I run 25% in mind the only way to keep the engine cool is by the high speed needle and plenty of smoke coming out of the engine exhaust because of the castor oil is what keeps the engine cool your settings I found for mine that work is two and a half to three quarters open from closed on the high-speed needle turn the high-speed needle all the way down turn it out two and a half to two and three quarter turns your low speed needle start at flush and turn out one turn and don't touch it again your idol pinch the fuel line and if it rubs up for three to five seconds and then cuts out that's proper and that works for me and I use a number four plug it don't matter by who and that works beautiful cold weather or even humid weather doesn't matter it always starts on the first Pole