Gray Beard, I've used taking the glow driver off and if it didn't drop rpm when I did, I knew I had it running right. I just never though of using that as a tuning tool though. You learn something every day. I've got an O.S 52 four stroke that has been giving me fits and I finally hit the sweet spot yesterday. I knew I had it because when I took off the glow driver, it didn't drop a beat. If I had though of your procedure, I could have had a week of fun flying.

Don