I've been toying w\ a 3W100. Weeks of adjusting and complaining. My stepson really discouraged. He would tweak and turn low end and high end. I installed nipple and tube to the fuse. still twist and turn. Flight after flight,and it still would burble and back fire, cut out when inverted or by pushing the nose over.WELL here is my fix! Start over at factory settings (Low 1 1\2 turns out and the high end 1 turn out.)My engine would fly but sounded terrible. Make sure engine comes to temperature before a decision is made of which needle to turn. Peak engine on the horizontal line and let it come to temperature.Note where the throttle is when you notice the problem. If the engine gurgled and spit from idle to half I would lean the low end if it was from half to full I would lean the high end.Important note: When they say adjust a needle a 1\6 of a turn at a time thats what they mean! Do not try to get a bit more because it will BITE you!Guys once I started over an followed these easy rules this engine started to talk. Be sure to let the engine get to operating temperature before you decide how to adjust it. In a few flights you will be as happy with your 3W as I am with mine. Happy flying.