I'm sorry wrong Jimmy its Jimmy Rivers @ JRPW
Approach a kart owner whose kart is OBVIOUSLY very good, and FAST.
Pay him whatever he wants, to sell you that motor, right off the kart.
Engine problem solved.
Now you get to face the reality of how to create a fast kart, without the weak excuse that the other guys
are cheating, or your motor is not good enough, or all those other excuses losers use.