# What Gas Do You Feed Your Kawie



## tx_brute_rider (Feb 18, 2011)

Just wondering what number octane gas you all are running in your Kawies and if you see any difference with the high octane fuel. 
I run the cheap 87 in my brute, seems to get the job done.


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## dirtydog (Nov 11, 2009)

thats right no need for anything different unless you jump the compression. alotta people do alotta things but mostly it is just for a piece of mind. there are no benifits from running higher octanes. there is a thread about it though and it has some real in depth info on this subject if you want the technical reasoning


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## Polaris425 (Dec 16, 2004)

#beatingadeadhorse lol I ran premium. Brute wouldn't run right on anything else. Even before the HC pistons.


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## Sanative (May 4, 2011)

Dad puts premium in mine. Haha. I "feel" that it runs better, that may just be me, but it sure feels like it 


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## NMKawierider (Apr 11, 2009)

With my CDI, 91 runs the best...and I have tried all the rest.


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## wcs61 (Jun 7, 2011)

Runs just fine on 87 octane and pure gas even with the power commander. None of that ethanol junk if at all possible. If I must run ethanol it has a touch of Seafoam added. Already took the carbs off twice before due to cheap as$ ethanol and from what I hear the Feds plan on raising the percentage of alkehall in the junk.


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## filthyredneck (Feb 10, 2010)

I run 93 in mine....11.5:1 compression, runs sluggish on some of the lower stuff, especially the gas that RaceWay sells gotta buy the expensive stuff from them and then I still like to run a fuel additive....typically SeaFoam here as well.
Same story with the Cummins in my Dodge though, I always throw in some Lucas when I fill up, already seen that crappy new diesel wipe out some injectors so....


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## dirtydog (Nov 11, 2009)

this was in the other thread

What *octane* Gas should I use?
How to “Get Gas” without leaving skidmarks 

One of the most frequently misunderstood issues among the atv community, and indeed among all folks concerned with performance and appropriate care and feeding of their motors is the subject of gasoline, and more specifically the mysterious *octane* number. Oil companies have gone a long way to foster this mystery, by marketing gasoline with higher *octane* numbers as “premium”, and inferring that the golden road to more performance, cleaner widgets, and hot chicks, is to spend the extra dough on the higher-octane stuff. Well, sorry to be the one to break this to you, but you’ve been had. So lets take a quick look at *octane*, and then get to the big point – what should you run in your atv? 

Now the truth is, *octane* is actually a chemical, which comprises an important part of the chemical soup that is gasoline. But here’s the thing – *octane* the chemical has absolutely nothing to do, with “octane” the pump measurement. So what is it?

In a nutshell, the *octane* rating of a fuel is a measure of its ability to resist detonation, ping, pre-ignition, or knock. The number we most often associate with *octane* is the "Anti-Knock Index", or the "Pump *Octane*" number. This rating is an average of two different measurements - the Motor *Octane* Number, and the Research *Octane* Number. Both of these measurements are taken using a special single cylinder test engine that has a variable compression ratio. The RON measures the knock resistance of a fuel during low RPM, light load conditions, while the MON is representative of high-speed, high load operation. As a result the MON will always be lower than the RON, but for our purposes the Research *Octane* Number is more significant because it more closely represents the way a low rpm V-twin motor is operated. So “Octane”, has absolutely nothing to do with the energy content or quality of gasoline. It’s just a measurement of when the gas will make a motor of a specific configuration begin to knock. 

Lets take a moment here to define a couple of things important to understanding this discussion. 

Knocking (also called pinking or pinging) in internal combustion engines occurs when fuel in the cylinder is ignited by the firing of the spark plug but burns too quickly, combusting completely before the optimum moment during the compression phase of the four-stroke cycle. The resulting shockwave collides with the rising piston, creating a characteristic metallic "pinging" sound. The fuel is normally ignited slightly before the point of maximum compression (the spark advance) to allow a small time for the flame front of the burning fuel to expand throughout the mixture, so that maximum pressure occurs at the point of maximum compression. It is only when this flame front arrives too early, for whatever reason, that the knocking effect occurs. If allowed to persist, knocking can cause vibration and damage to engine parts. 

