Capricorn have just dropped this higher spec .21 on road engine to add to their ONE range. Based on the R21 Euro Spec. from OS, the engine is a 7 port design and features a new hand tuned liner and specially made piston. The crankshaft has also been tuned to aid in performance along with a new under-head button. They claim that overall the engine will have more power than previous versions and not hinder run time in doing so. Light weight cooling head. Special back plate.