S&S Cycle 124 Hot Set-Up Kit For Harley Twin Cam The S&S 124 Big Bore Kit turns a motor into a high-compression 124 cubic inch setup built for serious street performance. Equipped with 4-1/8 bore pistons, 640 gear drive Easy Start cams and race-ready Super Stock heads, it delivers strong torque and sharp throttle response while fitting directly into the frame. It is a high-output upgrade for riders who want maximum performance without compromising fitment. Features: Huge displacement increase means huge power increase Stock crankcase, oil pump, and cam cover can be reused Wrinkle Black powdercoat finish heads matches factory finish, giving bike a sleeper advantage Original crankcase is used, so original engine serial number is retained Kit features 91cc S&S Cycle heads with 10.8:1 compression ratio, S&S Cycle 4-1/8 bore cylinders and pistons, a 4-5/8 stroke flywheel assembly, chain drive S&S Cycle 640 Easy Start cams, tappets, S&S Cycle pushrods, roller rocker arms, and all required hardware, gaskets and instructions .045 MLS head gaskets used Adds .096 to engine height