I just read in one of the posts that you should stay away from premium gas with the Polaris 400's.

I have a 96 Xplorer 400 and have run premium since day one thinking it is better for the machine. Any comments/experience?

Loyal

 

The guy mentioned something about premium causing you to run cooler and foul plugs. I can't believe it makes you run enough cooler to make a difference. If your engine doesn't require premium there is no real advantage to using it. I run premium in my 400 Scrambler and even though it runs rich (I haven't taken the time to set it up right) I haven't fouled a plug in over 500 miles.
Scott.

 

If you advance your timing the 400 will run fine on premium gas. If you increase you compression ratio premium is fine. Look in your owners manual the compression ratio is very low on two stroke engines. The lower the octane the more heat = more pipe heat = more power, exhaust gas leaving engine sucks more fuel in making more power. Advance timing with 87 octane = melt down. Advance timing with premium = more heat and more power. Two stroke engines always run the strongest right before the piston melts. If you do not believe me ask Jack Shultz he is a 400 two stroke Quad Father.

Air cooled 4 strokes run cooler on 92 octane also. High compression engines need high octane fuel to make power because of excess heat in combustion chamber. Diesel effect.