1938 BMW 494cc R51
Frame no. 514841
Engine no. 20735
When BMW-mounted Georg Meier became the first foreign winner of the Isle of Man Senior TT in 1939, it marked the pinnacle of pre-war success for a firm that, remarkably, had not built a motorcycle of its own until 1923. Originally an aero engine manufacturer, Bayerische Motoren Werke (BMW) had come into being in July 1917 when the Bayerische Fluzeugwerke (BFW) company was reorganised. BMW's engines proved their worth time and again in aerial combat in WWI, but on cessation of hostilities the firm had no option but to seek other work.
Slowly BMW succeeded in re-establishing itself, and in 1920 turned to motorcycle production. Its first two models, marketed as the Frink and Helios respectively, were failures but a successful proprietary engine was supplied to other manufacturers such as Victoria. Designed by Chief Engineer Max Friz and launched in 1923, the first motorcycle to be sold as a BMW - the R32 - featured a 494cc, twin-cylinder, sidevalve engine having horizontally opposed cylinders, and this 'flat twin' layout would forever be associated with the marque.
An important step forward in the development of BMW's long-running flat-twin occurred in 1936 with the introduction of the 494cc R5. Prior to that the BMW engine had been recognisably related to the first of its type, the 1923 R32, and like those of its (500cc) predecessors, the R5's engine dimensions were 'square' at 68mm x 68mm bore/stroke. However, the overhead-valve R5 engine broke new ground by adopting two chain-driven camshafts, a move that permitted shorter pushrods and higher revs. Maximum power increased to 24bhp at 5,800rpm. Top speed was an impressive 87mph. In 1938 the model was up-dated as the R51, gaining a telescopic front fork and plunger rear suspension, and continued in production until 1940, by which time 3,775 of these exciting sports roadsters had been sold.
Finished in BMW's traditional black with white coachlines, this R51 was purchased from a jointly owned Spanish private collection in 2006. The machine is offered with Spanish registration papers.