Spit back is usually caused by retarded ignintion leaking crankcase seals or rings I find G3 carburettors more reliable than Lm and G4 carburettors if you set them up correctly they are no issue at all. To set them up all you have to do is take out the beval gear hold the butterfly shut, then line the vane and throttle up with the thread hole for the gear cover then install the beval gear with one tooth left to the right of the small pinion gear and they are set.
Extra rpm can be gained with the toothed section below the governer spring or line up the factory lines.
Last edited by tomo4192; 22/06/17 07:59 PM.
