S&S Cycle 4" big bore cylinder and piston kits boost 96/103" Twin Cam engines to 110" respectively These bolt-in kits don't require any machining, rebalancing or engine removal, and include just about everything you'll need to complete the installation The biggest cylinder bore that can be installed in a stock crankcase without machining! Bolts in No machining, balancing, or splitting the crankcases 96" and 103" engines end up at 110" respectfully Complete kits include cylinders, pistons, gaskets, and instructions Choose from wrinkle black or silver powder coat cylinders - matches stock finish Set up for 4-3/8" stroke 4.937" Cylinder length Forged piston .75 pop up dome volume Compression ratio: 79cc S&S Cycle heads will be 11.2:1, 83 CNC heads will be 10.7:1, 85cc heads will be 10.5:, and 89cc S&S Cycle heads will be 10.2:1 Match with S&S Cycle 585 cams, Power tune Headers, MK45 mufflers and a S&S Cycle Stealth air cleaner for the best possible performance