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fowler175

another octane question!

11 posts in this topic

Just curious, has anyone had bad experiences runnind a low octane(like 87) fuel in their yzf? I'm not planning on cheaping out on fuel or anything, but I may have accidentally put 87 octane in mine, and was wondering if that could cause the probs I had with my bike acting like it was locking up? I have done everything. Checked the timing, head/valves, cylinder/piston, crank, flywheel & woodruff key, clutch, tranny, etc. and everything is perfect, so I'm really just guessing & grasping at straws now.

Anybody?

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I know the recommended fuel octane rating is 91 octane (pump gas); in fact one of the Motocross magazines recommended either using 91 or 92 octane (anything higher results in a waste of dollars spent and also slightly less horsepower ) when used in our four strokes. I doubt other than a little pinging, would you experience any other problems, especially if you weren't racing. I think a friend of mine ran 89 by accident one day when we rode together, and he didn't have any problems at all. I think you may have other problems, but that's just an educated guess....

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If your not racing dont worry about it, you wont notice much a difference.

Just try not to let it become a regular occurance.

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Well, that sucks. I was hoping it was something simple. Guess I'll just put er back together and hope for the best.

BTW, I do race, and my manual calls for 95 octane. I typically run 92-93 pump.

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on my 02 CRF450 and 98WR400 I ran middleof the road 89oct and it worked just fine. I understand at altitude you may be able to get away with this. I did notice the piston had more carbon on it though.

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my friend runs straight 87 in his crf-x seems to work just fine

It also depends on your altitude. The higher up you go, the less octane you'll need.

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I run 89 octane pump in my 99YZF here in CO (6k+ ft) and it runs great. I've actually been told several places that due to the nature of the YZF running hot that 95+ octane race gas will burn the valves and damage the engine Yikes!

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I've actually been told several places that due to the nature of the YZF running hot that 95+ octane race gas will burn the valves and damage the engine Yikes!
It's a myth. Race gas can be dangerous if you don't jet for it, but it usually isn't. Octane does not change the burn temperature or rate, the vaporization rate, or the energy content of the fuel. You need 91 to avoid pinging, but paying for more than you need is a simple waste of money. Note that VP U4 racing fuel is 92 octane.

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I stand corrected,good to know Grayracer! I seem to remember using race fuel as a kid racing desert and I thought it was closer to 100. I guess I talked my self into thinking the bike ran hotter. I still run mid-grade pump gas, that way I'll fill up the bike and the truck on the way to ride. :D

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I seem to remember using race fuel as a kid racing desert and I thought it was closer to 100.

Racing fuels for two-strokes sometimes are 100 octane or more, but four-strokes don't need it.

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