I hope someone can HELP. On my DA 85 from the very first start up, the mid range has a detonation popping sound
with a small amount of surging rpm's in the mid range more so. The idle seems good, the high end is ok at 6500rpm's. The engine
was returned to DA where they did the upgrade, but did not address the mid range problem. I have tried leaning out the low end a
little but has not helped. I have about 20 flights on it and it's not getting any better. I have this engine in a Aeroworks Yak 75
Any suggestions you guys have would be greatly appreciated.