The BSA B44 was a series of 441 cc (26.9 cu in) unit construction single-cylinder OHV four-stroke motorcycles made by the Birmingham Small Arms Company between 1966 and 1970. The machines were developed from the BSA World Championship Motocross machines, which were themselves based on the C15/B40.
Source : BSA - moto classique refroidie air (intervalles type epoque)