Bolt in - no machining, balancing or splitting the crankcases install can be performed with engine still in frameCast Ductile Iron Sleeve in cast aluminum for superior heat transfer88'' engines are boosted to 100''96'' and 103'' engines are boosted 110''10.5:1 compression (w/ stock 85cc heads) makes for a very streetable and dependable engine that also responds well to performance camsComplete kit includes cylinders, forged pistons, rings, piston pins, clips and gasketsNot for use with S&S 79cc heads.