R24
1948-49, 247cc, ohv single, 12bhp
First post war model based on the pre-war R23, it incorporated some of the
features from the Wehrmacht R75 model. Rigid frame with un-damped
telescopic front forks, black painted wheel rims, small fuel tank housing
a toolbox and single sided brake hubs. Exposed shaft-drive and new rocker
covers consisting of two covers held on by a central bolt and clamp, which
remained a feature of all following boxers until the 1990's.
R25
1950-51, 247cc, ohv single, 4 speed, 12bhp
Up-rated R24 with plunger rear suspension. Modifications included,
strengthened crankshaft, larger intake valves, a new cylinder-head and cam-type
shock absorber in the gearbox transmission.
R25/2 1952,
247cc, ohv single, 4 speed, 12bhp
Up-rated and improved R25 model. Minor modifications to the engine, a
sportier style and sprung saddle added to the general performance.
R25/3 1953-56,
247cc, ohv single, 4 speed, 13bhp
Up-rated and improved model with hydraulically damped front forks, air
filter mounted in the tank, and full width alloy brake drums.
R51/2
1950, 494cc ohv flat-twin, 4 speed, 24bhp
Based on the pre-war R51 with plunger frame and telescopic forks, sporting
a deep valanced front mudguard. The first model to sport the now common
brake and clutch leavers that were pivoted towards the centre of the
handlebar, rather than the end. Smooth torque from the engine with almost no vibration, but the clutch
tended to grab. Fishtail exhaust silencers and exposed shaft-drive. Some
cost cutting was evident, the needle bearings were replaced with plain
bearings and the rear main bearing was fitted directly into the crankcase
housing. Coil springs replaced the hairpin valve springs. Gear changes
were not particularly smooth.
R51/3
1951-54, 494cc ohv flat-twin, 4 speed, 24bhp
Restyled R51/2 with a little more power. Plunger frame with telescopic
forks and deep valanced front mudguard. Finned cylinder-heads, carbs
ducted to central air filter at rear of crankcase, gearbox bolted to back
of engine, magneto and camshaft at front in rounded cover and neutral
indicator lamp. The new narrower engine set the standard for the next 20
years. Full width brake hubs, rubber gaiters on front fork, alloy
wheel rims, larger tank and new style exhausts.
R67
1951, 590cc ohv flat-twin, 4 speed, 26bhp
The first new model design since the war, which was aimed at lugging a
sidecar. Bored out R51/3 engine fitted into the R51/2 running gear, including the
fishtail silencers and exposed shaft-drive. Twin leading shoe front brake
gave this model a little more stopping power.
R67/2 1952-54,
590cc ohv flat-twin, 4 speed, 28bhp
Up-rated and improved R67 model. The power out-put was improved by a few
modifications. Later renamed the R67/3.
R68
1952-54, 590cc ohv flat-twin, 4 speed, 35bhp, 105mph
The first true sporting model was basically the R67 with engine tuning and raised compression ratio, but
with pillion seat, lightweight mudguards, cable operated twin leading shoe
front brake, and full width alloy brake drums. Less than 1500 sold.
R26 1955-60,
247cc, ohv single, 4 speed, 15bhp, 73mph, 350lb
Earles front forks and frame sporting swinging arm rear suspension.
Very rigid frame and the first fully enclosed shaft-drive forming the
right leg of the arm. Larger fuel tank including a toolbox in the top,
smaller 18" alloy rims, restyled silencers and mudguards. Engine
gained diaphragm clutch and new gearbox layout giving a quicker gear
change.
R50 1955-60, 494cc ohv flat-twin, 4 speed, 26bhp
Earles front forks (invented by the Britain Ernie Earles) and frame sporting swinging arm rear suspension. Very
rigid frame and the first fully enclosed shaft-drive forming the right leg
of the arm. Larger fuel tank including a toolbox under the left knee pad,
smaller 18" alloy rims, restyled silencers and mudguards. Engine
gained diaphragm clutch and new gearbox layout giving a quicker gear
change.
R60 1955-60,
590cc ohv flat-twin, 4 speed, 28bhp
Basically a larger engined version of the R50.
R69 1955-,
590cc ohv flat-twin, 4 speed, 35bhp, 105mph, 445lb
Basically a larger version of the R50. In 1961 a sports model the R69S
was introduced with 42bhp and 111mph capability. Using hydraulic steering damper and bar end
indicators. Engine
gained diaphragm clutch and new gearbox layout. In 1968 there was a R69US North America
model with Telescopic forks instead of Earls, wider/higher handlebars and
12v electrics.
