I know there are guys running over sized engines. That is why I posted the link. They are small enough in size to not be noticed by the law. It would take a little will power to not mash down on the throttle but when needed, as in a steep climb, you would have the power waiting there for you.
Those would be great for a board tracker with some antique paint on them. The builder may be able to get by with a set of wheels from a downhill or freeride mountain bike.