The only reason to run higher octane fuel is to prevent detonation. That's it, period. That's the only reason to use it, because you "have to". It certainly does not help performance in a normal engine that has not been built to accept it. Otherwise why waste the $$$$ ??? Your quad will only run worse if it's not set up to "need" it, particularly two strokes. AV gas is the worst stuff to put in a high revving two stroke that I can think of. Also, those that are mixing race gas with regular pump high test don't get it. The mix is not linear. The mix always gravitates toward the race fuel, which actually robs your motor of hp. Don't believe all the "old mechanics" tales about AV or race fuel, find out first hand before your performance or equipment suffers.

<A HREF="http://www.godigital-design.com/96Polaris.html">Schultz Motorsports</A>

 

Jack your right on, but I never mix race fuel with regular gas when racing, its only for trails to make it cheaper. Also gas(Race or regular pump) is just a cocktail of many different additives. Some are made up of different stuff, so when mixed they mix, they don't stay separate like oil and water. Otherwise how would octain boosters work (I never use them though). And yes its to prevent premature detonation in a high compression engine, actually less octain allows it to rev more freely, but theres a limit to how free until the motors starts prematurely detonating, and then boom. And yes I have to run 100+ octain fuel in my engine.

 

Jack is absolutely right about racing fuel and av gas being generally unsuited for normal use. The lowest octane fuel your engine will burn without pinging from pre-ignition, is all you need. Any money spent for higher octane fuel simply goes out the tailpipe with little, or no, increased “bang” for your buck.

Nearly 30 years ago when I was stationed at Camp Friendship near Korat Royal Thai Airbase as an Army avionics technician, I had access to all areas of the airhead including the fuel dump. For transportation I had a ‘68 Honda CL350 scrambler, which was basically a high-piped street bike with one tooth less on the countershaft sprocket than its road-going twin brother, the CB350. I also had a hankering for more speed. The scuttlebutt among the bikers on the airbase was that the easiest way to turn ANY vehicle into a virtual rocket was to run high octane aviation fuel in it. And not the lowly 87/108 stuff they put in the single engine Cessna Birddogs, but the kick-butt 115/145 stuff that they used in the four-engine EC-121s.

The EC-121 was the military electronic reconnaissance version of the Lockheed Constellation passenger plane, the one with the triple tail that you may have seen pictures of. The EC-121 used four Wright Cyclone R-3350 Double Wasp radial engines. These 18 cylinder, air-cooled, twin turbo-charged, radial engines pumped out about 2200 horsepower each at takeoff when running on 115/145 av gas.

Man, even the non-bikers nodded knowingly when you told them “Yep, I’m running 115/145 in my bike. I can pass ANYTHING on Friendship Highway. I’ve already outrun the MPs half a dozen times coming home from the bars after curfew.” They never doubted it for a minute. They just knew it HAD to be true, ‘cause man you were running 115/145. Only Werner von Braun could have gone any faster.

From September of ‘69 until June of ‘70 I put 115/145 in my CL350. That bike would do an honest 160 KPH. (Thailand was on the Metric system, 160 KPH = 100 MPH). It accelerated like a scalded cat and there wasn’t nothin’ I couldn’t pass, at least until the first ‘69 CB750s appeared on base. Man, I could fly without ever leaving the ground. I felt like Superman.

A year or so later, after I was out of the Army, I had a ‘71 CB350 street bike that wouldn’t do better than 95 MPH no matter what. I no longer had access to any 115/145 av gas, but I remembered that the only difference between the CL350 and the CB350, besides the high pipes, was the countershaft sprocket. A quick trip to the Honda shop produced a 15 tooth CL350 countershaft sprocket with which I replaced the stock 16 toother. The Interstate Highway system was still being built at the time, and I-79 was under construction not far from my house. They had just about completed the five mile stretch between Bridgeville, PA and Carnegie, PA, but it was still closed to traffic. Gaining access to the newly poured concrete of the embryonic Interstate Highway system was no problem for a motorcycle. A quick blast down the nearly completed section of I-79 revealed that my slightly altered CB350 pretty much performed like my old CL350, and on regular pump gas too!

In retrospect the 115/145 av gas seemed neither to help nor to harm my CL350. But Oh Man, did it do wonders for my ego and my PERCEPTION of how my CL350 ran. Thirty years later I now run 87 octane pump gas in all my vehicles, from my Lincoln Town Car, my Dodge Intrepid and my Ford F150 right on through my Kawasaki ZG1000 Concours and Honda GL650 Interstate street bikes, my Honda NX250 dual-sport, my Kawasaki Bayou 400 and Bayou 300, and my Briggs & Stratton powered MTD lawn tractor. And the only noticeable difference between the 87 octane stuff and the 94 octane stuff is the 30+ cents per gallon more the latter costs.

Today, virtually all automotive manufacturers build their products to run on 87 octane pump gas. Unless you have a HIGHLY modified engine that will actually benefit from gas with a higher octane than the 94 octane pump gas you can buy on any corner, and the near professional level ATV racer skill to use that highly modified engine, save your money. Because unlike you paying $3.00+/gallon for your ego trip, my ego trip was free as the Air Force was paying for the 115/145.

Army Man

 

Armyman and Jack are both right in not needing race gas unless it's built to where it is called for. But TrxR was told he would need to run it by his builder, so thats why he was asking if AV gas is suitable or not (NOT), not if he should run it in his stock motor.

 

One thing that we're all missing here is the fact that a performance shop is recommending running AV gas!

Anyone who's worked on hi-comp engines at all knows the detrimental effects of AV gas in such engines.

Of course, stock engines, which run fine on the junk they sell at the pump, won't be adversely affected by the AV gas, but an engine with enough bump to require high octane fuel will have a serious allergic reaction to the "poor boy race gas"! It'll cause it to break out in "seizures".

To think that a "Performance" shop recommended this! Yipes!

Pam

 

Thanks for the replies. The guy I was talking is suppose to do beautiful work and he has run AV feul 100LL for years with no problems but he mainly run methanol which I wont be running. I think i will be buying race feul and mix it 50/50 with 92octane.

 

Thanks for the replies. The guy I was talking is suppose to do beautiful work and he has run AV feul 100LL for years with no problems but he mainly run methanol which I wont be running. I think i will be buying race feul and mix it 50/50 with 92octane.