I got it used, it ran good for a couple flights.I didn't take it apart,I didn't crash,It is in a new plane with new fuel tubing and tank.I am running coolpower 15% and a 14/10 prop. The plug is an OS type F. I'm wondering, could the timing be off 1 tooth. After thinking about it I can't be totally positive it ran right when I got it because it was over a year ago.

Thanks
Pat