Re: cheapest kits
Many have seen 4-5000++ out of bushed engines. (use a 24 to 30:1 mix).
I second the advice to not run WOT/high rpm very long. Short busts of 30 seconds or so? O.K.
Break in by varying the throttle and engine speed, don't lug the engine, and as stated short busts of wide open throttle.