hmmm your gonna end up with all sorts of problems if you start doing things to these engines.

old motors (especially bikes) were built very casually. things were not measured well and engines were not built to a high standard.

you might be better stripping it and getting everything a good fit, then look at compression and ignition. i dont believe they have the same carbs as bikes in recent times (i forget the names of the older carbs) but more fuel wont always get you more power. personally id leave it alone BUT if not go for it providing you have nothing to loose...any pics btw?