Wiseco 4329M07550 75.50mm 10.5:1 Compression 251cc Motorcycle Piston Kit Wiseco's forged pistons are tougher and more durable than cast pistons, and will stand up to the abuse that high performance motorsport applications require Piston kits contain one piston, rings, piston pin and piston pin circlips 2973XG ring set 251cc