Knocking is a different phenomenon from pre-ignition, which occurs when the air-fuel mixture in the cylinder ignites before the spark plug fires. Pre-ignition is caused by heat buildup in engine components or overheating of the air-fuel mixture during compression, and cannot be prevented by delaying spark plug firing. As such, if pre-ignition is allowed to continue for any length of time, severe engine damage can result. Pre-ignition is bad bad stuff, and changing the *octane* of the gas won’t affect it. 

Generally speaking, a higher-octane gasoline prevents knocking by either slowing the burn rate of the gas, or by increasing the difficulty of lighting it up. The idea here is to prevent the gas from burning too fast, and causing knocking. So the *octane* number has no bearing on the quality of the gas. But it does have a bearing, on how well your motor can utilize the gas and extract the maximum energy from it. However, getting too far into details of this would require a pretty darn big article, so I’m going to generalize a bit, for the sake of brevity here. 

First, consider that gas burns faster under pressure. The more pressure, the faster it burns. Therefore, a high compression motor will burn gas faster than a low compression motor. The big bore atv's are relatively low compression motor folks. So, we don’t really want a slow burning gas. 

Second, the burn timing in your motor is hugely important when considering how well the motor can develop power from a given amount of gas, and this timing is determined by the ECU, which can manipulate the spark advance of your engine. Normally, the timing in your atv differs between brands and sizes of engine but will be ~8 degrees before top dead center, but the ECU can and does retard or advance the spark timing to respond to certain running conditions of the motor, like coolant temperature, rate of increase of Rpm’s, or any of a number of other conditions. But none of these parameters are accessible (yet) by you, the itinerant tuner. So, you have no way to manipulate the spark to match the burn speed of your gas. Since utility atv's are designed by the factory to use 87 *octane* gas, if you run something different, the only possible way you have to tune your motor to use a different *octane*, is to manipulate the compression ratio of your pistons. 

So here’s the thing: Unless you have changed the pistons in your atv, a higher *octane* gas will have the effect of de-tuning the motor, and therefore reduce its performance. Now, the amount will probably be minimal, but it’s there. That’s the meat and potatoes guys, but there are a few more things we can infer. First, at higher altitude your compression will be slightly lower, and therefore you can get away with running a slightly lower *octane* gas. In fact, in areas like Denver, where the altitude is up around 5,000 feet, you’ll find gas stations selling 85 *octane* gas. But you’ll never find a gas station in Texas selling 85 *octane*. Since the altitude is much lower, the *octane* rating needs to be a little higher, so regular gas is typically 87 *octane*. 

Second, gasoline quality is dependant on a lot of things, but *octane* isn’t one of them. In fact, there is almost no real difference in “premium gas” other than the *octane* number. Federal law dictates the amount and type of most of the additives in gas. So by definition, they’re all pretty similar in nature.

Except. 

Gasoline is formulated according to climate in the US, and gasoline refiners use 6 basic formulations based on the expected temperature in the area they are expected to be sold in. Gas companies vary this by season, and by location (it also tends to be colder in Denver than in Dallas). So that gas you bought in Dallas might not give you great performance in Denver. 

These days, unleaded oxygenated gas is far superior in performance and energy characteristics as compared to the old leaded gas of yesteryear. We generally have very good gasoline available to us at the pump. 

Lastly, just remember this simple rule of thumb: You should always use the *octane* rating recommended by the manufacturer for your motor. But, if you are riding in a climate significantly different than sea-level at 80 degrees Fahrenheit, then use the lowest *octane* gas you can find that will not cause your motor to knock. 

