40mm Type 94
constant vacuum carburettors
RlOORS, AlOOS and R1oon with a heavier
dutyant1-warpclutchdisc
Thmner flywheel with 94 teeth
Transmission case with lengthwise external
ribbmg
6.Smm gear wheels and no sealing rings on
the cam plate bearing bolts
Selector fork guide thickness reduced by
Shift dogs on 3·o,i1· and 5"' gears
incorporated window sections
Starter transmission ratio increased
New Bosch relay and 28 Ah Varta battery
New sparkplug leads and caps
Frame included a second front transverse
tube and add1hona! gusset1ng
All /7s. and the A100S. featured plain
alum1rnumfork1egs
No standard steering damper on the RlOOS
and/7s
Black round mirrors on the R100S and
chrome-plated on other ns
Single Fiamm horn on the left for R100S
and/7
Handlebar switches w1th thumb extension
w>ngs
R100S and /7 ignition switch st11\ on the left
headlight bracket
All /7s featured R90S-style 24-litre steel fuel
tank !lush mounted filler cap
All 17s with fibreglass front mudguard without
a lower brace
Left-side handle black on the R100S and
chromeonother/7s
17 lower metal seal fixtures black instead of
chrome
New rectangular footpeg rubbers
R60/7 with front disc brake instead of drum
RlOORS distinguisl · features
1977 model year
40mm exhaust header pipes
Black lorklegs
Shorter fork springs and mod1f1ed front fork
damping to other t7s
Rear Boge shock absorbers without top
polished alloy spnng covers
Most fitted with spoked wheels with two blue
pinstripes on each wheel nm
40mm front brake ca11pers anodized
Narrow flat handlebar that fitted 1ns1de the
famng
Black Magura dogleg handlebar levers
Black rectangular rear v1ew mirrors
Steering damper standard
Twin Fiamm horns
lgrnhon key located between the voltmeter
and clock
Black rear mudguard
Flat black side panels with blue '1000cc'
Choice of two seats. a solo and dual
67
THE BMW BoxER TWINS BIBLE
R100RS, R100S, R100/7,
RS0/7, R60/7 1978
model year
The 1978modelyearwasoneoftrans1t1on
!or BMW Replacing the shorHived
R75/5 was the similar R80/7, and this
was effectively the Imai year for the
R60/7 before 11 was replaced by the new
generation R65. This year also saw a
variety of add1t1onalolhcial. police and
tounng models: the R60/7 T; R80/7 T; and
R80/7 N. In the US, the strong German
Markhadadetnmentaleffect.lorcingup
pricesandresult1ng1nd1m1nishmgsales
during 1977 and 1978. It was rumoured
up to 8000 motorcycles sat 1n dealers'
showrooms and only 1092 examples of
the flagship RlOORS were sold in the
Unrted States throughout 1978
In the US, noise and emission
controls, and the introduction of lower
octane low lead fuel, were also hurting the
engine - requmng complicated engine
breather systems and a general lower
stateoftune. lnthefaceofcheaperand
higher performing Japanese fours. the
expensive boxers struggled to find a
market in the US, although they continued
tomamtamaloyalfollow1n91n Europe. But
w1thonly29.580motorcyclesbuiltduring
1978, the future of the BMW motorcycle
remained uncertain.
1918w
tf>eflnl:. yoorfor
the R60/7
68
T HE /7-SERIES (TYPE 247)
Number sequences for 1g75 were as follows
R100RS (0325) 6086001-6082865 and us {0335)
6182501-6 1835g2:R100S(0324)6065001-6068753
and US (0334) 6 162501 - 6 163870: R1 00/7
(0323) 6045001-6047gg5 an d U S (0333)
6145001-61481g6; andasmall senesof R100/7T
(0344),61 1000 1-6110088.TheR75n(0326)for1g77
were from 6220001-6220278 (no US model th is
year); the R60/7 (0321) bet ween 60070 01 -600g844
and US(0331) 6101001 -6 101158 Finally, the new
R80!7 (0322) were from 6025001- 6021915 and US
(0332)6122501-6124go9
s1m1lar to the R75/5, but for 2.Smm large• pistons
and cylinders. and the engine type was known as
the Mas·. There was also a lower compression
version (R1. 50 horsepower). The valve sizes were
unchanged from the 750 and the claimed weight
for the 800cc engine (with starter. carburettor
and oil) was 63.Skg. Also new for the R80/7, a
flat-topped Bing carbu rettor wi thout a spring
seating the th rottle valve
There were only detail updates to the rest of
the range for 1g1a. A new camshaft. with the same
duration and va lve lift but advanced 6-degrees.
Engine
wa s installed together with a new camshaft drive
sprocket {without a tachometer drive spiral gear)
and new timing cha in case. Other engine updates
during theyearmcluded Seeger-pa tterncorchps to
For 1978 a new model, the R80!7, replaced the
A7517, although a few R7517s were produced as
1978 models for Europe. The RS0/7 was very
For 1978 ~heRI
w .poJ<
;e
ng1etrontr1
reramed tl
w~.andl
69
THE
BMW BOXER TWINS BIBLE
retain the piston wrist-pins: a redesigned piston
crown for improved combustion: and 'L' and 'R'
cast into the external top surfaces of the angular
rocker covers to make 1dent1hcat1on easier. The
c1rclips and piston updates featured on a\I R8017s
R100S from 6065101. and R100/7 lrom 6045408.
The R6017 also featured a lower compression
ratio this year, down to 8 .6:1 from 9.2:1. This
was achieved with a 0.7mm plate at the base of
each cylinder The gearbox housing was now
pressure-cast1nsteadofch1ll-cast
US examples. from R100RS 6183255: R100S
6163465: R10017 6147574, and R8017 6124338,
now included a double-sided breather ventmg
into both carburettor intakes, and new crankcase
top cover. This replaced the previous single-sided
type. and the new cover featured 'BMW' lettering
cast m each side, as well as an integral air intake
and a T-1unct1on with three breather hoses. At
the same time, US R100s received 38mm header
pipes: a deeper sump: new cylinder heads: new
mufflers. and Bing 40mm carburettors with slightly
leaner 1ett1ng (160 main 1ets) This year. warmer
Bosch W175 T30. Beru 17511413A or Champion
NlOY sparkplugs were spec1f1ed
The R6017 received a new Imai dnve ratio
for 1978, and all US R8017s un11I number 6124337
were fitted with the 1:3.36 ratio. Those after
number 6124338 had the 1:3.20 ratio . There was
also a change to the R10017 US final drive ratio
from number 6147575, now sharing the 1:3.09
of European models. The
R100RS was also ava~able with
an op11ona1 thermostatically
control!ed oil cooler
Chassis
rt: ATC
70
k
perswere
,;Js!lverlmm 1918
yNolanWoodbury/
The /7 frame was unchanged
!or 1978. but the cost of
manufacturing reduced
considerably because the
welding process now
involved inert gas instead
of tungsten-hydrogen. Detail
updates lo the front fork
included: a black cover on the
Mier cap instead of chrome:
a larger 10x13.5mm oil fill
washer (from 8x11.5mm); and
new upper fork spring retainer
Inside the front lork of the
RIOORS, R100S and R10017
were new damper rods
While the R6on. R8on, R100/7 and hrst
R100S and RlOORS retained the trad1t1onal
wire-spoked wheels. during the 1978 model year
the R100S and R100RS received 'snowllakQ
cast alloy wheels. Alt lront wheels featured tw(
larger (40x22x7mm) sealing rings. the wire wheei
received an updated front hub, and the cast alloy
wheels were lacquered to s1mphly cleaning. The
rear 18-mch wheel was now quite different to the
previous optional cast type, featuring a wider
2.75-mch nm and incorporating a drilled 260nu~
disc brake instead of the Simplex drum brake. The
brake disc was supplied by Brembo and featured
the holes drilled m a pattern of alternating two
holes (80 holes m double rows), instead of twos
and threes. later in the 1978 model year these
Brembo discs were also occasionally fitted to the
front wheel. The rear brake caliper was a twin
opposed-piston Brembo with 38mm pistons:
mounted on a large alloy plate and attached to a
pressed·steel brake torque rod . The Brembo rear
master cylinder diameter was 15.8mm
1978 US R10017s. R8017s and R60/7s
featured a single front disc brake, but European
R10017s and R80/7s included a second front disc
On European /7s the cast alloy wheels and rear
d isc brake (of the R100RS and R100S) were also
an option this year
The dual front brakes were unchanged for
the R100S and RlOORS with most silver RlOORSs
retaining the blue anodized front brake calipers.
Other R100RSs, the RlOOS and all /7s included
silver anodized brake calipers instead of black this
year. There was also a special R100/7 for the US
with alloy wheels and a rear drum brake - these
were the same wheels originally offered for the
1977 R100RS. a precursor to those fitted to the
R100Tin 1979
There were several deta•I changes to the
equipment for 1978- The fuel lank now included
a hose atfached to the overflow cavity dram,
directing luet overflow to the ground in front of
the rear wheel instead of on the engine as before
The screw-type fuel filler cap had a matt hnish
While the R100RS famng was much the same.
therewasanew fa1ringheadhg htcoverandhe ad
light rubber. The lower side panels that encircled
the cylinders were split so they could be removed
there
w1thout d1sturb1ng thee~haust system. and
was an add1t1onal metal support bracket. The
RlOORS also received new handlebar clamps
and instrument support, along with a revised
instrur:'lvnt light support and cover. The R100S
and all /7s now featured a vinyl covered loam
pad over the new upper triple clamp. a matt
black tail light housing and. from May 1978, a
new rear mudguard constructed of foam plastic
and painted matt black. The AlOOS now had twin
F1amm horns like the A100RS
were~i;1i~P';'iimiian
ergonomic upgrades
softer Magura handgnps. In
an effort to further improve the
gearsh1f1. the gear lever now
pivoted on the rider's foot peg
attachment and connected to
the small shifting lever with a
U rod that was covered with
a rubber bellows. The pivot
included a grease nipple
Other new features
included a folding cable lock
stored in the frame backbone
tube, and a toolk1t without tyre
levers because they weren't
suitable for the softer alloy
wheels. All dual seats included
the pocket for a first aid kit.
even 11 the kit wasn't included
1n the spec1f1cat1on (as in the US) The R100RS
was available 1n Metallic Gold (546) alongside the
ex1st1ng flat Metallic Silver for 1g75_ The Metallic
Gold RS had black pinstripes, red 'RlOORS'
engine emblems and ' lOOOcc· side cover decals
New colours for lhe R100S included Metallic Dark
Red with Gold pinstripes (553) and red '1000cc'
side cover decals. while the 17 was available m
Metallic Black (532), Blue (533). or Orange (534).
with tank pinstripes as before. Also available for
1978 was a Metallic Red (531). with AlOOS-style
gold pmstnpes and b lack side covers and rear
mudguard The optmnal engine protection bars
and luggage racks were also now black instead
of chrome
n
The most noticeable changes to all / 7s this
year were to the instruments. All the MotoMeter
instruments now had black faces with green
numerals. white needles and non-reflective glass
There was an electronic tachometer (instead of
mechanical). and an electric quartz clock for
the R1005 and RS. A single key operated the
1gn1tion, fuel tank cap, seat and fork lock. On
US models. the head light and tail light operated
whenever the engine was running and there was
no head light ·on1011· switch. US models also had
a loud turn signal beeper, wired to the electric
start interlock. Accompanying this beeper was
a change 1n the 1nd1cator light position to the
lop of the warning light panel. with the brake
failure light now at the bottom_ Completing the
Jrrangom. ,, pm ")(9 pos r o 'J'WselecrlOn
!Courresv Nolan Woo 100ry
Th Mc.t~11e• ~ K1St1 JllJfJ/ ~
had greP.n markwigs horn
1918. (Courtesy
M 'In Woodbury
THE BMW BoxER Tw1Ns B1eLE
The RIOORS was also
availableinGoldtrY 1978.
The
)lour range for 1978
Only rhe R 1OORS was
iv
bJeintheMera.
Gold and >1/ver. dnd a Datk
MPta/lic Red was exclus ive
rotheRIOOS
72
This year also marked the first of several
series of limited ed1t1ons with two hundred
Motorsport. painted white with orange and
blue p1nslnpes and a red head light surround.
It was available with matching white Krauser
saddlebags. and many came with dark blue seat
upholstery. There was also a special US model
A100S without the handlebar fairing, but with
higher R100/7 handlebars, clock and voltmeter
housed in accessory pods and an optional
touring package that included a Luftme1ster
falfing and Krauser luggage. Another special
ed1t1on was the R100S Motorsport. or RlOOSRS.
featuring a 70 horsepower R100RS engine. but
with a smaller S handlebar fairing. The colours
were 1dent1cal to the s1m1lar RlOORS Motorsport,
and equipment edended to s ingle and dual
seats (in blue tnm). engine protection bars and
a kmlh speedometer (with a mph speedometer
1n a separate box). No official data ex ists for
the number of Motorsport models produced.
but they were available 1n both US and non-US
series. US R100S Motorsports were around
numbers 6163000-6163870 and non-US
6067500-6067700. The RlOORS Motorsport
numbers were from around 6183000-6183592
for US and 6088000-6092865 for non-US
spec1f1cat1on
TH E / 7 - S ERIES (TYPE 247)
'7 distinguishing features
1978 model year
New camshalt. camshalt drive sprocket and
t1mmgchaincase
Seeger-pattemp1stoncirclips
Redesigned piston crown
T and 'R' cast into the top of rocker covers
US examples included a double-sided
breather
US R100s with deeper sump, new cylinder
heads.mufflersandleanerjett1ng
Warrnersparkplugs
R60/7 with lower compression ratio
Front fn1c with black cover on the filler cap,
larger 011 lill washer, new upper fork spring
retainer and new damper rods
R60/7, RBOn, R100/7 and first R100S and
R100RS with wire-spoked wheels
Most R100S and R100RS with cast alloy
wheels
All front wheels featured two larger sealing
rings
Rear 18-inch cast wheel with 2.75-inch nm
and 260mm disc brake
Rear brake disc with new drilled hole pattern
New pattern discs fitted to the front wheel
laterinthemodelyear
Rear brake caliper twin opposed-piston
Brembo with 15.Bmm master cylinder
us Rioon, Reon and R60ns with single front
disc brake
R100RT, R100RS, R100S ,
R100T, R100/7, RB0/7, R60/ 7
1979 model year
In the wake of the serious sales slump, virtually
the entire BMW Motorrad management team
was replaced at the end ol 1978. Only those 1n
the chassis department retained their pos•hons
AUd1ger Gutsche and Ekkehard Rapelius_ Dr
Eberhard Sarfert took over as general manager
from Rudell Graf von der Schulenburg and
Richard Heydenreich replaced Hans-GUnter
von der Marw1tz as Head of the Development
Department_ Klaus Volker Gevert repaced Hans
Muth, while marketing and distribution was now
under the control of Karl Gerl1nger. Completing
the new line up was Martin Probst, who moved
lrom automotive engine devetopment to head
engine development. Under this new regime the
boxer line-up was considerably expanded and
revised for 1979
With the release ol the new generation R65
Rest of World R10017 and R8017s with dual
Silver R100ASs retained blue anodized lront
brakecahpers
All other ATE calipers silver anodized
Fuel tank wrth hose attached to the overflow
cavity drain
Screw-type fuel filler cap with a matt finish
Vinyl covered foam pad over the new upper
triple clamp
Mattblacktaillighthousing
Black plastic rear mudguard
R100S with twin Fiamm horns
Instruments with black faces. green numerals
and white needles
Instrument warning light panel with indicator
at the top and brake failure at the bottom
Electronic tachometer
Single key operation for the 1gn1tion, fuel tank
cap,seatandforklock
Softer Magura handgnps
Gear lever pivoted on the rider's foot peg
R100RS included a new famng head light
cover, and head light rubber
R100RS with new handlebar clamps and
instrument support
the R60/7 disappeared from the US hne-up for
1979-though it was produced in small quantities
for other markets through until 1980. There
were now five 1000cc models, with the R100T
filling a void between the sporting A100S and
basic R10017 asa touring machine. Supplanting
the R100RS, with the highest price and most
equipment, was the full touring R100RT. Although
its life began precariously, aimed at the lick!e
US market, the R100RT ultimately established
a formula that was more successful than the
R100RS. The RlOORT lasted through until
1996
There were also other transitory variations
on the /7 theme, some specifically for the US
market - such as the R100S Touring and similar
R100T - because the R100/7 was especially
popular there. The R100T spec1ficat1on also
varied between markets and 1n the US included
standard chrome saddlebag brackets and engine
protection bars; voltmeter; quartz clock, an
electrical accessory outlet; and rear mud flap. But
73
THE BMW BOXER TWINS BIBLE
despite the high spec1hcat1on and keen pricing
($1415 less than the RlOORT), the RlOOT only
sold in very lirmted numbers
With only 24.415 motorcycles manufactured
during 1979, production was the lowest since
1974 In an effort to stem this downward spiral
a RlOORS was prepared for an attempt on a
series of long distance records. In October
1979. at Nardo 1n Italy, a team of four nders
(Di:ihne; Cosutt1; Milan; and Zanini) set five new
world records, including an average speed of
220.71tkm/h (137.14mph) over 100 kilometres
(62. 14m)- the lowered R100RS was only slightly
modified.
Frame numbers for the new 1979
model year R lOORT (code 0386) were
6155001-6157982. with two different
series for the US: 6190001-6 190004 and
6195001-6196039(codes0339 and 0399)_ The
R100RS (0377) numbers were 6095001-6097007
and us (0395) 6185001-6185421; R1oos
(0376) 6070001-6070651 and US (0394)
6165001-6165152, lncludmg 1980 (0436);
two series for the R100T (0344 and 0385)
began at 6115001-6115002, but the general
series was 6150001-6150173. There were
also new number sequences for: the R10017
(0375) 6050001-6051293 and US (0393)
6170001-6170414; and R80/7 (code 0374)
6030001-6030973, us (0392) 6126001-6126349
A small number of 37Kw R75/7s (code
0372) were produced m 1979 with numbers
6222001-6222005. The R60/7 also continued
as 29Kw (0371) with Police TIC (0381) versions
until 1980, numbers 6015001-6015382 and
6117001-6117273 (TIC)
Engine
For the 1979 model year the M65'
engme received its most significant
revision yet. Although the general
spec1ficat1onswereunchanged.there
were several subtle developments
to the camshaft drive, 1gmt1on and
driveshaft. There was also some
engme rat1onahsat1on for 1979, the
RlOORT and RlOOS both sharing
r~~~'.'J;~~~~,i~~~:~
fheR
~T -eplacedthe
R/OOR) flhet>ruclof/he
BMW motoo v 'lo!! range for
1979
74
R100RS,
including the
sameofBing
the
70-horsepower
engine
the
94/40/105 and 106 carburettors and
40mm exhaust header pipes. The
R100T and R100/7 engine was the
65-horsepower version of the 1g7g
RlOOS (with 40mm intake manifolds
and Bing 40mm carburettors) and
also included the 40mm exhaust
header pipes. All the 980cc engines
had 44mm inlet and 40mm exhaust
valves. Like the R100RS, the RlOOT
and Rl00/7 now used the smaller
alternator and Bosch W225 T30 or
W6D. Beru 200/14/3A or Champion
N7Ysparkplugs.
Developments began with
the crankcases which now had
black and silver highlighted 'BMW'
emblems on each side. instead of
an emblem indicating a particular
model and capacity. The AlOORS
had specific crankcases as 11
included an 011 cooler. but all /7s
crankcases included cast main
bearing shells, instead of forged.
with a c1rcumlerenhaf 4.Smm groove
THE /7-SERIES (TYPE 247)
as an add1t1onal 01! supply_ They also all shared
a new crankshalt which incorporated riveted
counterweights to the 1nneJ surfaces of the crank
webs, instead of tungsten plugs. The crankshaft
and balance factor for the 1000cc engine was
the same as that for the SOOcc. The new Vrton
rear crankshaft 011 seal wasn't as deep as the
earlier type and, to eliminate the persistent oil
weep from the cylinder base, from May 1g79 each
cylinder base included a g3x2mm O~ring seal and
modified head gaskets. During 1g7g the oil filter
cartridge was also revised. While the previous
type utilized a paper gasket and steel washer.
the end ol the newer version was crimped to the
outer lube. with the square section sealing rings
glued to the inside ol the filler_ For the R100RS
(and RlOORT} 1here was now a spec1f1c oil filter
with a hinge that provided easier removal and
1nstallat1on with the lull fairing on
All /7s also received a new camshaft drive
With 50-link. single row 3J8J1.7/ 32in chain - now
with a master link to aid servicing_ This ulcluded
a sprmg-loaded. hydraulically damped tensioner,
and there was a new front chain case and
crankshaft bearing cover that assisted 011 flow
to the rear main beanng. The 011 pump featured
a new inner rotor. and there was a new 011 pump
pick-up strainer which could no longer split at the
spot weld. thereby obscuring the pick-up hole and
blocking the d1pst1ck. The chain case now had
ornamental ribbed l1mng, and there was a new
outer cover, without any ribbing but 1ncorporat1ng
additional side vents European models included
the new aluminium top engine cover. with integral
air intake and double-sided crankcase breather
that was fitted on US eJ1.amples during 1978
Some engineers at BMW always believed
that the oil temperature of the 960cc was too high.
so most RlOOAS this year (but not all) included
a standard s1J1.-rOw oil cooler with the outlet
connection at the 011 filter head. Although the
R100RT and A100S shared the 70-horsepower
engine (with black rocker covers). !hey didn't
receive an oil cooler
kfentd1edby wba'1ges
manyengrneupddr, were
1919
,s rheRIOOS
lf'll 'JfP()r<i/ed/or
75
THE
BMW BOXER TWINS BIBLE
fork retainer nut, while a revised clamp secured
the instrument panel more ng1dly to the top
triple clamp All front forks were without rubber
gaiters but included the fork sleeves with felt
seals previously reserved for the AlOORS and
A100S. Setting the RlOORT. RlOORSand RlOOS
apart were black fork legs and the inclusion of
side reflectors on European models- previously
fitted only to US versions. From R100RT number
6232420 and US 6175169, the front fork included
add1t1onal compression spring dampers
Standard on all /7s this year were twm
front discs and cast alloy wheels. The AlOORT
RlOORS and RlOOS retained a rear disc brake
Chassis
Chassis changes were minimal for 1979. generally and 2.75in rim, whereas the RlOOT. R100/7 and
conhned to the equipment The rear subframe R80/7 included the Simplex drum brake with
received longer shock absorber mounts that 2.501n rear nm. The RlOOS now shared its rear
fac1l1tated the filling of pannier mounts The front a~le with the AlOORS. along with the smaller
fork incorporated a new upper triple clamp and diameter (14mm) rear master cylinder
cylinder heads with valve seats more suitable
for low lead fuel and 38mm exhaust header
pipes US models also included a different
engine top cover with slotted grill intake for the
engine breather These developments didn't
1mt1ally feature on the US R80/7s until number
6126147 - which included new cylinder heads;
the revised intake and breather setup; and new
carburettors (64/321321 and 322)_ From August
1979. all the R80/7 c arburettors reverted to the
domed top type
76
THE /7-SERll
(TY E 247)
This year the standard seat lor !he RlOOT.
A100/7 and ASon was the same type as on the
RlOOS, with a hbreglass base and !ail section
This included a larger black grab rail and new
sear cushion, but the older style seat was still
available. In add1t1on to the n ·s eiusting Red.
Black. Blue and Orange colour options. the RlOOT
was available 1n a special Red Metallic/Silver
Metallic (556) wrth silver side covers Other f 7s
were now with black side covers. A specific colour
for the US was Havana Gold Metallic {511) The
side cover decals indicated the model type 1n
addition to the capacity. Twin Fiamm horns were
included on all 1000cc models and US R100/7
and RSO ':'~ also featured the broader 682mm
handlebar of the R100RT. Complellng the 1979
upgrades were new handlebar switches. with a
more conventional left-side turn signal indicator
switch. and the unconventional location of a horn
button just above. The Magura handgrips were
larger and reshaped. and setting off the rear was
a new double chamber twin bulb tail light and
black housing
Expanding on the AS integral cockpit
concept, the R100RT famng was also developed
in a wind tunnel. Even with the high and
wide 690mm handlebar. the frame-mounted,
pressure-moulded fibreglass faJring was able
to provide hand protection. The high windsh1etd
was manually ad1ustable for three rake (over 10
degrees) and height pos1t1ons. Air intakes under
the tum indicators channelled aJr into the famng
through automotive style ad1ustable air vents with
a butterfly valve
The lefl tum signo ;v.XI'
was on me lefl hand/.Jbar fr
1979. 1<:-ourresv
Nolan Woodbury!
