Piston Kit (Cast BigBore)Cast-BB – Cast piston in original OE form for big bore cylinderAll pistons are heat-treated with a T-5 hardening and tempering cycleAll piston skirts are coated with a high-tech Molybdenum Disulphite coating for faster break-in time and increased piston lifeCast piston kits are gravity-cast aluminum alloy (not forged) with 18% silicone content, which produces an extremely light but very strong pistonBig Bore pistons increase engine’s displacement, torque, and peak horsepowerReplacement two-stroke piston rings sold individually; four stroke piston rings sold as a setSize Over Standard: + 5.60 mm