Power was provided by a British Anzani twin-cylinder 322 cc two-stroke engine producing and mounted transversely, driving the front wheels via a chain and three-speed gearbox. The engine was already used by various motorcycle manufacturers such as Cotton and Greeves, but in the Berkeley was fitted with a Siba Dynastart to provide both battery charging and electric starting. It was a very advanced two-stroke engine which incorporated a rotary inlet valve mechanism in the centre of the crankshaft. The gearbox was a three-speed Albion HJR5, using a steering column-mounted gearchange.