Depending on how big of a shot you run, you will need to retard yuor timing;
0-55HP shot - no timing change
60-70HP shot - 2 or 3 degree retard.
75-85HP shot - 4 degree retard.
And 90-100 - 5 degree retard.
Definately make sure your fuel sytem is in tip top shape (ie new fuel filter, bottle of fuel injector cleaner).
Copper plugs gapped at .35 or .40
You should (not needed) run premium (92 octane) gas.
I currently run a 75HP shot and have had no problems.