77
T HE /7-SERIE S (TYPE 247)
The head light cover with the same strange
five orange Imes was earned over from the R1 OORS
The instrument panel was similar to that of the
A100RSwoth an electronic tachometer: voltmeter;
quartz ctock: and speedometer There was
room for add1t1onal switches and control lamps
necessary for any of the wide range of optional
extras These initially included long-distance
headlampsandfoglamps.andlater.fhpoutdnv1ng
ljghtsmplaceofthea1rventsllketheR100RS,the
RlOORT had a restricted 70-degrees of steering
lockduetothepanel fitting around the fork tubes
The fork tubes were also sealed 1n the fairing with
rubber boots. and the lront of the lairing included
the open ynll of the pre-1g7g RlOORS
The fairing also included two large (6-htre)
lockable storage compartments beneath the air
vents. but there were some problems w1ththe early
model lids so these were replaced during 1979
The rearv1ew mirrors mounted onto the fairing and
there were new. stronger mounts from number
6165365and US6196836. The R100RT came with
luggage racks for the standard lockable Krauser
saddlebags and 11 shared the steering damper
and twin Fiamm horns of the R100RS. Standard
equipment also included a 12 volt socket behind
the left-hand battery panel; a cable lock (with yet
another key): and a heel-and-1oe rocker gearsh11t
pedal. Setting the A lOOAT apart lrom the R1 OORS
were cast wheels. painted a hue of Light Phoenix
Gold, and colours of two-tone Brown Metallic {552)
and Phoenix Gold Metallic_ The other colour was
Smoke Red. wrth Silver wheels{555). There was a
different seat with strengthened upholstery and,
although the upholstery was beige m the publicity
brochures. production examples were black
While the R100RS bodywork was as before.
the inclusion ol an 011 cooler resulted in a new
solid centre lower fa1nng panel. A dual seat was
now standard. with a larger black passenger grab
rail that included a rack. The solo seat remained
an option and, in add1t1on to metallic gold. there
was a two-tone Blue/Silver Metallic woth Red
pinstr1ping (554)
){TJ<11919RI
p;,mednPt.Jf/Jcbrowr w h
gbr goldwbee
The :llosear w,
s
in )(.'~ion
~'
the
Rlf"XJ '
?le im ~·-ld e<JitlC
M.Jurer ·yfe(JR100
a.s:n
80
yr&il
JC.~
were also matching light
silver. Unfortunately. the
blue stripes were stickers.
and this R100S was greeted
by BMW 1rad1t1onahsts w11h
d1sapprova!sothemodelwas
veryshort-hved
T HE 17-SEAIES (TYPE 247)
17 distinguishing features 1979
model year
Crankcases with black and silver 'BMW'
emblems on each side
New crankshaft with riveted counterweights
New rear crankshaft seal
Cylinder base with 93x2mm 0-nng seal
New 011 filter cartridge
A100RS and AlOORT with hinged 011 lilter
New camshaft drive with single row chain
Hydraulically damped chain tensioner
New front crankshaft bearing cover
New inner oil pump rotor and pick-up strainer
Chain C'\Se with ribbed fining and new outer
cover with side vents
All models with double-sided crankcase
breather
Most A100RS with an 011 cooler
Rear subframe with longer shock absorber
mounts that facilitated the fitting of
pannier mounts
New upper triple clamp and fork retainer nut
No rubber gatters on front !ork for RlOOT,
R10017 and R8on
AlOOAT, R100RS and RlOOS with black fork
there further price increases. the venerable
M65' engine was struggling to meet noise and
emission requirements whilst still maintaining a
respec1able power output As the price continued
to climb in America while the performance
d1m1rnshed, sales stagnated to such an extent
that only 3866 1000cc models were sold 1n the
US during 1979 and 1980
The production codes were unchanged for
1g50 but the engine received some evolutionary
developments. This was an interim solution
until the more efhc1ent AlO engine appeared
for 1981. Offered m lhe US this year was a
sport version of the R100T that included a low
handlebar and lamng. Frame numbers for 1980
were. R100AT 6157983-6169354 and US
61g6040·6196851 ; A100RS6097008-6100000.
6223001-6223330 and US 6185422-6185519.
R100S6070652-6071951;A100T6150174-61 50396:
R100/7 6051294-605363Sand US 6170415-6171344
and A80/7 6030974-6032475
'""'
Front fork with side reflectors
All with twin front disc brakes and cast alloy
wheels
R100RT, R100RS and A100S with rear disc
brakeand2.751nr1m
A100T, R10017 and R8on with rear drum
brakeand2.50innm
Brown RlOORT wheels pain!ed light Phoenix
Gold
Standard seat R100S-type with a fibreglass
base and tail section
Side cover decals indicated the model type
and not only the capacity
Twin F1amm horns on all 1000cc models
New handlebar switches
N- t win bulb tail light assembly
Larger and reshaped Magura handgnps
A100RS lairing w1l h solid centre lower panel
A100RT, A100RS, A100S,
R100T, R100/7, RB0/7 1980
model year
As most developmental resources were now
dnected towards the new K-ser1es and dual
PLirpose G/S. the 1980 larger boxer twins were
()fo1ens1b!y 1dent1ca1 10 those of 1979. BMW still
laceO many problems 1n the US. Not only were
81
THE BMW BOXER TWINS BIBLE
Engine
Several mod1lica!ions were made to US models
for 1980. primarily to allow them to run on
low lead or unleaded regular fuel, but also
to enable the engine to pass more stringent
EPA requirements. The combinat1on of a hrgh
compression ratio and lower octane fuel caused
detonation on 1979 US models, and from August
1979 all US 1000cc and 800cc models had
a lower 8.2:1 compression ratio and smaller
diameter (38mm) exhaust header pipes. The
claimed power for the 1000cc models was now
67 horsepower at 7000rpm. US models also
featured a redesigned sand-cast aluminium
air filter bmt with a flat air filter and twin snorkel
air intakes. 1dent1cal in design to the plastic
air box that would appear for 1981. The metal top
engine cover. also with 'BMW' cast into each side.
incorporated ten grill vents instead of an intake
bell. There were still three crankcase vent1lat1on
hoses. but the air filter and filter box we re
redesigned with a flat (instead of round) pleated
paper filter. The housing itself was sand-cast
aluminium and included a top with two snorkel
air intakes. Access to the filter was much easier
than before, as four spring clips located 1t.
The new intake system was intended to lower
intake noise while increasing volume -11 was so
successful that 11 featured on all 1981 engines
(albeit in slightly modified form). Comple11ng
the intake modifications (on US bikes) were two
10.5mm diameter tubes connecting the air filter
box to a threaded connection from each exhaust
l1
M<1nyLJ.,,; RtOOTswers
fitted out w11h optional
tr 1.mng equipment to
;timul<lte sra9nat1ng sales
82
port in the cylinder head. This Pulse-Air suction
em1ss1on sys tem was similar to one already
used by Kawasaki. and included a one-way
reed valve in the a1rbox. It was an endeavour to
reduce the level of un-burnt hydrocarbons by
m 1x1ng the exhaust gases w ith clean air. There
were also hotter sparkplugs specified for US
models: Champion N7Y or Bosch W6D. The
larger boxers for the rest of the world included
the crankcase ventilation and air intake of the
1979 US bikes for 1980. The A100T and Rl00/7
now featured black rocker covers in line with
the RT, AS and S
The other evolutionary development was
in the lubrication system. As a direct resul t of
experience gained through racing. from January
1980, the front 011 passage in the camshaft was
altered to send the oil three ways. Oil now went
to the new front main bearing bushings and
caps first, followed by the camshaft and the rear
main bearing. Previously, oil was fed initially to
the camshaft. then to the front main bearing.
with the rear main bearing last in the line. The
new crankcases we re 1dent1fied by 'ALCAN' cast
next to the clutch flange. There was also a small
update to the lubrication bores on the rocker
arm needle roller bearings, now diagonal instead
of straight. These updates were incorporated
from frame numbers: RlOORT 6158745 and US
6196045: RlOORS 6097660 and US 6185422;
A100S 6070786 and US 6165103: R100T
6150266: A100/7 6051658: R80/7 6031545 and
US6126171.
THE 17-SERIES (TYPE 247)
US models from Augus1 1979 (A100/7
6170415; R100S 6165103: R100RS 6185422;
A100RT 6 196045) included another set of Bing
carburettors. with revised Jetting (165 main 1ets
and 2.66 needle Jets) and a new choke housing
All the Bing carburettors included a new slide
top spring, and for 1he R80/7 new carburettor
pistonshdes
...
R60/7
Chassis
While there was little to visually d1st1ngu1sh the
1980 European boxers from the 1979versions. US
models included a few further updates: The choke
lever was moved to the clutch lever handlebar
bracket oecause there was no longer room for 1!
on the new air fill er box. The throttle cable setup
included a single cable connecting to a junction
with separate cables for each carburettor. There
were new convex mirrors, the under seat tool tray
now had a cover and audible turn signal beepers
were ehm1naled. Completing 1he developments
this year, was a federally mandated 85mph
speedometer. The colours for the AlOORT and
R100Swere unchanged for 1980. but the R100RS
was now avarlabte 1n the previous Dark Blue and
Silver (554) and Silver Beige Metallic (547). Three
colours were provided Ior the R80J7; Bronco Brown
{588): Dark Blue Metallic (550); and Metallic Red
(531). By 1980, 11 was obvious !hat the 1000cc and
800cc boxers had a limlled life m their current form
Although BMW management was committed to
thewater-cooledK-serie s.BMW"sengineerswere
also planning the next generation boxer twin. This
would be released for the 1981 model year.
17 distinguishing features
1980 model year
US versions with 8 .2:1 compression ratio and
38mm exhaust header pipes
US models with alum1mum air filter box, flat
filter and twin snorkel air intakes
R100T and A100/7 with black rocker covers
From January 1980 the front 011 passage in
the camshaft altered
Updated lubncatton bores on the rocker arm
MM:lle roller bearings
models With new Bing carburettors
models wrth choke lever on the clutch
--
R75n
- -17 frame numbers
Production dales
6000001-6005517
1977
05176-06/77
6007001-6009844
1978
07/77-12/77
6010035-6011412
1978
12n1-01115
6015001-6015382
1979-80 (29kW)
09/78-04/80
-
6117001-6117273
1979-80(TIC)
09/78-06180
6100001- 6100407
1977{US)
06176-05177
6101001-6101158
1978(US)
00n1-11n1
osn6-06n1
6020001-6024507
oen7-04178
6220001-6220278
1978
6222001-6222005
1979
6120001-6121474
1977 (US)
07176-06/77
~
R80/7
Rl00/7
-
01179
6025001-6021915
1978
04n1-01n8
6030001-6030973
1979
06178-08179
6030974-6032475
1980
09/79-06180
6105001-6105003
1978 A80 (TIC TN)
06178-07178
6108001-6108276
1978 R80 (TIC T)
06178-08178
6205001-6206315
1979-80 (37kW)
06178-07180
6130001-6130118
1979-80R80T(37kW)
09178-07/80
6132001-6133186
1979-80 R80T (41kW)
09/78-07/80
6122501-6124909
1978{US)
04177-07178
6126001-6126349
1979-80{US)
08178-07/~i:_
6040001 -6043414
1977
05n6-06177
6045001-6047995
1978
6110001-6110088
1978 R100/7(T)
03178-04n8
1979
06/78-08n9
6050001-6051293
04n7-0an8
6051294-6053635
1980
09n9-01100
6140001-6142451
1977 (US)
05n6-06/77
6145001-6146196
1978(US)
01n1-01n9
6170001-6170414
1979(USJ
09/78-08n9
09/79-07/80
6170415-6171344
1980(USJ
6115001-6115002
1979
07178
._______ ~50001 -6150173
1979
11n0-01119
R100T
83
THE
BMW BOXER TWINS BIBLE
6150174-6150396
R100S
R100RS
R100RT
lnf
84
eoeooo1-eout4I
..,,.
1980
6065001-6068753
1978
6070001-6070651
1979
-
09f79·07/80
04/77-07n8
06/78·07n9
6070652-6071951
1980
09/79-07180
6160001-6161385
1977(US)
05176·06/77
6162501-6163870
1978(US)
07177·07/78
6165001-6165152
1979·80(US)
08/78-09/79
8080001·6085159
1977
03f78-oem
6086001·6092865
1978
04/77-07n8
6095001-6097007
1979
06/78·08/79
6097008-6100000
1980
09/79-06180
6223001-6223330
1980
06180-07/80
6180001-6181263
1977 (US)
05176-06177
6182501-6183592
1978(US)
04/77-07/78
6185001-6185421
1979(US)
oana-om9
6185422-6185519
1980(US)
11/79-06180
6155001-6157982
1979
Olll78-00l79
09/79-07/80
6157983-6169354
1980
6190001-6190004
1979(US)
04/78
6195001-6196039
1979 (US)
08178-07/79
6196040-6196851
1980 (US)
09179-07180
\/V\1\/)1\/.veloce.co .uk & www.velocebo oks.com
n ~I
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I
CHAPTER V
RIOO & R80 1981-85
(TYPE 247)
C
ontmualrefinementolthe1000ccb.oxer
engine resulted in its qu1ntessent1a l
development for 1981. W ith s1gnil1cant
improvements to the engine and chassis, from
1981 until 1984 the RlOO boxer represented
the culmmat1on of a classic design_ Al though
the later monoshock twins were lunct1onally
superior. the twin shock BMW was more
aesthetically balanced. mamta1ning a trad1t1onal
class ic profi le
R100RT, R100RS, R100CS,
R100 1981 model year
A rationahsat1on of the line-up coinc ided w ith
the introduction of the improved A10 engine for
1981 . The R100RT and RlOORS continued with
a similar style, and the R100S evolved into the
RlOOCS. There was now only one basic model
in the range, the RlOO. Al though still o ffered
for police applications as the R80TIC. the only
regular 800cc model this year was the R80 G/S
Its outstanding success led to a prohferat1on of
800cc ~ers 1ons dunng 1982 and 1983
Frame numbe r s for 198 1 were
8i29 l:::::~~R1,,~
=~~o~~ ~~~~= ~::~~ ~~;ggg~~:i;122and
AlOORS (0427) 6075001-6080001
US (0437) 6225001-6225628; AlOOCS
{0426) 6135001-6136503 and US
(0436) 6188001-6188163; R100 (0425)
6035001-6037528 and us (0435)
6175001-6175593; there was also a pol ice
,..,...,..,,....._.,
R100TIC(0445)6193001-6193433
Engine (Type A10)
There were many more engine updates this
year. beginning with crankcase strengthening
underneath the starter motor The AlOORS
had spec1f1c crankcases as 11 was still the only
model with an 011 cooler. the RlOORT sharing
the engine housing with the RlOOCS and R100
All crankcases included mod1f1ed 011 passages;
a deeper sump cover with transverse 011 baffle
plates; new dram plugs, and d1pst1ck. This
increased the 011 c<1pac1ty to 2.75-htres on
the R100RS (with the standard 011 cooler) and
2.50-lotres on the other RtOOs, resulting m lower
oil temperature. The R100CS shared the engine
of the AlOORT. along wi th black rocker covers
One of the main updates was new cylinders
N1cas1I (by Mahle of Stuttgart) or Galmkal
{by Kolben-Schm1dt of Neckarsulm). Later
86
supplies were also obtained from the Italian
manufacturer, Gilardoni. AU the coatings
were 1dent1cal but for the brand name. Instead
of lining aluminium cylinders with cast-iron.
silicon-carbide was applied directly to the
a/um1mum cylinders. The we19ht-sav1ng was 3.4kg
with wear qual1!1es s1gmficantly improved The
cyhnders could no longer be rebored. and were
matched to the piston: however. with improved
heat d1ss1patron. wear was virtually nonex1stent
No liquid sealant was used at the base of the
cylinder. and the 0-ring was increased from 2mm
to 2.2mm. The rear cylinder studs were now the
same as the front (305mm), and the piston pm
offset from the cen treline was reduced to 1.0mm
{from 1.Smm). While European examples retained
the 9.5:1 compression ratio. producing the same
70 horsepower but at a slightly lower 7000rpm.
us models st11! had the lower 8.2:1 compression
ratio. There was no claimed power figure for US
81lamples
The crankshaft was unchanged, except
for a new tock ring and thrust washer for the
substan11ally lighter pressed- steel (rather
than billet-cast) flywheel This was akin to a
three-spoked cross w1lh riveted ring starter
gear, theflywheelO-nnginsidethellywheel
'"
·~~:~;,,~:::::;~;:";~.~~: '::
-rer
new exhaust valve seats. The
exhaust valve seat width
was reduced from 2.0mm
to 1.Smm, although valve
recession from lead free fuel
was still a problem in the US
The crankcase vent1lat1on
on all 1981 models was now
the same revised diaphragm
controlled double- sided breather that
first appeared on US 1979 examples. This
included the new vented top engine cover and
a revised cham case cover (to accommodate
thenew1gnit1on) -nowwith blackh1ghlight1ng
between t he ornamental lmmg, previously
reservedforthesmallerR65
Experience with the smaller R65 proved
the benefits of a lighter clutch and flywheel,
especially in combination with the driveshaft
shock absorber. and this was passed on to the
AlOengine. Thethmner(S.Smm) 165mm clutch
also had a stronger diaphragm spring and
assembly was reduced from
6kg to around 2kg, with a vast improvement
in throttle response. This new clutch was
accompanied by a new operating mechanism running 1n ball-and-needle bearings - that included
a new pushrod. clutch piston. and gearbox end
clutch 1ever.resul1mg ma JO per cent reduction
(100Nm to 70Nm) m draw effort
The/xJ\ ef"engJl1efOOlured
amuchllg/lrer-cJutch
assembly from I 981
Engine updates lflciuded
1igmerancfharder-Wt.'<lnf'9
Ml<aSJ/orGaiml«:. ·yhndefs
87
THE BMW B oxeR Tw1NS 8 1eLE
i>l>Jr
'1'
The live-speed transm1ss1on ratios were
unchanged, but there was a new mo1n shoft drive
p1mon and seal. and input shaft. Other updotes
included a new rear transm1ss1on cover. new kick
start ratio and spline for the optional kick start,
ond Heim 101nts for the gearsh1ft mechanism.
Dunng 1981, the black 'FW2' gearbox 01! seal was
updated to a 'KACO' seal to eliminate 011 leaks
between the gearbox and swmgarm. While the
shaft dnvetunnel m theswingarm was now a single
component. and only flattened on the inside. the
dnveshaft ramped coupler shock absorber was
new. The Imai dnve pinion needle outpu t bearing
wasnow15x30x18mm(insteadof15x32x17mm)
and the dnveshaft gaiter received a new hose clip
Completing the new rear end was a lighter and
stronger pressure die-cast final drive housing
s1m1lar to that ol the monoshock RSO G/S. and 1t
also included fins for improved cooling. US R100s
retained the 1:2.91 final drive. with the European
R100fea\uringthe 1:3.0ratio
The new 40mm Bing carburettors included
a more pos1t1ve location for the throttle slides,
with a supplementary piston gu1deway. There
was also the new flat pleated paper rectangular
air filter and a1rbox design that featured on 1980
US models. Although the a1rbox was the same
design, the body and top were now black plastic
rather than cast-aluminium, with two removable.
forward facing plastic snorkels. The smoother
plastic f1msh was claimed to reduce turbulence
and restnct1on, perm1t11ng leaner Jetting, and the
new setup also allowed easier access to the air
filter. US versions retained the twin air intake
pipes but now incorporated a vacuum shut-off.
connected to the reed valve inside the a1rbox
TheRrOORSre•
BmgcartJ;rerr
TwoW~
There were some changes to the exhaust
system, all models now recewing the 38x1.Smm
diameter exhaust pipes previously reserved
for the R80 and US versions. An add1t1onal rear
crossover balance pipe behind the sump helped
broaden the power band _Completing the exhaust
updates were new exhaust spider nuts and more
efficient mufflers, with spec1l1c mufflers for the
us
All A100s received an updated electric al
system including a more powerful Bosch Gl 14V
20A280W anernator: new micro element electronic
Wehrle E1951B/14V voltage regulator; improved
battery charging; and a Q_7kW Bosch starter
motor to ensure the engine turned over reliably
every time One of the more prachcal updates
was the Bosch TSZH eleclronic ignition. This
trans1stonsed bfeakerless system used a Hall
effect trigger w ith integral centrifugal advance
andtwolighter6Vcoi ls, thet,ming(advancefr om
1550-3000rpm with 32-degrees maximum) was
unchanged. The spaf1(plugs{ona111 OOOcc models)
were Bosch WSD, Beru 14- SD or Champion N6Y
for Europe, US sparkplugs were Bosch W6D,
Beru 14-60 or Champion N7Y. Also new. the
BMW Mareg28 Ah battery and Hella TBB 53 turn
s19nalmd1catorumts
with 95mm of trail, but a new rear subframe
imp roved access to the battery_ BMW"s
engineers learned from their development of
the monoshock ABO G/$, designing a stiffer
swing arm with an additional cylmdncal tube The
sw1ngarm included new pivot pins. seal nngs and
tapered roller beanngs - these bearings were
c hanged again 1n January 1981. New chassis
1dent1f1cation plates were fitted from April 1981,
and all 1981 A100s included a warning plate
regarding the transistorised 1gn1t1on
W. mmg s' Cicers aooun 'led
'"
mBt\!Mlm.::.ll'c
N
' G-
Chassis
The !rame and sw1n9arm received some subtle
updateslor1981.Therakewasst11128.5 degrees
89
THE BMW B OXER T w1Ns B 1eLE
Afthough the cast-alum1mum 'snow flak.e'
wheels look.ad s1m1lar to before. the front wheel
on all A100s was now a wider 2.15B•19m. The lyre
size (3.25Hx19) was unchanged. The rear wheel
on the R100RT and A100RS remained 2.758•181n
with a 4.00Hx18 tyre_ Unlike the R100S with its
rear disc brak.e, the R100CS had the narrower
2.508x181n rear wheel with a rear drum brake_ This
rear wheel, together with new brake lever, brake
shoes. and rear brake cam. was also shared by
the R100_ All wheels were silver. with the special
R100RT Phoenix gold discontinued
R100 & R80 198 1-85 (TV'PE 247)
While some brochures and catalogues
showed the AlOOCS with w1re·spoKed wheels
and plain alloy forK legs. most examples had
black fork legs and cast wheels. The A100CSs
!eaturmgw•re-sp0Kedwheelswereso ldpr1manly
1nAustraha. with different hubs to theearhertypes
and new distance bushmgs The alloy rim sizes
werethesameastheA100Sol1977.a 1.85Bx19m
on the front and a 2.15Bx18m on the rear. with an
action saw 011 transferred !rom the top to the
lower chamber. with the shock eventually settling
at a point determined by the controlling onf1ce
1nthecentralpumpmgrod Al!hough thesprmg
travel was reduced to 85.Smm. lhe shocks
were extremely eflechve and the N1vomat was
the most advanced suspens•on available for
a touring motorcycle m 1981 . Unfortunately.
troublesome seals tarnished the N1vomat's
While retaining the relatively narrow 36mm
forK tubes. the Sachs-built front fork was new.
and each leg required less fluid (220ml). although
the spring travel was unchanged. Although most
AlOORTs, RlOORSs and R100CSs had black fork
legs this year, on some R100s they were plain
alloy. The forks included shorter (539mm). but
thicker (4.25mm). springs and new dampers. The
fork legs were cast to accept the rectangular
reflector. The fork design was changed during
1981 (from A100RT 6232420 and US 6175169;
A100RS 6077830; and RlOO 6193063) to include
an add 1honal compression coil spring at the
base of the damping rod. Although the rear
Boge shock absorbers were unchanged. the
A100RT featured sell-leveHmg N1vomat units
that were optional on other AlOOs. The N1vomat
incorporated a high-pressure otVgas chamber in
the lower part ol lhe body, with a low-pressure
chamber •n the top. Repeated shock absorber
Magura front brake
mastercyhndertothe
handlebar. vastly improved braking performance
from 1heearher ATE floatmg piston cahpers. Wet
weather braking was claimed to be m1proved by
40 per cent The master cylmder p1s\on diameter
was 15mm(downlrom 16mm).andthefrontbrai..e
Imes included a T-1unct1on with pressure switch
n
fr
91
I_
THE BMW BOXER TWINS BIBLE
located on the top frame tube. underneath the
fuel tank The same Brembo disc as before was
at the rear. but with the smaller 14mm master
cyhnderof the 1979 RlOOS to provide an improved
leverage ratio
Although the speedometer. head light and tail
light were unchanged. the electronic tachometer
was new. with the RPM md1cat1on on the lower face
The new instrument light display included a 'H•gh
Beam' warning hght at the bottom. replacing the
'Brake Failure· item. US versions still had
the 85mph speedometer and hard~w1red
head light this year. The R100RT and
RlOORS retained the two-stage hydrauhc
steering damper, and the side and centre
stands were redesigned with rubber plugs
on the base of the centre stand. The side
stand was no longer self-retracting and the
centre stand was 10mm longer. Along with
a new rear turn signal mdicator bracket
there was a new set ol lootpeg mounts to
reduce v1brat1on - in a slightly higher and
more rearward location. This provided
more space between the rider's feet and
thecarburettors.thethreadholesnolonger
painted to minimise thread wear. The
passenger foot pegs were adjustable_ There
wasarecalleartyin 1981 toreplacetheright
side footpeg, as its location could prevent
ease-of-operation of the rear brake. While
the remote gearsh1ft linkage was s1m1lar to
the previous version, there was no longer
a grease nipple at the pivot
A100 & A BO 1981 85 _~T'l'PE 247
The Cl>Oka lev6' was
the left handlebar
Nico Goorgeo?Jou
All R100s now had the choke lever on the
left handlebar clutch assembly. The Magura
throttle assembly retained the e)lcellent cam
and chain system, but was of the type lilted to
1980 US models, with a single cable connecting
to a 1unct1on block and two cables running to
each carburettor. This was claimed to reduce
new throttle assembly was a throttle stop. New
blackroundmirrorswerefittedtotheR100CSand
R100. The frame tube cable lock still featured on
the A100RT, R100RS and R100CS (optional on
the R100). The 1gnit1on key location remained on
the left head hght mount and. while the A100CS
retained twin F1amm horns, the A100 still had
Acal)le/ot.>.wa~ptCNKJea
on most RIOOs, as was a
tyrepump {Courtt•Sy
N< - 0 93
THE BMW BoxER Tw1Ns B IBLE
A-;I ·;~;:·~,RIVORS for
........... and gold
94
R 100 & ABO 1981 -85 (TYPE 247)
New colours were also
available for the R100RS
Polaris Graphite Metalhc
(507) or Lava Red Me1a!hc
(508)-both without p1nstnpes
and white side cover decals;
Stratos Silver Metallic with
red pinstripes: and a John
Player Special Ed1t1on,
released to coincide with
theracmg6-seriesJPScars,
black with gold wheels and
decals. Most R100CSs were
Classic Metallic Black (506)
with golC ;Jinstnpes but they
were also available in Dunkel
Red Metallic (553). Although
the most popular colour for
theR100wasMetallicS1lver
with Blue pinstripes (505). 11
was also available 1n Black
(519) or Metallic Atlantic
Blue (504). The R100CS
had specific 'RlOOCS" side
cover decals this year. A
wide range of optional
equipment was available
for the RlOO. extending
to engine protection bars:
Nivomat shock absorbers;
electrically-heated handlebar
grips;wh1teorblackpann1ers;
magnetic tank bag; addrtional
instruments. and super
toolk1t. The optional touring
windsh1eld for the R100 was
redesigned. with simplified
mounts.
