I have run less than 1 gallon tyhrough the engine at 32:1. I have also seen this effect with glow engines so I figured this "resonance effect" was probably par for the course. I can't tell you how much time I spent trying to tinker that last bit of vibration out of this engine.

I suspect when I go to the synthetic mixture and re tune the carb I might be able to smooth a little more vibration out of it.

I just didn't want to throw it up in the air and have it go critical mass on me. Oh yeah, It's going into the Hanger 9 Extra 260 / 27%. 78" span, I hope to bring it in around 14.5 Lbs..... El Rocket Sleddo!

Thanks, Ken