[RyansCat]

Hi all, I just bought a used 2008 650 xt. The previous owner installed a performance CDI. I forget the brand but I remember the website said it advance the timing by 5 degrees. So should I be running higher octane gas? I filled it with my leftover 87 octane before I thought, so should I add some octane boost to the tank?

 

[dascrow]

I'm not an expert but I would guess it would run a lot better with 91+ octane in the tank.. I'd give it a shot and let us know if you notice a difference.

 

[Admin]

You want to run the lowest octane you can get by with. The lower your octane that you use (without getting detonation) will make more power. To be safe though, unless you know what to listen for i wouldn't push the edge. BTW, what altitude are you at? This can make a difference as the higher altitude you are the less octane you can get away with. Also, it matters if you use oxygenated fuel (ie, heavily ethanol based)