The Road To the K1
The road to the K1
1923 R32
BMW'S FIRST ACROSS-THE-FRAME-MOUNTED, 500CC, side-valve, flat-Twin produced a then-remarkable 8.5 horsepower at 3300 rpm. This engine’s radial-finned cylinder heads were cast into each cylinder as a single part, with removable valve caps. The transmission was a three-speed, hand-shift job. An exposed driveshaft transmitted the engine’s power into a bevel-box differential.
1935 R17
BY 1935 BMW HAD TWO 750CC ENGINES AVAILABLE: one with side valves and the overhead-valve R17. The R 17's short-stroke, 83 x 68mm engine produced 33 horse-power at 5000 rpm. By this point, a drum front brake was being used and the rear brake was an external clamping device around the driveshaft. The R17 also sported the first production telescopic fork with hydraulic damping.
1937 Streamliner
MVv's EARLY AERO!)YNAMI(' EXPERIMENTS WITh wind tunnels and scale models led to this aluminum-ensconced land-speed-record machine. Ridden by Ernst Henne, the bike, powered by a supercharged. 500cc fiatTwin which reportedly churned out almost 100 horsepower, streaked to l 73 miles an hour to set a world record just before World War II.
1938 R51
iii~ R51 FEATtJRFD A NEW. WEE I)ED-T(JBE FRAME TO accommodate its plunger rear suspension. This movement of the rear wheel also required the addition of a driveshaft U-joint placed at the end of the shaft. Three engines, a 500, 600 and 750, were available, all of them with fourspeed transmissions, and footand hand-shifters. A toolbox was built into the top of the fuel tank.
1955 R69
AFTER THE BNlWs S1.\YLit) FAIRLY VN(HAN(LI) until 1955. The R69 had a 600cc engine with a new clutch and redesigned four-speed transmission. The driveshaft was enclosed inside the right leg of the swingarm and footpegs replaced floorboards. An Earles-type, leadinglink fork was used as well as a revised rear suspension. The R69 also had a double-leading-shoe front brake.'
1969 R75
THE R75 11 Al t~RLl) ALUMINUM (`YIJNI)FRS ANU heads, a new, one-piece crankshaft, stronger connecting rods, a revised four-speed transmission, electric starting, a 12-volt battery and a new, lighter frame. A long-travel hydraulic fork drew mixed reactions from hard-core BMW riders who missed the Earles fork. A larger fuel tank was welcomed by all, as was a large, dual seat.
1973 R90S
OVERBORING A 750CC ENGINE PRODUCED A 900CC ENgine for 1973. Two models were offered; a standard version and a sport model called the R90S, which featured a higher-lift cam and a higher compression ratio. The first of the factory café racers which preceeded today’s sportbikes, the R90S featured a quarter-fairing and a stunning, “fogged" paint job.
1976 R100RS
WIND-TUNNEL-DESIGNED FAIRING CREATED BMW’s first sport-tourer, the R100RS. The eye-catching RS looked modern, sporty and fast. And its 980cc opposed-Twin engine was the most powerful production BMW to date. A stronger clutch, better five-speed transmission, larger-capacity battery, new fork valving and a stronger dual-disc front brake drew praise from buyers.
1984 K100RS
BMW's EON(i-AWAI1II) NEW INGINE FINALLY ARrived and it.was like no other engine in motorcycling; a dohc, lOOOcc inline-Four laid on its side. Fuel injection replaced carburetors, stainless steel headpipes routed the spent gasses into a single silencer and a single-sided swingarm (first introduced on the GS80 in 1980) let buyers know BMW was getting serious about sportbikes.
1988 R100GS
DRIVESHAFT-INE)IJ(1I) REAR-ENE) MOVEMENT HAl) long been a major complaint on shaft-driven motorcycles. The R I OOGS introduced BMW~s Paralever system to help reduce this effect. Floating the rear gearcase and utilizing a parallel (to the swingarm/driveshaft) torque arm proved an efTective cure. Indeed, the OS. a dual-purpose hike. was hailed as the best-handling BMW Twin ever.
