Octane question

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Tooner
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Octane question

Post by Tooner » Mon Jan 15, 2018 12:24 pm

Yesterday at Swan MX I saw a chubby middle aged guy like me on a bike identical to mine. I stopped to ask him a few questions about his 2018 crf450r and one thing he said was that I should be running 100 Octane fuel in my bike. My BS meter went to yellow alert, but he then said that he owned a power-sport dealership and that his mechanics told him they would see signs of detonation on high compression bikes. He also said, "check the owners manual" that it would confirm that I should be running 100 octane fuel. I was prepared to be surprised when I got home and pulled out the fairly well read manual for my bike and saw that is clearly said to use 91 octane fuel.

He gave me his card and I have no reason to doubt that his mechanic believes that he has seen evidence of detonation on high compression motors, so what do you think? Other than the added expense and hassle is there any down side to running higher octane fuel or should I just keep using 93 octane premium?
Shane
Current ride and track: 2009 CBR 1000rr
2018 crf450r

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DarcShadow
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Re: Octane question

Post by DarcShadow » Mon Jan 15, 2018 12:39 pm

I would guess the bikes the mechanics are referencing had other issues that the higher octane would compensate for and that a stock motor running correctly would be just fine on 91.
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turismon
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Re: Octane question

Post by turismon » Tue Jan 16, 2018 1:23 pm

Yea, run what your manual says, 91. anything else is a waste. 100 is just stupid.
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Re: Octane question

Post by DemonDuck » Wed Jan 17, 2018 1:32 pm

The higher compression the vehicle the more likely you could get pre-detonation with lower octane fuel. I am guessing that is what he is talking about but .... if your owners manual says 91 and you haven't done any mods then 91 should be just fine. I of course would run 93 just because its what I use in all my bikes but its not required and will most likely make no difference to longevity.
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Re: Octane question

Post by DarcShadow » Wed Jan 17, 2018 2:08 pm

It also depends on altitude. If manual says 91, 93 might actually be needed around see level, and you could probably get by with 89 in Colorado.
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Re: Octane question

Post by Tooner » Wed Jan 17, 2018 3:42 pm

Thanks for your responses, I have always used 93 octane and will continue to do just that.
Shane
Current ride and track: 2009 CBR 1000rr
2018 crf450r