Don't want to beat a dead horse, but you only need run as high an octane level that your engine requires to operate without predetonation.

If it will run on regular or mid grade without pinging, then that's your fuel.

"Premium" fuel isn't necessarily "better quality fuel".

 

One thing to think about also. While i was getting gas one day i looked at the gas pump, and how long the hose is going from the nozzle to the actual pump. If the hose is 6' long and say 1"-1 1/2" diameter there is close to 2 gallons of fuel from the previous fill up in the hose. So if you "buy" premium and the previous fill up is regular you are not going to get what you paid for, with our tanks only 2-3 gallon we are getting what ever is left in the hose. Wouldn't matter if you are putting 25 gallons in a truck, but with such little fuel storage its pointless to buy premium, you are only getting what the last guy got. Unless its an older style pump with a separate hose for each grade of gas. Just something to think about.... I have always used regular in all my bikes, no issues.

 

Ethanol blended fuel is becoming difficult to avoid. Ethanol has less energy than gasoline, so a decrease in miles per gallon is to be expected when gasoline is cut with ethanol. My personal experience is that ethanol blended fuel degrades and gums things up quicker than straight gasoline. If you are going to let your KLX sit be sure to drain the carb.

Kevin - who will be pulling his carb for cleaning tonight, do as I say not as I do!

 

EMS_0525: “there is close to 2 gallons of fuel from the previous fill up in the hose”
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Wow, thanks for doing the math EMS; that’s an eye-opener. I have often wondered about the volume of residual fuel from the last pump user, but I had just assumed it would not amount to more than a litre but when I run the math myself using conservative numbers, I get almost 2 litres in the hose alone. Who knows what also might be left in the internal plumbing of the pump itself?

I don’t run premium in my KLX so it’s a non issue in that regard. As you point out, it’s also not a big deal for my car which requires premium, but it is concerning with respect to my wife’s ZX6r which takes premium and which she routinely refuels at ½ tank (approx 8 litres). I think I’ll be keeping a jerry can of premium in the garage for her from now on!

mel brooks’ point, “"Premium" fuel isn't necessarily "better quality fuel".” is also worth re-iterating. There’s a prevalent misconception that premium fuel is somehow inherently better for your engine or yields more power. In fact: higher octane only means slower burning. It’s an absolute waste of money to use premium if the engine does not require it.

 

2 gallons! No way, more like 20 ounces, come on man! LOL

 

Agree with Mr. Brooks on this one.^ A way to test your engine is to drive/ride up a reasonably long incline. If your engine begins to ping and wheeze a bit, you're probably a bit low on the octane. (NOT scientific; so no flamers, please.) Try a tank of premium doing the same hill, and see if there's a difference. As for the ethanol E-10 stuff, Powershouse^ experience is same as mine; the stuff degrades FAST. For bike engines, I'd stay away from E-10 if at all possible. Try running a bit of Chevron Techron (properly diluted) in your tank once a month or so to fight the "gums," regardless of what you use. Don't over-do it, though. Fuel cleaner additives are highly corrosive.