Hi
I've had no problems with an inverted motor as long as your not priming the carb when your fueling and have always run the bottom end really lean and don't be afraid to run your glow in the red just to burn off excess residue in between flights and at worst you sometimes have to pull your plug to clean, don't get frustrated just learn a few tricks, check the o-ring on your needle because they do get to the point where they do suck air