500cc CS1/ES2 Piston: 79mm +0.020" - JP None Slipper Type (Approx 7:1 CR)

Product no.: 0388 C3/160-020

In stock

£255.00
Recommended Retail Price, plus delivery


This is a 79mm (500cc) piston to fit Norton 79mm x 100mm Lonstroke singles - from well known piston manufacturer - JP Pistons. These pistons are CNC machined and very well made. The piston shown here is of the none-slipper type orignally fitted to ES2 and CS1 engines, and is almost identical to the original Hepolite construction. I have compared this piston back to back with an original ES2 piston, and the only difference I can see is that this piston looks to have a fractionaly higher piston crown, which I would estimate to be approximately 7:1 compression ratio.

Note: for those wanting to check against their own engine - the most important dimension is the distance between the centre of the Gudgeon Pin (Little End) and the base of piston crown (i.e. at its outer circumference) - as this will determine if the base of the piston crown fouls the rim of the cylinder head.  For these JP pistons, as per the original 1950's ES2 piston in the photograph - that dimension is (approximately) 13.9mm.  The gudgeon pin diameter is the standard Norton single cylinder 0.875" type.

If you do not mind a slightly lower compression ratio than the normal International piston (i.e. approx 8.5:1) and you are not intending to use the engine for serious racing, then I would see no reason why this piston could not be used in SOHC Norton engines. I am able to supply this piston in STD, +0.020, +0.040 and +0.060 sizes. Note: When sizing pistons - the size represents the diameter of the bore, which means for a STD piston the bore should be exactly 79mm in diameter, and oversizes the exact number of thou on top of this (i.e.79mm + 0.020"). This listing is for a +0.020 (i.e. 79mm bore exactly) size piston.

Note: If stock position is at zero (red stock bar) - it means I do not have one in stock in this bore size, but can normally get one within 2 - 4 weeks, therefore email at sales@racingvincent.co.uk

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