OS 18Max but need to Modify the pilot shaft and this old style engine is not too much power. Later , I will be change the clutch set in the Kart . It must be better to brake and idle speed.
I have a go kart too but when I break in the engine for the 2nd tank, the tire started cracking at the edge and finally tear off at the 4th tank of gas. C- hing got any idea to replace another set of tire like foam? The ones come with the kit, sucks, go elsewhere when speed up!