1938 BSA M23 Empire Star 500cc OHV Motorcycle with Sidecar

Description

The Birmingham Small Arms Company (BSA) began motorcycle production in 1910 and went on to become one of the world's largest manufacturers in period. Named to commemorate the Silver Jubilee of King George, the Empire Star was produced at BSA’s Small Heath (Birmingham) factory between 1936 and 1939. It was developed from the popular Blue Star model and was designed by Val Page, previously of Ariel and Triumph. With its heavy frame and iron barrelled pushrod valves, the Empire Star had the legacy of the earlier BSAs however Page continued to lighten it and introduce engine tuning ideas throughout production. Available in three engine capacities – the 250cc 'B22', the 350cc 'R5' and the 500 cc 'Q8' – the Empire Star was powered by an OHV single-cylinder four-stroke, hooked up to a four-speed chain drive transmission. The engine had an alloy primary crankcase with a special high compression piston and a hardened cylinder bore. It also had modern touches for the period, such as a foot-change gearbox and dry sump lubrication. The Empire Star was ultimately developed into the Gold Star until World War II stopped production in 1939, and the BSA factory turned over to making munitions and producing the BSA M20 for the British Army.