R100 distinguishing features 1981 model year
Strengthened crankcases with modified oil
passages
Deeper sump with new dram plugs and
dipstick
N1cas1I or Galn1kal cylinders
Cylinder base 0-ring thickness increased to
2.2mm
305mmrearcylinderstuds
Piston pm centre line offset reduced to 1.0mm
Lighter pressed-steel flywheel
Thinner and lighter clutch with stronger spring
and plate
New clutch operating mechanism with ball and
needle bearings
Exhaust valve seat width reduced to 1.5mm
Double-sided engine breather
New vented top engine cover
New chain case cover
New gearbox main shaft: drive pinion and seal;
and input shaft
New rear transmission cover
New kick start ratio and spline for the optional
kick start
Heim joints for the gearsh1ft mechanism
New driveshaft ramped coupler shock
absorber
S\ro119er final drive pinion needle output
bearing
Lighter and stronger pressure die-casting final
drive housing
New 40mm Bing carburettors
Flat paper rectangular air filter and plashc
a1rbox
All models with 38mm exhaust pipes and
additional rear crossover balance pipe
R100RT, R100RS, R100CS,
and R100 1982 model year
With most developmental resources going into the
forthcoming K-ser1es. there were few changes to
the 1000cc boxer twins for 1982. A100 production
codes were unchanged for 1982 and frame
numbers were RIOORT 6232900-6236-060 and US
6241233-6242332; R100RS6390001-6392801 and
US 6225629-6226208: R100CS 6136504-6138122
and US 6188164-6188166; Rl 00 6037529-6040000
and US 6175594-6176319. An Rao was also
produced ror official use and used as the TIC
Pohcemodel
Engine and transmission
As most engine and transm1ss1on updates were
More powerful Bosch 280W alternator
Bosch TSZH electronic 1gn1t1on with 6V
coils
New rear subframe provided improved battery
access
Stiffer swingarm with an add1t1onal cylindrical
tube and new bearings
Wider 2.158x1g1n front wheel
R100CS with 2.50Bx18in rear wheel and drum
brake
New 36mm front fork
RlOORT with self-levelling Nivomat rear shock
absorbers
260mm front disc brakes with twin piston
Brembo cahpers
Magura front brake master cylinder located on
the handlebar
14mm master cylinder fOI' rear disc brake
New electronic tachometer
New instrument warning light display
Redesigned side and centre stands with the
s1destand manually retracting
Centre stand 10mm longer
New footpeg mounts to reduce v1brat1on
Footpeg thread holes no longer painted
Choke lever on the left handlebar clutch
assembly
Throttle assembly with a single cable spl1t11n9
into separate cables to each carburettor
Front mudguard with a new metal brace and
shorter mounting bolts
R100RT with closed centre farnng section and
new windsh1eld
introduced for the 1981 model year. engine
developments were minor this year. The protec11ve
tube pushrod rings were now braised onto the
cylinders to increase the pre-load on the rubber
seals and prevent 011 weeping. Early in 1g82. the
crankcase finishing hole plugs were updated and
the oil filter seal was a 4mm 0-rmg instead of a
washer and paper gasket. The oil dipstick was
also changed from silver-grey to black
The transm1ss1on also received some
developments early in 1982. From R100RT
6234533 and US 6242150; R100AS 6390466 and
US6226148; R100CS6137305; R1006039007 and
US 6175989; R806012gJ8, and ABO TIC 6211170,
the gearbox series number was placed on !he side
of the gearbox housing instead of the top. enabling
the number to be read without removal of the
95
THE BMW BoxER Tw1Ns BIBLE
wa •'!SSet"'I· '"
11,
'k.
µ
~bb<
air filter housing The gear selecting mechanism
was updated after gearbox number 56 476 to
improve gear selection. A green paint mark was
placed above the gearbox number, md1cat1ng an
improved hair pm selector spring and selector
d1sc, andamechamcaldev1cems1alledtoprevent
m1s ·Sh1ft1ng. Further gearbox improvements
occurred from gearbox number 58225 on models
R100RT 6235211. R100RS 6391446. RlOOCS
6137659. R100 6039576 and US 6176014 The
transmission rece1ved new helical input primary
gears and a new filth gear. To reduce noise and
wear the mesh angle was now 17_5 degrees, and
the new gears were marked with a cross. Improved
clu tch plates and a fully enclosed clutch housing
were standard from June 30th. 1982, model
numbers: R100RT 6235850; RIOORS 6392366
and US6226174. RlOOCS 6137944; R1006040199
andUS6176211.R100TIC6193369;R606012984
R80 TIC 6211523; R80RT 6420016
R100 & R80 1981 -85 (TYPE 247)
Chassis
Frame updates lor 1982 included strengthening
of the side stand frame mount. and a new side
stand. The side stand now featured a corrugated
stepandrubberstop,andwasspnngloaded This
mod1f1cat1on occurred after RlOORT 6234677;
RlOORS 6390944; R100CS 6137484; R100
6039221. and R806012949 Shortly afterwards,
the frame number was stamped on the right
downtube, above the side stand instead of the
steering head, from frame numbers R100RT
6235895and US 6242301; R100RS6392466and
US 6226176; R100CS 6137994; RlOO 6040238
and us 6176222; RlOO TIC 6193423; R80
6013030; RSOTIC6211546; R80RT6420171 and
US 6172020_ Early m the model year (week 49,
1981}. the frame radius was altered to provide
eas1eraccesstotheo1lfiltercover
Other minor developments this yearincluded
a one key lock and the R100RT N1vomat shock
receiving an el<.tra spring to ensure 11 could
handle a full load. These shocks were marked
with an 'l' on the lower mounting hole. Many
Karcoma (but not Germa) fuel petcocks now
had the feed angling backwards instead of
down to clear the throttle and choke cables
The optional 40-hlre pannier bags were a new
rectangular style, with an omproved latch to the
frame mount New rear turn signal indicator
brackets featured on US models from R100RT
6242152, R100RSs 6226150. R100CS 6188165,
and RlOO 6175996
c;;)fJJ('RIOORSs weri
offeredmwfl.•owth
redpnstripes ro
<ii;
iC::>wtt1Sy.JelllNh1f.lockt
MxKir~p;.1tr
I<.
TfleRSRth1Sat 1r/Jef
hm11tld etMIOfl RIOOR::O
97
THE BMW BOXER Tw1NS BIBLE
The range of colours was also e)(panded
slightly for the 1982 model year. The R100RS
was available 1n an optional Mother-of-Pearl
Metallic White (571) with red pinstripes. There
was a numbered limited ed1t1on R100RSR in Black
with white and red pinstripes, primarily for the
Japanese market The A 1OOCS (colours unchanged
1••!11•!1111!!1
fhl..Rl1 JRS ·/•Uhadanoil
COOier U'd clo5tJd central
f. lf'l9 ec:ion Bluewasone
comffl'Jn :oJours
lflhe
N
"""''
lrom 1981)was still
available in Europe
for1982.w1thblack
fork legs and cast
alloy wheels, but
was dropped from
the official US
line-upeven though
a very small number
were manufactured
Instead of the
two
A100CS.
verS1onsoftheA100
were offered 1n the
US; the Touring and
the Sport _The Sport
came with the CS
sport fairing and
narrow handlebar
as standard, while
the Touring was
fitted with standard saddlebags. Both these US
model R100s included non-painted fork legs and
black rocker covers; 'RlOO' side cover decals:
and cast alloy wheels with a rear drum brake.
R100 colours were the same as for 1981
->'JO£g80g/Oo1
RlOO distinguishing features 1982
model year
Protective tube pushrod rings now braised
ontothecyhnders
Oil filter seal now a 4mm 0-nng
Black oil dipstick
Gearbox number on the side of the gearbox
housing
New gear selecting mechanism
New helical input primary gears and a new
fifth gear
New clutch plates and a fully enclosed clutch
housing
Strengthened side stand frame mount and
new side stand
Frame radius changed to improve access to
oil filter
One key locking
Nivomat shock with an eJ1tra spring
New rectangular style ophonal panniers
R100RT, R100RS, R100CS
R100, RSORT 1983 model ye'ar
In an effort to overcome stagnating R100RT
sales, the R80RT Joined the R100RT for the 1983
model year The R80RTwasalmost identical to the
larger version but with the ABO engine, a rear drum
brake. and without standard luggage or N1vomat
rear suspension. Although the performance was
extremely leisurely. 11 was popular and, when the
revised bol!ers were offered in 1984, the ABORT
survived. It wasn't until 1987 that the R100RT
would make a return_ The RlOOmodelscontinued
much as before, the R100CS still not available in
the US. For Europe the A100CS had black fork
legsandcastalloywheels
The frame numbers for the 1983 model
year were: R100RT 6236061-6237429 and us
6242333-6243216: A100RS6392802-6395887
and US 6226209-6226731; R100CS
613B123-6138797 and US 6188167-6188174; A100
6400001-6401588 and US 6176320-6176735
RSORT (code 0444) 6420001-6424026 and US
{code 044B) 6172001-6173121.
Engine
Although the 1000cc boxer was nearing the end
of its envisaged production, a few small updates
were introduced for 1g93_ From January 1983,
the cylinder base 0-rings returned to the 2mm
thickness of pre-1981 - to overcome the barrel
deformation caused through incorrect assembly
(the worst case scenario). From week 9, 1983. an
improved 011 retaining ring was fitted to the clutch
end of the crankshaft, and, from week 20, the 011
seal for the alternator was grooved
With the four-cylinder K-series destined to
replace the 1000cc boxer. the boxer's future now
lay with the smaller capacity 800cc engine. This
was already powering the ABO/GS and. unlike the
1000cc models. there was only one specification
ABORT engine. US and European e~amples
using ostensibly the same engine as the earlier
R80/7. but with the lower 8.2:1 compression ratio
N1kasil cylinders, lighter clutch and flywheel, and
electronic ignition. There were new valve seats for
the 42mm and 3Bmm valves and shorter (44mm)
valve guides Distinguishing the R80RT were
plain alloy, rather than black, rocker covers To
compensate for the moderate horsepower, the
ABORT came with a 1:3.36 (37:11) final drive ratio
The R80RT also had new 32mm Bing carburettors
with different throttle return springs. From ABORT
6421094 a 148 main 1et was lilted to 1mpro~e
low speed running and. from May 1983 {ABORT
6243167 and US 6173082), all R80 carburettors
R100 & R80 1981-85 (Tvpe 2 47)
had new needles. throttle valves and 135 main
1ets. US versions now had a 40 idling jet .and
2.68 atomizer The Bosch electronic 1gnit1on
system for the ABORT was the same as for the
R100 but with d11ferent spark plugs Bosch W7D.
Beru 14-70. or Champion N10V.
Reinforced clutch housing and harder
wearing clutch plates were fitted early in the
model year {R100RT 6236140; R100RS 6392820
and US 6226222: R100CS 6138170 and US
6188167; R100 6400621 and US 6176912;
ABORT 6420740 and US 6172253. This was to
alleviate clutch slipping problems on full load
caused by undersized ground housing. From
these frame numbers, a 0.2mm washer was
installed to spring load the dished spring_ The
size of this pre-load washer was increased to
0.4mm after frame number RlOORT 6236173;
R100RS 6392868 and US 6226235; RIOOCS
6138204; A100 6400644; ABORT 6420811
and US 6172267. Soon afterwards (after
frame number RtOORT6236312 and US
6242478; RtOOAS 6393187: R100C/
6138269; R100 6400792 and US
6176497; R80RT 6421255 and
US 6172379) the washers were
discontinued. Marked by a
brown paint marl<. the clutch
housing was now stiffer
and more accurately
machined
Furthergeart>ox
mod"'""'"'
selector camplate, 1nclud1ng deepened detent
valleys to eliminate false neutrals_ First featured
on the RSOGJS and ST, this update provided
an add1t1onal 0.6mm clearance for the ha1rp1n
spring. From gearbox number 88 401 (with kick
start) and 88 47B (w1thou1 kick start). all the
components of the gear selector mechanism
were more precisely f1n1shed to reduce friction
and improve gear selection
Chassis
The ABORT was ostensibly 1dent1cal to the
R100RT, sharing the touring lamng that still
included an adjustable windsh1eld. The ABORT
hadnovoltmeter.clock.orluggageasstandard
equipment, but these were available as an
opt+on. The front fork was also the same, but
with plain aluminium fork legs. and the brakes
and wheels were shared with the R100 The front
brakesweretwin8rembo.wh1le therearwheel
andbrakewasa2.50Bx181nw1throd-operated
200mmS1mplex Therearsuspens1onwasalso
the standard R100 B o g .e twin shock absorbers,
with Nivomat an option. Standard equipment
on the RSORT included a steering damper. twin
F1amrnhorns,andexternalpowersocket.RBORT
colours were Pac1!1c Blue Metallic (544) and
Red Metallic (566). Other models also received
newcolours:theRlOORTnowinSphericSliver
Meta!l1c (573) and Magenta Red Metallic
(572). and the RlOORS 1n Alaska Blue
Metallic (542). alongside the existing
TheRBORT~\lastheflfli:.
'/kabsorl:>erbo~er
~pM,,_e.,eo_d_W_,h_''•_·.,,-,<-~tw-'"~"'°"
99
THE BMW BOXER Tw1Ns B 1BLE
!<18~
As BMW gradually phased out production of
the twin shock absorber. R-seneschass1s updates
for the 1983 model year were minor A four-position
front brake lever was standardised after R100RT
US 6242440; R100CS 6138235 and US 6188168;
AlOO 6400685 and US 6 176446: and ABORT US
6172280 From January 1983 therewas a revised
side stand with a new stop. positioned closer to
the frame. This was fitted after RlOOAT 6236401
and US 6242527: R100RS 6393505; R100CS
6138298; R100 6400921 and US6176510: ABORT
6421404 and US 6172572. The centre stand was
also redesigned, with a sheet metal lever instead
of tubular-steel. The stand pwots were redesigned
and the bushes at the frame were countersunk to
prevent loosening through use. From week 33,
the gear shift pedal received grease-tilled needle
roller bearings at the pivots instead of bushes
The front fork was also updated 1n January
1983 from R100RT 6236572; RlOORS 6393753
and US 6226333: RlOOCS 6138324: R100
6401020: ABORT 6421668 and US 6172638. The
damper valve was revised to provide a quieter
action. with more accurately machined valve
discs and a coil spring to eliminate axial play
Other developments during 1983 included a new
air filter top (from May) and an add1honal locating
dowel for the final drive (from March)_ There was
a new wmng harness and mod1f1cat1ons to the
pannier latches and keys. From January 1983, the
speedometer and tachometer glass face covers
were replaced by plastic items, and this year also
saw the return of the 140mph speedometer on
US ell.amples
R100 and RBO distinguishing feature:
198 '•model year
2mm thick cylinder base 0-rmgs
New oil retaining nng al ctutch end of the
crankshaft
G rooved alternator oil seal
Reinforced clutch housing and new c lutch
plates
Improved gear selector camplate with deeper
detents
Gear selector components were more
accurately machined
Four-position front brake lever
New s ide and centre stands
Front fork damper valve revised
New air filter top
New wiring harness
Add1t1onal locatmg dowel for the final drive
Plastic speedometer and tachometer face
Needle rol!er bearings for gearshift lever p ivot
R100RT, R100RS,
R100CS, R100, ABORT
1984-85 model year
Although K100 production had
commenced as a replacement for the
247-senes. the R100 continued for one
more year m 1\s trad1t1onal twin-shock
form_ The RlOOCS continued for 1984
with plain fork legs and "R100' side cover
decals. and a R100CS Motorsport - m
dark blue with orange and light blue
pinstripes - was also available in small
numbers. As BMW intended to retain the
boxer 1n smaller capac1t1es only, in order
tocelebratetheendofthe247hneseveral
final ed1t1ons were produced towards the
end of 1984. lromcarty.)ustasthe 1000cc
twins were about to be superseded
the RlOORT finally became accepted m
the US. But the success of the R80RT
eclipsed even that of the reiuvenated
R1OORT, and 11 was the 800cc version that
survived m the wake of the new K-senes
The A80AT then reappeared tn 1985
followed by a new R100RT in 1988
100
R100 & R 8 0 1981-85 (TYPE 247)
Frame numbers for lhe 1984 and 1985 model the R100 resurrected JUSt two years la1er in
years were R100RT 6237430-6237516 and US Monoleverlorm. The newfour-cyhnder K100was
6243217-6244165: Al OORS 6395868·6396033. US technologically and functionally superior but
6226732-6227337 and6308001-6308050. R1 OOCS as it lacked the charisma of the boxer, 1t wasn't
6138798-6138864; A100 6401589-6401795, US greeted as en1hus1ast1cally as expected The
6176736-6177382 and 6186001-6186040: ABORT K100 chassis was more rrg1d and the handling
6424027-6425163. US 6173122-6174022 and superior. but the four-cylinder engine vibrated
6186101-6186300 There was no further engine or disconcertingly and lacked character. With the
chassis development but. from R100RS 6396757 new technology came mcreased bulk and weight
and US 6226353: R lOOCS 6136324: R100 6401022: and the K100 weighed in at a considerable 249kg
R80RT 6421671 and US 6172638. the gear shift with a full tank of fuel. As soon as the 247-series
mechanism included the ball Joint setup of the fm1shed, 1t was replaced by the Monolever R80
R60 GIS. During 1984, the cast wheels included and A80AT, with a 1000cc version appearing for
additional support material around the spokes to 1988_ Although. for many enthusiasts. the new
el1minatecrack1ng
R100s were a pale 1m1tat1on of the ong1nal. the
AlOORS final ed1t1ons were produced large capacity boxer twin was far from dead and
1n separate series for Europe and the US. A would last another decade
numbered AlOORS Serres 500 in blue
ands1lverw1thmatchingsil\lflfpann1ers
was available outside the US The
fairing came with a small numbered
plaque on the side. and the seat was ...,_... · ·• •
thicker with different upholstery. The
fairing screen was also tinted. The US
R100 final ed1t1ons, of which 250 were
made. were wh1tew1th thin red. orange
and blue pinstripes and panniers. as
standard with s1ng!e and dual seats
and a BMW System II helmet. They
had a 'Last Ed1t1on' plaque on the side
covers. For the US there was also a
small run of hmtted ed1t100 AlOOCSs
and R100ATs, but 1t 1s not known how
many were produced. Additionally,
California received a specific version
with slightly different pinstripes
These final senes were intended to
be the end of the line for the 247-type.
but pressure from enthusiasts saw
.....
- -
Frame numbers 1981-84
RBO (TIC)
6210001 - 6212790
ABORT
ABORT
R80AT(US}
8172001 - 6173121
R80AT(US}
6173122-6174022 _
Productiofldates
1981-84 (37kW)
09/80-11/84
6420001-6424026
1983
07/82- 08/ 83
6424027- 6425163
1984
09/83-11/84
1983
08182-06183
1984
06183-10/84
~
A80RT(US)
6186101 - 6186300
R100
6035001 -6037526
---
-
1985
11184-12/84
1981
06/80-06181
101
THE BMW BoxER Tw1Ns B1BLE
11111
I
/I
I
,,
09/81-06/82
6400001-6401588
1983
06/82-08183
R100
6401589-6401795
1984
09183-10/84
RlOO(US)
6175001-6175593
1981
09180-08/81
R100(US}
6175594-6176319
1962
09181-08182
R100{US)
6176320-6176735
1983
09/82-08183
R100{US)
6176736-6177382
1984
06183-09/84
R100(US)
6186001-6186040
1984
12/83
RlOO(TIC)
6193001-6193894
1981-84
11/80-09/84
06180-08/81
R100CS
6135001-6136503
1981
R100CS
6136504-6138122
1982
09/81-08/82
R100CS
6138123-6138797
1983
09/82-08183
RlOOCS
6138798-6138864
1984
09/83-10/84
09/80-08/81
R100CS (US)
6188001-6188163
1981
RlOOCS (US}
6188164-6188166
1982
10/81-08/82
R100CS(US)
6188167-6188174
1983-84
09/82-09/84
06/80-12/81
R100RS
6075001-6080001
1981
R100RS
6390001-6392801
1982
12/81 - 08/82
R100RS
6392802-6395887
1983
09/82 -10/83
R100RS
6395888-6396033
1984
11183-11/84
R100RS (US)
6225001-6225628
1981
09/80-08/81
RlOORS (US)
6225629-6226208
1982
09/81-08/82
R100RS{US)
6226209-6226731
1983
09/82-08/83
09/63-09/84
RlOORS (US}
6226732-6227337
1984
R100RS(US)
6308001-6308050
1984
12/84
R100RT
6230001-6232899
1981
08/80-08/81
R100RT
6232900-6236060
1982
09/81-08/82
R100RT
6236061-6237429
1983
09/82-08/83
R100RT
6237430-6237516
1984
09/83-10/84
1981
06180-08/81
RlOORT (US)
6240001-6241232
R100RT {US)
6241233-6242332
1982
09/81-08/82
RlOORT(US)
6242333-6243216
1983
08/82-08183
R100RT(US)
6243217-6244165
1984
09/83-09184
r---102
..
6037529·6040000
RlOO
f---RlOO
I
1
CHAPTER VI
PosT-1984 AIR-COOLED
TWINS
W
ith the new generation water-cooled
K-senes set to replace the lOOOcc twins
from 1985, the flat twin remained m the
hne-up to satisfy the trad1t1onal enthusiast and
maintain a classic trad1t1on w1thm the company
The BOOcc RSO/GS and RSOST continued
much as before, and m1t1ally the smaller R45
and R65 were also available for 1985. but soon
d1scontmuad. In the wake of the dual-purpose
RSO G/S success. two new street ABO GJS-based
twins, the RSO and ABORT. also became available
for 1985. The renaissance of the bo11er twin was
underway, even before the final death knell
Conce1ved1nthestyleolthefirst/S,these
revamped twins were the ant1thes1s of most
m1d-1980s motorcycles. Res1stmg the trend
of emphas1smg engme performance through
increased compleK1ty without consideration of
weight saving, the new boKer twins reiterated the
trad1t1onalBMWboKerformula-s1mplic1ty.ag1l1ty
and hghlness were placed ahead of ultimate
horsepower. looking remarkably similar to the
pre-1984 twms. the new RBO offered improved
brakes and handling but. unfortunately, 11 could
not match the earlier RlOO for performance
By 1987, with the K-series no longer seen
as BMW's road to the future. the ABO-series was
further eKpanded Calls by trad1tionahsts for a
resurrection ol the 1000cc boKer twm resulted
in a new R80-based R100RS and R100RT By
1988, a complete line up of RSO-based twins
101ned the K100 and K75, lasting mto the neKt
decade
RSO and RSORT 1985 mod el
year
Even when 11 was conceived back m 1976, the
air-cooled 247-senes boKer twin was limited as a
high performance design and always envisaged
as a short-term solution. By the early 1980s.
increasing noise and em1ss1on requirements
painted a bleak future for the 247 engine. already
struggling to reliably produce 70 -horsepower
m production form. While the dec1s1on was
made to replace the larger capacity twins with
the four-cylinder K-series. the boKer twin had a
1he rwo new ;treet bomrs
for 1985 wero meR8(1and
RBOT. with monoshr ck roor
,uspen'iKYI
TH E BMW BOXER TWINS BIBLE
producing onry
E'JJQ.rnr meRI
J)laas.nt
all r~d
surprising repneve with the RSO G/S. As a result,
BMW decided to continue development o! the
boxer twin for appl1cahons up to 60 horsepower
- the figure deemed to provide a balance between
power and re!iab1hty. For 1985. 1he 800cc tw in
range was made up of five models (R80; RSORT;
RSOST; ABO G/S, and ABO G/S Pans Dakar). As
the evolution of the l 1nal 247-series was continued,
only the two pure street models (ABO and ABORT)
are discussed here (G/S motorcycles and their
derivatives are outside the scope of this book)
Assembled alongside the K-senes 1n the
Spandau factory 1n Bertin. the new RSO wasdenved
from the ABO G/S and RSOST but incorporated
many K-ser1es features. The SO-horsepower
engine was shared with the G/S and ST but, instead
of a two-into-one exhaust system. the RSO and
ABORT received an upswept conical two-into-two
exhaust system that reduced noise levels by 3dBA
and improved midrange power
No longer with matching engme and
frame numbers, ABO (produchon code 0453)
frame numbers for the 1gB5 model year
were 6440001-6443233 and US (0463)
64B0001-64B0542, with the ABORT (0457) frame
numbers 6470001-6472g57 and US (0464)
6490001-6490812
Engine
The 800cc engine was basically that of the R80ST
with a few updates aimed at reducing noise From
November 1g84. all 800cc engines received new
cylinder heads with revised bases and supports
for the rocker shafts. To el1mmate no1seemanat1ng
fromthevalveoperat1ngmechan1sm,fromJanuary
1985. new rockers with axial bearings and plastic
washers were installed. Instead of zero axial end
tloat. there was now 0 03-0.07mm. Further noise
reduction came through the 1nstallat1on of twelve
rubber buttons between the cylinder head fins
The valve seat material was also changed to
overcome the valve seat recession problem with
unleaded fuel. From February 1985 there was a
new crankcase 01! pressure relief valve. with a
16mm {instead of 11mm) compression spring
and a 14mm blind plug. These mod1f1cat1ons also
appeared on the RSO GIS and R80 ST. although
the general 800cc engine spec1l1cat1ons were
unchanged for the R80 and ABORT The valve sizes
remained at 42mmand3Bmm. w1tha Bosch TSZH
electronic 1gnit1on and the Bosch double-ended
1gnit1on coil ol the ABO G/S. Carburet1on was by
Bing V64/32/353-354mmcarburettors. the32mm
Bing carburettors now sharing the float bowls of
the larger 40mm type. US models retained the
SAS secondary air in1ect1on em1ss1on system and
the RSO had black rocker
covers. A Bosch 2BOW
alternator powered the
electncal system. and the
battery was increased
from 16Ah to 20Ah for
more reliable starting
in colder weather. The
new twins also included
an attract i ve. but
restrictive. new exhaust
system, with a large
welded pre- mufflN
1nterconnectmg the left
andr1ghlexhaustp1pes
before the twm mufflers
This effectwely retained
the horsepower of the
previous engine and
was a claimed three
decibels quieter. The
RSO included only a
smgte exhaust gasket
up until Oclober 1985
and lhe claimed power
was also modest. with
SOhofsepowerproduced
at6500rpm
P os T- 1984 AIR- COOLED TWINS
Further updates to the 800cc twms occurred
m March 1985. with another new gearbox mput
shaft; kick start spline; input helical driving gear.
and thrust moont. Themputhelical dnv1ng layshaft
now had a 17.5-degree gear cut , instead of the
previous 15-degree. The final dnve assembly,
with a more substant1a1castmg for 1985. was also
new_ This included a new crown wheel set and
a 25:>A7x15mm mner tapered roller bearing (from
the K-series). insteadoftheprevioos35x50x20mm
needle roller type. The ABO final drive ratio was
1:3.20 (10/32). with the ABORT and R65 receiving
a1:3.36(11/37).
