The BSA M20 was a British motorcycle made by Birmingham Small Arms Company (BSA) at their factory in Small Heath, Birmingham. Initially viewed as a near failure by the War Office in 1936, the M20 evolved into one of the longest serving motorcycles in the history of British military motorcycling, as well as becoming the most numerous type produced for World War II with 126,000 in active service, so many are still in use around the world today.
Development
At the outbreak of World War II BSA were Britain's largest motorcycle manufacturer with a long history of armaments supply to the armed forces. Designed by Val Page the BSA M20 started development in 1937 as a heavy framed sidecar model with a simple 500cc single cylinder side valve engine. It had low compression and plenty of low end torque through a standard BSA gearbox.
Early K-M20 models from 1939 were made from standard civilian parts with the addition of military fittings, such as a large 8 in Lucas DUl42 headlight (fitted with a black out mask), a timing-gear cover with a screw-in plug for access to the magneto drive-pinion nut and special filler caps the petrol and oil tanks. These early military M20 models were also fitted with a long spiked prop stand on the rear nearside pivoted from a lug brazed on to the rear frame tube. Factory ledgers show that BSA exported K-M20 models to Sweden, South Africa and India, as well as civilian dealers and distributors.