1928 BMW 490CC R57 Frame no. 26907 Engine no. 70321 Following the collapse of its aero engine business after WWI, BMW turned to other areas of manufacture, motorcycles among them. The first BMW branded motorcycle (in 1923) - the R32 - featured a 493cc twin-cylinder, sidevalve engine with horizontally opposed cylinders, and this "flat twin" layout would forever be associated with the marque. This first effort was expensive but superbly engineered. For 1928, BMW reorganized its range of engines, which now included a brace of 750s: one sidevalve, one overhead-valve. The new, overhead-valve R57 sports bike's engine was "square" with 68mm for both bore and stroke. It ran a hand shift 3-speed gearbox. Electric lighting, was standardized throughout the roadster range. R57 production lasted for only three years and today this rare BMW is among the marque's most sought after machines of the period.
above : the R57 featured a
68mm square bore & stroke
a better transmission than the predecessor R47
below : owner Gary Lewis with Superstar Model Courtney on the set.....