Octane rating?

[Kyleiniowa]

Will it hurt, help, or make no difference if I were to run airplane 110 or VP 110 in my 250R? I usually run the 93 ultimate from BP with a little octane boost and of course my Amsoil.

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[oldskool83]

Does it have a high compression motor...high octane is only for built high compression motors.

[86125m]

Just ask my cousin about race gas in a basically stock 250sx. It made the engine run so hot it melted his mudflap and eat the lining in his tank. In our stock bike we just run regular pump gas and we don't have any trouble. Of course we run the gas out of the bikes so fast it doesn't really matter. My brother on his 70 runs a tank a week.

[The_Steve_Man]

It makes no difference. The best gas to run in that would be ethanol free.
The 110 won't hurt anything but your wallet.

[Kyleiniowa]

Does it have a high compression motor...high octane is only for built high compression motors.
Just had the motor redone, but it's stock. Bored out just a hair. I didn't know if there was a higher energy potential in 110 octane gas than 93, in addition to the extra resistance to combustion.

Is airplane fuel still leaded? Would that hurt the reed valves?

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[oldskool83]

Your just wasting money. Run 93. Its a stock motor.

[350for350]

If I recall correctly, the higher the octane rating, the slower the gas burns. The reason that it's used for high compression engines is to reduce detonation. If you use 110 octane gas in a stock compression engine, it won't run right. I have a friend with a stock '06 trx450r. His oldest daughter's boyfriend borrowed it one weekend to take to the dunes. He and his "genius" friends put some race gas in it and it would barely start and run. It would also backfire out of the exhaust. After running a tank of pump gas through it, it now runs just fine. Another friend has a pretty hot Banshee. He tried some 118 octane gas in it once and it would barely pull itself along. He now runs 110 octane mixed 50/50 with pump gas.

[barnett468]

.

If I recall correctly, the higher the octane rating, the slower the gas burns.

In general, this was the case many years ago, however, it is not so much the case now . . If one emails a fuel mfg's tech department, they can tell them what the the flame speed of the fuel they are interested in is.



If you use 110 octane gas in a stock compression engine, it won't run right.

Actually, it will run just fine if it is properly jetted.

[barnett468]

Is airplane fuel still leaded?

Some is, 100 is high lead and 100LL has less lead.



Would that hurt the reed valves?

No.

[just ben]

Av gas is 100 octane and leaded.runs great in my tecate but it has a high compression dome and was jetted with it.

[Kyleiniowa]

.
Actually, it will run just fine if it is properly jetted.

Maybe you can help me with my understanding of octane rating... I thought it was a measure of the resistance to combustion? Wouldn't that be more of an issue with the compression being to low or the spark plug not hot enough to ignite the fuel rather than jetting? Or by jetting do you mean like the importance of a proper a/f ratio which would probably solve all of that too?

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[barnett468]

Maybe you can help me with my understanding of octane rating... I thought it was a measure of the resistance to combustion?
It's complicated, but basically yes.



Wouldn't that be more of an issue with the compression being to low or the spark plug not hot enough to ignite the fuel rather than jetting?

No, all gasoline and race fuel will ignite with even an average intensity spark.



Or by jetting do you mean like the importance of a proper a/f ratio which would probably solve all of that too?

Yes, different gasolines and race fuels require slightly different jetting, this is partially determined by their specific gravity . . Alcohol requires drastically different jetting.

This may be helpful.

http://www.capitalcityoil.com/pdf/The%20four%20most%20important%20properties%20of%20 racing%20fuel.pdf