Pauluk, Go by bubbas settings i agree with him, i have set up a few nexstars right out of there boxes, they would fall flat on there face when you slap the stick, it sounds like low end mixture screw is to lean, I found that all were to lean and adjusted them in, try that first because these 46fx engines are sweet hearts when set up right. I installed mine in a ultra stick fourty and fly it every weekend with out a flaw. also when not in use they tend to gum up in the needle valve area and cause a no start so turn the mixture screw in to bottom then turn it out to the settings bubba has posted and try again. best way to resolve this problem from happening again is to run the engine dry every time after use.