Raptors where their flatheads. And the animals are their OHV. Basic difference in these motors v.s. the lawnmower motor is bearing instead of bushings. They are sleeved, have diff tune on carb, and some internals are upgraded. (Know it was the rods primarily in the flatheads) All this done to accompany the fact that they are ungoverned and designed to be used for racing of a sort generally. If I've understood correctly up until now.... XD