The basic internal design of the BSA A65-A50 engine actually changed very little in the transition to unit construction. The layout was the same with the same basic gearbox. All of this was tucked into a new set of unitized engine cases. The two engines, the 500cc A50 and the 650cc A65, shared most parts in common, including their stroke, at 74mm. The A65's bore was 75mm for a displacement of 654cc, and a nearly-square ratio. The A50's bore was 65.5mm for 499cc. Both came out with single carburetors and alloy heads.

Originally a Michigan bike. This A50 is in exceptional condition. Upgraded Boyer ignition, new tires, chains,sprockets,shocks,fork rebuild, coil and sprockets. Unique in it's one year only color with matching side car attached. Popular in the British Isles, sidecars were common place. Providing additional space for family and enhancing the daily use of motorcycles as the main means of transportation. Sidecars on BSA are rarely seen in the U.S. This bike and it's sidecar present an opportunity to have a British Icon with a twist.