What causes the engine to hesitate when going from 1/2 to full throttle during flight? Not very quick response time. And when I shut off the engine via the throttle trim and the carb is completely closed, there is fuel sitting in the carb. I read the thread on engine tuning and what is the 2 stroke and 4 stroke sound I'm looking for? How do I know if it is too lean (too lean as in damaging the engine). Can't get to the field today so I was going to try to work on the engine but I am a complete noob.