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View Full Version : What Octane for the 400ex


zuLi0
05-05-2002, 08:35 PM
On a stock 400ex motor, what octane was the motor built for?:huh
05-05-2002, 08:44 PM
any good 92 octane will work good on a stock 400. i use race gas cause it should lower the temp a little.
05-05-2002, 09:11 PM
Would 91 be alright , tahts the highest i can find around here
05-05-2002, 09:15 PM
91 is fine...normally the only time you may need higher octane is when you run into a detonation problem. i carry a can of octane boost when i ride far from home in case i get bad gas etc.
05-05-2002, 09:47 PM
What do u exactly mean by detination problem?
05-05-2002, 09:52 PM
detonation refers to the fuel air mixture igniting before it is supposed to. normally modified engines with higher compression require the use of high octane fuel. the higher the octane rating the slower the fuel will ignite. if you hear what sounds like 3 marbles in a coffee can when you are under load that s what detonation sounds like.