What Brand, and OCTANE of fuel is everyone using!!What seem's to be the best.. :)

Im using 91oct pump gas. I was at a union 76 the other day and there was a big banner up that said something like:

"No MTBF in our gas"

I heard during the winter the gas companies have to mix the gas with ethynol or something like that due to the EPA. Im not sure if there is a difference on the moto with or without the wintertime additive but Id guess without would be better. why would union 76 be making a stink about it if it wasnt?

Out here in the east. I can buy 94 octane from the pumps at Sunoco.


MTBE is an oxegenate that improves vehicle emmisions during winter months when due to the cooler weather fuel has a harder time vaporizing.

The problem with mtbe is that very small amounts in our ground water are able to be tasted.

Alcohol or ethanol tosses your throttle response to the wind and should be avoided at all costs.

I did some fuel testing with my 14~1 444cc wr-f and found no hp gains with race fuel, except nutec. I had also rejeted for each combination.

92 pump gas from the bp was within 1hp of B32&B37 even with blending in my own mtbe to raise the % of 02.

Hope this helps.

BTW, I could tatse the nutec when I changed the oil and got some of the oil on my hands....

I use Amoco Ultimate, 92 octane. 93 octane is recommended.

Only Chevron Supreme 91 octane !


I like to use race gas in my bike not for the horsepower gain but because it burns MUCH cleaner than pump gas. An easy way to verify this is to look at the inside of your header after running a tank or so of pump gas and you will find it to be all black and carbon coated. Then do the same after running a tank or so of race gas. You will find it to be clean with a white coating. In my opinion this has to reduce carbon deposits on valves and the top of the piston over time. My .02, Eric




I use the crap sold at the stations in Vegas. Good enough for me.

My understanding of octane ratings is as follows:

1)you must run high enough octane to prevent detonation (random ignition at the wrong time). Very destructive. This is different from preignition (also bad). They seem similar, but have different causes. Timing, compression, cylinder temps, fuel mixture all factor in.

2)avoid running a higher octane than necessary. The higher the octane the more 'resistant' the fuel is to igniting. It also burns hotter. This may explain Blue Boner's cleaner exhaust pipe. We want to keep our cylinder/piston/valve temps as low as possible.We have ethanol blend gas available at virtually every station year-round here. It does add a couple of octane points but burns much hotter. Not good for small engines. Avoid it for bikes, though I like it in cars.

3)as SFO pointed out, (and he is running high compression), there is no significant HP to be had from octane above and beyond what is needed.

4)some high perf. motorcycle manufacturers such as Cobra with their extreme rpm, high HP to cc ratio specifically warn against using race gas.

5)many carburetors have components that will be damaged by race gas. I wouldn't be surprised if the highly complex carb on our bikes is included.

For all of these reasons as well as plain old availability and price, I run 92 octane Amoco/BP premium. Pricey enough! Run a web search on octane, it will keep you busy for a long time...

As always, "I may know just enough to be dangerous!" :):D

Oh, stay away from aviation gas! Different, high altitude, cold-air stuff.

On my last ride, I ran 92 octane with ethonal, only because I was too damn lazy to drive the extra 30m miles to get my normal 93 octane non-oxigenated (Standard Oil)fuel. For this weekends ride, I will be draining the tank and carb of that politicaly correct fuel. With the ethonal crap, I experienced the first overheat problem. Bike did not have the normak snort I became accustomed to.

The manual that came with the bike ('02 WR426) says to use 95 octane minimum. Can't find any such thind without paying the price for racing fuel.

So I have pondered using aviation fuel. Does anyone out there know if av-gas is OK? Does it have lead, ethonol, or any other additive that could result in potential engine damage? I used to run it (in the '70s) in my 2-smokers and gave my rides a bit more pizzaz!

I use 200 Proof......Sometimes it's hard to get, especially when the ATF bust's my still....ummmmm I mean, my pumping station.....

Bonzai :)

Highsider1, I have been searching for a higher-octane gas, in CO all we can get is 91. So I read my owner’s service manual and it states that for US bikes only use 95 premium unleaded or higher. I am not sure if chaindrive is correct about using to high of an octane? Why would the manual say or higher and not put a top end on the octane? Is there too high of an octane?

For bikes in AUS it just said to use unleaded, and try different brands if knocking or pinging occurs. Then it said leaded can be used if no unleaded is available.

