Big Bore kit yields excellent results with stock cylinder heads. Easy installation no need to bore or split existing cases, just swap the cylinders (unless otherwise noted). Cylinders are constructed from premium aluminum castings with cast-in iron liners. Kit includes cylinders, pistons, rings and gaskets (head, base and exhaust). Made in the U.S.A.. Project requires a skilled technician. It is the responsibility of the person assembling the parts to check all clearances and assembly specifications..