Photo ou archives : F-M. Dumas
500 RS "ClientÂ” Â– 1954
Return to racing
As a result of GermanyÂ’s defeat in WWII, the country was barred from competing in international racing until 1951. Then BMW reappeared on the circuits with machines directly derived from the successful prewar blown 500, but with the supercharger removed to comply with the new regulations. It was not until 1952 that the manufacturer was able to produce a new racing bike, the 500 Rennsport, known as the 500 RS.
Works Riders Only
In 1953, the solo RS Â— noteworthy for its modern frame, with Earles front fork and swing arm rear suspension, in contrast to the telescopic fork and plunger rear end of the sidecar version Â— was exclusive to the works riders Baltisberger, Mette, Zeller and the Meier brothers.
Available at a Price
Engine-wise, BMW retained its distinctive layout of twin overhead-camshafts acting on the valve stems through short rockers, but the engine had "square" dimensions, and the crankshaft ran in three roller bearings. Engine, gearbox and final drive were far more compact than previously, and the weight was down. In 1954, BMW sold 500 "client competition'' versions of the 500 RS Â— at a steep price! The main difference lay in the engine which was slightly undersquare. Initially a telescopic from fork was fitted, but it was very quickly replaced by an Earles. A modified version of this production RS became the official mount of Walter Zeller up to BMWÂ’s withdrawal from racing at the end of 1957, but even all his talent could not prevail against Gilera, Guzzi and MVAgusta.
Engine: 493cc (66x72mm) air-cooled flat-twin four-stroke
Power Rating: 45 hp @ 8000 rpm
Valves: two shaft-driven overhead-camshafts per cylinder
Fuel System: wwo Amal-Fischer carburettor
Transmission: 4-speed, shaft final drive
Suspension: Earles forks (front); swing arm with twin spring/dampers (rear)
Brakes: two leading shoe drum (front & rear)
Wheels: 18 inch wire (front & rear)
Weight: 297 lb
Maximum Speed: 121 mph
The RS engineÂ’s power output could be boosted to over 60 hp with different cams and big DellÂ’Orto carbs.