This 883cc to 1200cc conversion piston kit features forged pistons that convert any 883cc or 1100cc engine to 1200cc. Bore the stock 1985-'03 cylinders from 3 inch to 3-1/2" bore. For 2004-'16 models we recommend that new 3-1/2 inch bore cylinders be purchased. No combustion chamber modifications are required due to the dished piston dome. Stock 883 heads produce a reasonable 9.6:1 compression ratio. No engine removal, crankcase splitting, or rebalancing is required. Coated piston skirts for reduced friction during break-in. Includes pistons, rings, wristpins, and clips.. +.030" bore.