Bolt in - no machining, balancing or splitting the crankcases; install can be performed with engine still in frame, Cast Ductile Iron Sleeve in cast aluminum for superior heat transfer, 88" 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 cams, Complete kit includes cylinders, forged pistons, rings, piston pins, clips and gaskets, Not for use with S&S 79cc heads.