Athena Big Bore cylinder kits are a bolt on performance replacement kit specifically designed for each application. The kit includes a new aluminum cylinder with nickel carbide coating designed with wider water jackets, Vertex Forged piston with molybdenum coating, piston pin, rings, clips and all the gaskets required for the job. For Yamaha WRF 450 2007 to 2015 models, brings the CC up to 480cc with a 98mm piston.