Chassis
A combination of RBOST and K-senes components
formed the chassis of the revamped bo~er. The
frame was inhented from the R80ST, a twin loop
main frame similar to Iha! of the first /5, but with
a Monolever swmgarm_ The steenng head angle
was 28.85-degrees, providing 116mm of trail
While the frame and sw1ngarm were similar to
the R80 G/S and R80ST, the wheels, brakes
and suspension had more in common with the
K-senes. The K-style centre-a~le included beefier
38.5mm fork tubes and provided considerably
less travel than before (175mm). To improve
front end rigidity the fork also incorporated an
integral fork brace with the front mudguard, and
a larger diameter hollow axle (25mm). Unlike the
previous Type 247 senes, the forks included a
forward mount for the Brembo 08-senes brake
cahpers. The fork legs were plain alloy tor the
1985 R80. US versions mcorporat1ng reflectors
in each fork leg.
The monoshock suspension
Uf!Jt artached dlfectly to the
final drrve housing
The 1985Europ8iJllR80RT
f'ladasmglefronld1SC
braJ..e ThelcJri<.Jegsweie
plainaloythls~
105
THE BMW BOXER TWINS 81BLE
The single gas-c harged Boge rear shock
absorb e r pro vided 12 1mm of travel, and
attached to the trailing loop of the main frame.
via a forged steel mount_It also mounted on the
rear a•le ho using (like the K-senes) instead of
For tht IS. thv RBORT
raceived ;t;;ndard luggage
nd a dua (11s. ·from brake
"the
106
dashtx 'Ud
the sw1ngarm, the ta1d -down pos1t1on resulting
in a hig her leverage raho than on the ABO G/ S
and RSOST Both the front fork and rear shock
absorber were non-adjustable, although the rear
shock absorber drd include lour spring p re-load
settings
Although BMW boxer twins had featured
a 1g-inch front wheel since the first /5, the ABO
received an 1B-inch front wheel. The same
MT H 2.50• 18in front and rear. these c ast alloy
wheels were K-senes derived and
now accommodated t ub eless
tyres. The Y-fork and H-cross
section was designed to provide
spoke elasticity with rim ng1d1ty
The rear wheel incorporated a
200mm drum brake and the rear
hub featured a four bolt reta1mng
system (unlike the ABO G/S and
RBOST). A narrow 90190H18 front
tyre (usually a Metzeler Perfect
ME11) contributed to agile steering
without compromising braking
performance, the rear tyre was a
reasonably large 120190H18(often
a Metzeler ME99). The front brake
was also upgraded. with a larger
slotted 285x5mm disc, a dual 36mm piston
Brembo caliper and 14mm master cylinder. The
ABO and ABORT had a single front d isc for Europe,
while twin front discs brakes were fitted on US
examples for 1985
While the steel fuel tank retained
the same classic shape as the previous
247-senes, 11 now held only 22-htres
This was due to the relocation of
some electf!cal components from
the head light shell to the frame
backbone. The fuel filler tank cap
was an EPA-mandated spring-loaded
type. While the narrower seat also
continued the previous theme, the
abbreviated plashc Iron! mudguard
was more angular. 5.5-htres of storage
space was provided underneath the
seat and new side covers facilitated
visual checking of the battery acid
level. Continuing the classic theme
were the smaller diameter MotoMeter
instruments and single. or sometimes
twin, round Bosch horns_ The ignition
key was moved to the handlebar
protective cover and the new handlebar
switches were specific to the ABO
More logical than the K-senes, the
left switch block on US versions didn't
incorporate a light switch as the head light was
hard-wired. A 21 -piece toolk1t was standard, as
was a 12V power socket. The side stand was
improved, and the centre stand p ipe diameter
increased to 38.Smm f0t improved strength and
stability. The ABORT lairing now incorporated
a clock and voltmeter. and factory accessories
for both RSOs were plenhful. extending from
panniers and tank bag to four-way flashers and
a30Ah battery.
•
BothlheR80and RSORT
were modest perlormers. the
50-hoisep()wer boxer engine
working quite hard 10 propel
the210kg R80toatopspeed
of 176km/h (109mph). and
the 227kg AS ORT to170km/h
(105.6mph)_ The range ol
colours was hm1ted Polaris
· - - · - S1tverMetalhc.ColoradoRed
or Black Metallic for the ABO.
and Colorado Red Metallic
or Yukon Blue Metallic for
lheASOAT
I
ABO distinguishing features 1985 model year
Rockers with axial bearings and plastic washers to reduce
noise
Twelve rubber buttons inserted between the cylinder head fins
New seat material to overcome the valve seat recession with
unleaded fuel
New crankcase 011 pressure relief valve with a 16mm
compression spnng
20Ah battery
Exhaust system with a large pre-muffler
New gearbox input shaft, kick start spline. input helical
driving gear and thrust mount
New final drive assembly with inner tapered roller bearing
Centre-axle fork with 38.Smm fork tubes, plain alloy legs.
175mm travel and integral brace
25mmaxle
Single Boge rear shock absorber mounted on the rear axle
housing
2.50x18m Y-fork and H-cross section wheels
200mm rear drum brake
Rear hub with lour bolt retaining
285mm front disc brake wrth twin piston Brembo cahper
22-htrefueltank
Narrower seat with 5.5-htres of under seat storage space
Angular front mudguard
New side covers
Smaller diameter instruments
lgmt1on key on the handlebar protective cover
New handlebar switches
Centre stand pipe diameter increased to 38.5mm
ABORT fairing now with clock and voltmeter
THE BMW BOXER TWINS BIBLE
RSO, RSORT and R65 1986
model year
New fO£ the 1986 modeJ
yoor w;:is me R65, very
1mdar to me RBO
The R80 and R80RT contmued for the 1986
model year largely unchanged and. with the
demise of the smaller 248-series. were iomed
by the R65. The R65 was also produced 1n
RT form: as a police model and as a specific
27-horsepower version for the German market.
as well as bemg available m the US with a
covers plain aluminium to sel the engine apart
from the 800 With its black covers. The final dnve
ratio for the 205kg R65 was 1:3.36 (11/37)_ The R65
chassis was identical to the R80 and for the 1986
model year the fork legs were black on all twins
All twins this year had a smg1e front disc brake as
standard
RBO and R65 distinguishing features
1986 model year
650cc R65 introduced
R65 with p!am alum1mum rocker covers
Black fork legs
All twins with a standard smgle front d isc
brake
R100RS, RSORT, RSO and R65
1987 model year
slightly de-tuned (from Europe) 45 horsepower
Production codes were unchanged from the
previous year and frame numbers for the 1986
model year were R80 6443234-6445826 and US
6480543-6480906; ABORT 6472958-6475887 and
US 6490813-6491267; and R65 (48
HP) 6073001-6074774 and US
6128001-6128516
Although ostensibly 1dent1ca1
totheprev1ousR65type248engme,
the new R65 engine was updated
to provide a wider power band
and run more easily on unleaded
fuel. Engine dimensions stayed
at 82x61.5mm and, with a 6 .7:1
compression ratio. the power was
reduced lrom 50 to 46 horsepower
at 7250rpm_ The maximum torque
of 478Nm (35. 2 ft/ lb) was developed
at a lower 3500rpm_ Valve sizes
on the A65 were 40mm and
36mm. the carburettors 32mm Bing
V64/32/359-360. and the rocker
108
Although BMW intended the K-senes to
replace the larger boxers. repeated calls for the
remtroduct1on of the 1000cc twm saw the release
of a new R100RStowards theend ol 1986 tor the
1987 model year. Based on the R80 Mono and
not the earlier Type 247. the resurrected R100RS
was imt1ally intended as a limited ed1t1on of 1000
units but stayed in production until 1993. The
ABORT. ABO and R65 continued as before for
1987. Frame numbers for the 1987 model year
were: RlOORS {0455) 0160001-0161672; ABORT
6475888-647B620 and US 6491268-6491452:
RB06445827-6447156andUS64B0907-6481120.
and R65 6074775-6118807. Only a few R65s
were built for the US this year; the concept of a
small capacity engine m a larger dimensioned
motorcycle was anathema m the US
Engine
With increasing noise and emissions
controls to be 1nst1gated m Europe
from 198B (ECE A 40). the resurrecled
compromised
was mev1tabty
R100RS
While the
motorcycle.
a performance
as
A100RS started hie as a 70-horsepower
high performance motorcycle 1t was now
derived from the ABO. and the 1000cc
Ll!~~~~~J~~~;:~?:.~i
~~~~:ed~~sw~~s~~~~~ :1~:~~~ver~~~= ~"~~~~~~
!~~~~=!~:E~~~~:::=::::
and run on regular unleaded fuel
The R100RSengme d1mens10ns of
94x70.6mm were shared with the earlier
vers1onbut thecyhnderheads1ncluded
~~~:;~l~~4;h:~;~:;rv~~:~1 ~x~:~~; !"",.;..5;~~~;:;::~~~?.~~~;:.fijfi]
valves ol the 1984 A100AS. From June
19B7 (on all boxer twins). the valve seat
angles were changed to 43 degrees for
the inlet and 30 degrees !or the exhaust
(from 45 degrees for both) to improve
their hie on unleaded fuel. The R100RS
compression ratio was slightly up on
the R80 at 8 .451. carbu1et1on was by
32mm BmgV64/32/363-4carburettors. .~.-::{:t]f~blQa~!B~
and the pre-muffler exhaust system
was the same as the R80. While the
power was reduced to 60 horsepower
at 6500rpm. the maximum torque of
74Nm {55ftllb) was now produced at a
low 3500rpm (compared lo 6000rpm on
the earlier engine). Atlhoughon-the-road
performance was similar at legal speeds.
the new A100RS was no11ceably down
on top speed (1B5kmlh or 115mph). 11
featured a slandard 011 cooler and 30Ah
Mareg battery. but man other respects I
the engine was as for the ABO. Included
was the same 280 watt alternator. and.
also shared with the ABO. the 1:3.00
(11/33)1maldnve
Chassis
Underneath the AS bodywork was a
similar Monolever chassis lo the R80
and A65. The tront fork was the same
K-series t ype with 38.5mm lork tubes,
and the single rear shock absorber
a Boge. Twin Iron\ disc brakes were
standard on the A100RS. but the rear
brake was a 200mm dn.im instead of the
disc on the earlier A100AS. Also shared
w11h the ABO were lhe 18-mch wheels,
although the RlOORS wheels were black
withplam alloy accents
..._ _..I
L,..-;.;.-.O:iof~~:::_.;..;....._r-""'"~illio-""'"''""""""'
T HE BMW B oxER Tw1N s 81BL E
New for 1988w, the
RIOORT. ostensibly an
n1a1gam ol the RBORT
andR100RS
The fa1nng was ca rried over from the 1984
R100RS. but now featured larger black mirrors; the
front section of the pre-1979 R100RS. mcludmg
vented grill. wi th the oil cooler at the top. No
hydraulic steering damper was included, but the
protective pad on the AS was the same as befo re
and looked strange wi thout the damper knob - a
round BMW badge sat in its p lace. Unlike the R80,
the R100RS was fitted with dual Fi amm horns.
and two types of saddlebags were available as
an option; the A-type or squarer K-type. The
colours for the R100RS were Mother-of-Pearl
White Metallic with blue stripes. or Henna Red
with black stripes and black famng base. With
its shorter (1447mm) wheelbase. lighter weight
(229kg). and more rigid frame. the resurrec ted
A100RS provided more agile and surefooted
handling than the earlier version. However, the
reduction in horsepower did little to endear 11 to
a new breed of enthusiasts.
RlOO, R80 and R65 distinguishing
features 1987 model year
RlOORS with 42mm inlet valves and 40mm
exhaust valves
New valve seat angles from June 1987
R100RS with 32mm Bing carburettors
R100RS w ith a standard oil cooler
R100RS with 30Ah battery
R100RS with t win front d isc brakes as
standard
R100RS with 200mm rear drum brake
R100RS 18-inch wheels black with plain alloy
accents
A100RS fairing with larger black mirrors and
ventedfrontgnll
No hydraulic steering damper on R100RS
R100RS with dual Fiamm horns
R100RT, R100RS,
RSORT, RSO and R65
1988 model year
With most boxer development centred
on the Paralever GS there were
few updates to the existing lme-up
This year the R100RT was added.
os tensibly a combina tion of the
R100RS engine and R80RT chassis
The R80RT and R80 were now no
longer available m the US. and 1988
was the final yea r for the R65 (except 1n
27-horsepowerfortheGermanmarket)
With response to the resurrected
A100RS being overwhelmingly positive
it now went mto regular production
Frame numbers for the 1988 model year
were: R100RT(0459)6016001-6017067
and US (0469) 6292601-6293172;
RlOORS 0161673-0162358 and
US 6247001-6247548; ABORT
6478620-6483775,
RSO
6447157-6448032, and R65
6118808-6131123
Updates to the street boxer range
were minor for 1988. The steering
head angle was reduced slightly to
,~)·I(~~ ~;h~e~~~~:~=e~~~. ~~~~:r ~~n~a11~~~
were revised. Thes1ngled1sc RSORT. ABO
~~Iii@~~=~~~;~~~==~~!~: theclutchpushrodandreleasebearing
and R65 received R100GS solrd discs
and a 38mm Brembo calrper from July
1988. but the twin disc R100s retained
the previous slotted type disc
110
Desp,'.1 its n :>desr power
')urput. tlie R 00 ~ WilS
.c t. fanefft1Ct1ve/(Jf1f"t9
m< '.• .'Cyde
As an amalgam of the existing ABORT
and R100RS, the R100RT wasn't exactly
groundbreak1ng. The R100RT bodywork was
identical to that of the ABORT, and the chassis
equipment to the RlOORS. As on the RlOORS the
ef1Q1ne included a standard 011 cooler. front brakes
Wi!retwindiscsandtherewasnohydraulicsteering
damper_ Standard equipment included a quartz
clock; voltmeter and panniers. and a single key
operated the 1gnit1on, steering lock, fuel tank cap.
seat and panniers. The weight of the R100RTwas
234kg and colours for 19BB were Bermuda Blue
with Dual Silver pinstripes and a black seat
R100, R80 and R65 distinguishing
features 1988 model year
Reduced steering head angle of 27.8-degrees
and120mmoftrail
New clutch pushrod and release beanng
Single disc models with a solid disc and
38mm Brembo cahper from July 1988
Al OORT introduced with R80RT bodywork
and R100AS engine and chassis
R100RT, R100RS, ABORT and
ABO 1989 model year
By 1989, motorcycle production at the Berlin
Spandauplantwasaround24,000unitsw1ththe
A-series boxer accounting for about half ol that
Motorcycle sales worldwide gradually declined
during the 1980s and BMW relied strongly
on their domestic German market. By 1989
Germany accounted for a third of motorcycle
sales. BMW achieving about a 10 per cent share
of the German market. W1th1n this static climate
development was curtailed. with resources
focused on the four-cylinder Kl. Apart from the
introduction of the Paris-Dakar R100 GS. there
was no change to the A-series this year. Frame
numbers for the street A models for the 1989
model year were: A100AT 6017068-6018000
and US 6293173-6293399; A100AS
0162359-0163754 and US 6247549-6247599;
ABORT 6483776-6486351, and ABO
6448033-6448814,
R100RT, R100RS, ABORT and
R80 1990 model yea r
Like the 1989 model year the A-series evolved into
1990w1th veryhttledevelopment. Production of the
A100RS was gradually scaled down (and 1t wasn't
available in the US this year) with only 337 being
produced. Frame numbers for the 1990 model
year were A100AT 6167001-6168000 and US
6293400-6293579; A100AS 0163755-0164009;
ABO RT 6486352-6488024, and ABO
6448815-6450000. The minimal updates for 1990
included an improved rear drum brake. the brake
111
THE BM W
B OXER T w1NS B IBLE
padw1dth1ncreasad to27.5mm(from25mm),along
with new mounts !or the brake shoes. The ABORT
gamed dual disc front brakes as standard
R100RT, R100RS, R100,
RBORT and RSO 1991 model
year
1he R80 cont,nued wtui.11/y
!"Changed for many yeu~
/f/o 199<: ~ )('/ w, very
.m :irtc 11ur,,119&
112
With most A-series development centred on
the successful G/S models lhlS year. the street
A-series was again largely unchanged. Although
the R100AS was no longer available m the US. the
regular RlOO made a return for the US market m
1991 . This was essentially an RBOwith the R100RS/
RT engine, only lasting for one year before 1t was
replaced by the RlOOA for 1992. With only 157
produced. 11 was one of the rarest more modern
BMW boxer twins. In Germany, a!I R80s were now
available with a 27-horsepower engine. Frame
numbers for the 1991 model year were: R100RT
6337001-6337902 and US 62935B0-6293729:
R100RS0164010-0164292;R80RT6488025-6490000.
andR800121001-0122608
Optional on all R-senes was the US-style
SecondaryA1rSystem(SAS).Des1gnedtoreduc e
HC em1ssrons by 30 per cent and CO emissions
by 40 per cent, the SAS used exhaust pressure
pulses to move two diaphragm valves in the air
filter housing. drawing in fresh air_ Two tubes
directed this fresh air into the cylinder head and
exhaust system, behind the exhaust valve. The
combmat1onofadd1t1onala1rw1ththeh1ghexhaust
temperatureensuredmorecompletecombust1o n
of HC and CO Exhaust m1sfir1ng was controlled
by interrupting the secondary air supply when
the engine wasn't under load. the left SAS valve
had no effect on engine performance or fuel
consumption
Although the twin disc R100RT. R100RS and
German market R80 retained the earlier slotted
front disc rotors, the single disc ABO received a
new disc rotorlor 1991. To eliminate squeaking the
brake disc was attached to the carrier by rollers,
allowing the brake disc to float with the brake pads
and utilise the full amount of pad surface. The
colours were rationalised for 1991, all A100 and
R80 street models available in Red Metallic, Topaz
Red Metallic, and Bermuda Blue Metallic.
R100 and RBO distinguishing features
1990 and 1991 model years
Wider rear brake linings (1990)
SAS system optional
Floating front disc rotors f0< single disc
models
R100R, R100RT, R100RS,
RSORT and RSO 1992 model
year
As the release of the new generation R259 boxer
twin was still more than a year away. for the 1992
modelyearBMWreleasedtheinterim-theRlOO R
Roadster. Based on the R100GS. and designed
to reflect BMW's classic twin tradition. the R100R
was sold alongside the ex1st1ng twins and was
surprisingly successful. During 1992
the RlOOR was BMW's best-selling
motorcycle, accounting for 23 per
cent of production. with B041 sales
Although it was arguably a parts-bin
special. the A100R had a certain
appeal. The styling and execvtion
was questionable. but the chassis
was functionally superior to the
earlier street boxers and the engine
made adequate power. The existing
range of lOOOcc and BOOcc boxers
continued much as before. although
the RlOORS was now 1n its final year
As a final effort. before the advent
of the R1100AS, nearly 1000 were
produced. Also built during 1992.
a special series of 30 Rennsport
1n trad1t1onat blue and silver with a
numbered plaque The wheels were
no longer black h1ghhghtad on this
limited ed1t1on
Frame numbers for 1992 were: RlOOR
0240001-0247618 and US 0280001-0280546;
RlOORT 6337903-6338475 and US
6293730-6293881;R100RS0164293-0165331 and
US 6247600-6247750; ABORT 0270001-0271732;
R80 0122609-0123205
R1 OOR
Engine
As with the earlier RSOST, the R100R was based
on its dual-purpose stable mate, in this case the
R100GS. Except lorthed<fferen\ exhaust system
and the older-style rocker covers. the R100R and
RlOOGS engines were 1dent1ca1. Included on the
R100Rwasthelargersumpofthe 1991 GS, lighter
layshaft starter and 40mm Bmg carburettors
(a\\houghUSmodelsreta1ned32mmcarburettors)
The layshafl starter used a smaller electric motor
but provided the same torque. with an 1nte1med1ate
transmission. The overall reduction m weight was
2kg. With lhe R100GScompress1on ratio of 8.5:1.
the power of the R100R was 60-horsepower. with
ma1omum torque ol 76Nm (56 ft/lb) produced at
only3750rpm . TheRlOORe•haustsystemfeatured
a large pre-muffler. 38mm chrome-plated header
pipes and a low mounted round stainless steel
KlOO muffler. lnsteadofmountmgtheo1I cooler on
the engine protection bar as on the GS. this was
now positioned 1n front of the engme. The classic
look e)(tended to the older style sparkplug caps
and the rounder rocker covers first seen on the
R68, lastm9 on the sporting twms until the 1976
/6. As on all bo)(ers for 1992. the SAS em1ss1on
control system was an option on the R100R
f , ' Rem -parr iJmed /J
num~ed ptaqu
Chassis
The silver painted R100R frame and Paralever
swmgarm came from the successful dual purpose
R100GS. Featured !or the first time on a street
bo)(er twin, the Paralever contributed toe)(cellent
handlmg. Thesteeflng head angle and 101mm of
trail was unchanged from the R100GS. as was
the long wheelbase of 1513mm. Another !irst
lor a BMW motorcycle was the use of Japanese
Showa suspension. The non-ad1ustable 4 lmm
front fork provided 135mm of travel and the rear
smgle gas pressurised Showa shock absorber
mcluded adiustable rebound dampmg. There
113
THE BMW BoxER Tw1Ns BIBLE
AltflOugh "flly 111!1Ylded
s
renmn,odel,
AIOORwasBt\Mf
gmotcn-y(
992 ThetramE w,
.terlh
led
114
were six spring pre-load setlings and 140mm of rear axle. An alloy strut connected the gear case
travel and. as with the R80. the shock absorber to the frame, (ust below the swmgarm pivot. Thus
bolted directly to the final drive housing
the swingarm, stay arm, gear case and frame
- - - - - - - formed a parallelogram, with pinion
torque feeding into the lower strut
instead of the swingarm The slight
fore and aft movement of the gear case
was absorbed by the laid down single
shock absorber. As the parallelogram
arrangement increased the radius of
the wheel elevation curve, it provided
the same effect as a 1400mm long
swingarm_ Although the Paralever
increased the weight by 1.6kg. 1t
allowed the full travel of the Showa to
be used more effectively
Further emphasising the classic
image were cross-spoked wheels, with
Akront aluminium rims, a 2.50x18m
on the front, and 2.50x17m on the
rear. The front brake was a single
perforatedlloat1ng285x5mmd1scw1th
a four-piston Brembo cahper from the
K-senes. The cable-operated 200mm
rear drum brake was the same as the
GS.AlsofromtheGSwastheta1124-litre
fuel tank. The round 180mm head light
The Paralever swmgarm was designed to came from the K75, but with a chrome shell, while
m1mm1se the effects of driveshaft movement the plastic nacelle contained R100GS instruments
under acceleration. As the ideal swmgarm The720mmchrome-platedhandlebarwass1milar
length for the shaft drive twin was an 1mpract1cal to the RBOST, with K-ser1es handlebar switches
1,700mm, BMW's engineers. Rene Hmsberg and and end weights to m1mm1sevibration. but without
Horst Brenner. created the Paralever double-joint the K-series self-cancelling indicator function
swingarm. Inside the single sided swingarm was a Specific A100R features included the handlebar
second universal J01nt. freeing the rear gear case cover. side covers, passenger grab handle and
and hub assembly and allowing 1t to float on the rear mudguard
The loot controls were also similar
to the GS. with the same reversed
gearsh1ft linkage. Styling coosiderat1ons
extended to the two-tone seat with
a silver rear rack. The seat core 1nd
foam were new but seat height was
still relatively high at 800mm. from
March 1992. an optional chrome kit
was available which comprised a
chrome-plated forl< stabiliser; valve
covers; carburettor tops: instrument
panel; direction 1nd1cator housings:
fuel tank cap: mirrors. and exhaust
nuts AlOOR colours for 1992 were
Classic Black with Silver pinstripes
(656), Amethyst Metallic {685). and
from January 1992. Turquoise Green
(525). BMW hit the nail on the head with
the R100A. 11 was the nghl machine at
the right tome Naked machines were
Posr-1984 AIR-COOLED TWINS
beginning to reassert 1hemselves and, al though
not powerful, the A100A was light enough (218kg)
w•th the Paralever swmgarm and shorter travel
suspension contributing to arguably the finest
handling boxer yet
The A100AT. AlOORS, R80RT and R80
continued as before. but now all featured a
Marzocchi front fork The colours were Classic
Black Metallic 656 (all models). Red Metallic 654
(R80. R80RT and A 100RT). and Pme Green Metallic
684 (R100RS and R100RT).
