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Thread: Regular Gas Or Hightest

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    Default Regular Gas Or Hightest

    What gas do you burn in your ATV, regular gas or hightest. I burn regular but my buddy says that you save yourself a lot of engine headaches over the long haul if you give it the good stuff.

    I have heard that hightest is good for small engines like chainsaws but an atv is not a small engine.

    What say you

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    Quote Originally Posted by BEARBOB View Post
    What gas do you burn in your ATV, regular gas or hightest. I burn regular but my buddy says that you save yourself a lot of engine headaches over the long haul if you give it the good stuff.

    I have heard that hightest is good for small engines like chainsaws but an atv is not a small engine.

    What say you
    There are thousands of pages out there on this topic. Higher octane fuel is less prone to pre-ignition, so it can be used with higher-compression motors. It's the higher compression (which is a mechanical function of the motor design) which gives the higher performance, not the high-test fuel. High test doesn't burn appreciably cleaner or hotter/colder than regular fuel in an engine designed for 87.

    If it helps you sleep better at night, go with the high test. The oil companies will thank you (it costs them hardly anything above the cost of 87 to produce, but they sell it for 20 cents more per gallon). Otherwise, if you engine was designed for 87, just use 87...as long as it isn't knocking on acceleration.

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    Quote Originally Posted by BEARBOB View Post
    What gas do you burn in your ATV, regular gas or hightest. I burn regular but my buddy says that you save yourself a lot of engine headaches over the long haul if you give it the good stuff.

    I have heard that hightest is good for small engines like chainsaws but an atv is not a small engine.

    What say you
    Your buddy doesn't know what he's talking about

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    92 or 93 octane in an engine designed to run on 87 can INCREASE carbon and deposits due to incomplete combustion as a result of lower compression. (Yes it is true - do the research). Do yourself a favor and use what your owners manual says. The manufactures really want you to be happy with your ATV so use what they recommend.

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    I'm not sure what all the hype says about it. I'll tell you what I have found, not what I have read.

    I use the high octane and I notice the difference. When I was at eureka this last weekend I came out with high in the tank and the next day I filled with 87. When I was going up the same hills I could feel the lower power, the engine sputtered a few times when I open it wide open, and I had to keep my thumb on the throttle to keep it from dieing when I dumped the gas at high altitudes. I haven't noticed if it is different at lower alts because I have never used 87 in the valley.

    Another thing to consider is the fact that I have a carb and not EFI. I don't know what you are working with, but that's what I've found.

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    Quote Originally Posted by Zirak View Post
    I'm not sure what all the hype says about it. I'll tell you what I have found, not what I have read.

    I use the high octane and I notice the difference. When I was at eureka this last weekend I came out with high in the tank and the next day I filled with 87. When I was going up the same hills I could feel the lower power, the engine sputtered a few times when I open it wide open, and I had to keep my thumb on the throttle to keep it from dieing when I dumped the gas at high altitudes. I haven't noticed if it is different at lower alts because I have never used 87 in the valley.

    Another thing to consider is the fact that I have a carb and not EFI. I don't know what you are working with, but that's what I've found.
    You have a mikuni in that atv, sounds to me like your jetting isn't set properly.

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    Member AKMuddy's Avatar
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    This debate comes up every few months. I have done my best to share the truth with a many of you as will listen...The bottom line is that you don't need high octane fuel unless you are running high compression race parts in your ATV or you are experiencing "knock" or "ping". I ran Eureka two weeks ago with my Rhino 660 (carb). I noticed loss of power and it wanted to die every time I let off the gas pedal. What was the issue? It was jetting!!!! My Rhino runs great now that I am back down in the valley. Most folks say they see a difference from using higher octane fuel. The facts are they want to see a difference because they assume higher octane fuel is "better". It just proves they don't know what octane does for fuel. You want to prove me wrong??? Find a dyno and lets test your theories. This has been done time and time again with the results always being the same...the higher octane delivers no more power or performance that regular unleaded fuel. It actually can lead to higher carbon deposits on your motor in the long run.

