i have a goped sport! only runs on idle and when i press the throttle then it shuts off! why?

Question

the goped i have is a goped sport! and i got it from sumone else but rite before they handed it to me they installed a brand new PISTON! and now whenever i start the goped it only runs on idle and once i hit the throttle lever it shuts off! and sumtimes a little bit of smokes cums out! it did work before he is installed the piston! it runs on idle and once i press the throttle lever a little bit it shuts off! and smoke cums out and the engine gets real hot! why? (i do have a brand new piston installed)

Answer 1

maybe the fuel/oil mix is too rich?

Answer 2

There may be a problem with the fuel. Or the cam may be out of time. good luck.