You may also check to make sure you are using a 4 stroke glow plug. I always use an O.S. Type F. They are not cheap but I've had them run for years. You should also check your fuel system. If you are priming the carburator the engine will run till it burns up the prime fuel then it will die. You could have an air leak or a restriction somewhere in the fuel system( check the carb needles too.). A Saito engine is a high quality engine so you should be able to get it running great unless this engine is old and worn out or it needs the valves adjusted. Good Luck! Dennis