If you have the cowl off and the engine idling, pinch the fuel line. You should hear the engine speed up. If it does your idle needle is too rich. Screw it in (clockwise) about an 1/8 turn and try the pinch test again. Keep doing that until the engine doesn't speed up any more or just quits. Your very close to a good idle now. You may have to back it out 1/8 turn. When the engine idles good for a minute or two hit full throttle. The engine should accelerate immediately. If it quits instantly on acceleration your idle needle is too lean. An engine will run very good inverted. It just requires a good idle setting.