Ghost 212cc Kart Racing upgrades compared to the regular Predator 6.5 HP 212cc engine include high-silicon valve springs, a forged carbon steel crankshaft, high-flow intake port, and racing piston ...

A third 212cc engine is made for your go-kart and doesn't advertise itself as 6.5 hp like the other two. User reviews note it could reach 11.8 hp, so it seems you'll get some kick out of it.

Though smaller amounts of ethanol aren't a problem on their own, and you can use E10 on the Harbor Freight Predator 212cc Engine as E10 is found in the vast majority of gasoline sold in the U.S ...