An easy and economic way to increase displacement of 883 and 1100 Evo Sportster models to 1200cc. This kit with 3-1/2” bore forged pistons only requires to bore the stock cylinders from 3 inch to 3-1/2 bore, or purchase new 3-1/2 inch bore cylinders. No combustion chamber modifications or flywheel rebalancing is necessary. Compression ratio will be a very streetable 9.5:1. The piston skirts are coated for reduced friction during break-in.