hello andy here in greece i have see 2 projects.1)mc21 with original engine and malossi 360cc kit and crank from rz/rd350 with alot of work in the crankcases.i think is 420cc abaout.2)mc21 with original engine with cylinders from crm250 with alot of work in the base of the cylinder and the crankcase.and he had feex from 2 cranks of cr250 1crank.and these is 500cc.but we are taking alot of work and many hours in the machineshop. (sorry for my english)