R50/2 1961-68, 494cc ohv flat-twin, 4 speed, 26bhp
Un updated and refined R50 model with stronger crankshafts, chromed piston
rings, enhanced case, which also improved the breathing. For 1961-63 a sports model R50S available, with hydraulic steering
damper and bar end indicators. In 1968 there was a R50US North America model with
Telescopic forks instead of Earls and wider/higher handlebars.
R60/2 1961-68, 590cc ohv flat-twin, 4 speed, 30bhp
Apart from changing the compression ratio the R60/2 was basically an R60
with stronger crankshafts, chromed piston rings, enhanced case, which also
improved the breathing. In
1968 there was a R60US North America model with Telescopic forks instead of Earls and
wider/higher handlebars.
R27 1961-67,
247cc, ohv single, 4 speed, 18bhp
Improvements on the R26 consisted of increase compression ratio. This led
to vibration which was cushioned using rubber
mounted engine and exhaust mountings. There was also an automatic timing chain tensioner, and
the marque was
offered in single or dual seat options.
R50/5 1969-72,
498cc ohv flat-twin, 4 speed, 32bhp
Redesigned engine with the pushrod tubes cast into the new alloy barrels
with larger fins replaced the cast iron., the crank case was much taller
housing the electric starter and air cleaner. The engine was also rotated
through 90 degrees to raise the cylinders by placing the camshafts, etc
below the crankshaft, thus giving better ground clearance for cornering.
High pressure oil feed meant that the big ends could revert to solid
bearing shells which were more rigid and suitable with the multi-grades of
the era. New 12V electrics from a 200 watt generator were a considerable
improvement and the bikes were fitted with four square indicators. Considerably
lighter frame using new layout consisting of a duplex cradle around the
engine fixed to a substantial backbone running from the headstock. BMW
banned sidecar use which voided the manufacturers warranty. Telescopic forks with gaiters replaced the Earls design. A range of
colours was available for the first time instead of black with white coach
lines. Manufacture was transferred from Munich to Spandau in West Berlin.
1972 minor changes to engine and tyre sizes, also an automatic side stand
that flipped up when the weight of the bike was removed. The tank size was
slightly reduced. In 1973 the swinging arm was braced and lengthened by 2
inches, which resolved a high speed instability problem.
R60/5 1969-72,
599cc ohv flat-twin, 4 speed, 40bhp
Basically the same as the R50/5 but with larger engine.
R75/5 1969-72,
746cc ohv flat-twin, 4 speed, 50bhp, 103mph
Basically the same as the R50/5 but with larger engine.
R60/6 1973-75,
599cc ohv flat-twin, 5 speed, 40bhp
Restyled series 5 model with plastic side panels, up-swept exhausts, extra
gear in gearbox, 280 watt generator and revamped handlebar clusters. 1975 saw the kick starter
dropped.
R75/6 1973-75,
746cc ohv flat-twin, 5 speed, 50bhp, 457lb, 62mpg
Restyled series 5 model with plastic side panels, up-swept exhausts, extra
gear in gearbox, 280 watt generator and revamped handlebar clusters. Single front disc
brake.1975 saw drilled discs and the kick starter dropped.
R90/6 1973-75,
898cc ohv flat-twin, 5 speed, 115mph, 60bhp, 460lb (S model 67bhp), 51mpg
An all new model, based on the R75, but with a bigger engine. Single disc front brake with twin on the sports model,
and the sports S model having a nose fairing, which housed a clock and
ammeter. 1975 saw drilled discs and the kick starter dropped.
R60/7 1976-77,
599cc ohv flat-twin, 5 speed, 40bhp, 51mpg
Series 7 was basically the same as the 6 series, but with sleek S model
fuel tank, stiffer frame, restyled rocker
covers, barrel fining and alloy tappets. The 600 gained a single front
disc brake.
R75/7 1976-79,
746cc ohv flat-twin, 5 speed, 50bhp, 62mpg
Series 7 was basically the same as the 6 series, but with sleek S model
fuel tank, stiffer frame, restyled rocker
covers, barrel fining and alloy tappets.
