Unlock your dirt bike's hidden potential with the power producing and durable Cylinder Works big bore kit. No need to waste your time and money on getting your factory cylinder bored out because the Cylinder Works cylinder is stronger and more reliable. Best part about this cylinder is that it mounts directly to the factory crankcase and head. The piston and rings that come with the Cylinder Works big bore kit are reliable for any motocross race. Even down to the gaskets Cylinder Works employs high quality gasket materials for reliability. Take your 450cc engine and add 3mm for a big bore 478cc with the Cylinder Works kit. The Cylinder Works big bore kit includes: big bore cylinder, big bore piston, piston pin, piston pin rings, gasket kit. Note: to achieve optimum performance re-jet the carburetor with the available jet kits.