Hi I am having engine trouble as well I am running a ENYA .50 ss w/gn type carb.It idles sweet and turns over effortlessly the problem is when I build up rotor speed usually at 1/4 throttle the engine quits I have been at this for at least 4 hours after work for about 3 days now.It's a three needle carb and I must have tried 100 different needle setting combinations.

P.S. Hope your hobby supplier gets you more 15% sounds like this 30% flying makes for one hell of a clean up after flying.