BMW 1928 R47 494cc 2 cyl ohv 3501

BMW 1928 R47 Sports Model 494 cc ohv transverse twin frame # 5109 engine # 35678
In the nineteen twenties the BMW side valve models are marketed as touring machines, the more exclusive overhead valve types are presented as Sports mounts. The first is the R37 that is brought out in 1925 and has the smallest production run of all commercially produced models in the company’s motorcycling history: only 152 leave the factory. The R37 is replaced by the improved R47 that is introduced alongside the side valve-engined R42 tourer, both models benefitting from a redesigned and more powerful engine. The engine is set further back in the duplex loop frame, which improves weight distribution and enables straight front down-tubes to be used. The braking gets its share of attention too: the old block-and-pulley type rear brake is replaced by a drum on the driveshaft gripped by external contracting bands. The front brake is a 150 mm internal expanding device. A practical feature is the centre stand, used on BMWs from 1923 on. Most other makes still have the cumbersome rear stands in the twenties, some even till far into the 1930s.
Maximum power output of the R47 is 18 bhp @4000 rpm and its top speed is 110 km/h. Compression ratio is 5.8:1 and there are two litres of oil on board. The machine weighs 130 kgs and production lasts for just two years, 1,720 machines being sold. Petrol consumption is 4 to 5 litres per 100 km and for this distance 0.2 to 0.3 litres of oil are consumed. This very rare Sports BMW has been restored to a high standard, with Bosch electric lighting and UC6 horn, Carmen Werk Stuttgart steering damper and 140 km built-in speedometer. She is in running condition but has not been used on the road after the restoration.