ORIGINAL: RCVFR
My experience with glow engines using a Pitts style muffler has been that there is insufficient muffler pressure to sustain WOT. The test for this is to see if you are able to run WOT and tune to overly rich. If you can, then you likely do not have this problem, as the tank is receiving enough muffler pressure. If it does not pass this test, the solution I have used is to plug one of the 2 exhaust stacks.
Good luck.
So far none of the flameouts were at WOT. They were all straight & level flight with the engine in the low midrange area. I can get it fat running WOT on the ground and holding it in any orientation. Both initial flameouts were after an upline move. Once after a stall turn after getting levekl and back to mid-field and then again after a split-s and back to level and at mid-field.
I am puzzled. Between this and my hard as hell to start 30cc MX2, I think a couple of airplanes will be cowl-less this weekend and just working on tune-ups!