Noone will EVER EVER EVER tell the difference on a 100hp motorcycle. In an F1 car where milliseconds count - sure, but in a street motorcycle, any difference would be unnoticeable.

 

Run it on the lowest octane you can without getting a "precombustion" knocking...

Anything more is just wasting cash.

As it happens though, in the UK the lowest we get is 95 octane, premium is 99 octane which is total overkill for almost ALL engines on the street.

 

Seafordguy- Sorry man, you got nothin'! You go ahead and run your 86 Octane, hey it's your bike after all. Have you ever run a tank of Race Gas through your bike? Tell me THEN that there's no boost in performance for running a higher Octane, and I'll say you are a genius! Till then: stick to my science about the higher the octane= the quicker the burn. The quicker the burn= the better the performance.As I said: The long and the short of it...

 

i thought it was higher octane=slower burn and thats what helped against predetonation............

you know, jet fuel is better than race gas even, i have heard if you run that it makes your bike as fast as a jet.

 

No, its a faster and more complete burn, and predetonation (or dieseling) is caused by unburned fuel igniting on the next firing cycle. Think of it like diesel fuel: its more like kerosene or vegetable oil or lighter fluid. Start a fire with lighter fluid or gasoline and tell me which burns hotter and quicker. Oh, and jet fuel is awesome, but I can't seem to keep the bike from taking off, makes it kinda hard to steer-JK

 

So that we are clear - I burn premium in all of my toys, however, I do not hold any preconceived notions that it enhances performance in any way on those toys which do not require the higher content.

Fuels ability to ward off unwanted pre-spark detonation is all that octane ratings relate. More power could only be created through altering densities or oxygen content. While your science may be correct the fact remains that noone can tell the difference on a 100hp motorcycle between 87 and 91 octane fuel.

EDIT - http://en.wikipedia.org/wiki/Octane_rating


Be sure to pay special attention to this paragraph:

Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.

 

I had no intention of turning this thread into an argument. I just had a simple question. But I have learned a little bit about fuel haha.

 

Seafordguy- sorry, man I kinda came off like an *** on that last post. I keep telling myself I shouldn't drink and post, but it never fails...
Anyhow, I read that whole wiki article and it straightened me out on a few things, and reaffirmed a few things too, but the one thing that stuck with me was the part about higher compression engines needing a higher octane to guard against predetonation. And since our bikes have pretty darn high compression ratios, it makes sense to me to run premium for that fact alone. Nothings too good for my baby...

 

DUDE - NO problem whatsoever. I also run the higher test stuff because I read somewhere that fuel will lose octane points if it sits, and sometimes I don't realize it but my bike will sit several months without being started so I just play it safe.

 

These gas threads are funny I look at it like this: Gas is beer for bikes. I give mine whatever she has a taste for

Actually I'm far more concerned with gas manufacturers than octane. Had some bad luck with the Getty down the block from me. Messed with my gf's car and my bike ain't happy either.