This rebuild kit is designed for the 77mm stock bore cylinder and piston assembly of compatible YZ250F models from 2001 to 2013.It includes all components required to replace a damaged or worn cylinder head end assembly: one aluminum cylinder, one forged piston with anodized finish, one set of piston rings, one 16mm steel wrist pin, two circlips, one cylinder base gasket, one cylinder head gasket, one exhaust gasket, and one chain tensioner gasket.The cylinder features a nickel silicon carbide coating.Bore diameter is 77.00 mm and stroke is 53.6 mm.Displacement is 249cc.Compression ratio is 12.7:1.Piston pin diameter is 16mm and pin length is 38.5mm.This kit is intended for standard bore size replacement and restores function.Compatible With YZ250F 2001–2013.Part numbers included for reference: Cylinder 5XC-11311-20, 5XC-11311-10, 5XC-11311-01, 5XC-11311-00, 5UL-11311-00, 5NL-11311-00; Cylinder Base Gasket 5NL-11351-00; Cylinder Head Gasket 5NL-11181-00; Piston (Std) 5NL-11631-10, 5NL-11631-20; Piston Pin 5NL-11633-00; Piston Ring Set (Std) 5NL-11603-00; Circlips 93420-16086; Exhaust Gasket 5NL-14613-00; Chain Tensioner Gasket 4FM-12213-00.Compare part numbers and dimensions with your existing components to confirm fitment.