A agree with vegashd. A couple of years ago I researched
AVGAS for use in my high compression dirt bike and the
answer was that AVGAS is formulated for constant load,
not acceleration like automobile gas. If the bikes compression
has not been raised with a modication, pump sauce should
work fine. If not there is something wrong with the engine.
If you run a higher compression engine, you should mix in
some race gas. Call your local dirtbike retailer and find out
where to get it. Incidently, leaded gas runs cooler and acts as
a lubricant to valves and valve seats. Those of us that are
old enough to remember the change-over from leaded to
unleaded fuels can also recall that lots of old engines burnt
valves and needed rebuilds after using unleaded gas. I had to
put a set of sodium filled exhaust valves into my Dad's old 59
international because the unleaded fuel destroyed No 6
exhaust valve.
mb