    Here is a repost of another thread I did for Grizzly Central:

    The Simple Definition

    An octane rating (87 vs. 89 vs 92, etc.) is a measure of a gasoline's ability to resist detonation, which manifests itself in a pinging or "knocking" noise. Higher numbers indicate that the fuel can be compressed to a higher level before detonation / knock occurs in an engine, which occurs when. As described in "Detonation, Knock, and Pre-Ignition 101", detonation / knock occurs when air and fuel that is ahead of the combustion flame front ignites before the flame front arrives.

    The Complicated Definition

    Octane is actually more than just a rating - it is a hydrocarbon just like methane (single carbon atom), propane (three carbon atoms), butane (five carbon atoms), and heptane (seven carbon atoms). Octane (C8H18) is a hydrocarbon with eight carbon atoms and eighteen hydrogen atoms. 100% octane fuel is remarkably resilient to compression (i.e. it does not combust when compressed) and is thus resilient to detonation / knock. This resilience is derived from the branching of octane's carbon chain (see figure). Because of the nature of octane as being resilient to detonation, all fuels are compared to 100% octane as a benchmark fuel, from which an "octane rating"can be obtained. Heptane, a hydrocarbon with seven carbon atoms, compresses very poorly and spontaneously combusts even under small amounts of compression. In other words, Heptane's behavior when compressed is diametrically opposed to Octane's behavior under the same conditions. For this reason, Heptane (which has an octane rating of zero) is the other benchmark fuel used in the octane rating system to determine a fuel's octane rating. A fuel that spontaneously combusts (knocks) under the same amount of compression as a fuel composed of 87% octane and 13% Heptane would have an octane rating of 87. This is not to say that 87 octane gasoline is made up of 87% octane and 13% heptane, rather that the 87 octane gasoline "knocks" in a laboratory knock engine at the same compression ratio as a fuel composed of 87% octane and 13% heptane.


    The coomposition of an octane hydrocarbon.

    Unfortunately, it gets even more complicated. Because various fuels respond differently under varying engine loads, a gasoline may get a different octane rating on a free running engine and one under load. For this reason, the octane rating label that we see at the pump (monitored by the U.S. Cost of Living Council) is actually an average of two octane ratings - the motor method rating (where the engine is run under a load) and a research method rating (where the engine is run freely). The formula used to get the CLC Octane number on gas pumps in the United States is thus: (Motor Octane Number + Research Octane Number) / 2.

    What's the benefit of higher octane?

    Higher octane fuel has only one beneficial feature - it allows an engine to run at higher temperatures with more advanced ignition timing under higher levels of compression witout detonating / knocking. Higher octane fuel does NOT have more potential energy and will not make an engine perform better unless that engine is knocking. On modern engines with knock sensors, higher octane fuel may make the engine run better if the knock sensors are retarding the ignition timing, which hinders performance. High octane fuel does not burn cleaner, it does not clean your engine, it does not increase horsepower or torque (unless you are experiencing knock), it does not smell better, it does not increase fuel economy (unless you are experiencing knock) and is not better for the environment. If you buy higher octane fuels for any of the above reasons, STOP!

    When should I switch to a higher octane fuel?

    First off, never run lower octane fuel than is recommended by the vehicle's manufacturer. If the vehicle manufacturer recommends 89 octane gasoline, this means that the engine has been tuned to perform optimally without detonation on 89 octane fuel. Once you've done some modifications to your engine, the manufacturer's recommended gasoline may no longer suffice. Obviously, if you can hear detonation inside your engine in the form of pinging or "knocking", try a higher octane fuel. You will also need to run a premium grade fuel (91+ octane) if you have a supercharger, turbocharger, or if you have an ignition programmer that advances your ignition timing.

    Why is higher octane fuel more expensive?

    Higher octane fuels are more expensive because they must go through more refining steps that increases the octane rating. These additional steps do not make the fuel better in any other way.

    How is it possible to have 100+ octane gasoline?

