Bore: 94.96mmCompression: 11.4:1 CompressionSizing: Standard BoreTop End kit includes: piston, rings, wrist pin, clips, top end bearing, and gasket kit. MOS2 (Teflon/Molybdenum) Coated Skirts A rolled on application process provides a bond that is 10 times stronger than other spray on coatings. Benefits include increased heat transfer, reduced friction and helping to eliminate cold seizures. Machined Smooth Heads Reflects combustion heat and reduces carbon buildup, protecting the top of the piston. Some tests have shown this feature can increase horsepower and fuel economy by up to 6%. Anodized Domes Increases heat resistance and durability; pistons with anodized domes are 75% stronger than non-anodized pistons. Hypereutectic Casting Process Provides higher silicon content for reduced expansion rates and additional wear resistance; it also has an ability to withstand higher cylinder temperatures.This item fits the following vehicle applications:compatible with Yamaha YFZ450R 2009-2015compatible with Yamaha YFZ450R SE 2009-2015compatible with Yamaha YFZ450X 2010-2011compatible with Yamaha YFZ450X Bill Balance 2010compatible with Yamaha YFZ450X SE 2011