+1

we use a different octane rating system in the US compared to many other countries so its impossible to simply compare numbers without looking at the rating system used.

 

Like said earlier, the higher the octane the more it resists ignition. Higher octane burns slower. Running higher octane allows you to tune for more power like running higher compression ratio, super charge or what ever. The higher the demand for stability the higher the octane. Basically you want the ignition controlling the timing, not heat. If you think about it you probably want to run the lowest octane as reasonable. What's the point of running more? With that being said my KLX is happy on 87 in all conditions and altitudes thus far.

As far as quality and additives vs octane that's an entire different topic. I agree on avoiding ethanol if possible as well.

 

deej

Try this link for ethanol free gas in Washington state

Ethanol-free gas stations in the U.S. and Canada

Doug

 

Hey Doug, thats awesome! Thanks!!!

 

And there is an app for that!!! Awesome!

Iphone https://itunes.apple.com/us/app/pure...9068?ls=1&mt=8

Google https://play.google.com/store/apps/d...toLean.puregas

 

https://mn.gov/commerce/weights-and-...ctaneFacts.pdf

If you bike isn't pinging or running poorly higher octane will not help it in any way. You only need higher octane or a more expensive gas if you're having a problem with preignition or detonation. If you are not nothing will change at all.

As far as cheaper gas being "grotty" they're coming out of the same refinery, it's the same industrial process. It's just a very slightly diffrent chemical formulation.

A 250s will run fine on regular in any conditions.

If you've changed your bike in ways that will cause it to run hotter you may benefit from higher octane but it has not been my experience.

If you're not hearing that detonation crackle under acceleration switching to a higher octane isn't going to help.

 

I tell you what 87 octane at a place called usa gasoline here in vegas is just plain sludgy. Its gross and my bike ran like **** (not bad gas ive run 3 tanks of the stuff pn diff occasions) then i bought their 91 and it was much better quality.


If a sports car gets gummed up from dirty 91 the law suits would be huge! That honda civic that runs on 87 wont care so much about lower quality gasoline

 

I am not sure what I can say about the gas at a specific location, but there may be a problem with their tanks or something.

In any case, the only problem that a higher octane will cure is preignition or detonation. These are sometimes collectively called knock.

Your 351 has higher compression than a 250 which raises the temperature of the mixture as it is compressed to a higher level. This creates conditions which could lead to knock. So, under some conditions (high load, operation at very high RPM, high ambient temps) you may benefit from higher octane, but only if you are experiencing knock.

As with oil, there's a lot of psychological effect with gasoline. People want to "do something" good for their engines. Unless you have a very fancy ignition system that automatically listens for knock and then advances or retards the ignition curve you will not benefit from higher octane.

In a simple low cost bike like the KLX, not a high performance machine, but rather a simple one sold on world markets with a very old engine design that head isn't one that needs high octane gas.

 

I agree. All Im saying is, in my experience, 87 octances in general tend to be of a lower quality (or lower quality control) than higher octane gasoline

 

How do you determine the quality of one gasoline to another?