i have a cr 250 that that i want to run a higher octane (no ethanal bull shittt ) i was looking in to running avgas (100ll)how much will the head halft to be shaved down to get it running it full potenchal on av gas . my shop teacher is a machinist and sed he wil do it 4 me but has no clue on how much to take off???? 20, 30 ,60 ????? thanks zac