I will now get to my point. The only fuel in my area above 91 octane is aviation fuel. It is 100 Octane, good, but it is a LL or low lead fuel, bad. I have called three dealers all of which said if I mixed the Aviation fuel with premium 50/50 I would decrease the lead level while boosting my octane. The only draw back to this was that I might get more carbon build up on my plug. I have only run about 6 gallons/2tanks of this mixture in my bike so far. I feel like does improve my performance and as of yet no build extra build up on the plug. I am a little nervous about running the LL fuel I don't want to mess up my engine, but if AUS bikes can run leaded I don't see why I can't safely run my mixture. Maybe some one else can shed some light on this? Are AUS bikes that different, or is AUS fuel different than us??? :):D

I doubt that Aus bikes are significantly different. Maybe leaded won't really hurt our USA bikes, but to comply with regulations, the manual says not to use it. I still will not try it unless I'm sure of the effect. Guess I'll try a can of racing gas next time out and see first hand the performance difference.

For those considering using race gas but not wanting to use a leaded fuel you are going to have a harder time finding an unleaded race gas. Almost all race gas in leaded. I have used leaded fuel in my bike for years with no problems so I wouldn't worry about damaging your engine. If you were to walk around the pits at racing events and see red or blue fuels in gas jugs or tanks on bikes it is safe to assume it is a leaded race fuel. I think Yamaha says not to use leaded fuels purely for an emissions/environmental standpoint.

As far as race gas damaging parts in the carb, that is completely false. Methanol on the other hand will eat rubber seals if left for a period of time. Truthfully, I think if you use the highest grade pump gas that you can get for your car you will be fine, but don't be scared to use a leaded race fuel either. Eric

This is just like the "which oil is best" post a while back. You can get all the info you need and you'll still hear only what you want...Unlike the Mobil1 MC oil vs. Mobil1 car oil (where so many people wanted to save $2.50 on the cheaper oil, it seems some folks in this case WANT to spend $2.50 per gallon of gas more :) )

That said, a search on Yahoo: gasoline octane ratings yielded 3,300 hits. Found a couple good ones, though I certainly didn't even look through them all!

Bottom line: we are all right...and wrong. Much depends on pump premium vs. race gas; engine demands, etc.

Go to this motorcycle tech line and scroll down their index to an answer to the same question. Then buy what you prefer. :D

FYI, I tested race fuel and pump gas in my 14~1 444cc wr-z.

The pump fuel worked great.

I am now running Phillips B35 105 unleaded to have one fuel for my bike and my wives bike which is tweaked too.

I like the no lead for no deposits and it doesn't bugger up my o2 sensors I run on the dyno.

The yz combustion chamber is very tolerant of pump gas. Even at 14~1 I experienced no detonation on pemex premium.

Trying to get more power with race fuel is hard because all of the ignitions are mapped for pump gas. Even the vortex.

I get the B35 for 4.75$ a gal btw, delivered.

Here are my fuel tests.

Now THAT is hard facts! :) Great job, Bill! Looks like Jon should be running your engine! Wow!

But for a relatively stock WR/YZ (no compression increase), Pump premium unleaded in the 92 octane range is just fine?

How is that traction curve measured? This is cool stuff!

Originally posted by Chaindrive:

Now THAT is hard facts! :) Great job, Bill! Looks like Jon should be running your engine! Wow!

But for a relatively stock WR/YZ (no compression increase), Pump premium unleaded in the 92 octane range is just fine?

How is that traction curve measured? This is cool stuff!

Actually Jon has my 97mm top end now.

The traction curve is part of the dual setting vortex ignition.

I am working on a 100mm wetliner billet barrel for the yz-f now, it will offer racers the potential to switch displacements and classes with a liner/piston swap as opposed to needing to have complete cylinder piston sets.

It will also stop the sealing issues that arise on occasion with the 97kit and make bigger bores possible because there is room and the red horde is breathing down our backs.

Pump premium should be fine, BTW.

[ September 20, 2002, 01:00 PM: Message edited by: SFO ]

I paid a shop to install a 13.5-1 piston. They told me to run race gas so I was running Cam II. The bike kept getting slower. After about a month I sent it to a shop for the dyno. It came out about 30HP. The mechanic couldn’t figure out the loss of power. Tore the bike down and saw the piston and everything was carboned up. He Also noted the engine had the stock piston in it. He said the race fuel was not completely burning. He installed a real Weisco piston, rejetted and mapped the fuel curve or something like that. All I know is I had a monster on my hands. Boy, do I love that motor. Anyway, I started running the cam II again until Kamakaze told me to run Klotz. Man I love the Klotz. I do not know if the bike runs any better with the klotz but it defiantly smells better. Since I am not a great rider yet, so I go with the smell. If anyone is near Maryland you are welcome to come over and smell my bike. It is wonderful.

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