Kit includes complete aluminum cylinder, with a nickel carbide plated bore, cylinder head, piston, rings, 10 mm wrist pin, circlips, carbon reeds and all required top-end gaskets This cylinder kit can be installed without making any changes to the engine crankcase Piston head is domed Bolt on It is recommended that Athena's 17.50 mm or 19.00 mm scooter carburetor be used with the bolt on big bore kit.. CYLINDER KIT YAM/MALAGUTI