what tach you using? I used TrailTech TTO worked OK, cheap to buy. I wouldn't worry about rpm, heat is the problem. with stock engine, I ran mine wide open all the time, no issues. with 70cc kit, would turn over 10,000, but always ran hot, never could get it figured out, finally decided air cooled engine couldn't take it, cooling fins not large enough area to keep engine cool. cheers
