2 replies to this topic
Posted April 22, 2003 - 09:55 AM
Ok guys, I've seen a few questions about what octane gas to use in our bikes since the manual says 95 or higher. I've been asked this question before, usually by my race gas using friends while filling up my gas can at the local gas station. So, here goes...In the manual it says "research octane number of 95 or higher". There are two octane numbers we should be concerned about for our purpose, "Research" octane, and the octane number on the pump where you buy gas. If you look at the pump, it will have a little sticker that has a formula next to the octane number (R+M/2) What this means is, Research octane + motor octane divided by two. Motor octane, (M), is lower than research octane, therefore, the octane listed on the pump will be lower than "Research" octane. I won"t go into the difference between Motor octane and Research octane because it's irrelavent for our discussion. Most race gas octane is listed as RON (research octane number) which is higher for the same fuel using R+M/2. You may be suprised at how some race gas compares to the best premium pump gas. Most bikes (including MX bikes) run fine on premium gas. Higher octane fuel burns slower than low octane. High compression engines need higher octane fuel to prevent pre-ignition (knock, pinging). If your bike is not pinging, it may run WORSE with higher octane gas. Save your nickles for trick parts.