Engine Cylinder Seal Ninja 6R 636 2003 2004 Fit For Kawasaki Ninja ZX-6R ZX636 2003 2004 motorcycle piston ring direct piston assembly installation , piston groove size , no or adjustment needed tight cylinder wall sealing , reduces consumption , maintains stable compression during speed riding hardened anti friction material , smooth ring surface to lower cylinder wall abrasion machined ring gap size , consistent elasticity to fit tightly under variable operating temperature complete set matched to cylinder bore standard , convenient for single cylinder engine overhaul