    There are some fuels that are even more resilient to compression than 100% octane. Some additives, like tetraethyl lead, increase the gasoline's ability to operate without knock. Some racing and airplane fuels have octane ratings of 110+!
    2007 Yamaha Rhino 660
    2007 Yamaha Grizzly 700 SE w/EPS
    http://www.grizzlycentral.com/

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    My 660 used to give me the same grief in eureka. after I piped and jetted it, it's fine. the dynojet setting must have bumped up the elevation range it runs good in
    Zirac, if adding some premium will help your machine run tops at elevation I would stick with premium at elevation instead of digging into the carb.

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    Quote Originally Posted by jupiterak View Post
    92 or 93 octane in an engine designed to run on 87 can INCREASE carbon and deposits due to incomplete combustion as a result of lower compression. (Yes it is true - do the research). Do yourself a favor and use what your owners manual says. The manufactures really want you to be happy with your ATV so use what they recommend.
    Incomplete combustion also means lower exhaust temps, which is a bad thing when your pipe temp has a big effect on how your machine runs...

    Pretty sure when somone swears up and down that higher octane fuels help them, its just plainly a placebo effect. Just like taking a sugar pill....its all in your head...

  10. #10

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    I don't know if it's been mentioned (lots to read) but high octane gas actually releases less energy in combustion. If you've ever lived or visited high altitude areas you'll notice they sell 85 octane as standard and 89 as premium. At higher elevations you need to burn lower octane levels to maintain the same detonation levels and released energy you experience at sea level. You do your machine, any internal combustion machine, a disservice by using high octane fuels at high elevation unless required by manufacturer or high performance/compression upgrades.

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    Member Bullwinkle50's Avatar
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    Default High altitude

    Sorry guys but Eureka isn't high altitude. Just because tree line is below 3,000' elevation and you are above tree line, doesn't make it high altitude. I ran regular gas in my atvs for years when I lived in Colorado and we ran passes over 12,000'. And yes, regular gas there is lower octane than here. I would say it has more to do with either your machine in particular or the placebo effect.

    Randy

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    Quote Originally Posted by Bullwinkle50 View Post
    Sorry guys but Eureka isn't high altitude. Just because tree line is below 3,000' elevation and you are above tree line, doesn't make it high altitude. I ran regular gas in my atvs for years when I lived in Colorado and we ran passes over 12,000'. And yes, regular gas there is lower octane than here. I would say it has more to do with either your machine in particular or the placebo effect.

    Randy
    I have a buddy that works in a Yamaha shop in Denver and he was telling me their machines were jetted differently from the start. The dealer re-jetted (because of the manufactures recommendation) when they built the machines for the customer because they were constantly having to re-jet them anyway. It was dealer policy to re-jet before the customer took possession. Most of the time the customer didn't even know it was done unless the salesman thought to tell them. I will agree that Eureka is not that "high" in altitude (we saw 4716ft on our GPS) but other issues contribute to the jetting issue...Temp, Humidity, air density, and any mods you may have made to your bike.

    If my Rhino (with hi-flow air filter, CDI, and hi-flow exhaust tip) runs great everywhere I go and then stumbles a little bit when I climb to Monument and then (without touching anything) runs great once I get back down near sea level...I would say it is a jetting issue. Not bad enough to re-jet for what little time I spend at 4700ft but a jetting issue just the same.

    Having my Rhino die on me every time I let off the gas and come to a stop (never done it before or since Eureka) is not a placebo effect.

    Changing to a higher octane fuel would not fix the problem either.
    2007 Yamaha Rhino 660
    2007 Yamaha Grizzly 700 SE w/EPS
    http://www.grizzlycentral.com/

  13. #13

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    So, use low test gas in my atv and don't listen to my buddy.

    But since you guys know so much and on a scale of 1-10, mechanically I score a minus two, is it best to use hightest gas in chainsaws, ice augers, whipper snippers and most small engines (because they are high compression ?????).

    Be gentle with me.

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    All the things you listed will run best with 87 octane. That is what they were designed to use.

    I agree with everything that has been posted above but have one thing to add. When you buy 87 octane you are generally getting fresher fuel. The gas station goes through 10 times as much regular as it does premium. In rural areas that premium may be months old. I had so much trouble burning local premium in a snowmobile that required it (water in the fuel) that I just began mixing my own higher octane fuel using avgas and regular mixed.

