I removed the K&B1L and stuck in an OS#8 with no success.
I didn't check the clunk, however the tank was full and when I pumped the gas from the tank it pumped out fine.

I had a similar problem the first time I took this plane out to the field. It was overheating. I added a little baffeling and the next 2 times it was fine. Although I hadn't done any 3D with it. Basically I just flew the pattern at 1/2 throttle.

I guess that I can try starting the engine again tonight and if it runs ok it must have been an overheating issue. Would you agree with that?

If that is the case. Is there anything I can add to the Byron fuel that will help the engine run a little cooler? I have 1/2 gallon of 5% left and I will drop down to 0% which will also help.