BMW 1961 R50S 494 cc 2 cyl OHV 3605

BMW 1961 R50S 494 cc transverse OHV twin frame & engine # 564463

Bayerische Motoren-Werke is known in English as the Bavarian Motor Works, or more simply as BMW. The firm launched its first horizontally opposed twin in 1923, and has stood by this style of engine layout ever since. The opposed design offers riders buttery smooth performance as the engine has inherently good balance. In 1955 BMW created its R50, R60, and R69 models. These new models had a similar engine and the same shaft-drive as earlier models, but were fitted with modern swinging fork rear suspension for the first time. The telescopic forks at the front of earlier models were abandoned though, in favour of the swinging or “Earles Fork” system. In 1960 the twin range was revised as the “/2”, with quite a few improvements, most of them inside the engine. The Sports model R69 was taken out of production and two new Sports models appeared: the 500 cc R50S and the 600 cc R69S. The R69S delivered 42 hp @ 7000 rpm and its smaller brother 35 hp @ 7650 rpm.
The standard R50 had a 6.8:1 compression ratio, that was upped to 9.2:1 for the S type; also various transmission ratios were changed to reach the higher top speed. A notable external feature was that the cylinder heads had only two ribs while the standard R50 had six.
Although the R50S was good for 160 km/h, many customers chose for the more expensive but faster (175 km/h) R69s. From this model 11,317 machines were sold between 1960 and 1969. The R50S production was stopped in 1962 after only 1634 machines were produced, hence this model is one of the rarest postwar BMWs and much sought after by BMW collectors.

This recently restored machine proudly shows the chrome “R50S” logo on the rear mudguard. The R69S was the only other BMW with that type of model designation on that particular place. The former owner bought the machine some time ago as an unfinished project, that came with new old stock petrol tank and mudguards, that still bear the original factory enamel and lining. A non-exhaustive list of the work carried out: the frame has been powder coated and the engine and gearbox have been thoroughly checked. The crankshaft bearings had already been renewed; the cylinders have been honed, new piston rings have been fitted and the valve seats have been recut. New bearings have been fitted in the swingarm and steering head. The wheels got new stainless steel spokes and new tyres and a maintenance-free dry cell battery has been placed in the original-style battery housing. The rear wheel brake lining is new, the front brake was still in good condition. All in all this sporty and rare BMW, with fresh Dutch road registration, is ready again for many trouble-free kilometres!