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    Member AKMuddy's Avatar
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    Quote Originally Posted by BEARBOB View Post
    So, use low test gas in my atv and don't listen to my buddy.

    But since you guys know so much and on a scale of 1-10, mechanically I score a minus two, is it best to use hightest gas in chainsaws, ice augers, whipper snippers and most small engines (because they are high compression ?????).

    Be gentle with me.
    Are they really "High" compression??? I would look at the owners manual and follow their directions. If you can list the actual compression ratio, maybe someone will have a better answer. I would think regular unleaded would be all you would need.
    2007 Yamaha Rhino 660
    2007 Yamaha Grizzly 700 SE w/EPS
    http://www.grizzlycentral.com/

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    Quote Originally Posted by Bullwinkle50 View Post
    Sorry guys but Eureka isn't high altitude. Just because tree line is below 3,000' elevation and you are above tree line, doesn't make it high altitude. I ran regular gas in my atvs for years when I lived in Colorado and we ran passes over 12,000'. And yes, regular gas there is lower octane than here. I would say it has more to do with either your machine in particular or the placebo effect.

    Randy
    Ya, right, Were you the one tearing apart my carb all those times or the one handing out placebo pills Eureka is EXACTLY AT THE ALTITUDE FOR JETTING PROBLEMS. a DIFFERENT setting is used from 0-5000 than 5000+. I can tear apart and mess with carb setting and jets blindfolded and don't have to be all hopped up on placebo pills to do it

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    Quote Originally Posted by Bullwinkle50 View Post
    Sorry guys but Eureka isn't high altitude. Just because tree line is below 3,000' elevation and you are above tree line, doesn't make it high altitude. I ran regular gas in my atvs for years when I lived in Colorado and we ran passes over 12,000'. And yes, regular gas there is lower octane than here. I would say it has more to do with either your machine in particular or the placebo effect.

    Randy
    I have to somewhat agree here. The elevation along the trail system in Eureaka shouldnt be giving too many "fits" to people in the jetting department.
    I personally have never had a problem with jetting issues due to altitude during the summer months on my wheeled toys. On my current toys my CRF 450R and my 450 Foreman do just fine without skipping a beat. The Foreman has a aftermarket Penland HMF exhaust,Twin Air air filter and a snorkeled intake. All of which effect jet settings. I personally had to go from a 132 main to a 135 and move the needle to the last setting adding a nylon washer under the circlip. Basically Im saying that I dialed it in at sea level and it runs just fine at altitude as well. I would be surprised to find a stock bike that has fitts getting over Monument due to jetting issues.
    Ive ridden Eureaka over the years on a Big Red,YZ465,KX500,KX250,CR500, CR480,XR600,Tri-z 250,ATC 250R(84 & 85),KXT Tacate 250, Polaris 6x6 400, polaris 6x6 300, Honda 300 4x4, and now a 06' CRF 450R and 450 Foreman (and others I'm sure I'm forgetting).I honestly have never had fuel or air issues. If you think it may be the culprit get on the straight aways on the ridge before getting to Monument and do a plug test. Take a fresh plug with you and spend 5 minutes easing your mind.
    Im sure if you are running lean enough to hesitate or pop through your acceleration it will be worth the quick test.....Although my opinion is unless you have jetting issues at sea level perhaps due to poor jetting from changes or modds on the machine you wont find a problem.

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    Member Bullwinkle50's Avatar
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    Default Octane or Jetting

    Guys, we weren't talking about jetting here. The whole thing was about fuel octane. Yes, the machines in Colorado are jetted different for the higher altitude. The dealers I dealt with always made the comment about having to change the jets when they were brought in because they were all shipped with sea level jets. I was around a lot of machines there and there was always at least one in the group that started having problems on the high altitude rides, that is why I said it might be machine specific. If we all want to turn this into a jetting discussion instead of an octane issue, a new thread should be started. This isn't answering the original question.

    Randy

  19. #19

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    I haven't found no diff in performance between 87 or 94 octane from Chevron..Except price..

  20. #20

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    Use what the manufacturer recommends, they know what their machines are designed to run on.

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