BMW 1939ca R51 494cc 2 cyl ohv 3606

BMW 1939ca R51 unfinished restoration 494cc ohv horizontally opposed twin frame # 512929 engine # not clearly visible

In the late thirties BMWs are sold in considerable numbers, in spite of their high prices; in the UK a 1938 BMW R51 costs £123, while a Triumph Speed Twin can be had for less than £77. The make has built up an excellent reputation for quality and luxury: from 1938 on all BMWs have both front and rear springing, a feature which is at the time very uncommon for most other makes. From 1938 till the war stops production of civilian bikes all BMW twins share a common frame and cycle parts. All engines are interchangeable and share the same transmission, only the rear axle ratios are different. The R51 has many features in common with its predecessor, the R5. That boasts such features as a double cradle arc-welded frame made of oval tubes, hydraulically dampened telescopic forks, foot-operated gearchange, a new type of engine with two camshafts, hairpin valve springs and quickly detachable and interchangeable wheels. New for the R51 is the plunger rear springing. Power delivered is 24 hp @ 5,600 rpm, good for a top speed of around 140 km/h.
The machine we offer comes without history or registration papers: She has stood in a private collection for years and it is not known why the restoration has not been finished. The odometer appears new but is not connected. The carburettor intake tubes and the cover of the voltage regulator are missing and the carburettors themselves would appear too young for this model. The identification plaque on the headstock is new and lists frame number 507891, which differs from the frame number located to the left-hand rear suspension mount of the motorcycle, recorded as 512929. We have taken off the valve covers and on the valve mechanism the small BMW stamps are visible. The front engine cover has also been taken off and the coil and distributor are all in place. Detailed photos of this promising machine are available on request.