KB410020 Performance, 883-1200 big bore piston kit. +.020"

This KB Performance conversion kit is the go-to for bumping a 1986–2022 Sportster 883 up to 1200cc. These are +.020" oversize flat-top pistons designed to work with your stock, unmodified 883 cylinder heads while achieving a 9:1 compression ratio. They are cast from T6 heat-treated 390 hypereutectic aluminum with 16% silicone, allowing for tight tolerances and minimal piston slap. Sold as a set, this kit is a proven way to add significant displacement. Note that for 2004 and later XL883 models, you will need to purchase 1200cc cylinders rather than boring the stock ones, as the original liners are too thin. Always ensure the top compression ring is gapped according to the included instructions.