Hey, are you an "Ultralight Airplane" guy? Me too. Probably have around 500 hours in ultralights and used to be an ultralight instructor. (I've got around 1000 hours in various single engine general aviation planes too.)

PM me your e-mail and I'll send you some pics of the balance process I use. Can't find the text part, I'll have to type that up for you. It is fairly easy to do, and works really well. Any engine I have balanced this way has had less vibration in most cases than stock/original.

AV8TOR