R100 and R80 distinguishing features
1992 model year
Final R100RS Rennsport series in trad1t1onal
blue and silver
R100R based on the R100GS released
R100R featured a layshaft starter, 40mm Bing
carburettors, and old-style rocker covers
R100R frame painted silver and included a
Paralever swingarm
R100R with 41mm Showa Iron! fork and single
Showa rear shock absorber
RlOOR with cross-spoked whee ls and
aluminium rims
R100R with single front disc brake and four
piston Brembo caliper
RlOOR with cable-operated rear drum brake
R100R with K75 round head light
AlOORT. R100RS, RSORT and R60 with
Mariocch1frontfork
R100R, R100RT, RSOR , RSORT
and R80 1993 model year
The creation of the new generation R259
boxer for the 1993 model year engulfed most
of BMW's developmental resources and. as a
result. the existing A-series continued much
as before. Surprisingly, in the wake of updated
K-senes and the R259. the RlOOR sales success
continued. In some markets the new RBOR
replaced the ABO. and in Germany the RBOR was
available in 50- and 27-horsepower form. Frame
numbers for the 1993 model year were_ R100A
0247619-0250000 and 0165501-0166916 with US
02B0547-02B0788: R100RT6338476-633922tiand
US 6293882-6294013: ABORT 0271733-0272533.
and RSO 01232B6-0123509
With the formula of the moderately powered,
light and simple twin flfmly established. there
were only cosmetic changes to the R100R for
1993. The RBOR was very similar to th e A100A ,
but without an 011 cooler Setting the 1g93
R100R (and RBOR) apart. on turquoise green
metallic (525) examples. were large 'BOXER'
emblems on the sides of the fuel tank. These
retained the silver frame and rear rack. while on
black RlOOAs. these features were also black
Colours for the 19g3 model year were Classic
Black Metallic 656 (all street R models): Myshc
Red Metallic 527 (A 100RT, ABORT and ABO):
Turquoise Green Metall•c 52B (R100RT, A100R
and RBOA); and Amethyst Metallic 6B5 (R100R
and RBOA)
rn.. R! XIRS R<. 9 Ix"'
repl->ced t/11' RIC
THE
BMW BOXER TWINS BIBLE
Po sT-1984 AIR-COOLED TWINS
R100 and RSO distinguishing features
1993 model year
A100A and A80A with large 'BOXER'
emblems on green metallic examples
R100R, R100R Mystic,
R100RT, RBOR, RBORT and
ASO 1994 model year
By 1994 it was inevitable that production ol the
trad1t1onal air-cooled boxer twin would end; rt
was only a matter of how long 1t could survive
The R101'R received dual disc front brakes, the
SAS emission system was standard. and 1t was
joined by a special Mystic version_ Designed to
appealtotheconno1sseurofclassicmotorcycles,
theMysticwasapart icularlyattract1verend1t1on
of the R100R. All R80s were available in either
50- or 34-horsepower this year, with kits available
to transform a 50-horsepower engine into
34-horsepower, and vice versa. For 1994 the
US RT100RT included heated grips. a custom
touring seat, and rear top case. In Australia 11
wascalledtheR100LT.
the
f or
numbers
Frame
R100R
were
year
1994 model
0166917-0167941 and US 0280789-0280858.
R100R Mystic 0169001 -6435634 and US
0400001-0400145; R1OORT6339227-6339787 and
US 6294014-6294248; ABORT 0272534-0273337,
andR800123510-0123695.Coloursforthe 1994
model year were: Classic Black Metallic 656 (all
street A models), Mystic Red Metallic 527 (R100RT
and R80RT) and Turquoise Green Metallic 528
(RlOOAT, R100R, ABORT and R80R)
R100R Mystic
Although incorporating only cosmetic alterations
to the R100R. the Mystic managed to impart a
quality image that was lacking with the standard
R100R. Along with the special Red Metallic paint,
the frame was painted black. the side covers
were new and there was a shorter licence plate
bracket. The handlebar was lower. and the seat
and tailp1ece restyled. Additional chrome-plated
components included the head hght support.
instrument surround with new warning light
setup, and indicator supports. The muffler
was also turned 3cm to the inside. along the
long1tudmalax1s.
Some vetslO(>s ''me
RIOORTworesokfwirh
stJl'ldard~igq.ige
117
THE BMW BOXER TWINS BtBLE
118
Po sr - i984 AI R-COOLED TWINS
R100 distinguishing features
1994 model year
RlOOR with dual disc front brakes
R100R with SAS em1ss1on system standard
Mystic with red metallic paint and black frame
Mystic with new side covers and restyled seat
and ta1lp1ece
Mystic with lower handlebar and shorter
licence plate bracket
Mystic with chrome head light. indicator
supports and instrument surround
Mystic muffler turned 3cm 10 the 1ns1de. along
thelong1tud1nalax1s
TheMysr11.;lei' ·rer:Jt1ie
trad r10nil wiri :poked
''Meis J/f/1<- RIOOR
R,
R tOOr"fua,lr
. '""'
t
RiDOR, RiooR Mystic,
R100RT, RSOR, ABORT and
R80 1995 model year
For the 1995 model year BMW released four
'farewellmodel'RlOOboxers AlongsldetheRlOOGS
Paris Dakar Classic were three street models
the R100R Classic. R100R Mystic and R100RT
Classic. The standard R80 was d1scon\1nued
but the R80RT remained 1n production Frame
numbers for the 1995 model year were RlOORT
6339788-6340000 and US 6294249-6294455:
R100RT Classic 0470001-0470400: R100R
0167942-0169000 and US 0280859-0280929
RlOORClass1c6469000-6470000: RlOOR Mystic
6435635-6437226 and US 0400146-0400255.
R80RT0273336-0273599
"'
T ~E BMW BOXER TWINS BIBLE
D1s t1 ngu1shm9 the R1 00R Classic wa s its
black f1msh. with m any componen ts h1ghhghted
in black This included a black seat with new
upholstery. head light su p por t. instr ument
console and grab handle The handlebar levers
wt>re silver epoxy and the avus b lack fuel tank
was embellished with wh ite double hnes and a
R100R Cl.:iss1c" model des1gnat1on. Along with
double front disc brakes and the SAS sys tem
st.1ndard fea tures included cylind er protec tion
b,1r s. hazard warning flashers and a luggag e
The R100R Mystic was finished 1n Mystic red
metallic . 11 d11fered from the A100R Classic by
feat uring a chrome-plated instrument console. a
more sporting seat and d1flerent tail section. The
R1 00AT Cl assic was finished m two -tone metallic
paint (Arctic Grey and Graphite). the upper half
of the famng and fuel tank accentuated by a
doubles1lverhne. Thetank camedthedes19nat1on
A1 00RTClass1c' and comple1mg thespec1flcat1on,
a rear 22 -litre top case and side panniers. special
comfort seat, cylinder protection bars and heated
handgri ps
POST 1984 AIR
THE BMW BOXER TWINS BtBLE
1996 model year
At the end ol 1994 BMW announced that
productiori on the range of trad111onal air-cooled
boxers would cease at the end ot 1995. As
production 1as1ed only a few months 11110 the
1996 model year there was no d1flerence to any
of the tour ·Farewell Models- R100R Classic
frame numbers for the 1996 model year were
0125001 ·0125874 Although the street R models
f1n1shed m December 1995. production of the GS
Basic continued for a little longer An RBOGS
Basic was the final air-cooled boxer. the last
leavmgtheSpandauproductoonlineooDecember
19, 1996. The end fmally came lor one of BMW's
most classic engme designs. It remained 1n
production lor 27 years and was remarkably similar
at theendas1t waswhen1tbegan.Cons1denngthe
Type 246 was originally perceNed as an interim
engme design, 11 was astomsh1ng 11 lasted so
long.Themr·cooledboxertwmenduredbecause
1\ was reliable arid charismatic_Ultimately, noise
and emission regulat1onsk11\ed 1t, but for the many
thousands who bough\ and rode air-cooled bo~ers
they remarned mdeslrucl1ble
ThefinaJtradl
wasmeRBO S&.
•IY
r
1996
RlOO Classic distinguishing features
1995 and 1996 model years
RlOOR Classic with black seat. head light
support, instrument console and grab
handle
The R100RT Classic with two-tone metallic
paint. standard top case and panniers
- - --
Frame numbers (1985-96)
Iii!''·' !Ill
R65(48HPJ
6073001-6074774
1986
06/85-08/86
A65
6074775-6118807
1987
09/86-08/87
A65
6118808-6131123
1988
09/87-10/88
R65 (45 HP US)
6128001-6128516
1986-87
07/85-05187
A65(RTTIC)
6460001-6461 092
1986-88
07/85-11/88
R65(27HP)
6430001-6433 529
1986-93
04/85-06193
Rao Mono
6440001-6443 233
1985
03/84-07/85
R80Mono
6443234-6445 826
1986
09/85-08/86
-~Mono
6445827-6447156
1987
09186-08/87
R80Mono
6447157-6448032
""°"'~
6448033- 6448814
"""
09/88-08/89
1989
09/87-08/88
123
THE BMW BoxER Tw1NS 81eLE
....
R60Mono
-
6446615-64&1000
1990
09/89-06J90
06/90·08191
R60Mono
0121001-0122606
1991
R60Mono
0122609-0123285
1992
09/91·08192
A80 Mono
0123286-0123509
1993
09/92-08/93
R60 Mono
0123510-0123695
1994
09193-01195
---
A80 Mono (US)
6460001-6460542
1985
07184-06185
R80 Mono (US)
6480543-6480906
1966
09/85-08186
ABO Mono (US)
6480907-6481120
1987
09/86-07/87
R80AT Mono
6470001- 6472957
1985
07/84-08/85
R80AT Mono
6472956-6475687
19B6
09/85-08/B6
A60AT Mono
647588B-6478620
1987
09/86-06/B7
A60AT Mono
6478620-6483775
19B8
09187-08186
I
A80RT Mono
6483776-6486351
1989
09/BS-OB/89
I
R80RT Mono
64B6352-64BB024
1990
09/B9-0Bl90
R80RT Mono
64BB025-6490000
1991
09/90-04/91
R80RT Mono
0270001-0271732
1992
04191-08192
R80AT Mono
0271733-0272533
1993
09192-08193
ABORT Mono
0272534-0273337
1994
09/93-08194
ABORT Mono
027333B-0273599
1995
09/94-11/95
ABORT Mono (US)
6490001-6490B12
19B5
07/B4-07/B5
ABORT Mono (US)
6490813-6491267
1986
09/85-08/86
ABORT Mono (US)
649126B-6491452
1967
09186-04/87
A100RS Mono
0160001-0161672
1987
07/B6-0Bl87
A100AS Mono
0161673-0162356
19B8
09/87-0B/88
AlOORS Mono
0162359-0163754
19B9
0918B-OBIB9
A100RS Mono
0163755-0164009
1990
09/89-0Bl90
09/90-08191
A1 00AS Mono
0164010-0164292
1991
R100RS Mono
0164293-0165331
1992
09/91-10/92
R100AS Mono (US)
6247001-624754B
19BB
OBIB7-0318B
A100RS Mono (US)
124
-
-
6247549-6247599
19B9
09/88-09/89
R1 00RS Mono (US)
6247600-6247750
1992
02192-08/92
R l OOAT Mono
6016001-6017067
198B
07/87-06/SB
R100AT Mono
6017068-6016000
19B9
09/B8-09JB9
I
I
1
r
I
- - -
P osT-1984 AIR- COOLE.D TWINS
ProductlonGetes
AlOOATMono
6167001-6168000
1990
09/89-06190
AlOORT Mono
6337001-6337902
1991
06190-08191
RlOOAT Mono
6337903-6338475
1992
09/91-08192
RlOORTMono
6338476-6339226
1993
09192-08/93
RlOORTMono
6339227-6339787
1994
09/93-08194
R100AT Mono
6339788-6340000
1995
A100RT Classic
0470001-0470400
1995
11/94-02195
A100RT Mono (US)
6292601-6293172
1988
08187-08188
RlOOAT Mono (US)
6293173-6293399
1989
09/88-09/89
AlOORT Mono (US)
6293400-6293579
1990
02190-08190
AlOORT Mono (US)
6293580-6293729
1991
11190-08191
A100RT Mono (US)
6293730-6293881
1992
09191-08/92
-
09194-11/94
A100RT Mono (US)
6293882-6294013
1993
09192-08193
AlOOAT Mono {US)
6294014-6294248
1994
09193-08/94
RlOORT Mono (US)
6294249-6294455
1995
09194-02/95
R80R
0260001-0263503
1992-94
03191-06194
AlOOR
0240001-0247618
1992
03/91-08/92
A100R
0247619-0250000
1993
09192-02193
02193-08193
0165501-0166916
1993
AlOOR
0166917-0167941
1994
09193-07194
RlOOA
0167942-0169000
1995
09/94-03195
6469000-6470000
1995
03195-07195
0125001-0125874
1996
07195-12/95
0280001-0280546
1992
09191-08192
09192-08193
RlOOR
~c''""
Ctass1c
RUS
A100A US
0280547-0280788
1993
AlOOA US
0280789-0280858
1994
AlOORUS
0280859-0280929
1995
12/94-12195
09193-01194
R80RMystoc
0390001-0390090
1995-96
03/94-03/95
A100R Mystic
0169001-6435634
1994
12/93-08194
AlOOR Mystic
6435635-6437226
1995-96
09194-12/95
_AlOOA Mystic US
0400001-0400145
1994
03/94-08194
AlOORMysticUS
0400146-0400255
1995
09/94-09195
~
l
125
CHAPTER VII
RACING
/SS, /6S AND /7S
E
ven before the /5 was
conceived, BMW had a long
andillustriousracmgh1story.
It began with Franz B1eber's
victory 1n the 1924 German Road
Champ1onsh1p on an R37, and
continued into the late 1920s
with the R63 of Paul KOppen and
Ernst Henne in the Targa Florio.
By the time the Second World War
broke out m 1939. BMW's SOOcc
Kompressor was one of the leading
racing motorcycles m Europe.
After the war. the Kompressor
wasresurrected. lorm1ng the basis
of BMW's racing program and
spawning the fabulous RS54.
The 500cc RS54 engine
shared the Komprnssor's bevel·
gear driven double overnead
camshaft setup, with short
w, •er z,
'!f was BMW's
-J(J ng
racer- dunng
the 19.50~. on the Earles
For~ RS54 and its factory
derrvar1vos
XJrTt!SylvardeGlff/
126
rockers and two straight cut gears
m the cylinder head, but it was
updated with a pair of more modern
Fischer-Amal 30mm carburettors.
The RS54 was also fitted with a
single-plate dry clutch, matched
to an all-indirect four-speed
gearbox, and an Earles leading link fron1 fork,
Walter Zeller won 1he 1954 German Champ1onsh1p
and, fol!ow1ng the return of von Falkenhausen to
head the compet1t1on department 1n 1955, the
factory racer was further developed For the
1956 Grand Pnx season, former 350cc Wor!d
Champion Fergus Anderson was signed alongside
Zeller and Ernst Hiller. although Anderson was
killed at Floreffe in Belgium early in the season
Zeller claimed second overall in the 500cc World
Championship, behind John Surtees on the MV
Agusta.
Although 1956was the high point of post-war
BMW solo racing, it also coincided with a severe
downturn in motorcycle sales and a reduction in
racing development Results during 1957 were
less 1mpress1ve, and at the end of the year BMW
officially wi thdrew their support for solo racing
They continued to provide machines to selected
riders for 1958. including legendary champion
Geoff Duke, now without a factory ride following
Gilera'sretirement from racing. Dickie Dale raced
the AS dunng 1959, and Japanese rider Fumio
Ito 1omed Hiller on the RS during 1960. By now it
was obvious the BMW twin was never going to
succeed in the solo arena. although 11 continued
to have a long and successful career powering
Grand Prix s1decars.
During this time the production R50 and
R69S had limited success in endurance events
London BMW dealer MLG en tered an R50 1n
the 1958 Thruxton 500-mile race for production
bikes. fourth place encouraging them to enter
again in 1959. This time John Lewis and Peter
Darvill won, and later that year, Darvill, partnered
with Bruce Daniels, won the Barcelona 24-hour
race. They narrowly failed to win a1 Mont1u1ch
in 1960. but w11h factory assistance. 1he MLG
R69Swonaga1n 1n 1961. Even by 1964 the BMW
twin was competitive. with Oarv1ll and Norman
RA CING
PncemanagingasecondplaceintheBarcelona
endurance event
Although the R69S had isolated success 1n
long distance racing during the 1960s. von der
Marwitzalwaysenv1sagedthe/5asamoresu1table
basis for competition. The R69S was difficult to
set up for racing and required a specific riding
approach to attain its best_ Von der Marw1tz may
not have succeeded totally in creating a motorcycle
that handled as well as a Manx Norton but, by the
standards of the day. it was surprisingly close
Not only did the /5 handle better than the /2, the
engine design was considerably stronger. Von
der Marw1tz gave BMW a motorcycle that had
real sporting potential. and could acquit itself in
production and production-based racing.
R75/5 Racers; 03hne and
Butenuth
the race was shorlened to three laps, Butenuth
finishing fourth at 93.75mph (150.Skm/h)_ The
private machines of Tom 01ck1e and Tony Anderson
managed seventh and ninth, a promising resul! 1na
field dominated by Triumphs and Nortons_ 01ck1e
also managed eighth 1n the Formula 1 750cc TI
Helmut oahne also applied to ride his R75/5 in the
1971 Isle of Man Productmn TT, but was re1ected
by the British ACU because 1t didn't consider him
e11periencedenough
With the advent ol Formula 750 in 1972.
Butenuth and Oahne entered the inaugural lmola
200 in April, on special R75/5s. Developed with
unofficial factory assistance. Oi:ihne and Butenuth
put up a good showing but were out-paced by
the hoard of factory teams Oahne's machine had
a narrower GP-style frame. shortened forks , and
the engine was fed by Oell'Orto carburettors.
His 13'' overall at lmola earned him his first rode
in the TT.
Thech1elracingexponentsoftheR75/5
in Europe were Hans-Otto Butenuth and
Helmut Oahne. A heavy plant engineer
with an oil company. Butenuth was
a veteran BMW racer, beginning his
career on an RS54 Rennsport in 1957.
culminating in victory in the 1971 German
Championship on a factory-prepared
RS. Born 1n November 1944, after Joining
BMW 1n 1959 as an apprentice mechanic.
Diihne rose to become a development
engineer and test rider. In 1967, Alex von
Falkenhausen lent him an R69S engine
to race. "He allowed me to reduce it from
600cc!o500cc, in the factory and after
~::~~:~h:t:~~~~=-t~~:a:ss~ ~~~:~~ . . .--~~·
So I had to race. This 1s how my racing
career started." He began racing seriously
in1968,andasanamateurwon the1970
German 8-grade championship_ During
1971, Oiihne began racing an R75/5 in
German production racing events
As soon as the R75/5 was released.
Hans-Otto Butenuth rode a near standard
machinem the 1970 Isle of Man Production
750cc TI Although one of the slowest
machmesinthe!1eld,Butenuthach1eveda
verycred1table6"'.coveringthefivelapsat
an average speed of 93.54mph (150 .5km/
h). W1thonly Bntishmachmesaheadof
him. Butenuth!in1shedcomfortablyahead
of all the Honda 750 Fours. This promising
•esult prompted BMW to provide Butenuth
Wlthaspec1alracing R75/5forthe 1971
lsleofManProduct1on 750ccn Th1syear
/SS, /6S AND /7S
Helmut Dahne on hi "'"Y 10
fourth place in the 19721.<:Je
of Man 750cc Productl(J(J
TT. (Courtesy Two \tVhl
THE BMW BOXER TWINS BIBLE
0..1hne rode lfl both me
1973 750ccProductlon
and Classic 7Ts. finish rig
flll'thherelfllhe~
(Cain
yHeJmutfJahrlf
Butenuth wasn't entered this year but Dilhne.
armed with his lmola F750 machine as well as
the production R75/5, had a very successful
week at the TT He managed fourth 1n the 1972
Production TT at an average speed of 92.3mph
(148.5km/h). and 11"' in the F750 race at 92.65mph
(149km/h). Dahnecont1nued
to develop his R75/5 during
1973. Reta1mn9 the short
wheelbaseframeofthe 1970
model, this year he came
14'' at the lmola 200. Diihne
also managed fourth place
in the 750cc Production
TT, but conditions reduced
his average speed
to a slower 90. 32mph
(145.3km/h). Butenuth.
riding a protolype R75/5
with sand-cast crankcases,
managed seventh inthe 750
Production TT. Dahne also
f1mshed mnth m the F750
TT. at 96 79mph (155.7km/h). The 1973 season
was a moderately successful one for 03hne. who
also won five production races in Germany on the
A75/5. The year 1973wasthefinalyearfora 750cc
hm1t 1n the production TI. but BMW already had
the R90S waiting for 1974
Butler & Smith R75/5
Racers
On the other side of the Atlantic, a
parallel racing program also operated
BMW motorcycles were distributed
in the US by Butler & Smith. based in
New York and owned by the Bondy
family prior to 1g70_ During 1969,
Butler& Sm1thserv1cemanager. Helmut
Kern, persuaded Michael Bondy to
enter two telescopic fork R69US
models 1n the Danville(Virg1ma)S-hour
endurance club race. The teams were
Kurt Liebmann/John Potter and Fred
S1mone/B1ll VanHauton. from the
AMOL Prec1s1on dealer/machine shop
in Dumont. New Jersey. With minimal
preparation by Edward Mitchell, Udo
G1etl and Helmut Kern. the BMWs
&JtJer~ Smlh frstrace
surprised everyane with a comfortable
wa l'l efllry in the 1970 1.2v1ctory. During 1970,Butler&Sm1th
l/IR fN& hour enduran
moved to a new facility 1n Norwood,
rac won by Kurt Liebmann New Jersey and Volker Beer (their
~nd r;tiwloc. Dearborn
lull-time BMW factory representative)
XJrl1JSyUdoG..-:-r1
recommended an e~pansion ol the
128
1
racing program. In April 1970. a Canadian entered
R75/5 finished second in the 24-hour Harewood
marathon race. covering 1635 miles (2630 7km)
and encouraging Butler& Smith to seek a repeat of
its earlier Danville result. NewVicePres1dent. Peter
Adams, decided to sponsor the entry which was
coordinated by Volker Beer and AMOL Precis•on.
Helmut Kern spent 92-hours blue printing the
750cc engine in time for the race in September
1970. Liebmann, partnered by Charles Dearborn,
won convincingly, three laps ahead ofthe second
place Honda 750
At the end of 1970, Beer organized for the
factory to supply many racing components
already tested by Diihne in Germany. Four racing
frames and a variety of engine parts, ranging
from magnesium castings to htanium conrods.
were provided to Udo Gietl so he could build
two 750RS racing bikes for the 1971 season
German-born. but US educated, G1etl was an
electrical engineer with experience at NASA and
on the Polaris submarine nav1ga11on systems_ In
1959 at the age of 19. he helped a friend rebuild
an R68, and when the people at Butler & Smith saw
it they offered him a1ob. G1etl's racing experrence
beganw1thmotocross1n 1961 and,afterspending
lime in the army repairing communications gear
in Korea. and at Cape Canaveral. by the end of
the 1960s he was back at Butler & Smith
R AC ING /55, / 65 AND /75
Thefu51 8 ,.
racer 1! 191 1 3d
Fotiranab
)Ufl•·y.ldc
By 1971 G1etl was work•ng
11~:o~~u~~~10~7!~hp;~~~
-~==-- :~~.
Precision G1etl, produced one
racer forL1ebmannw1thanother
latermtheyear. !orJustusTaylor
The resulting 750RS racer was
commendablynarrow,butd1dn't
handle as well as e11pected as
the frame wasn't suff1c1ent1y
strong around the steering head
Only two of the four frames were
used and, while Giel! and l<ern
commissioned C&J in California
to build two s1m1lar frames. the
handling on these was also
deficient. A third F750, us111g a
production R75/5 lrame. was built
ror Charles Dearborn. along with
aproduclionracerforl1ebm1.mn
While the 750RS had limited
success that year, L•ebmann
(with John Potter) again won Th ra-row f1an ::in /hrs
the Danv1He 5-hour production o rrty ~ CJt v.as a ;pee
race on the R75/5 Dearborn B MW M<.>l<XSpOrt type
used by Dahn8.-i£urape
)U{tt
·v /do Gil ~
129
THE
BMW BOXER TWINS BIBLE
/
l<.tlf1Lll!Ln lnnr« 'iJdt/le
LlP
130
TheButler&Sm1th fnmch1se
was sold to the Adams in 1971,
and 1t expanded the operation
by opening a West Coast office
in Compton, Cah!ornia. Helmut
Kem was general manager. with
EdwardM1tchell(partsmanager),
Matt Capri (sales manager)
and Miles Rossteucher (shop
mechanic). At 1he end of 1971,
w1thR75/5salesstagnant,Kern
approached expatriate Briton.
Reg Pridmore. to nde in the
1972 West Coas1 Production
senes. Pridmore tested one of
Udo G1etl's special R75/5s and
recalls "When I rode the bike
I was quite impressed . It had
no brakes. bu\1tranqu1\ewell.
