I have made sure that the O ring is compressed and the throttle is fully closed, there is no opening when throttle is fully closed. I have tryed the petroleum jelly. and the engine still keeps on running, could the engine get air from the crank case because I have now found out that the engine will stop when it is cold and not warmed up properally. When the engine is warmed up and running after the flight the engine will stop after a little bit of time. My other idea is that because the engine is an ABC could it be that the piston when the engine is warmed up does not seal properally and lets some air through.

Andrew