I have been reading on some other forums about this and would like you guys thoughts on it. I have been reading that you should be running high octane in air cooled motors, be they 4 or 2 stroke. this one ('00 warrior) is my first aircooled quad. I have been running regular 87 octane in it. I will be heading out in the morning for a days worth of riding. I have filled up the tank with 93 octane this time. what do you guys suggest I run in it and why? my motor is stock except for a filter and pipe. I understand the need for added octane in a high compression motor (i drag race mustangs also) but not in this one.

 

Go back to the cheap (I use the word cheap lightly lol) stuff.

 

Stay away from those forums, and run the cheap stuff like bberck said. High octane (110+) can burn so slowly that it will burn down the exhaust pipe and this is not good for power or anything else.

 

I am just running 93 octane in it right now, no 110. only reason I can think of to run anything higher would be if you have high compression or you are out riding for a long period in very hot weather.

 

Only time you need to go higher octane than pump gas is if your compression is 12:1 or above. Else you're just wasting your money. Running the highest octane pump gas probably isn't necessary even for 9:1 air cooled engines, but the flame front propogation speed loss in 93 octane is pretty small, so run it if you wish for peace of mind, to avoid heat related pre-detonation. You don't run enough gas thru your quad to be too concerned about the additional cost.

 

i whould not run 91

 

At what compression ratio do you folks make the change from 87 octane regular unleaded to 91 octane premium unleaded pump gas? I've always considered 9.5:1 to be the upper limit for 87 octane regular unleaded gasoline.

So for me that means I run 87 octane regular unleaded gasoline in my 4.0 liter I-6 cylinder Jeep, the wifes 3.8 liter I-5 cylinder GMC Canyon pickup truck, the Rhino 660, and our Grizzly 700s. All of those engines run with no more than a 9.2:1 compression ratio. But I always run 91 octane premium unleaded gasoline in my KTM dirt bike, because it has an 11.9:1 compression ratio.

That same general rule would mean that the Raptor 700 with its 9.2:1 compression ratio could run on 87 octane regular unleaded gasoline, but the YFZ 450 with its 11.4:1 compression ratio would require 91 octane premium unleaded gasoline.

DV

 

I think altitude also has something to do with it. The higher up you go the lower octane needed (for stock rigs).

 

<div class="FTQUOTE"><begin quote>Originally posted by: derrelw

I think altitude also has something to do with it. The higher up you go the lower octane needed (for stock rigs).</end quote></div>

ive always ran around sea level so i guess that why even on stock quads i run 91.

 

Actually going up in altitude (less oxygen) richens you up, which lessens pre-det, so octane change is not required for altitude.