This 612cc performance kit is one that we have developed, tested and proven over a number of years. The difference in performance is unbelievable, yet keeps a nice rideable street bike that will start and tick-over without fault. An engine with this very kit has been officially timed by Classic Bike Magazine at 120mph (with fairing). Using the silencer supplied with the cone removed, this typical engine was tested on the dyno at 39.6bhp at 5,500 revs. When compared to the same test on a standard 500 Bullet, we have an increase in rear wheel horse power of 150%!

In the Dyno chart (shown above) the blue line shows an unmodified 500cc Bullet! This reading is at the rear wheel, and yes is only 16bhp. This is typical of any standard 500 Bullet.
The green line shows our 612cc performance kit straight out of the box.
This gives nearly 40bhp.
The red line is a further development of this for competition, which reaches nearly 45bhp.

Parts included are: European main bearings, big bore kit with forged piston, long stroke English crankshaft, tuned cylinder head with performance valve assemblies, compression plates, gasket set, pushrods, silencer, oil pumps, 32mm Amal MK1 carburettor kit, clutch springs, camshafts plus all small parts needed. Please see details of the individual parts listed separately in this catalogue.

Note 1: That although a set of heavy duty clutch springs are included, we would recommend an uprated clutch to cope with the extra power.

Note 2: There are now so many variations between years and models that we need to collect some extra information in order to make sure the kit we provide is suitable for your bike. Please overtype the text in the in the appropriate 'Details' section of the order form (below) with the following information:

Year of Manufacture
4 speed or 5 speed
Left shift or right shift
Kick or Electric start

Please provide detaeils of the motorboke this part is intended for ...