bsa motorcycles - 1915 BSA K





BSA new singles range debuted in 1937, the two biggest sidevalve-engined models being the 496cc M20 and 596cc M21. The latter started out with bore/stroke dimensions of 85x105mm, but in the interests of rationalisation was soon revised with the 82mm bore of the M20, which required a lengthening of the stroke to 112mm for a capacity of 591cc. Ruggedly built and endowed with copious low-speed pulling power, both M-Series models were highly successful in their intended role as sidecar tugs and many did sterling service with Allied forces during WW2. Production of the M20 ceased in 1955 while the M21 lasted until the end of 1958, though it remained available to special order until 1963. One of the organisations that continued to favour the faithful old M21 was the Automobile Association, whose distinctive yellow-liveried combinations, ridden by patrolmen wearing military-style khaki uniforms, were a regular sight on British roads well into the 1960s. Today these AA combos never fail to attract a crowd at classic vehicle shows.


Photo from kind permission of the Motorbike Search Engine

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