R100/7 1976-80,
980cc ohv flat-twin, 5 speed, 116mph, 47mpg (S model 65bhp, RS model
70bhp)
Fully faired model (claim to fame - first fully faired mass-production
bike) which cost a fortune in wind tunnel design, became the first
Sport-Tourer. Also
available in a sports model with higher compression. The fairing gave the
rider a pocket of still air to sit in, even at 100mph. At 50% higher cost
than it's counter parts, this was a superlative motorcycle. 1977 a single
disk hydraulic rear brake, along with 18 other minor improvements. 1981
new coated alloy bores replace steel cylinder liners, clutch improvements
and oil-ways redesigned. 1978 saw the RT model which was a tourer
with larger fairing and rubber mounted handlebars, which at 550lbs by far
the lightest touring bike, being 100lbs lighter than the Suzuki GS850 and
almost 200lbs lighter than Honda's GL1100 Goldwing, although it did get
the nickname of the Gummikuh "Rubber-Cow".
R80/7 1977-84,
797cc ohv flat-twin, 5 speed, 111mph, 473lbs, 59mpg
Replacement for the R75, bigger bore engine. The ST model was basically a
Street Fighter aimed at the US market, but lacked power and off-road
traction to attract it to their market place. New mono-lever rear suspension
R45
1978-83, 473cc ohv flat-twin, 5 speed, 452lb, 35bhp,
99mph, 62mpg
Smallest flat twin ever produced. Also produced for the German
market to take advantage of lower power outputs, the R45N giving 27bhp,
which was rather limp for a bike of this size. Smooth power out put from
the nicely balanced engine. 1981 new coated alloy bores replace steel
cylinder liners, clutch improvements and oil-ways redesigned.
R65
1978-84, 649cc ohv flat-twin, 5 speed, 452lb, 108mph, 61mpg
Replacement for the R60 in it's various guises. Nice power delivery
from the new dynamic ignition advance, although vibration was noticeable
at the 70mph cruising speed of the UK. Cast alloy wheels were standard on
this model. 1981 new coated alloy bores replace steel cylinder liners,
clutch improvements and oil-ways redesigned. A sports version R65LS with
small nose fairing, new front mudguard and cast wheels, dropped handlebars
and more flamboyant colours.
K100 1983-90,
987cc twin ohc flat four water-cooled fuel injection, 5 speed, 540lb,
132mph (RT 595lbs)
Dubbed the 'Flying Brick', this was a radical departure for BMW, which
maintained it's low centre of gravity shaft driven machines. Developed
over many years this was an outstanding success and with the full fairing
was compared to riding a two wheeled car. The four cylinder, twin overhead
cam, fuel injected inline engine, with 5 main bearings was laid on its side and the alternator and oil pump
counter-rotated to overcome the torquing effect, but unfortunately there
was a significant high frequency vibration transfered through the foot
pegs at speeds above 55mph.
K75C
1984-90, 740cc twin ohc flat three water-cooled fuel injection, 5 speed,
124mph, 500lbs
Not as popular as the K100 as it cost only £100 less, although it was
smoother and sportier than the bigger bike. The engine consisted of a
three cylinder arrangement and a counter rotating oil pump which included
balance weights. This eliminated the vibrations common to the K100. The
press dubbed this as the most beautiful bike to come onto the market for a
long time. In 1986 a sports version K75S was
launched.
R80
1984-95, 797cc ohv flat-twin, 5 speed, 110mph, 462lbs
New rear suspension called a para-lever eliminated the up & down
motion of the bike when the throttle was blipped at a standstill. This was
acheived by fitting a parallelagram arm/spring arrangement and an
additional knuckle joint in the drive shaft.
BMW have gone on to pioneer ABS braking using a pressure reduction
system, 4 valve heads on both twins and the K range. The R range went from
being called Air-heads to Oil-heads with the introduction of a new design
of engine comprising vertically split crank case, 4 valve single overhead
cam and an oil cooling system driven by a second oil pump, which assisted
the air cooled cylinders in areas like the exhaust valves. Tele-lever
front suspension, which comprised a parallelagram arrangement eliminating
brake dive. In 1993 they
partnered with Aprilia to launch a new engine built by Rotax which
comprised a 652cc vertical single with 5 valve head and chain final drive.
The heritage has continued and in 2006 they launched an 850cc vertical
twin with toothed rubber final drive belt.
Few manufacturers can boast such a long line of continuous manufacture.
None will exceed this acheivement.
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