Vincent HRD needs no introduction as a maker of some of history’s fastest, most beautiful and altogether most alluring motorcycles, and it was the Comet engine which was instrumental in establishing that reputation. 

Very early Vincents had been assembled with JAP engines, but in 1935 Phil Vincent and business partner Phil Irving unveiled a bike with an engine of their own design, an almighty 500cc single.

In basic tune, the new engine went into the Vincent Meteor, but a warmed-over version was developed for its even sportier sister, the Comet. 

The first Comet, the Series A of 1935, was good for 90mph, but Vincent realized that even better performance could be generated by turning the sloping 499cc single into a 998cc V-twin, which appeared first in the Rapide of 1936 and, post-war, in the legendary Black Shadow.

While the Series A had features which might be considered experimental, it was refined into the Series B and further developed into the Series C after the war. 

It was the Series C which represented the pinnacle of the Vincent single-cylinder and, although never so glamorous as the twin, it remained popular as a cheaper but still enormously capable alternative, and so continued into production until financial losses (for the best machines are never the most saleable) forced Vincent to cease production in 1955.

While the obvious use for this engine would be for the restoration of a Comet or to keep as a spare, we oughtn’t overlook the fact that Vincent engines found many other uses in period. 

Quite a number were turned into stripped-down, streamlined sprint specials and raced hell-for-leather in a frenzied dash for oily glory, or their engines were transferred to special competition frames such as those constructed by Fritz Egli. 

Other people became the envy of the coffee-bar crowd with their Vincent-engined café racer specials, such as the well-known Norton Featherbed-framed Norvins.

The engine for sale is in excellent condition, having been rebuilt by the vendor, a well-known and long-established Vincent restorer who has owned Vincents since he was 17, has restored over a dozen and has the spares department to show for it.

He acquired the engine in late 2020 in a part-rebuilt condition, with the bottom-end having been rebuilt by another prominent Vincent expert, and completed the build over the spring and summer of 2021. 

At that point, it had no barrel or head, but the vendor sourced them and assembled the top-end with +0.030” Specialloid pistons. He then fitted a cylinder head which had been newly refurbished to a very high standard. 

For the cams, the vendor used “quite racy” Stellited Mk. II cams with Stellited followers. The engine retains the Comet’s standard 7.3 to one compression ratio.

With the cylinder, crankcase and gearbox all assembled, the vendor saw to the ancillaries, and fitted a Miller dynamo and Lucas magneto, both of which have been completely reconditioned. 

He will supply a carburettor with the engine, and the buyer may choose whether it is an original Amal for a standard Comet, or a more modern Amal which would suit an Egli-Vincent or a similar sort of special.

As can be seen, the engine is complete with its footrests and is essentially ready to go straight into a frame, although it would be necessary to source or fabricate an exhaust pipe.