At what PSI do i need to run race gas? 93xp 650

[pwc507]

I just recieved a new performance head for the XP. I'm going to do a compression test before, and after, and was wondering at what cyl. psi, do i need to worry about running gas other than 93 Octane. also how much, "generally" will i need to rejet? i have stock jets now.


Also what is the 93 650 head bolt torque?

[Bill O'Neal2]

Re: At what PSI do i need to run race gas? 93xp 650

Although PSI really does not tell the whole story, if you have at least .050 squish clearance and no more than 175 psi, a 657 motor will live on 93 octane pump fuel with oem ignition timing.

This does not apply to all models of SD motors. If you tried that on a 951, you would have a detonating piston eating engine.