the mossbarger watercooled cylinder is based off a cr250 cylinder, but with way more aggressive ports in addition to boost ports. The mossbarger will be as fast or faster then the cr cylinder, and it will be cooler with a full watercooled set up. if you can find a percision boring fl250
motor ((
Internal Combustion Engine ? )) then that thing will whip the butt of anything it comes near. the percision boring engines were the fastest of the 250cc engines, and cost around 5,000 back in the day. as far as piston modification and timing is concerned, i run a stock cr250 piston in a cr250 block with a watercooled head and an aftermarket reed cage in one of my cars, and that works fine.