I Think you need more power . Here is my super cheap Thunder Tiger starter starting my Saito 270 (45 cc) engine on 24 volts . I had replaced the crankshaft bearings in the Saito (it has 3 of them) and wanted to run it before installing it in a plane . My Sullivan Dynatron will start it easily on 12 volts but the cheap bargain brand won't crank it over without 24 volts applied .