BSA 320cc Model A

6.5 HP @ 2500 RPM

This Model A was manufactured by BSA Ltd at the Redditch Works England in C1956

These engines were made in capacities from 65cc up to 420cc. This engine is a four-stroke side valve engine. The engine is air cooled by a fan running off the flywheel. Fuel is supplied to the engine by a Solex carburettor. Spark is generated from a magneto and delivered through an 18mm sparkplug. Engine speed is controlled by governor. The engine is designed to run between 1500 and 2500 RPM under normal workload delivering a maximum of 6HP. It can however run at 3000 RPM delivering 8HP. BSA stress though that this is absolute maximum for the engine.

The significance of this engine is, it is an alloy crankcase engine making it much lighter than the cast iron engines. It also retains the heavy flywheel of its predecessors and external magneto ignition. It was in this era that Villiers developed what was known as the Villiers type flywheel magneto. This development was the fitting of magneto components in under a hollow and lighter flywheel, making engines more compact. It was the dawn of the modern engine. With time the Villiers development took hold with engine manufactures. This spelt the end for engines like the BSA model A.