More horsepower for your 883cc or 1100cc Sportster. This kit makes it easy to give your 883cc or 1100cc a larger displacement by boring the stock cylinders and installing the pistons in our kit. The 883cc requires head combustion chamber modification to reduce compression ratio to a workable level of approximately 9.5 to 1. This is achieved with a hand grinder -- no expensive machining is necessary. On 1100cc no head work is required. The end result is a 1200cc Sportster. In the kit is a complete set of instructions, including use of template for head work on 883cc. Fits 1986-1990. For 1991-later also purchase #64419 rocker cover gasket kit.