So I remember reading a thread/arguement a while back about which gas grade we should be running in our bikes. I was talking to a college buddy of mine who is know a regional sales rep for the largest refinery in the intermountain west. I threw a few questions at him and got some straight answers.

1. What the manual actually says - Our manual states 2 octane standards, the ron + mon/ 2 = 87 and the MON = 91. He said in the US all gas stations go by the r+m/2 formulation, so 87 is the recomended minimum octane.

2. But gas stations don't sell 87 - The majority of gas stations sell 86, 88, and 91.At higher elevations some stations will sell an 85 or 87, but most are being fazed out. The rule of thumb is the higher the elevation, the less octane you need...so you sea level folks need to be running mid-grade, us higher elevations folks could get away with regular (but he didn't recommend it).

3. Now that stations have one nozzle for all 3 grades, andour tanks are so small, if we buy the good stuff we are probably getting the leftover regular in the line? - Wrong! While that line looks thick, the inside diameter is pretty small. When you stop filing up, the last drip you get is the line draining out after the hose bend. Everything before the hose bend is drained back into the tank through a special valve.

That being said, you do get a small amount (less than a pint) of whatever gas was in the line before. But, here's something you don't know. Those minimum octane grades are just that, minimums. Pumps are tested buy the feds on a regular basis. They take reg and premium samples in 1 quart containers. If they fall short of the minimum ( say 91 comes in at 90.8), the refinery is slapped with HUGE fines. To make sure that never happens, the refineries actually boost the octane higher then advertised. It's usually half an octane point (or more) higher so that the quantity coming out of the pump is always at least the minimum. In large quantities the consumer comes out ahead, it our tanks you get exactly what you pay for.

Another tid bit of info, most stations only have reg and premium tanks in the ground. Mid grade is actually blended right at the pump, and if I understanded him correctly, it's calibrated to compensate for any leftover gas in the line.

Hope this clears up the gasoline grade debate.

 

+1
Good info and I agree with very word written.


I might just add that if you think that you are running lean it may not be a bad idea to use premium (90+) octane fuel, this will keep the cylinder head and piston temperatures lower and add life to the little power-plant.

 

I just usualy fill up with whatever the highest octaine is. seriously for a 1.9 gallon tank i dont think $3.25 is goin to hurt, its not like ur filling up ur car or truck with the high octaine. Heck burns cleaner the higher the octaine right? once in awhile i put midgrade or the high in my suv just to clean everything out.

 

I got the opportunity several weeks ago to put 95 octane Sunoco gas in my KLX and I couldn't believe how much faster and better it ran then on the Shell 91 octane (which I usually run) - but then again the KLX does have a 11:0-1 compression ratio - I wouldn't use anything lower than 91 octane - but hey, that's me.

 

Thanks for the interesting information, so we should run the highest grade? Will it run better and be better for the engine? (sorry for using better twice in one sentence.) My Thesaurus didn't have another choice.

 

Higher octane doesnot have any more energy, in fact, it has less. Higher octane wont boost your HP.

 

Are we going through this again?!? [&:]

KLXer is 100% right. Higher the octane, less volatilty. For maximum performance, use the lowest octane that doesn't make the engine knock. The KLX250S is made to run fine on 87 octane. I am at sea level, it was 90 degrees yesterday and I had it going full throttle up a very steep hill. No pinging whatsoever.

Also higher the octane, the quicker it turns to crap. If you don't ride the bike for a couple of weeks at a time, leaving high octane in the tank is a very bad idea.

Finally unless you go to a gas station that has individual hoses, regardless of what you pay for, you are getting a gallon and a half of whatever the guy before you bought(in most cases 87 octane). So in the case of the 1.9 gallon KLX tank.....well you can do the math.

KLX250S_rider, does your station have individual hoses? If not, then you have probably been running on 87 all this time. If they do have individual hoses, then it has to be the result of aplacebo effect.

The bottom line is, putting high octane in a vehicle that is desingned and runs fine on 87 is a complete waste of money. Not only that, you will not get any increase in performance and in theory, would actually get less.

 

No way! Higher compression engines need high octane gas which burns slower - cheap gas = carb gunking up, poor performance and the head gasket blowing. But Kawasaki wants you to use the cheap a*s stuff so you'll need to have it serviced more. The owners manual doesn't even recommend the first oil change at 600 miles and the next at 7500 miles - INSANE! Not all pinging is noticable either especially with a thumper. Just go out and put some 95 octance gas in your tank and see what happens.

The octane rating is an anti pinging number. The higher the number the less likely a fuel is to ping and therefore the higher the compression you can run. You want a higher compression in order to combust more of the fuel more completely.

So basically, you get the best results from high octane fuel from a high compression engine.

If you have a low compression engine, much of the benefit of the high octane fuel will be missed... but you will still get a benefit from the additives/detergents that premium fuels have.


"The recipe for perpetual ignorance is: be satisfied with your opinions and content with your knowledge." - Elbert Hubbard

 

High compression is a very relative term depending on the size of the engine, state of tune, and the efficiency of the combustion chamber.
11:1 inour KLXis not high compression at allbecause the engine is very small, has a very low state of tune,and has afairly efficient combustion chamber.
11:1 would be very high compression for a 1970 ChevyOHV V8 w/ 2valves per cylinder displacing454cubic inches, because the engine is huge, is in a high state of tune, and has an extremely inefficient combustion chamber.

Also the high octane is more likely to gunk up the carb than the low octane.

As for the 95 octane, I can assure you in the current state of tune that I have my KLX250S, it will not increase performance. None whatsoever.
And even if I wanted to try, they don't sell that stuff in CT. We have 87, 89, & 93. With an occasional Sunoco stationcarrying 94 Ultra.

 

You will probably not gain any performance from running a higher octane fuel than Kawasaki recommends in these little bikes.
These mills do have 11:1 compression (med-high) but there are other factors that determine octane requirements such as ignition timing and cam profile just to name a couple. Here is a link to the FTC site with some good, basic information regarding fuel octane myths and urban legends.
http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

None-the-less, this is a like debating religion or politics.