S3 S3 Piston Kit - GasGas Pro, TRS, Vertigo 280

About this S3 S3 Piston Kit - GasGas Pro, TRS, Vertigo 280

Superb quality longlife forged S3 Racing piston kit to fit:
GasGas Pro 280cc from 2002 to present
TRS 280cc from 2016 to present
Vertigo 280cc from 2020 to present
Kit includes piston, rings, gudgeon pin and clips

Size A 75.965mm
Size B 75.975mm
Size C 75.985mm
18mm Gudgeon Pin by 56mm long
Centre of the gudgeon pin to the top edge of the piston 28.7mm
Overall height 66mm
Height from top to the edge of the piston 3.9mm
Weight including rings, gudgeon pin and C-clips 318 grams

Also listed as suitable replacement piston for the following bikes.
Beta 270
Sherco 290
Jotagas 280
Ossa 280 (Barrel would need re-boring)
But please check very carefully as the distance from the centre of the gudgeon pin to the edge of the piston may be slightly different so the squish clearance must be checked and the base gasket thickness adjusted to suit.

For example on the Sherco, this piston is 2mm shorter, 0.015mm larger in diameter, 0.4mm shorter from the centre of the gudgeon pin to the edge of the piston and the radius on the top of the piston is larger so the height from top to the edge of the piston is 0.6mm shorter than the original.
So if you have your cylinder bore replate to fit this piston, you can use it but it will lower the compression slightly and increase the squish clearance, unless you shorten the cylinder by 0.4mm or reduce the base gasket thickness but I wouldn't recommend going below 0.5mm on the Sherco base gasket. To do it properly the head would need reshaping to suit the larger radius on the top of the piston and bring the compression ratio back to standard.