Pistons, rings and liners

Unless requested not to we will supply the nearest oversize piston available. Do not bore your barrel before obtaining a piston, as the size you require may not be available. In any case a barrel should always be bored to suit a piston. If when boring the barrel you find that a larger oversize than that which you have obtained is required we will exchange it without levying a handling charge. Available over sizes are given in thousandths of an inch. 20 = .020” or .5 mm.

If you are not sure whether your piston, bore or rings are worn or not then your local automotive machine shop will normally check them for you without charge. The clearances are listed under each section.

We may have many ‘new old stock’ pistons in stock so please enquire also state if you are prepared to accept one of the ‘newly manufactured’ pistons as an alternative. All pistons are complete with rings, gudgeon pins and circlips. Current availability is shown below. We can frequently help with pistons for earlier models.

Some pattern pistons are heavier than the originals. We have asked the suppliers if they can reduce the weight, the answer is that they can but at about £1000 tooling for each type. Particularly on twins we recommend that the crankshaft be dynamically balanced to reduce the vibration, which is a good idea anyway.

All Pistons are Complete with Rings, Gudgeon Pin and Circlips.