I have an EVOLUTION .46 with about a hundred fights on it that is now giving me fits. I installed the engine in a trainer last summer and flew all summer without needing to make adjustments. As the weather got cooler, it started going dead-stick. I don't have a lot of experience with glow engines but I have tried just about everything other flyers have suggested. New glow plug, new fuel tubing, I have adjusted the needle valve WAY rich and nothing. The engine seems to run fine on the ground, but if I tip the pland vertical the engine dies almost instantly no matter where I have the needle valve adjusted. Is it just too darn cold? I have noticed another guy at the field struggling with his EVO.

Thanks--

Sounds to me like the clunk is stuck in the front of the tank. Have you checked this?

I had the exact same problem when it got colder too. I finally said screw it and took it home and tore it apart. Found a lot of stuff (grass, dirt, etc...) in the carb. I put it together and fired it up. I also put the muffler baffle BACK IN! Used the pinch test to set it up and she now can idle for hours. I dont think she likes the loss of back pressure when it gets cold. I would at least clean the carb and put the baffle back in. I'm guessing you have it out.

Thanks for the replies! I don't believe that the clunk is stuck in the front of the tank as I have completely replaced all plumbing and tank trying to solve the problem. The baffle in the muffler has not been removed-- the muffler has never been taken apart-- maybe the baffle was never there...? I have been thinking about installing one of those dubro exhaust deflectors to try and increase the back-pressure. I have not torn the thing apart yet. Do I take the carb apart? Or do I just take it off and try to clean it out really well?

Thanks--