Athena P400485100073 304cc Big Bore Cylinder Kit (85mm Bore) - Forged Piston Performance Upgrade, Converts 250cc to 304cc, Compatible with Yamaha YZ250F & WR250F 2019-2023 Raceline Designed specifically for the RM65

Designed specifically for the RM65 chassis

Updated tread compound enhances wear resistance and durability

Now that's tough

and paved streets

Ideal for trail

Athena P400485100073 304cc Big Bore Cylinder Kit (85mm Bore) - Forged Piston Performance Upgrade, Converts 250cc to 304cc, Compatible with Yamaha YZ250F & WR250F 2019-2023 Raceline Designed specifically for the RM65UPGRADE YOUR DIRT BIKE TO THE NEXT LEVEL OF PERFORMANCE Extract massive power, aggressive low end torque, and unmatched acceleration from your 250cc four stroke engine with the Athena Big Bore Cylinder Kit (Part No. P400485100073), a premium race proven package engineered in Italy to seamlessly convert your factory setup into a high revving, high output 304cc powerhouse. Entirely cast from high grade aluminum and treated with a specialized Motor