BSA B31

The BSA B31 was a 350 cc pre-unit, single-cylinder, overhead valve four-stroke motorcycle made by the Birmingham Small Arms Company at its Armoury Road factory in Small Heath, Birmingham. It was the first new motorcycle BSA introduced after the Second World War, launched in August 1945 and built until September 1959. Its design traced back to the 1937 Silver Star by Val Page and the wartime B29 and B30, and it brought telescopic forks to BSA. A competition version, the B32, followed in 1946 and a 500 cc version, the B33, in 1947. Later changes included plunger and swinging arm frames, a dual seat and, in 1958, an alternator with coil ignition.