Thanks all for the insight. Tore it down and cleaned it up today. Found some grass and a little dirt on top of cylinder, from separation of muffler then half gainer with a twist through the weeds[X(].Bolted up to old trainer and ran two tanks of fuel through on the ground then two more in the air. Ran smooth with no noticeable vibration or power loss. I used a muffler off of an old MDS 40 (that refused to stay lit) and seemed to work OK. Not what I'll stay with, but seemed to do ok. Thanks all for taking the time to help.