BMW wanted to move a lot of
750s that were sitting around
People thought the BMW was a
good old man's tounngmachine
and didn't believe 1t was a good
handl•ng performance machine
I enjoyed a good rapport with
Buller & Smith. They kept developing the bikes
and things 1ust got better and better We had a lot
of success. and they sold a lot of bikes An A75/5 production racer was built on
the West Coast using many components from
G1etl's GP bikes. A 19-inch wheel was f1tted on
the rear. and the cylinders shaved to increase the
compression ratio During 1972 and 1973. the
engine rece1vedshorterconrodsand 10.8:183mm
Venoha pistons with lightweight wnst-p1ns. located
closer to the piston crowns. The rockers pivoted on
George Wenn needle bearings and Jerry Branch
ported the cylinder heads. Valve tram weight
was reduced with S&W valve springs. hollow
steel tappets and aluminium pushrods. From the
GP bikes there was a heavily drilled flywheel to
reduce weight, and tungsten plugs inserted 1n
the crankshaf t. Lubrication modi fications saw
an add1t1onal 011 groove cut into the base of the
cylinder. with a high pressure orihce feeding this
groove for add1t1onal piston skirt lubrication.
By the end of 1\s development the transmission
was also five-speed. Just about all these racing
developments eventually found their way onto the
production models. again evidence that racing
improves the breed.
R ACING
Square windows were cut in the air intake
hoses. and holes drilled in the air filter housing
While the chassis was stock. Kern spent
considerable time and effort reworking the front
suspension. With FerodoAM4 green linings in the
front drum brake. the B&S R75/5 was possibly the
most effective production racing motorcycle in
the United States during 1972and 1973. Pridmore
managed 15 wins and 6 second places out of
23 starts, winning the AFM production class
champ1onsh1p As the series was confined to
the West Coast 11 had l1m1ted exposure, However.
when Cycle magazine tested the R75/5 racer 1n
11s May 1974 issue. Pridmore received nationwide
fame. CycJe"s performance figures at Orange
County Raceway were 1mpress1ve, espec1alty so
considering the surprisingly stock looking and
very quiet mufflers. Into a strong head wind, the
R75/5 rana 12.7-second standing quarter-mile at
104mph (167.3km/h). Pridmore also took the A FM
750cc Grand Prix lftte on the 75DRS
During 1972. the East Coast racing program
continued with Udo Gietl developing the 750RS.
both with the standard and racing frame. The engine
now produced 86 horsepower but performance
was limited by the AMA-sanctioned four-speed
gearbox. The machine was commendably light
and. with the special racing frame. weighed
only 150kg. Raced by Liebmann. Dearborn and
Pndmore, the 750RS had some success this year
Liebmann contested the 100-mole Junior race at
Daytona. where he failed to finish. but went on to
win the Pocono SO-mile road race on August and
AAMRR open class Grand Prix lltle. Dearborn also
managed another win on the R7515 1n the street
class at Bridgehampton in Apri!. and, teamed
with Liebmann, took first place in the Two-Hour
production race a week later. Dearborn"s best
finish on the GP bike was third at V1rg1n1a 1n
September 1972.
Encouraged by the AMA request for
manufacturer involvement in compet1t1on, Butler
& Smith continued to race the F750 racers during
1973. but again they were outclassed. The racers
now featured a Harley-Davidson full lamng, a
Ceriani front !Ofk with twin Honda disc brakes,
and now had a live-speed gearbox. Ridden by
L1ebmann.JustusTaylorandPndmOfeintheAMA
National Road Race Championship. Pridmore
summedthemupw1th:"thoseearlyGPb1keswere.
what you might say, shoestring racers."
Attheendof 1973 Pridmore introduced frame
builder. Englishman Rob North. to Kern and Capri
NOfthm1gratedtoSouthemCahfOfn1aduring 1973,
and Pridmore, who was racing a North s1decar
racer at the time. suggested North provide a
/55, /6$ AND /7$
frame and fuel tank s1m1lar to
those of his highly successful
Triumph and BSA 750cc triples
North subsequently built two
~~~~=· ~r~~~~~s~~~~~e~~1~ !J-~~~~~~-~~~
development coincided with
an expansion 1n workshop
lac1ht1es at Norwood. with a
new dyno. flow bench and
welding equipment. G1etl
agreed to the North proposal for
a Triumph-style racing frame
althoughhehadToddSchuster
on the East Coast fabricate a swingarm that was
longer by 2 inches. The wheelbase was quite long.
at 1470mm (57.9 inches). but the double-cradle
chrome-molybdenum steel frame was strong and
1mmed1ately tamed the handling of the R75/5_ The
drtveshaft ran 1n the nght-s1de of the swingarm.
but with an exposed U-joint to save weight The
engine was also located higher than that of the
Triumph, for improved ground clearance
JIAI
131
THE BMW BOXER TWINS BIBLE
n Norttiframe Jn tile
14 Butler & Smi/h r, ~er.
w p.1llerned0111hat
'ltie ·,uccessful BSA
:1 Tnumph lnple\ , and
Wed a ulptured fuel
'JI<. ;{))rte y lwoWh
132
Two North-framed F750 machines were
prepared m time for the 1974 Daytona 200-mile
race, both eKtens1vely modified boKer twins
Overbored to the maK1mum allowed (1mm). the
763cc engine was based on Pndmore's successful
R75/5 product•on racer, with input from many of
Cahlornia's leading Hot-Rod eKponents_ It was
further developed throughout 1974and 1975. Jerry
Branch reworked the cylinder heads w11h 44mm
intake valves and stra1gh1 intake ports. as the
carburettors no longer needed to clear the rider's
shins, while S1g Erson developed the camshaft
Along with lightweight steel cam followers.
the rocker assemblies included needle thrust
bearings. After e11perimenting with aluminium
and titanium pushrods. Gietl setlled on steel units
that f!eKed less_ The camshaft drive was initially
by a single-row chain to minimise power loss
however, as revs increased and heavier valve
springs were required, the chain sprockets failed
and the dupleK chain was reinstalled. According
to Reg Pridmore "roller cam followers were tried
at one stage. 11 revved like a banshee but didn't
show the rehabihty the boss was looking for." Due
tothe1rstrongerbeanngsupportsthecrankcases
were /6, w ith all eKcess metal machined. There
were also mod1ficat1ons to the lubrication and
crankcase vent1lat1on system. with a smaller
diameter 011 pump, enlarged oil passages and high
volume crankcase vent1lat1on. At peak revs 11 was
found the stock oil pump drew five horsepower,
and the smaller oil pump reduced cavitation. A tiny
011 reservoir was incorporated in the crankshaft
journals. All the machine work was done by Kurt
L1ebmann's father. Oscar. at his company, AMOL
Precision.
Carburet1on was by M1kuni, initially 38mmbut
later reduced to 36mm_ The 83mm 12:1 pistons
were Veno Ira and the gudgeon pm. located 12mm
closer to the crown, allowed each machined Allin
cylinder to be 22mm shorter. improving ground
clearance. lgrnt1on was electronic Krober. with twin
sparkplugspercyhnder. two triggers and four coils
The crankshaft rod 1ournals incorporated a second
011 supply hole and weight saving eKtended to
lighter counterweights {by 80 grams). re-balanced
with metal inserts and removal of the generator
The 10mm shorter conrods were t1tamum and. to
improve throttle response, the standard flywheel
was drilled to weigh only 1.6kg (from 3.6kg)_ The
larger sump carried another 1.1-htres of 011. and a
Triumph oil cooler kept everything cool at gsoorpm
Initially producing between 82- and SS-horsepower.
by 1975. the 750cc engine was rumoured to
produce 100horsepower at the crank. During " 173.
the AMA sanctioned five-speed gearboxes and.
as the R75/5 only featured a lour-speed gearboK.
a five-speed Kaiser-converted unrt was used. By
1975 thegearboK was a BMW unit. but with a drum
shifting mechanism instead of cam-plates. There
was a choice of eight final drive ratios. ranging
from Daytona·s 1:2.62. to a 1:4.25 for the twisting
SearsPomtcircu1t
Knowing that his BMW racers suffered
a horsepower deficiency compared to the
competition, over its two and half year
developmental period. Udo G1etl concentrated
on improving the suspension. The racing Cer1am
forks, similar to those of the racing MV Agustas.
had Betortnpleclamps, whilethetw1nG1rl1ngshock
R ACING
/55, /65 AND /7$
K
'
absorbers featured heavier damping with light
spnng1ng_ This suited the peculiar characteristics
of shaft dnve and steering and handling were
vastly improved. The magnesium wheels were
designed by G1etl, cas1 by Morns and machined
by AMOL Braking was by double 230mm drilled
cast-Iron disc brakes with dual-piston Lockheed
cal1pers on the front, and a s1ngled•sc on the rear
At 152kg ready to go, the B&S racer was lighter
than the Yamaha and Suzuki two·strokes. capable
of around 265kmfh (164 7mph)
The Norlh-framed machines were hopelessly
outclassed at Oaytona 1n 1974, with only Pridmore
qual1fy1ng PndmOfe managed to get up to 12'
before a cracked valve forced his retirement It
wasrumouredthatPr1dmore'smachmed1splaced
1000cc,buth1sret1rementw1thacrackedvalve
ehmmated the embarrassment of a post-race
\eardown. Reg says. "The two Rob North GP
racers were really good, bu\ their effort 1n GP
rac•ng was knocked down by all the TZ Yamahas
The BMW was competitive against the 350s. but
thenthe700sand750scamealong. I found that
on certain shOfter tracks I could beat 80 per cent
of them. bul 11 lacked horsepower at places like
Daytona "Wh•le not especially suited to Oaytona,
the B&S GP mach1n.es were eff&c!lve 1n regional
road racing Their high point was a magnificent
1-2 victory at Summit Pomt. West Virg1n1a, 1n
Ap11\ 1974 In the Open EKperl GP. Justus Taylor
led home Kurt Liebmann, despite fracturing an
•ntakevalve
THE BMW BO)(ER TWINS BIBLE
•/Ji.JS/
- - - - ' I f -- ;
bablythefas testpushrod
; ; : ; ; ; ; : : : : theywerepro
twins ever Pridmore was running 13
~=~~;:~~=~~-~~~
;
:
Although four-strokes appeared
dead in AMA racing. Buller & Smith
entered Liebmann and Pridmore on the
F750 racers. in the 1975 Daytona 200
Now at the peak of their development.
producing around 100 horsepower at
the crank and running to 10.500rpm.
but
of 80.Gary
field 30·
thefinish
saw inhim
a good effort
problems
Fisher was drafted alongside Pridmore
for therema1mng races of the 1g75AMA
F750 season. and during 1975 G1et1
experimente d with monoshock rear
suspension on Gary F1sher"s bike. In the
final race for the F750 BMWs(at Laguna
Seca), Fisher put the monoshock bike
on the fron t row. dicing with Kenny
Roberts for the lead during the race
until the monoshock la1led. Pridmore
also proved the F750 BMW"s potency
by out accelerating the Yamaha 700s
at Road Atlanta. Olten top !en lin1shers
1n AMA Nationals. and faster than the
once-domin ant Harley V-twins. the
B&S GP racers remain testimony to the
magmhcent era when BMW in America
was comm!l!ed to racing. against all
odds. and when racing developmeflt
trickled onto the production bikes
R ACING /5$, /6$ AND /7$
R90S and R100S Production
Racers
The release ol the RgOS at the end of 1973 was
fortuitous lor BMW. as 11 coincided with a move
away from 750cc-based Production racing to
1000cc. Forthe Bot d"Or 24-Hour endurance race
atleMans.23September1973.BMWprepareda
factory R90S. Ridden by D3hne and Gary Green.
this finished third, covering 3200km (19884m)
Oahne. assisted by Helmut Bucher. also continued
to develop his older R75/5 racer for Production
events. With the Production TT capacity limit now
1000cc. they installed a new 900cc engine with
l1ve-~;...~d gearbox and dual disc front end on
the R75/5 chassis. "I always raced with the short
wheelbase R75/5 chassis. even with the R90S
engine. This was for weight and handling reasons
I never had any stability problems.- says Dilhne
In the 1974 Isle of Man 1000cc Production
TT Butenuth also raced an R90S. This was a
special 1000cc version developed by Paul Blum
Butenuth came second at 97.7mph (1572km/h)
and D3hne third at 97.0lmph (156.1km/h)_ Oiihne
was also entered on a A50R and R75R 1n the 1974
Senior and Classic TTs. although his R90S was
substantially faster. Dahne went to work for the
Met zeler tyre company as race manager in May
1974, but continued a close assoc1at1on with the
BMW factory
The 1975 Producl1on TT was a 10-lap
handicap race w11h two riders and D3hne teamed
with Werner Dieringer. The Daytona Orange R90S
jst1llintheshortchass1s)eng1neleaturedalarger
sump: Krober electronic 1gn1t1on: titanium conrods;
high compression pistons: larger valves: hotter
cam: larger Dell'Orto carburettors: megaphone
racing exhaust. and a close-ratio transmission
After two Laps Dahnewas 1n the lead by a minute
when he knocked a hole m1he r1ght-s1de cylinder
head cover. causmg severe 011 loss and engine
seizure. Dahne carried a spare rocker cover
strapped to the side of the bike but the damage
was already done . He hnished ninth 1n the Open
Classic TT on the same bike later in the week. the
first four-stroke home He averaged 99.67mph
(160.36km/h)lor thes1x-lap race. and h1sbest lap of
101.89mph (163.94km/h) was the f1rst 100mphlap
by a BMW at the Isle of Man. BMW also returned
to the Sol d 'Or in 1975. Dahne teaming with Rene
Guill to finish fourth
this time determined not to suffer from the ground
clearance problems of the previous year Special
10.s-1 Mahle pistons. with raised gudgeons and
shorter conrods. 1rimmed 22mm or1 each side
The crankshaft and flywheel were lightened by
2kg. and there were l1ghtei. thinner (10mm rather
than 12mm) alloy pushrods enabling the engine
0.11me s 19, R90S
racer rtr uned tl '1)orT
na
wlle<>/ba> Rl
bur ~1, sutfcnldgnltlfJ<l
ev
anct 'fJ'C:>Vlem
'lflCet.1 by the
135
THE BMW BoxEA TwtNS BIBLE
to rev safely to8000rpm. Diihnecommented that
"The valve tram was very fragile. So I developed a
two-part alloy push rod with a spacer 1n the middle.
together with mushroom cam followers. It cured
the valve spring b1eakage problems by absorbing
some of the valve shock when the cam came very
abruptly otf bottom dead centre. I also made a
ma1or change to the valve gear by obtaining an
unmach1ned crankcase off
the production line. This
was sleeved to allow the
cam follower and push rod
to line up straight because
1n the standard engine
they're six degrees out
of line, with the pushrod
always being moved
sideways. This was done
rn ant1e1pat1on of the
larger. 94mm, cylinders
for the later R100." The
powe1 of Oahne's R90S
was 80~horsepower at
7000rpm. and the weight
was 185kg
A 1mm thicker top triple clamp tightened the
handling for the bumpy TT course and, teamed with
Butenuth. Dahne led the 10-lap 1976 Production TT
from start to finish. averaging 98 .82mph (159km/h)
Under the handicap system, they were credited
Dur.ng 914, Pridmore rode
me new RQ(JS le. some
e inwo: r coast
Producbon raclfl')
Jrt yTw<Jl/VheelsJ
136
with filth - the first time the fastest finishers
didn't win aTT 08hne's fastest lap of 102 52mph
(164 .9Skm/h) remains the best ever lap of the Isle of
Man by a push rod boxer twin_ Martyn Sharpe and
Abe Alexander on another R90S hmshed second
across the line. averaging 95 Smph (153.7km/h)
but werecred1tedw1th 15'"overall. D3hnereturned
to TT in 1977 with a boxer twin for the TTF1 race
but retired after one lap
'
The release of the R90Salso comcKled with the
expansion in production. and production-based
racing 1n America_ As Reg Pridmore and the
Butler & Smith R75/5 were the most competitive
combination m West Coast production racing
during 1973, 11 was no surprise to see them on
the leader board with the new R90Sduring 1974
Liebmann campaigned the production R90S
on the East Coast. Gietl and Kern, wrth Todd
Schuster assisting with fabrication, worked on
the R90S, boosting the power output to around
90 horsepower. Although chassis specification
had to remain basically stock. they used wider
wheel rims with an offset to clear the driveshaft
Pridmore found the R90S to be a forg1v1ng bike:
"I used to ground the heads a lot but the handling
was OK with some suspension changes, If you hit
something down on another bike 11 would pick up
the front end and usually throw you away. A lot of
times the BMW gave warning signs of lifting. then
1t would come back. I didn't fall off them a lot."
R ACING
Pridmore was denied a win in at Laguna Sec a
when an 1gn1tion wire broke, but made amends
at Ontario where he finished so far in front of
the Yoshimura Kawasakis of Yvon Duhamel and
Steve Mclaughlin, they assumed they had won
On the podium. Duhamel said to Pridmore: "What
are you doing here? Didn't you crash?" Reg rates
this victory as his most memorable on the R90S,
andoneofthemostunforgett ableinh1scareer
He continued to ride the production R90S (now
Daytona Orange) during 1975, finishing fourth in
the Daytona production race. But as production
racing evolved in to Superbike racing in the US,
sodidtheR90S
Butler & Smith R90S and
R100S Superbikes
With the demise of compet1!1ve four-strokes 1n open
class rac ing m the US. and a consequent massive
drop in public interest, for 1976 the AMA created
the Superb1ke series for racing motorcycles
based on production models. The Superb1ke
rules required the machines to look stock, even
retaining a tail light, but underneath the street
bodywork they were highly developed racers
Udo G1etl was on the AMA Compet1t1on Board
rules committee and instrumental in the creation
of this series, coming the word 'Superbike • In
that first year of Superb1ke, on!y Butler & Smith
exploi ted the new Superb1ke regulations to the
full. Initially, Superb1ke preparation was a sole
East Coast (Norwood) pro1ect, but, ultimately, 11
became a comb ined effort by both racing arms
of Butler & Smith. Team manager Udo G1etl, with
Todd Schuster. Kenny Augustine, AMOL Prec1s1on
and West Coast executives Helmut Kem and
Matt Capri. worked tirelessly to crea te the R90S
Superb1kes, arguably the most spectacular BMW
racmgmotorcycleseverbuilt
G1etl began preparing the R90S Superb1kes
for the upcoming Daytona Superb1ke race in
October 1975. He knew that. to compete wi th the
Kawasa ki Zl, he wou ld need as much power as
possible, with better handling . G1etl then went to
extraordinary lengths to achieve it. gsmm forged
Venoha pistons bumped the capacity to 1000cc
and provided more than 12.6:1 compression
Th ree differen t brands of piston ring were used
a special L-sect1on top ring; Chevrolet middle
nng. and a Perfect C ircle oil control ring As the
engine had to revsafely to9200rpm, the gudgeon
pins we re machined from Kl 1 heat-treated steel
Inside thecylmder head were t1tan1um 46mm inlet
and 39mm exhaust valves. Augustine flowed the
cylinder heads. Schuster bored and worked the
/5$, /6$ AND / 7$
38mm Dell'Orto carburettors to 40mm, and the
camshaftwasbySigErson(w1 th 12.8mmofmtake
valve lift). The shorter Smith push rods were of 4130
steel and very thin steel valve li fters came from
Germany. To increase cornering clearance the
cylinder barrels were shortened and the conrods
were 10mm shorter. German forged titanium
(125mm instead of 135mm). The rocker covers
were bevelled and fitted wrth steel skid plates.
the crankshaft was rebalanced for higher rpm
and included two holes for the conrod bearings
and the counterweights were removed. As the
BMW crankshaft was only supported at the ends.
without a centre bearing. 11 was always prone to
llexath1ghrpm
G1etl fabricated an all-metal dry clutch
and. while the close-ratio gearbox retained the
stock BMW third. fourth and fifth gears. AMOL
Precision made up closerf1rst and second gears
Four coils fired the twin spark.plugs per cylinder.
and all superfluous components (such as the
electric start and air hlter box) were discarded
Pridmore retained points 1gn1t1on while Fisher
and McLaughlin's was electronic, and the large
front-mounted 011 cooter came from an English
MGB sports car. As stock mu filers were required
by the regulations, these were gutted and fitted
with a reverse-cone megaphone. designed by
C.R Axtel for Harley XR750s. When they lined
up at the inaugural Superb1ke race at Oaytona 1n
March 1976, the Butler & Smith R90Ss produced
92 horsepower at !he clutch. During the season 1t
was continually developed. eventually producing
102 horsepower at 8600rpm (with roller follower
camshalts)
G1etl also looked hard at the chassis
regulations, stretching them to the hm1t A loophole
indicated that the swingarm could be modified
and the rear suspension relocated, and this 1s
exactly what hed1d. Gietl reworked the swing arm
to incorporate a single, semi-horizontal, Korn Fl
racing car shock absorber. Udo said. "Earlier.
Volker Beer provided an R90S with a bent frame
from a crash and Schuster and I developed the
monoshock wrth this bike. R1d1ng 11 gave me a
better understanding and ultimately Jed to the
1976 Superb1kes." All this fabr+cat1on had to be
done 1n secrecy. so the welding was done at the
Norwood shop with the assistance of AMOL
Precision. A spacer behind the gearbo11 shifted
the engine forward 25mm. and upwards 10mm,
and the eng•ne was also repos1t1oned Smm to the
right, to allow clearance between the Michelin
shck tire and dnveshaft. As gusset1ng and added
stillness to the production lame was permitted,
G1eU and Schuster added a pair of diagonal frame
137
members. connecting the steering head to the
swingarm pivot This also enabled one ol the
lower frame cradles lo be removed. the motor now
hanging 1n the lrame. fac1litating quicker engine
removal for serv1c1ng
The stock BMW forks were reworked.
strengthened with a huge alloY top triple clamp
and braced The internal fork rubber bumper was
replaced by a short bottoming spring. Front fork
travel was limited to six inches. and rear suspension
travel. five inches(w1th either suspension layout)
W1derWM4andWM5 (1aterth1swasaTZ750WM6)
18-inch alloY wire -spoked wheels allowed wider
'38
M1chehnshcktyres.w1ththerearlaced8mmtothe
left tor even more clearance. Initially the brakes
were still the stock ATE floating cahper type, with
260mm alum1mum discs. The overall weight was
at the AMA regulation 370 pounds (168kg) All the
testing was done in secrecy on the llow bench.
dyno and illegal test rides . "One of these test
ndes came at the cost al some skin in one of the
crashes I had... says Udo.. "The b•kes didn't lee.
fast compared to my heavily mod1hed strM>t bike
but the dyno said otherwise Time moves quirkly
when you are having this much fun. and soon •l
was show time at Daytona.·
R AC I NG / SS, /GS ANLt /7S
Three R90S Superb1kes were prepared and
G1etl's plan was to run two riders. Pridmore and
Fisher. w1thonemachmeasaspare. But.at the last
minute. Mclaughlin was dr<1fted m_ Peter Adams
wanted a third rider. and Matt Capri convinced
Adams and Kern to include Mclaughlin. As G1etl
says: "wewere up to the hilt. Wearroved at Dayton a
with three complete bikes. but very few spares.
hardly even an elttra piston ring_ The West Coast
guys also knew nothing of the monoshock until
Oaytona I did this secretly. g1vmg the welders a
six pack of beer to complete 1t. When Helmut Kern
saw 11 he was !1v1d, and 11 caused a lot of friction in
the team " As Udo left the twin shock mounts 1n
place 1t was decided. as Pridmore was the number
one rider, to leave his bike twm shock to allay any
possible protest. Reg tells it slightly differently• "I
didn't like the tension m the shorter rear spnng,
and I couldn't make the dampmg keep up with the
lack ol movement m the shock So I couldn't ride
11 and had Helmut Kern remount the twin shocks "
Udo says ··we had a huge selection of springs.
and Kern selected a heavier spring tor Reg, whole
Steve and Gary used much softer ones "
Unexpected hum1d1ty, and the high
compression. resulted m 1gnol1on problems during
practice. but the speed was 1mpress1ve and the
bikes were reasonably fresh for the mam race
Fisher was timed at 144 5mph (232.5km/ h) and
all three riders quahhed for the final. Fisher was
first, Pridmore second and Mclaughlin third In
the first US Superb1ke National final on March
5, Fisher built-up a large lead until a fouled shift
lever caused the transmission to pop out of gem
He over-revved theengme. break mg a rocker ium
two laps from the lm1sh Mclaughlin assumed
the lead until Pridmore caught him. On the Imai
lap. Pridmore led. but Mclaughlin dratted past
across the lm1shmg lme to win by three inches
Pridmore was 1mt1a!ty credited with victory, but the
139
TH E BMW B OX ER TWIN S BIBLE
lvfcLdvghJ1r1 ceh.'brates with
P 1Cimcxe dftar one of the
t finishes 1r1 Daytona
tusrory rCourtesy
TwcWh<:?els,I
'fer l1r: hlfl9 ec?nd at
went
"8)11 )(18 PrKlmo
)(l/Oµrovide81.,1Ww1rh
,, "111/v AMI ;per/J.~e
l_"o
Ct>arnoton>h1p
photo finish equipment later proved Mclaughlin
the winner. It was one of the closest race finishes
ever at Daytona, and the race average was
99.Smph (160.57krnlh). So dominant were the
BMWs that they made the rest of the field look
second-rate
At the next
round at Lacoma.
New Hampshire,
the experimental
alum1mumbraked1scs
were problematic
Mclaughlin missed
a shift. over-revving
and shearing the
flywheel, while Fisher
and Pridmore were
beaten by Baldwin's
Brembo-braked
Moto Guzzi Le Mans
Tw1n-p1ston Lockheed
front callpers with
Hurst-A1rheart steel
discs graced on the
front for LagunaSeca
While Fisher retired
with a broken 011 cooler leak. Pridmore and
Mclaughlin diced for the lead. McLaughlin
crashing spectacularly on the final lap. allowing
Pridmore to win.
