7 replies to this topic
  • Ranger_426F

Posted May 01, 2002 - 05:20 PM


I have seen alot of posts regarding "RACAE GAS". I don't want to spend the extra money for 108 octane gas. But was wondeing if the octane BOOST additive do anything for you. I would buy the good stuff to add to the extra fuel I have. I basicaly fart around an the weekends with my son, I would like to try a poker run or hare scramble. The maint book recommends 95 octane, but I can't find anything but 92 around here. Guess I could go to the airport and get somr fuel there. WHAT DO YOU RECOMMEND

  • Thumpster

Posted May 01, 2002 - 05:44 PM


100LL (low lead) avgas is not good for your valves. Over time it leaves a build up of lead on your valve seats. If you're trail riding the local "high grade" pump gas is ok. It works fine in my bike anyway. Competition riders will have other input. :)

  • BigLou

Posted May 02, 2002 - 01:10 AM


Ranger-The manual recommends minimum "95 Research Octane". U.S. pump gas is rated on an average between the Research Octane Number (RON) and the Motor Octane Number (MON). Typically the difference, or, "sensitivity" of the fuel is 10 points, with the MON being lower.

So your 92 pump octane fuel actually has a RON of about 97 (and a MON of about 87). That also explains the little equation you see on a sticker on the gas pump: Minimum Octane using the R+M/2 method.

The short version is that pump premium will more than meet the minimum octane requirements for the 426F. :)

  • Fireballsocal

Posted May 02, 2002 - 07:41 AM


Exactly. The long and short of it is that you only need race gas (Higher Octane) if your engine pings. The ping is detonation. A stock bike will run the best on pump gas, only needing race gas if the compression has been raised. One plus to race gas is that it does burn cooler. On the other hand, I've been riding in sand dunes just south of death Valley in 119 degree heat and my 99 YZ400 never even hiccuped. Stick with pump gas and smile to yourself when someone tries to tell you how much extra power race gas gives them. The power in a race engine comes from the compression, not the gas.

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  • BigLou

Posted May 02, 2002 - 09:19 PM


These tidbits from a fuel paper I wrote/plagiarized:

A lot of people tend to believe that running race gas will make an engine run cooler. This is not true if the engine isn't experiencing abnormal combustion (knock or pre-ignition) without race gas and you maintain the EXACT same air fuel ratio. However, the resulting richness of the race gas’ air-fuel ratio can tend to lower cylinder head temps.

It's a commonly held misconception that higher Octane fuel slows down the flame speed, which keeps the engine from knocking. Flame speed is a function of fuel chemistry, not the Octane rating! The component make up of the fuel will determine the flame speed whether it's a high-octane fuel or not.

  • Shawn_Mc

Posted May 02, 2002 - 11:41 AM


If you decide to try some octane booster, look for PJ1. I dont know what your state laws are, but the PJ1 booster that uses Tolulene as the primary chemical is illegal in Ca. (along with everything else). Ive tried lots of different types and brands of boosters, the PJ1 worked far and away the best.

I run race gas in my 426 mostly because it seems crisper and is easier to start. And ya gotta love that smell!

  • John_Lorenz

Posted May 02, 2002 - 11:56 AM


Speaking of Smell
When I go to the hills I frst stop at Super Tacaria, to fillup on High Methane Boooritoes... By the time I get to the hils I have enough properllant built up to pass anyone :)

And believ me when I pass,,,,, no one tries to follow.... :D

  • BigLou

Posted May 02, 2002 - 12:15 PM


Don't get me wrong, I wasn't knocking race gas (get it, knocking?!). The one thing you will get with race gas is consistancy from batch to batch, unlike playing the pump swill lotto. And yes, you can get crisper throttle response when propery jetted with race gas. And even a pony or two. :) Right now, here in the MidWest, I am running Amoco Ultimate (92 pump octane). When I make the jump, it will be Phillips B35 oxygenated.

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