Air is less dense at higher altitudes, thus less air is compressed and less octane is needed for the same compression ratio.


The theory behind running higher octanes in air-cooled motors is for protection against the higher operating temperatures that these engines can reach. Because of these higher temperatures pre-detonation is more likely. However this is rarely a problem with most air-cooled motors that are internally stock. It's only after significant modifications that can create much higher heat loads (like thinning the cylinder wall when you go "big bore") that one needs to worry about making fuel changes. Short of that and lean jetting on a very hot day you won't be having any problems.


There is no "rule" for compression ratios, there are simply too many factors to say that all engines need a certain octane at a certain compression ratio. However you can make generalizations based on engine model and build, but you cannot compare the compression/octane in one engine (say yfz450) to the octane needed for a compression ratio in another engine (say 350 warrior).

 

I just got from the trails. I ran a tank of 93 octane through and no problems at all. it felt a little peppier. it was extremely muddy and I had mud about 3 to 4 inches thick everywhere and no problems with it overheating or anything. I think I may just keep running 93 in it to be on the safe side. at only a couple of dollars more, its not going to break the bank. I will check the plug tommorrow to see what it looks like.

 

Just in case you haven't caught the sentiment of the thread thus far:

It's unnecessary and the higher octane rating yields no benefits. All you're accomplishing is spending more money on gas, and higher octane can even theoretically hamper your performance.

 

i always tell ppl to run the higher octane fuel in their quads. it accually is a lil cleaner then say 87 octane, because almost everyone buys 87 for their cars and the tank is always being filled and emptied which keeps the sediment stirred up. the 92 or 93 octane is more expensive and far less ppl realy buy it so the sediment settles on the bottom of the tank away from the floating pick up.( the pick up in an underground fuel tank floats so it doesn't pick up the heavier water that accumulates in the fuel tank.... thought i'd throw that in since most ppl don't know that.) so thus you get less dirt in your fuel system. and high test is not that much more expensive to where a quad or dirtbikes lil gas tank is really going to brake you. its only about 60-80 cents per tank diferance on a 4 gal tank. if that will brake you ya probably better not ride it, just so you don't brake anything.... in the long run 93 has better detergants in it too, its well worth the 60 cents. and in some motors like your some of your sport quads you need to run higher octane to allow the motor to run right because of their higher compression ratios. (I.E. raptors, Z400's YFZ's ect, ect, ect)

 

The raptors don't have a high compression ratio, and neither does the 350 warrior/raptor. The sediment argument is valid except for the fact that the filters between the tanks and the fuel pump remove essentially all of the offending contaminants. As far as detergents go that is largely based upon the fuel vendor. The difference in detergents from regular to premium fuel varies significantly from one gas company to another. IE, you may not have the same difference from regular to premium at a Marathon gas station as you would from a Shell or vice versa. Fuel additives are also very location specific, so what you get in your premium fuel in California is different from the premium fuel that goes in your tank in New York.

The point I'm trying to make is that it's subjective at best, but if it helps you to think that spending more money (however small a cost increase it may be) means you're making an impact on performance or reliability then I say to each their own.

 

http://www.highperformanceatv.com/FAQs.html


Embler,

I did some research for ya. I searched around my area and if you read on this link you will find that 91 will help you alittle in horsepower. It's proven. You won't feel the gain of a horsepower or two but still. Take Care!

 

<div class="FTQUOTE"><begin quote>Originally posted by: raptor010

<a target=_blank class=ftalternatingbarlinklarge href="http://www.highperformanceatv.com/FAQs.html
">http://www.highperformanceatv.com/FAQs.html
</a>


Embler,



I did some research for ya. I searched around my area and if you read on this link you will find that 91 will help you alittle in horsepower. It's proven. You won't feel the gain of a horsepower or two but still. Take Care!</end quote></div>

thanks.

 

<div class="FTQUOTE"><begin quote>Originally posted by: maddog56

Just in case you haven't caught the sentiment of the thread thus far:



It's unnecessary and the higher octane rating yields no benefits. All you're accomplishing is spending more money on gas, and higher octane can even theoretically hamper your performance.</end quote></div>

just in case you didn't notice, i am the original poster of this thread and only wanted opinions on the subject. theoretics go out the window, imo, when it comes to a single cylinder air cooled motor compared to say a water cooled v-8. i run 87 in my mustang most of the time, but run 93 at the track due to advancing the timing and such. the thing is, its water cooled and stays at a constant 180 degrees. my warrior is air cooled and the temp is definitely not consistant with it. as i said before, i would rather run a better octane in it to prevent any detonation and it doesn't matter to me if i "theoretically" gain or lose a couple of horsepower

 

Any stock motor is designed to run on regular unleaded gas

If you desire to put in higher octane gas up to Sunoco 93 go ahead it's not going to hurt anything other than your wallet because it will not improve your power but it cannot hurt either.

Some gastations buy the cheapest crap they can buy and a higher octane gas in some casses will equal what the regular stuff should be doing.

They dynoed a Honda Rincon one day, the guy worked at the dyno shop and he was bored so they strapped his quad to the rollers and made several pulls with regular unleaded gas than hooked a bottle of 93 unleaded to his quad and there was no difference in the power band or Hp when it was all said & done.

A mid size quad? why would you even ask about higher rated gas in the first place?

When in doubt read the owners manual.

Garman

 

what about 2 strokes? regular or high octane? with not even a 3 gallon tank, putting 93 in it isn't going to hurt my wallet. if it did, then I don't need to be riding in the first place.