I took the plane home and checked the fuel lines and tank. It turned out that the clunk line inside the tank split. The engine could draw enough fuel up to about half throttle, but anything over that was too much pressure for the split fuel line and it would open up and not draw enough fuel to accelerate.


I'm glad bigedmustafa mentioned that. If you do simply take the fuel and exhaust lines off and blow through them as I mentioned; it will not show that there is a problem with the clunk line. The only way that I know to check the clunk line is to take the stopper and clunk out of the tank to inspect. Takes a little time, but could save you a lot of time in the end trying to fix a problem that's not really the problem. My son had the same engine on a Pulse PNP version that was rock solid. Once broke in and tuned correctly; it was unreal (to me). That engine could idle for 5 minutes and still transition from idle to wide open with no hesitation. Usually the 2 strokes will "load up" while idling for longer periods of time and will not transition as smoothly as this one did.