One more thing – many cars these days have anti-knock sensors built into them (atv's don't), and those sensors are used by the ECU to manipulate the spark timing. So, if you run an *octane* significantly different from the manufacturers recommended *octane* number, the ECU will detune the motor in real time, and you won’t get any knocking – but you absolutely will lose performance. Use the recommended gas. If you’ve been running a higher *octane* gas, and spending the dough to do it, then I hope this little article will save you some bucks, and in the process gain you some performance. Good luck!


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## wcs61 (Jun 7, 2011)

:tragedy:inhale.........so I'll stick with 87 octane.


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## dirtydog (Nov 11, 2009)

copy paste lol


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## NMKawierider (Apr 11, 2009)

wcs61 said:


> :tragedy:inhale.........so I'll stick with 87 octane.


Just run what runs best man. The book says 87.. I think.. but try all and stick with what your Brute likes best. Not going to hurt anything but power with the wrong one. Rule of thumb; the higher compression ratio, the higher Octane needed. On a stock motor probably 89-91s probably the max you want to run.


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## Roboquad (Sep 8, 2009)

91......05 over, and ngkcr7eix. Plugs. Burn longer, helps start. Also keep the corn in the corn fields, not in the gas tank. NM, has a point,every bruit has a little different tune. How many people here have tried to use the same programmer with less than satisfactory results. I use 91 because it works. And to be honest, it sits a lot now. Wish I had more time to play. ; )


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## Bruiser (May 21, 2011)

I run mid grade 89 just bc it makes me feel better


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## phreebsd (Dec 16, 2004)

I run 87 from Entec most of the time


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## Stogi (Feb 24, 2010)

I run 93 unless I have s few extra bucks for some Sunoco 110. It does fine on the 93 but with FST11.5's ,cams, advanced timing ,and running no resisters it loves the Sunoco. Plus it smells better...hahaha


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## oldmanbrute (Apr 15, 2009)

Had to much 'kick back' when I ran 93..... broke off several teeth on starter gear..... went back to 87 w/no problems.


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## tx_brute_rider (Feb 18, 2011)

Seems like 87 is the best to run with stock motors and anything above that is for built motors. Looks like I'll be running 87 only. Thanks for the info guys.


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## J2! (May 8, 2010)

Stogi said:


> I run 93 unless I have s few extra bucks for some Sunoco 110. It does fine on the 93 but with FST11.5's ,cams, advanced timing ,and running no resisters it loves the Sunoco. Plus it smells better...hahaha


 Same here. Most of the time I mix the Sunoco 110 and 93 (no ethenol) together half and half and my 12:1's like it. But they LOVE the straight 110 !!! And I agree it smells ALOT better !! :rockn:


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## Coolwizard (Feb 28, 2009)

I usually run 87 but the other day I filled up with 93. I noticed some backfire on decel a couple times then it ran as normal. It was almost like it had to get used to the extra octane.


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## wyo58 (May 13, 2011)

With a compression ratio of 8.8 to 1 there is really no need for 91. What really causes problems is the ethonal that they put in. In some cases they are using ethonal to raise the octane rating. Thye have found that fuel stored in a plastic container ( BF fuel tank ), losses it's octane rating over a pretty short time. Those chemicals they use to set the ratings have a nasty habit of getting in between the molecules of the plastic leaving you with bad fuel. So if you store it for long periods between rides I'd use the 91. 87 is kinda rare in my area because of the elevation (no air=lesscompression). As a matter of fact my scrambler is at 13 to 1 compression (two cycle) and 91 does not detonate at 9,000 feet above sea level. I've watched it real close checking the top of the piston and the inside of the head for years now and no sign what so ever of detonation. But really what ever you fell comfortable with, I'd do it!!!


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## MinnKawi (Jun 8, 2010)

Where I ride premium doesnt have ethynol so I use it for my sleds and quads.


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## Polaris425 (Dec 16, 2004)

We have 1 local store here that sells ethynol free 87... BUT it cost the same as mid-premium gas. Usually about 10-20 cents more than 87 w/ ethynol. B U T, if you buy $25/gas you get a free soft-serve Ice Cream cone. :bigok: #Winning


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