Athena's extensive experience gained in supplying the most prestigious O.E.M. motorcycle manufacturers has brought to their R&D technicians the skills necessary to make their exclusive high-quality components. Athena forged pistons offer the best solution in terms of performance, cost and reliability. Compared to cast pistons, Forged pistons are tougher and more durable , and will stand up to the abuse of todays high performance motorcycles. Athena pistons are produced with a special high-performance aluminum alloy, with a backward-extrusion forging process. Developed and engineered in Italy by Athena R&D Department, the Athena Pistons need to pass several bench tests and track sessions to achieve the highest level of performance and reliability. Technical solutions and quality standards are the same or better than those used in the OE productions. A screen-printed Molybdenum Bisulphide special sintered coating is applied on the piston skirt. This allows to increase smoothness, performance and durability, reducing friction and noise. The piston rings, included in the kit, are state-of-the-art, made in Japan components, produced in special steel with PVD coating or chrome nitrides. They are developed to perfectly be adaptable to the cylinder walls even at low tangential load. Forged piston kits are made to OEM stock specifications and include friction reduced coated piston, rings, circlips and wrist pin. Pin dimensions 18x10.5x44.5, Bore diameter 96.95 mm, Compression Ratio 12.5:1, Compression Height 24 mm. Fitment: Yamaha YZ450F 10-13 OEM Replacement D.96.95