The Vincent Comet was designed and built at the Vincent works in Great North Road, Stevenage, Hertfordshire UK. Developed from the Vincent Rapide by Australian engineer Phil Irving in 1935, it was one of four 499cc single models. As well as the sports Comet, Vincent produced a TT racing model, the Comet Special (a TT model with lights) and the standard Vincent Meteor which shared many of the same cycle parts.
An unusual feature of the valve design for these motors was the double valve guides, and the attachment of the forked rocker arm to a shoulder between the guides, to eliminate side forces on the valve stem and ensure maximum valve life under racing conditions.
The prototype series A was refined and developed into a production model B but after World War II it was the development of the series C that represents the ultimate Vincent 500cc single. A series D (designated as the Vincent Victor) was actually designed and one was built at the factory. Others had to be subsequently made up from spare parts as Vincent production ceased in 1955.
The 499 cc single cylinder high camshaft OHV, air cooled Vincent engine had a light alloy barrel with a cast iron liner was really 'half a Rapide', although it had the Black Shadow compression ratio (7.3:1) and the larger carburator. It did not have the polished internals of the Shadow nor was it selectively assembled. It had a Burman four speed gearbox and a 'backbone' type frame with the engine incorporated into the frame. All the The Comet line had both front (Girdraulic) and rear suspension when most manufacturers had only front suspension.