Pridmore also went on to win the fourth and
final race of the inaugural Superb1ke season at
R1vers1de. a favourite track that he knew well.
ensuring victory in the 1976 AMA Superb1ke
Champ1onsh1p G1etl's book-keeping showed the
racing season had cost Butler & Smith $250,000.
but it ensured the sales success of the A90S m
US. and forever changed the perception of Bt
motorcycles. According to Udo Gietl. .. at I~
13 racing bikes came out of the Butler & Sn
Norwood shop during the 1970s." and, with the
JOb done, Peter Adams decided to pull the plug
the expensive program. Udo goes on to say. "Pt
Adams had to come to terms with the expend it
so termination ol the pro1ect was inevitable
sad. and disturbing, part for me was all the rac
equipment went to Compton on the West Co
where it was destined to be sold." For rac
machines, the R90S Superb1kes were extrerr
reliable. with the same pistons that took first <
second at Daytona still in the bikes at Laguna Se
After Daytona, Cycle magazine nicknamed
B&S bikes the "Bavarian Murder Weapons:· I
the obsessive racing season came at a cost. 1
marriages of Pridmore, McLaughhn, Fisher, Gi
Augustine and Schuster all ended. "This was •
only part that wasn't a team effort!" says Udo
Although Buller & Smith was no Ion(
seriously involved in racing the R90S Superbi
one machine was entered for the 1977 Dayto
Superb1ke race. Monoshock rear suspens+
was banned by the AMA Superb1ke this ye
and the Butler & Smith R90S was a Wt
Coast entry coordinated by Helmut Kern. N(
painted red AlOOS colours (but still an RQ(
because thrs was the only homo!ogated mod£
Pridmore rode rt at Daytona. qualifying faste·
McLaughlin rode Udo Gietl and Todd Schuster
Bel Ray-sponsored R90S, while Pierce rode
NorthChesterMotorcyclePartsentry. McLaugh,
quahhed second, but his motor failed m the ra(
and he didn't finish
R ACING /5$, /6$ AND /7$
Pridmore finished fourth in the 1977 Day1ona
Superb1ke race (behind Cook Ne1lson's Ducat•
and the Kawasaki Zls of Wes Cooley and Dave
Emde), but the d1flerencem trap speeds between
Pndmore's 142mph (228.5km/h) and Cooley's
153 06mph (246.27km/h) signified the end of any
official Butler & Smith involvement in Superbike
racing. As Pndmoresa1d: "I wasn't too upset The
new bike had d11ferent steering geometry and I
thought the handling was much worse. making
11 harder to go inlo turns." G1etl and Schuster
continued !heir involvement,ass1st1ng Ron Pierce
to provide the Mclaugh\1n Daytona-winning bike
(also now painted red), another victory at Loudon
in June 1977. The San Jose bike {Fisher lt21) also
gave BMW another AMASuperboke voctory. when
Harry Klinzmann won at lacoma 1n 1978
For the 1978 season Goetl and Schuster {GS
Performance) contmued developing their R90S
Superboke Udo managed to persuade Peter
Adams 1oprov1desomeass1stance. "Peter Adams
was eio:tremely enlhus1ast1c about the racmg
program. and also sympathetoc when o\ ended
When asked to continue on a small scale on my
own. he agreed to the use of the Norwood lac1hty,
some parts. eio:cept1onal discounts and tome oil
Without his support this last R90S pro1ect would
never have happened "
An mdependent team was tormed. w1thGoetl
responsible for design and dnvetram; Schuste1
!or chassos. machining and fabrication. and Tom
Cutter for assembly, maintenance and track
support. In the hands of the already successful
M1am1 rider John long, they almost provided BMW
with their second AMA Superb1ke Champ1onsh1p
Development saw the engine modolied to 1mpJOve
rehab1hty With later RlOO crankcases, to reduce
crankcasepressu1eloss. thebrealherled1ntoa
foam-filled bo~ lhrough reed valves The 95mm
Venoha pistons were lighter by 50-60 grams,
141
THE BMW BoxER Tw1Ns B1eLE
enabling tighter clear;mces. and 1he 45mm inlet
valves were from a Chrysler Hemi V8. Schuster
lubricated 40mm smooth bore Oell'Orto
carburettors and. 101 shorter tracks, G1etl installed
a 36mm intake restrictor For improved intuke
flow. thestockcurvedmtakemanifoldswerecut
off and labncated slra1ght ones welded on at a
different angle The 330-degree camshaft was
by Crane. with double coil Crane springs. Smith
pushrods and W1esmann steel tappets straight
out of an aftermarket automotive catalogue Later
in the season. G1etl fitted a set of Harley-Davidson
XR750 l1ghtwe•ght roller tappets_ The Carillo
conrods were nickel steel. still lOmm shorter
than stock and. when combined with the steel
and twin sparkpLugs per cylinder. the top plug
fmng at 34 degrees BTOC and the lower plug at
32degrees. "Th1swusa setting I first tried onthi
Butler & Smith Superb1kes, uod 11 worked," said
G1et1. Other mod1l1cahons e"'tended to a heavliy
milled flywheel. contributing to a reduction in
engine weight to only 52kg. The transmission
was a special reworked close-ratio set from
BMW For the Loudon race after Daytona. Gietl
built a second engine with roller cam followers
and a chrome molybdenum steel camshaf;
ground by Crane. The camshaft ran 1n needle
beurings, and the 1gmt1on was replaced by
Krober electronic magneto. The power was
appro,..1mately 102-104-horsepowerat8700rpm,
and the camshaft compressmn ratio and port
sizes were altered for each track. as were the
gear ratios and final drive
~~~I{,~"'.. .
1
:::
moved forward 15mm in the frame
to improve weight d1stnbut1on, and
two welded slruts connected the
swingarm pivot to the steering head
Extra plates also strengthened the
steering head, and the head angle
was decreased to 28.5 degrees
(from31 degrees). Theswingarmwas
extensively reinforced, and the twin
Koni shock absorbers considerably
re-worked. The wheels remained
wire-spoked (a WM4 at the front
and WMS on the rear, with Michelin
slicks}. white the stock BMW 36mm
fork included very soft springing and
modified damping. After Daytona. to
restrict fork travel under hard brak,ng.
Gietl incorporated a mechanical
ant1-d1ve with the twin Lockheed
brakecalipers mounting on a floating
alloy rocker arm pivoting from the
front axle. Each rocker was linked
...<..- - -I C'
. .. .
by ballJo•nt and pushrod to the lower .____.._
fork crown. transmitting rotational
torque to the lower crown. This setup allowed a Massachusetts dealer. but Long continued
some dive during braking, but aided cornering to campaign 11 dunng 1979, finishing fourth at
ground clearance. The twin front discs were Daytona, and ninth at Loudon
Ex-AMA 250 champion Dave Emde also
light-weight plasma-coated aluminium. or caststeel for shorter circuits_ Superbike regulations rodeoneoftheex-Butler& Smith R90Ssin BOTT.
allowed a 20 per cen\ weight reduction from Sponsored by San Jose BMW. Emde was so
stock, providing the Goell-Schuster BMW a fast in the wet at Loudon in 1981 that his team
considerable weight advantage over the Suzuki also entered him m the Superb1ke race. Starting
from the back of the grid Emde ran as high as
and Kawasaki 1000s
The GS Performance R90S handled third before finishing fourth. While that was the
extremely well and was perlecUy balanced. At end of the BMW twin in AMA Superb1ke, Long
Daytona. Long finished thord, out dragged to the continued to race the GS R90S until 1983, m the
Battle of the Twins Grand Prox Class
finish line by Reg Pridmore. now on a Kawasaki
A second at Loudon, followed by fifth at Sears
Australian Castrol Six-hour
Point. retirement at Pocono and fourth at Laguna
Production Race
Seca, saw Long ending the season with a points
tie for !he 1978 AMA Superbike Championship
with Pridmore. Due to a starting infringement Production racing was ext1emely popular on
at the second Loudon race, lowering their third Australia 1n the early 1970s. and the Castrol
place to eleventh, Long was credited with second S•x-hour race for production motorcycles was
overall. It was an astonishing achievement for the premier motorcycle racing event on the
a privately entered pushrod twin to succeed so calendar. Broadcast nationally on live telev•s•on,
well in a field of factory-prepared fours. Long the rules were slnctly administered. The race
also won the Canadian Superb1ke Championship. was first run m 1970 and whole several R75/5s
clinching •t with a win at Mosport. This last wereenteredmtheearlyyears, theyd1dn'tf1gure
victory represented the end of an era An era prominently on lhetoghl 1.9kmcorcuot that favoured
where the shaft-drive pushrod BMW twin was smaller and lighter motorcycles. However. 1n 1973
a real racing force, and could compete with the the BMW R75/5 surprised the held. Tony Hatton
best the rest of the world could offer. At the end riding the six hours single-handedly woth only two
Of 1978, the GS Performance R90S was sold to luelstopstofimshthird
Schu:!~~;~~ri:;_\~::~~7~e
·--.l<.li
Yigf: · 1:00
JoflnLong
by Tom Cut:,,,,.- and Todd
Schus:ert<l-/era'nehr.sh
on the GS Perlormance
R90S (Courtesy t.m
Je'
'"
Even before the 1974 Castrol S1)(·hour race
was run. 11 waspackedwothdrama. Theorgamsers
decided to ban motorcycles with famngs.
el1minat1ng the R90S. so the BMW distributors.
Tom Byrne. entered nn R9016. Bryan Hindle
and Clive Kmght crossed the hne first. covering
346-laps at an average speed of 112 22km/h
(69 73mph). W•th another R9016 (Gary Thomas
and Graham Karri) third. Unfortunately, BMW's
victory was short-loved. as an exnminat1on by the
scrutineers after the race resulted on both BMWs
exclusion from the results The spacers on the
front forks were from the R90S and, apparently
incorrectly pos1t1oned. pre·load1ng the springs for
more ground clearance As the factory manual
was 1mprec1se. !hos fmdong was contenl•OUS. but
R ACINI
/5$, 16$
1d1sputable. and the R9016s were ellcluded The
bonus for BMW was that SO.OOO people watch1119
the race on TV saw the R90/6 cross 1he hnish
Jmehrst
A rule change allowed 1he R90$ to beeh91ble
for the 1975 Castrol Sill-hour race. and this year
Kenny Blake rode solo. fin1sh1ng second. No
longer allowed to ride the Sill hours solo. Blake
teamed with Hatton for the 1976 race and. again.
finished second. The promise of the previous
four years was finally realised 1n 1977. Taking
ma1<1mum advantage of being able to run for
more than two hours between fuel stops. the
BMW RlOOS of Blake and Joe Eastmure set a
new r::._e record. covering 355-laps in Siil hours
Helmut Oahne and Tony Hatton finished fifth on
a similar machine. Although not the fastest or
bes! handling. the ultra-reliable R100Ss proved
that. with a smooth rrd1ng technique. they were
more than a match for the higher performance
Kawasak1s or better handhng Oucat1s. Although
Blake and Dave Burgess rode the RlOOS to fourth
place 1n the 1978 Castrol S11l-hour race. they
failed to qualify in the top fifteen and the future
for the venerable boxer twin in this event looked
ominous. The reality of beating the new wave of
improved Japanese Superb1kes hit home. and
for the 1979 Castrol Six-hour no oll1c1al BMWs
were entered
145
APPENDIX
TECHNICAL SPECIFICATIONS
R5015
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
1970-73
67
70.6
'98
8.6:1
Overall length
2100mm (2450mm
Wheelbase
1385mm (1435mm
1973)
1973)
Weight including
oil and fuel
2 10kg (205kg
Top speed
1971)
157kmlh (98mph)
Valve timing (2mm
valve clearance,
;t 2.5-degrees)
intake opening
!ntakeclos1ng
E•haust opening
E•haust closmg
Horsepower
Leftcarburetor
R1ghtcarburetor
Ma1n1et
Needle Jet
Jet needle no
Needle pos111on
Idle Jet
Sparkplugs
lgnit1ontim1ng
Po<ntsgap
First gear
Second gear
Third gear
Fourth gear
F1f11hgear
Final drive
Overall width
Seat height
146
TDC
40' ABDC
40° BBDC
BOC
32 at 6400rpm
Bing 1/26/113
Bmg 1126/114
135
2.68
46-234
3
35
Bosch W230T1 ,
Champion N7Y,
Beru230/14/3A
9 deg BTDC
0.35-0.40mm
3.896:1
2.578:1
1.875:1
1.50:1
09:32
740mm
810mm
Year
Bore (mm)
Capac1ty(c cJ
Compression ratio
Valve t1mmg (2mm
valve clearance,
:t 2.5-degrees)
intake opening
Intake closing
Exhaust opening
Exhaust closing
Horsepower
Leftcarburetor
Right carburetor
Main jet
Needle jet
Jet needle no
Needle position
Idle jet
Sparkplugs
lgmt1on t1ming
Overall width
Seat height
Overall length
R60t5
Stroke (mm)
Points gap
First gear
Second gear
Th1rdgear
Fourth gear
Fifithgear
Final drive
1970-73
73.5
70.6
Wheelbase
599
9 .2:1
Weight including
01land fuel
TDC
40" ABDC
40° BBDC
BOC
40 at 6400rpm
Bing 11261111
Bing 1/26/ 112
140
2.68
46-234
R75/5
Year
Bore(mm)
Stroke(mm)
Capacity(cc)
Compression ratio
Valve timing (2mm
valve c learance,
:t 2.5-degrees)
intake opening
Intake closing
Exhaust opening
Exhaust closing
Horsepower
Leltcarburetor
2
40
1.875:1
11:37
740mm
810mm
2100mm (2450mm
1973)
1385mm (1435m m
1973)
Top speed
Bosch W230 T1.
Champion N7Y.
Beru230/14/3A
9 deg BTDC
0.35-0.40mm
3.896:1
2.578:1
2 10kg(205kg
1971)
167km/h (104mph}
1970-73
82
70.6
745
9.0:1
10" BTDC
50° ABDC
50BBDC
10° ATDC
50at6200rpm
Bmg64/32/3
(64/3219 from
TECHNICAL SPECIFICATIONS
R1ghtcarburetor
Ma1n1et
Needle jet
Jet needle no
Needlepos1t1on
ldle1et
Sparkplugs
lgmt1ont1ming
Points gap
First gear
Second gear
Third gear
Fourth gear
F1fithgear
Finaldnve
Overall width
Seathe•ght
Overall length
We1ghtinclud1ng
oil and fuel
Top speed
R60/6
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valvet1m1ng{2mm
valvec!earance,
:t 2.5-degrees)
intake opening
Intake closing
Exhaust opening
Exhaust closing
Horsepower
Leftcarburetor
R1ghtcarburetor
Mainiet
Needle1et
Jet needle no
Needlepos1t1on
1971)
Bmg64/32/4
(64/32/10from
1971)
140(150from
1971)
2.73 (2.70)
46-241
44-950
BoschW200T30,
CharnpionN7Y.
Beru200/14/3A
9degBTOC
0.35-0.40mm
3.896:1
2.576:1
1.875:1
1.50:1
11:32 (10:321971)
740mm
810mm
2100mm (2450mm
1973)
1385mm (1435mm
1973)
210kg(205kg
1971)
175kmlh (110mph)
1974-76
73.5
70.6
599
9.2:1
Idle Jet
Sparkplugs
lgmt1onhming
Points gap
First gear
Second gear
Third gear
Fourth gear
Fifilhgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
Weight including
oil and fuel
Top speed
R75/6
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve t1m1ng (2mm
valve clearance,
± 2.5-degrees)
intake opening
Intake closing
Exhaust opening
Exhaust closing
Horsepower
Leftcarburetor
R1ghtcarburetor
Ma1n1et
TDC
40° ABDC
40" BBDC
BOC
40at6400rpm
Bing 1/26/111
(1126/123from
1976)
Bing 1/26/112
(1126/124 1rom
1976)
"o
2.68
Needle jet
Jet needle no
Needlepos1t1on
Idle jet
Sparkplugs
lgnit1ont1mmg
Points gap
First gear
Second gear
Third gear
Four1hgear
35
BoschW230T1.
Champion N7Y,
Beru230/14/3A
9deg BTOC
0 .35-0.40mm
4.40:1
2.66:1
2.07:1
1.67:1
1.50:1
11:37
740mm
610mm
2180mm
1435mm
210kg
167kmlh (104mph)
1974-76
82
70.6
9.0:1
10°BTOC
so· ABOC
50BBDC
10° ATOC
50at6200rpm
B1ng64/32/9
(64/32/13from
1976)
B1ng64/32/10
(64/32/14from
1976)
135(145/rom
1976)
2.77 (2.66 from
1976)
46-241
3
4544-950
Bosch W200 T30,
Champion N7Y,
Beru200/14/3A
9deg BTDC
0.35-0.40mm
4 .40:1
2.86:1
2.07:1
1.67,1
F1f1thgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
We1ghtmclud1ng
oil and fuel
Top speed
1.50.1
10:32
740mm
810mm
2180mm
1435mm
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve timing (2mm
valve clearance.
:t2.5-degrees)
intake opening
Intake closing
Exhaustopenmg
Exhaust c losing
Horsepower
Leftcarburetor
R1ghtcarburetor
Mam1e1
Needle1et
Jet needle no.
Needle position
ldle1et
Sparkplugs
1974-76
90
70.6
898
9.01
lgn1t1ont1ming
Points gap
First gear
Second gear
Third gear
Fourth gear
F1fithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
We1ghtinclud1ng
oil and fuel
Top speed
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
215kg
175kmlh{110mph)
WBTOC
SO ABDC
SOBBDC
10 ATDC
60 at 6500rpm
Bmg64/32/ 11
B1ng64/32/ 12
150
2.68
'
4544-950
Bosch W200 T30.
Champion N7Y,
Beru 200/14/3A
9deg BTDC
0.35-0.40mm
440:1
2.86:1
2.07:1
1.671
1.50:1
740mm
810mm
2180mm
1435mm
215kg
188km/h (117mph)
1974-76
90
70.6
898
9.51
"'
TH E BMW B ox.ER Tw•Ns 1970- 1995 B1eLe
Valve t1m1ng (2mm
valve clearance.
± 2 5-degrees)
1ntakeopemng
Intake closing
E:<haustopening
E:<haust clos1ng
Horsepower
Leftcarburetor
R1ghtcarburetor
Mam1et
Needleiet
JetneedleflO
Needle pos111on
ldteiet
Sparkplugs
lgn1tlont1mmg
Pomtsgap
First gear
Second gear
Third gear
Fourth gear
Frfithgear
Fmaldr1ve
Overall width
Seat height
Overall length
Wheelbase
We1ghtinclud1ng
01landfuel
Top speed
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve timing (2mm
valve clearance.
±2.5-degrees)
mtakeopernng
Intake closing
E:<haustopen1ng
Exhaust closing
148
10 BTDC
50" ABDC
50BBDC
10" ATOC
67 at 7000rpm
Oell"Orto
PHM38AD
(PHM38BD from
1976)
Del/"Orto
PHM38AS
{PHM388S from
1976)
155
260
3
60
Bosch W200 T30.
Champion N7Y.
Beru200/ 14/3A
9 deg BTOC
0.35-0.40mm
4.40:1
2.66:1
2.07:1
1.67:1
1.50:1
11 :33
740mm
810mm
2 180mm
1435mm
220kg
200kmlh (124m ph)
1977-60
73.5
70.6
599
9.2:1
Horsepower
Leftcarburetor
R1ghtcarburetor
Main/et
Needle jet
Jet needle no
Needle position
ldle1et
Sparkplugs
Jgmt1ont1mmg
Pomtsgap
First gear
Second gear
Third gear
Fourth gear
Fiflthgear
Finaldnve
Overal!w1dth
Seat height
O verall!ength
Wheelbase
We1ghtmctud1ng
oil and fuel
Top speed
R75/7
Year
Bore (mm)
Stroke (mm)
Capac1ty(cc)
Compression ratio
Valve t1m1ng (2mm
valve c learance,
±2.5-degrees)
intake opening
Intake closing
E:<haust o pening
E:<haustclos1ng
Horsepower
Leftcarburetor
Rightcarburetor
Mam jet
TDC (6 BTDC from
1978)
40 ABOC (34
ABDC from 1976)
40 BBDC (34
BBDC from 1978)
TDC {6 ATDC from
Needle Jet
Jet needle no.
Needle pos1t1on
Idle jet
Sparkplugs
1978)
40a!6400rpm
Bing 11261123
Bing 1/261124
1<0
2.68
46-234
2
"
Bosch w200 T30,
Champion N7Y,
Beru 200/14/JA
9 deg BTOC
0.35-0.40mm
4.40:1
2.86:1
2.07: 1
1.67:1
1.50:1
11:37
746mm
8 10mm
2180mm
1465mm
215kg
167kmlh(104mph)
l9mtiont1m1ng
Points gap
First gear
Second gear
Third gear
Fourth gear
Fil1thgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
Weightmctud1ng
oil and fuel
Top speed
R10017
Year
Bore(mm)
Stroke(mm)
Capacity(cc)
Compression ratio
Valve timing (2mm
valve clearance,
± 2.5-degrees)
intake opening
lntakeclosmg
1977-79
82
70.6
745
9.0:1
10° BTDC
50' ABDC
50 BBDC
lO" ATDC
50 at 6200rpm
Bing 64/32/ 11
(64/32/313from
1978)
B1ng64/32/ 12
(64/ 32/ 314from
1978)
150 (145from
1978)
266
46-241
3
50
Bosch W200 T30,
Champion N7Y.
Exhaust opening
Exhaust closing
Horsepower
Leltcarburetor
R1ghtcarburetor
Main1et
Needle Jet
Jet needle no.
Needle position
!dle1et
Sparkplugs
lgrnt1ont1ming
Points gap
First gear
Second gear
Third gear
Fourth gear
F1fithgear
Final drive
Overall width
Seat height
Overall length
Beru200/1413A
9deg BTDC
035-0.40mm
4.40 1
2.86:1
2.07:1
1.67:1
1.50:1
10:32
746mm
810mm
2180mm
1465mm
215kg
177kml h (110mph)
1977-78
"
70.6
980
9.1:1
10 BTDC (16
BTDC from 1976)
50ABDC (44
ABDC from 1978)
50 BBDC (56
BBDC from 1978)
10 ATOC (4 ATDC
from 1978)
60at6500rpm
Bing64/32/19
81ng64/32/20
150
2 .66
46-241
3
50
Bosch W200 T30,
Chamn'on N7Y.
Beru200/ 1413A
9 deg BTDC
0.35-0.40mm
4.40:1
2.66:1
2.07:1
1.67:1
1.50:1
11:34
746mm
810mm
2180mm
T ECHNICAL SPECIFICATIO NS
Wheelbase
We1ght1nclud1ng
oil and fuel
Top speed
R
Year
Bore(mm)
Stroke{mm)
Capac1ty(cc)
Compression ratio
Valve timing (2mm
valve clearance,
±2.5·degrees)
int..ke opening
Intake closing
Eichaustopen1n9
Eichaustclosing
Horsepower
Leftcarburetor
"
Rightcarburetor
Main jet
Needle Jet
Jet needle no.
Needlepos1t1on
ldle1et
Sparkplugs
lgnit1ont1m1ng
Points gap
First gear
Second gear
Third gear
Fourth gear
Fifithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
Weight including
oil and fuel
Top speed
Year
Bore(mm)
Stroke(mm)
Capac1ty{cc)
Compression ratio
215kg
188km/h(117mph)
Valve timing (2mm
valve clearance.
:i:2.5·degrees)
intake opening
Intake closing
1978-80
84.8
70.6
Eichaust opening
797
E)(haustclosing
9.2:1
Horsepower
Leftcarburetor
16"BTDC
44°ABDC
56' ABDC
4°ATDC
55at 7000rpm
Bing64/32/13
(64/321201 from
1976)
B1ng64/32/14
(64/32f202from
1976)
145(135from
1978)
2.66
46-241
3
50
Bosch W200 T30,
Champion N7Y,
Beru 200/14/3A
9deg BTDC
0.35-0.40mm
4 .40:1
2.861
207:1
1.67:1
1.50:1
10:32
746mm
810mm
2180mm
1465mm
215kg
182km/h{113mph)
1977-80
94
70.6
960
9.51 {8.2:1 US)
R1ghtcarburetor
Ma1n1et
Needle jet
Jet needle no
Needlepos1t100
Idle jet
Sparkplugs
lgmt1ont1ming
Points gap
First gear
Second gear
Third gear
Fourth gear
F1flthgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
Weight including
oil and fuel
Top speed
(124mph)
R100RS
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valvetomong(2mm
valve clearance.
.t2.5-degrees)
mtakeopening
Intake closing
E)(haust opening
10 BTDC{16
BTDC from 1978)
50ABDC(44
ABDC from 1978)
50 BBDC (56
BBDC from 1978)
10 ATDC (4 ATOC
from 1976)
65 at 6600rpm
(70at7250rpm)
Bing94/40/103
(94/40/105from
1979)
Bing94/40/104
(94/40/106 from
1979)
170
2.66 (2.68 from
1979)
46-341
3
45
Bosch W200 T30.
Champion N7Y,
Beru 200/ 14/3A
9 deg BTDC
0.35-0.40mm
4.40:1
2 .86:1
2.07:1
1.67:1
1.50:1
11:32
746mm
810mm
2160mm
\465mm
220kg
Over200km/h
1977-80
94
70.6
960
9.5:1 (8.2:1 US)
10 BTDC(16
BTOC from 1976)
E)(haustclosing
Horsepower
Leftcarburetor
R19htcarburetor
Main1et
Needle Jet
Jet needle no
Needlepos111on
Idle jet
Sparkplugs
lgn1t1ont1ming
Points gap
First gear
Second gear
Third gear
Fourth gear
F1fithgear
F1naldnve
Overall width
Seat height
Overall length
Wheelbase
Weight including
oil and fuel
Top speed
R100T
Year
Bore(mm)
Stroke{mm)
Capac1ty(cc)
Compression ratio
Valvetim1ng(2mm
valve clearance.
± 2.5-degrees)
intake opening
Intake closing
E)(haus! opening
Eichaustclos1ng
Horsepower
left carburetor
R1ghtcarburetor
Main Jet
Needle1et
Jet needle no.
