I've recently purchased two GMS engines (the 40 remote needle and the 47 front needle) and I had to push out the spray bar in both carbs due to fuel hole misalignment and then reinstall them. Also these two engines of mine had to be set on the high speed needle first ( a couple of clicks rich) and then set the low speed needle so that when you pinch the fuel line at idle the rpms just barely rise then the engine will die. Remember to throttle up and clean out the engine between adjustments. This has worked on both my engines and they idle and throttle up with out any problems as well as they will fly perfect until the tank runs out. I am also using an OS a-5 plug, Omega 15% and the altitude is 4000 feet where I fly.