Needle pos111on
Idle Jet
Sparkplugs
50ABDC(44
ABOC from 1978)
50 BBDC (56
BBDC from 1978)
10 ATDC (4 ATDC
from1978)
70 at 7250rpm
Bing94/40/105
Bing94/40/ 106
170
2.68
46-341
2
'5
Bosch W200 T30
Champion N7Y
Beru 200/14/3A
gdeg BTDC
0.35-0.40mm
4401
2.66:1
2.07:1
1.671
1.50:1
11.33
746mm
610mm
2180mm
1465mm
230kg
Over200km/h
(124mph)
1979-80
94
70.6
980
9.5 1 {8.2:1 US)
16 BTDC
44'ABDC
56 ABDC
4·ATDC
65 at 6600rpm
Bing94/40/103
Bing94/40/104
170
266
46-341
2
45
Bosch W200 T30.
'"
THE BMW BoxER Tw1NS 1970- 1995 BieLE
19n1t1on 11mmg
Pomlsgap
F1rs19ear
Second gear
Third gear
Fourth gear
Fif1thgear
Final drive
Overall width
Seathe19ht
Overall length
Wheelbase
We1gh11nclud1ng
oil and fuel
Top speed
R100RT
Year
Bore(mm)
Stroke{mm)
Capacit y(cc)
Compression ratio
Valve t1m1ng (2mm
valve clearance,
± 2.5-degrees)
intake openmg
lntakeclosmg
E)thaust opening
E)thaustclos1ng
Horsepower
Left carburetor
R1ghtcarburetor
Main jet
Needle1e1
Jet needle no
Needle position
ldte1et
Sparkplugs
tgn111ont1mm9
Points gap
First gear
Second gear
Third gear
Fourth gear
Filithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
Weight including
011 and fuel
150
Champion N7Y.
Beru200/14/3A
9deg BTOC
0.35-040mm
4.40:1
2.86:1
2.07:1
1.67:1
1.50:1
11:33
746mm
810mm
2130mm
1465mm
215kg
190kmlh{118mph)
Top speed
190km/h(118mph)
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve liming (2mm
valve clearance,
±2.5-degrees)
intake opening
Intake closing
Exhaustopemn9
Exhaust closing
Horsepower
Leftcarburetor
1981-84
94
70.6
Rightcarburetor
1979-80
94
70.6
960
9 .5:1 (8.2:1 US)
16''BTOC
44°ABDC
56°ABDC
4°ATOC
70 at 7250rpm
Bing94/40/105
Bing94/40/106
170
2.66
46-341
2
45
Bosch W200 T30,
Champion N7Y.
Beru200/14/3A
g deg BTDC
0.35-0.40mm
4.40:1
2.86:1
2.07:1
1.67:1
1.50:1
11:33
746mm
810mm
2130mm
1465mm
234kg
Main 1et
Needle1et
Jet needle no
Needle position
Idle Jet
Sparkplugs
lgnit1ont1rning
Pomtsgap
First gear
Second gear
Th1rdgear
Fourth gear
Fifithgear
Final drive
Overall width
Seathe1gh!
Overall length
Wheelbase
Weight including
oil and fuel
Top speed
R100CS
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve t1m1ng (2mm
valve clearance.
~ 2.5-degrees)
intake opening
Intake closing
Exhaust opening
960
8.2:1
16"8TOC
44°ABOC
56-ABDC
4'ATOC
67at7000rpm
Bing94/40/111
(113 US models)
8ing94/40/112
(114 US models}
160
2.66
46-341
3(2)
"
BoschW6DC,
Champion N7Y,
Beru 14-60
6 deg BTOC
Electronic lgmtion
4.40:1
2.86:1
2.07:1
1.67:1
1.50:1
11:33
746mm
810mm
2210mm
1465mm
225kg
190km/h (118mph}
Exhaustctosmg
Horsepower
Leftcarburetor
R1ghtcarburetor
Mam1et
Needle1et
Jet needle no
Needle pos1t1on
Idle jet
Sparkplugs
Ignition timing
Points gap
First gear
Second gear
Third gear
Fourth gear
Filithgear
Finaldnve
Overall width
Seat height
Overall length
Wheelbase
Weight including
oil and fuel
Top speed
R100RS
Year
Bore(mm)
Stroke(mm)
Capacity(cc)
Compression ratio
Valve timing (2mm
valve clearance.
± 2.5-degrees)
intake opening
JntakecJosing
E)thaust opening
Exhaust closing
Horsepower
Leftcarburetor
1981-84
94
R1ghtcarburetor
70.6
960
9.5:1
16°BTOC
44°ABDC
56°ABOC
Main jet
Needle jet
Jet needle no.
Needle position
Idle jet
Sparkplugs
4ATOC
70at 7000rpm
Bmg94/40/111
(113USmodels)
81ng94/40/112
(1 14 US models)
160
266
46-341
3(2)
"
BoschW5DC.
Champion N6Y.
Beru 14-50
6deg BTDC
Electronic lgmt1on
4 .40:1
2.86:1
2.07:1
1.67:1
1.501
11:33
746mm
810mrn
2210rnm
1465rnm
220kg
200kmlh (124mph)
1981-84
94
70.6
960
9.5:1
16°8TOC
44°ABDC
56°A8DC
4°ATDC
70 at 7250rpm
B1ng94/40/111
(113 US models)
Bing94/40/112
(114 US models)
160
2.66
46-341
3(2)
45
Bosch WSDC,
Champion N6Y.
Beru 14-50
T ECHNICAL SPECIFICATION S
Ignition timing
Po•ntsgap
First gear
Second gear
Third gear
Fourth gear
Fifithgear
Final dnve
Overall width
Seat height
Overall leng th
Wheelbase
Weightmcluding
oil and fuel
Too speed
Year
Bore(mm)
Stroke(mm)
Capacity{cc)
Compression ratio
Valvet1ming(2mm
valve clearance,
± 2.5-degrees)
intake opening
Intake closing
Exhaust opening
Exhaust closing
Horsepower
Lef1carburetor
Rightcarburetor
Ma1n1et
Needle Jet
Jet needle no
Needle pos1t1on
Idle jet
Sparkplugs
lgnitionhmmg
Points gap
First gear
Second gear
Third gear
Fourth gear
Fif1thgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
We1gh t includmg
oil and fuel
6deg BTDC
Electron1clgnition
4.40:1
2.86:1
2.07:1
1.50:1
11:33
746mm
810mm
2210mm
1465mm
230kg
190kmfh {118mph)
Top speed
185kmlh(115mph)
Year
Bore(mm)
Stroke(mm)
Capacity(cc)
Compress1onra1io
Valve timing (2mm
valve clearance,
.±2.5-degrees)
intake opening
Intake closing
Exhaust opening
Exhaustclosmg
Horsepower
Leltcarburetor
1983-84
84.8
70.6
1981-84
"
70.6
980
9.5:1
16°BTDC
44"ABOC
56°ABOC
4°ATOC
70at7250rpm
Bing94/40/111
{1 13 US models)
Bing94/40/112
(114 US models)
160
46-341
3{2)
45
BoschW50C.
Champion N6Y,
Beru 14-50
6deg BTDC
Electrornclgnit1on
4.40:1
2.86:1
2.07:1
1.50:1
11:33
810mm
2210mm
1465mm
245kg
Rightcarburetor
Main jet
Needle Jet
Needle position
ldle1et
Spark plugs
lgnit1ont1mmg
Points gap
First gear
Second gear
Th1rdgear
Fourth gear
F1fithgear
Final drive
Overall width
Seatherght
Overall length
Wheelbase
Weight including
ml and fuel
Top speed
Year
Bore(mm)
S1roke(mm)
Capacity{cc)
Compression ratio
Valvet1ming(2mm
valve clearance.
.±2.5-degrees)
mtakeopening
Intake closing
Exhaustopenmg
16°8TOC
44°ABOC
56°ABDC
4°ATDC
50at6500rpm
Bmg64/32/305
(323 US)
Bmg64/32/306
(324 US)
150
2.66
46-241
3
BoschW70C.
Champion NlOY,
Beru 14-70
6 deg BTDC
Electronic lgn1t1on
4.40:1
2.86:1
2.07:1
1.67:1
1.50:1
11:37
746mm
2210mm
1465mm
235kg
161km/h(100mph)
1985-96
84.8
70.6
797
8.2:1
Exhaust closing
Horsepower
Leftcarburetor
R1ghtcarburetor
Main1et
Needle jet
Jet needle no
Needle position
Idle jet
Sparkplugs
lgrnt1ont1mmg
Pomtsgap
First gear
Second gear
Th1rdgear
Fourth gear
Fifithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
We1ghtincludmg
oil and fuel
Top speed
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve 11mmg (2mm
valve clearance.
.± 2.5-degrees)
1ntakeopenmg
Intake closing
Exhaust opening
Exhaust closing
Horsepower
Leflcarburetor
R1ghtcarburetor
Ma1n1et
Needleiet
Jet needle no
Needleposrtion
ldle1et
Sparkplugs
lgnit1on11mm9
Points gap
First gear
Second gear
50at6500rpm
BingV64/32/353
BingV64/32/354
BoschW7DC.
Champion N9YC .
Beru 14-70U
Ele<.:trornclgrnt1on
4.40:1
2.86:1
2.07.1
1-67:1
1.50:1
11:37
960mm
807mm
227kg
170km/h(106mph)
1985-95
84.8
797
8.2:1
50 at 6500rpm
81ngV64/32/353
BmgV64/32/354
BoschW70C.
Champion NQYC.
Beru 14-lDU
Electronic Ignition
4.40:1
2.86:1
151
JI"
THE BMW B OX ER TWIN S 1970 -1995 BIBLE
Thordgear
Fourth gear
Fil1thgear
980
8.45:1
210kg
Capac1ty(cc)
Compression ra110
Valve timing (2mm
valve clearance,
;1:2.5-degrees)
intake opening
Intake closing
E"'haustopemng
Exhaust closing
Horsepower
178km/h(111mph)
Leltcarburetor
1986-88
R1ghtcarburetor
Mam jet
Needle jet
Bing V64/32/363
Bing V64/32/364
82
61.5
650
8.7:1
Jet needle no
Needle pos1t1on
Idle jet
Sparkplugs
1.67:1
1-50:1
10:32
Fmaldnve
Overall width
aoomm
Seat height
807mm
Overall length
Wheelbase
Weightmctud1ng
oil and fuel
Top speed
R65
Year
Bore{mm)
Stroke{mm)
Capac1ty(cc)
Compression ratio
Valve timing (2mm
valve clearance.
± 2.5-degrees)
intake opening
Intake closing
EKhaust opening
EKhaustclos1ng
Horsepower
Leflcarburetor
R1ghtcarburetor
Mam1et
Needle1et
Jet needle no
Needle pos1t1on
Jdle1et
Sparkplugs
Ignition timing
Points gap
First gear
Second gear
Th1rdgear
Fourth gear
F1fithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
Weight including
011andtuel
Top speed
Year
Bore(mm)
Stroke(mm)
152
48at7250rpm
Bing V64/32/359
Bing V64132/360
BoschW7DC,
Champion N9YC,
Beru 14-7DU
Ignition timing
Points gap
First gear
Second gear
Third gear
Fourth gear
Filithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
We1ght1ncluding
oil and fuel
Top speed
210kg
174km/h (108mph)
1987-93
94
70.6
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve timing (2mm
valve clearance,
± 2.5-degrees)
intake opening
Intake closing
EKhaustopening
EKhaustclosing
Horsepower
Leftcarburetor
Right carburetor
Ma1n1et
Needle1et
Jet needle no.
Needle position
BoschW70C.
Champion N9YC.
Beru 14-7DU
Ignition timing
Pomtsgap
First gear
60 at 6500rpm
BoschW7DC,
Champion N9YC,
Beru 14-70U
Electronic Ignition
4.40:1
2.86:1
2.071
1.67:1
1.50:1
11:33
800mm
807mm
2175mm
229kg
185kml h(115mph)
RlOORT
Electroniclgmt1on
4.40:1
2.86:1
2.07:1
1.67:1
1.50:1
11:37
800mm
807mm
2175mm
1447mm
ldle1et
Sparkplug s
1988-95
94
70.6
980
8.45:1
60 at 6500rpm
B1ngV64132/363
Bing V64/32/364
Second gear
Th ird gear
Fourth gear
Filithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
We1ght1ncludmg
oil and fuel
Top speed
R100R
Year
Bore(mm)
Stroke(mm)
Capac1ty(cc)
Compression ratio
Valve timing (2mm
valve clearance.
±2.5-degrees)
mtakeopemng
Intake closing
EKhaust opening
EKhaustclosmg
Horsepower
Leftcarburetor
Rightcarburetor
Mam jet
Needle jet
Jet needle no
Needle pos1t1on
Idle jet
Spark plugs
lgnitiont1mmg
Points gap
First gear
Second gear
Th1rdgear
Fourth gear
Fifithgear
Final drive
Overall width
Seat height
Overall length
Wheelbase
Electroniclgn1t1on
440:1
2.86:1
2.07:1
1.67:1
1.50:1
11:33
960mm
807mm
2175mm
1447mm
234kg
185km/h(115mph)
1992-95
94
70.6
980
8.5:1
60at6500rpm
BmgV64/40/123
BmgV64/40/124
BoschW7DC.
Champion N9YC.
Beru 14-70U
Electronic Ignition
4.40:1
2.86:1
2.07:1
1.67:1
1.50:1
11:34
1000mm
BOOmm
2210mm
1495mm
T ECHNICAL SPECIFICATIONS
Weight including
oil and fuel
Top speed
p
Year
Bore(mm)
Stroke (mm)
Capacity(cc)
Compression ratio
Valve timing (2mm
valve clearance.
., 2.5-degrees)
intake opening
218kg
181km/h (112mph)
1992-94
84.8
70.6
797
8.2:1
1ntakeclos1n9
Ew.haust opening
Ew.haustclosing
Horsepower
leftcarburetor
R1ghtcarburetor
Main jet
Needle jet
Jet needle no
Needlepos1t1on
ldle1et
Sparkplugs
Points gap
First gear
Second gear
Third gear
Fourth gear
F1fithgear
Fmaldrive
Overall width
Seat height
Overall length
Wheelbase
We1ghtinclud1ng
oil and fuel
Top speed
50at6500rpm
Bing V64/32/349
BingV64/32/350
Bosch W7DC.
Champion N9YC.
Beru 14-7DU
Electronic Ignition
4401
2.861
2.07:1
1.67:1
1 50:1
10:32
1000mm
800mm
2210mm
217kg
168km/h (104mph)
lgm t1ont1ming
_,prot_"f1Jn
I Model
1 1970
11971
11973
!Total
I R50J5
12053
11737
\1546
17865
I RS0/5
14116
16645
14730
122.121
16116
110.390
laa94
138,370
production1974modelyear
f6ptoduclion1975modelyear
A60/6US
A60/6US
A75/6
I
I
I
I
Dales
1197'
08/74-08/75
11575
08/74-07175
1593
08/74-08/75
11198
08174-08175
1984
08174-08t75
11802
08/74-09175
11376
08174-08175
lsn
Lproouction1976model year
A75/6
R75/6US
09/75-07176
R90S
09/75-07176
153
THE BMW BOKER TWINS 1970-1995 BIBLE
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A LSO FRO M V ELOC E PU BL I S HIN G -
Custom1s1ng BMWs - does 1t work? This book. the fors! ot its kmd solely devoted
to the BMW custom bike scene. proves I hat 11 does' FeatUfes stunning images ol
custom.$ed BMW singles, twms and lours from contnbutors around the globe. many
complemented by owners' stories and tec:hrneal descrip!>ons
Hardback • 25~25em • £19.99' UK/$39.95' USA • 126 pages • 270colour and b&w
pictures
To ORDER, OR FOR MORE INFORMATION ON ANY OF THESE TITLES, PLEASE VISIT OUR WEBSITE
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ALSO FROM VELOCE PUBLISHING -
Showcasing fanta sti c cu stom BMW caft'l racers from all over the globe, from the old to
the new, thts book presents them 1n all their innovative glory. Featuring owner's stories
and technica l descriptions. BMW Caft'l Racers 1s a book guaranteed to interes t BMW
fans and members of the caft'l racer scene alike - see the ·caft'ld' side of BMW
ISBN: 978-1-845845-29-2
Hardback • 25 x25cm • t25 " UK/$39.95" USA • 128 pages • 205 colour pictures
To ORDE , OR FOR MORE INFORMATIO N ON ANY OF THESE TITLES, PLEASE VISIT OUR WEBSI E
WWW.VELOCE.CO.UK
C L +44 (0)1305 260068, OR E-MAIL SALES@VELOCE.CO.UK
156
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ALSO FROM VELOCE PUBLISHING -
From the old to the modem. from honzontal-smgles to mime sixes, !his bool< covers the
evolu tion the cafe racers based on Italian motorcycles
ISBN 978·1·845847-49-4
Hardback• 24.8x24.8cm • 1::25· UK/$39_95· USA • 128 pages• 321 colour pictures
To ORDER, OR FOR MORE INFORMATION ON ANY OF THESE TITLES, PLEASE VISIT OUR WEBSIT'
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(0)1305 260068, OR E-M AIL SALES@VELOCE.CO . UK
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'57
A LSO FROM V ELOCE PUBLISHING -
The first book to solely cover the evolution of the Japanese cruise r into metri c custom.
Japanese Custom Motorcycles is an insight into the growing trend of customising
metnc bikes into chopper, bobber et al, et al - be they high-end bikes. garage built
beauties. or more recent Japanese cruisers. Superbly illustrated with e)(amples from
all over the world, and featuring owner's stories and technical descnpt1ons. this book is
guaranteed to interest metnc bike fans and members of the custom scene ahke - see
the 'custom' side of Japanese motorcycles
ISBN: 978-1-845845-30-8
Hardback • 25)(25cm • £25" UK/$39.95" USA • 128 pages • 275 colour pictures
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INDEX
AAMRA 131
ACU 32
ADAC Winter Rally 7
Adams. Peter 128, 130, 139-141
Adler 13
AFN Production champ1onsh1p 131
AJS 15
Alexander.Abe 136
AMA 131, 132, 134, 137, 140-143
America 134, 136
AMOL Precision 128, 129, 132, 133, 137
Anderson. Fergus 126
Anderson, Tony 127
August ine, Kenny 137, 140
Austra lia 117, 143
Austral ianCastrolSiK-Hourrace 143 1'5
Axtel,C.R. 137
Baldwin. Mike 140
BatlleoltheTwins 143
BavananAircraftWorks(Bavanan
Flugzeug-Werke) 6,7
Beer, Volker 128
Belgium 126
Berhn 7, 14, 16, 104, 111
Bieber, Franz 126
Blake.Kenny 145
Blum, Paul 135
BMW Flugmotoren-Gesellschaft 17
BMW Maschinenlabnk Spandau 17
BMW Motorrad GmbH 58. 73
Bold'Or 135
Bondy, Michael 128
BOnsch. Helmut Werner 15, 37
Branch, Jerry 130, 132
Brandenburg1sche Motorenwerke
(Bramo) 17
Brenner. Horst 114
Bridgehampton 129, 131
BritishACU 127
BSA 131.132
Bucher. Helmut 135
Burgess, Dave 145
Butenuth. Hans-Otto 52.127.128, 135.
136
Butler & Smith 33. 128-134, 136-138,
140-142
Byrne, Tom 144
C&J 129
California 40, 59,60, 129-132
Canadian Superb1ke Championship 143
Cape Canaveral 128
Capri, Matt 130, 131, 137, 139
Compton 130, 140
Cooley, Wes 141
Cosut ti 74
Cutter, Tom 141, 143
Cyc le magazine 131, 140
Dachau 80
Diih ne. Helmut 38.52. 74, 127-129, 135,
136, 145
Dale, Dickie 126
Danv111e(Virginia)5-hourrace 128.129
Darv1ll, Peter 126
Daytona 131-134, 137-143
DaytonaBeach 52
Dearborn, Charles 128. 129. 131
Dickie, Tom 127
Diermger,Wemer 135
DKW 13
Douglas 7
Ducati 141, 145
Duhamel, Yvon 137
Duke.Geofl 126
Dumont. New Jersey 128
East Coast (USA) 131, 136. 137
Eastmure.Joe 145
Emde. Dave 141, 143
Enders, Klaus 13
Engelhardt.Ralf 13
England 7,46
Erson.S19 132
Europe 109. 126. 127, 129
European Championship 12
Falkenhausen,Alexandervon 12. 16,
126,127
Fisher. Gary 134, 138-141
Fitt1paldi, Emerson 47
Flink6
Floreffe 126
Florida 40,52,59. 60
Fokker 6
Ford 45
Frankfurt42
Fr1z, Max 6,7,15
Gall, Karl 12
Garm1sch -Partenk1rchen 7
General Motors 37
Garlinger. Karl 73
German Championships 126, 127
German Manufacturers 13
GermanMarket 108,111,112
Germany 7,8. 16, 111. 115, 128
Gevert. Klaus Volker 73
G1etl,Udo 128-133, 136-143
Grand Prix races 9
Green, Gary 135
Guilli,Aene 135
159
THE
BMW BoxER TWI NS 1970 -1995 B1BL E
Gutsche. RUdrger 22.25.37.38. 73
Hanfland 6
Harewood 128
Harley·Dav1dson 131
Hatton, Tony 143.145
Hellos 7
Henkel 15
Henne, Ernst 8. 126
Heydenreich. Richard 73
Hiller.Ernst 126
Hindle.Bryan 144
Hinsberg. Rene 114
Hockenheim 17
Honda 37, 127.128
Horex 13
Hussein.King 47
lmola200 127.128
International Six-Day Trial (I SDT) 22
lsleo!Man(TI) 11-12.52. 127,128. 135.
136
ltaly65,74
Uo.Fumm 126
Jardin. Ferdinand 16,37
Jordan47
Kairl.Graham 144
Kawasaki 37, 137.1 41 .143, 145
Kern. Helmut 128-131. 133. 136, 137,
139.140
Klinimann,Gary 141
Kmght.Clive 144
Koch, Hans 58
Koppen, Paul 126
Korea 128
Koima, End re 11
Krauser, 'Gigi" 31
Kreidler 15
Lacoma. New Hampshire 140, 141
LagunaSeca 134.137.1 40, 143
Laverda37
Le Mans 135
Lewis.John 126
Liebmann. Kurt 128-134.136
Liebmann, Oscar 132
Long.John 141.143
Loudon 141-143
Luti, Bob 29.37, 46. 52, 64
Marw1tz, Hans-Gunter von der 15, 16,
19,23,25,27.37, 45,58, 65.73
Massachusetts 143
MaudesTrophy 32
Maurer.Walter 80
160
McCandtess. Rex 15
McLaughlin. Steve 137.139-141
Meier. Georg "Schorsch" 11
Metzeler 135
Miami 141
Milan 74
Mitchell, Edward 128, 130
Mosport 143
MotoGuzzi 140
MUiier. Hardy 37
Mumch 6, 12. 16, 17. 31, 80
Mumch-M1lbertshofen 12
Muth , Hans A. 43. 45, 46. 58, 62. 64,
65. 73
MVAgusta 45, 126. 132
Nardo 74
NASA 128
Neckars ulm 86
Neilson, Cook 141
NewYork 128
North Chester Motorcyc le Parts 140
North , Rob 131 -133
Norton 15. 23. 127, 132
Norwood 137. 140, 141
Nuremburg 21
Oberw1e senfeld 6
Ontario 137
Ora nge Count y Raceway 131
O regon 40, 59, 60
O tto. G ustav 6
Pierce. Ron 140, 141
Pininfanna 65
Pocono 131, 143
Polanssubmarine 128
Po pp. Fran z- Joseph 6, 7
Porsche 15
Potter, John 128, 129
Pressley. Bob 144
Pri ce, Norman 126
Pridmore, Reg 130-134, 136. 139-141.
143
Probst, Martin 73
Rape lius, Ekkehard 73
Rapp Motor Works 6
Rapp, Karl 6
Reister. Dr Dietrich 58
Road At lanta 134
Roberts, Kenny 134
Rossteucher. Miles 130
RU c ker. Ctausvon 15
RuhrValley 45
San Jose BMW 141, 143
Sarfer1, Eberhard 73
Schleicher, Rudolf 7. 15
Schulenburg, Rudolf Graf von der 37. 73
Schuster. Todd 131, 136. 137. 140 -143
Sears Point 132. 143
Second World War 126
SemorTT 11,12
Sharpe, Martyn 136
Siemens & Halske 17
Simone, Fred 128
Six-Day Race 7
Spandau 16. 17, 36. 47. 104, 111 . 122
Spintler. Horst 58
Stolle. Martin 7
Stuck, Hans Joachim 47
Stuttgart 62. 65, 86
Summit Point , West Virginia 133
Surtees. John 126
Suzuki 133.143
Targa Florio 126
Taylor, Justus 129. 131, 133
Thomas, Gary 144
Treaty of Versailles 6
Triumph 127, 131, 132
Udet, Ernst 6
US (United States) 14, 23, 27. 29, 30,
32- 35, 38, 40. 46, 51, 55, 61 , 62, 65,
68, 70, 72, 73, 75, 77. 81, 82, 87, 88,
92. 93, 97, 100, 101 , 104-106, 108 ,
110-112.117. 128, 131 , 137, 139
US Mannes 37
VanHauton. Bill 128
Virginia 131
Von Kuenheim 37
Wenn, George 130
West Coast (USA) 130, 131. 136, 137.
139. 140
West German Motorcycling Federation
32
West, Jock 12
Wilcke,Claus 31
Wirth. Gerd 37, 58
World Championships 13. 126
World War 16
WorldWarll 11.12,17
Wuppertal 45
Wurst.Wolfgang 37
WQrzburg 46
Yamaha 133, 134
Zamm 74
Zeller, Walter 126