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Discussion Starter · #1 ·
Could someone please take the time to give some info on the pros and cons of running a stock two-stroke on high vs. low octane gasoline?

I don`t think I got it quite figured out myself.
 

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Do a search and you will find many previous discussions on this issue. There is no advantage to using a higher octane than your engine is designed for, but there is some potential for causing damage to the engine if you use a lower octane than what the engine is designed for. If you use a lot more octane than required, then you will actually lose power in a 2 stoke engine. Using higher octane levels than needed will not improve performace and will cost you more money, so you decide what is right for you.
 

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<div class='quotetop'>QUOTE (94ZR580 @ Jan 4 2007, 09:41 AM) <{POST_SNAPBACK}></div>
Do a search and you will find many previous discussions on this issue. There is no advantage to using a higher octane than your engine is designed for, but there is some potential for causing damage to the engine if you use a lower octane than what the engine is designed for. If you use a lot more octane than required, then you will actually lose power in a 2 stoke engine. Using higher octane levels than needed will not improve performace and will cost you more money, so you decide what is right for you.[/b]
Very well written.
Exactly correct....you want to basically use as low of octane as you can get away with....but be sure it does not cause pre-ignition ( detonation) or you will ruin your engine.
If your sled is stock and the manual suggests regular gas, just run regular.
Using premium can cost you not just cash, but as much as a few horsepower lost as well, and generally its also considered to be a little harder to start a sled on premium as its not as volatile as regualr.
All octane really does is cause a fuel to be harder to ignite. :beer_cheers:
 

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Discussion Starter · #4 ·
Thanks guys, had a notion that all high octane does is prevent "knocking", but friends of mine persist that it does the engine good in all kinds of ways, and adds HP.
 

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Your motor will make the most HP and preform the best with the lowest octane you can run before it starts detonating. You should be able to run 87-89 in your XF1000. If you have motor mods, you should probably run 91-94.
 

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I'm not saying I don't believe you guys but my sled pulls way harder when I'm running premium. This is only judged by the 'seat o' the pants dynomometer' so I could be crazy, but I can feel a difference.

Would it make a difference 'cause mines a 30 year old 500 free air?
 

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I dunno what you are talking about octane doesn't give you any boost in power i have a friend and his car was dynode at 318 HP at the wheels on pump gas and on races gas witch to my under standing is basically a really high octane fuel then dynode at 400 HP at the wheels it runs just fine on the street no problems and since 4 stroke and 2 stroke motors run on the same basic principles it would stand the same for 2 strokes but if you would see a difference between 87 to 91 it would be so such a small difference you probably wouldn't notice I never thought that higher octane made a rats a$$ of a difference but i cant argue with the facts but then again I don’t know what all is in race fuel so somebody correct if i’m wrong
 

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Run premium fuel through your sled. My uncle has an 03 zr900 and at 3000 miles he burned out a nice hole on top of the piston. And guess what it is a stock sled with all the stock ignition run on the 87 octane fuel that is recommended by the manufactue. Talk to the old timers such as my father who is actually a cat master. If you want your sled to run better for longer DON'T put in cheap oil or cheap fuel.
 

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LOL you guys that think higher octane means more HP

run the octane recommended

If Cat wanted you to run premium they would put it in there manual

as for the car on race gas

HMM maybe they changed the timing

Same goes for a sled change the timing or compression ratio you change the octane
 

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This thread is going to be a fight soon Freeze, it's best to stay clear of octane related topics because my uncles, brothers, friends, sister-in-law said these topics run better on low adrenaline than high adrenaline!
 

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Actually, for the guys who think premium fuel is the best choice for a stock sled ... go right ahead. A lot of people go that route. If you guys don't mind spending a couple bucks more per fuel stop, it doesn't bother anyone else either.

As far as burndowns due to 87 octane? We as snowmobilers know there's always a chance you could get some bad gas. That's a risk you take when filling up at some of these resorts out in the middle of nowhere with less traffic than a normal gas station.

As stated before, the only advantage to running premium fuel is if you have some modifications done to gain HP - timing, air flow, exhaust - these are all mods that would require premium. Otherwise, if all you do is clutch and stud your sled, run what the manual recommends.
 

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Well said Chris. If it makes you happy, go for it. But, reality is that it's not a benifit on stock sleds.


<div class='quotetop'>QUOTE (LabonteF8 @ Jan 7 2007, 09:36 AM) <{POST_SNAPBACK}></div>
Actually, for the guys who think premium fuel is the best choice for a stock sled ... go right ahead. A lot of people go that route. If you guys don't mind spending a couple bucks more per fuel stop, it doesn't bother anyone else either.

As far as burndowns due to 87 octane? We as snowmobilers know there's always a chance you could get some bad gas. That's a risk you take when filling up at some of these resorts out in the middle of nowhere with less traffic than a normal gas station.

As stated before, the only advantage to running premium fuel is if you have some modifications done to gain HP - timing, air flow, exhaust - these are all mods that would require premium. Otherwise, if all you do is clutch and stud your sled, run what the manual recommends.[/b]
 

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If you're running a carbed sled in very cold conditions you're probably better off running premium, just a little added insurance.

As far as cost, it's about $1 a tank to run premium fuel over regular.

Race gas, if you're getting a major HP gain from different fuel without timing changes you have to using an oxygenator. This does require jetting changes. Regular race fuel in an engine with normal compression at reasonable RPM's won't do anything but smell great.
 

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<div class='quotetop'>QUOTE (Gotts2BMe @ Jan 7 2007, 03:29 AM) <{POST_SNAPBACK}></div>
Run premium fuel through your sled. My uncle has an 03 zr900 and at 3000 miles he burned out a nice hole on top of the piston. And guess what it is a stock sled with all the stock ignition run on the 87 octane fuel that is recommended by the manufactue. Talk to the old timers such as my father who is actually a cat master. If you want your sled to run better for longer DON'T put in cheap oil or cheap fuel.[/b]
Don't forget now with ethanol in the fuels depending on the amount you may have to increase your jet sizes
 

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If your running a 30 year old sled I would guess the recommended octane for the sled is pretty high. Octane levels in gas has been gradually lowered over the last 20 years. My F7 is designed for 87 octane which is reg gas today.
I had a 1990 mach1 and the manual said to run reg gas (93 octane?? can't remember exactly). I was running in Quebec back then,,,,,, Then started to run in Ontario,,,,, well Ontario lowered there octane numbers and I didn't know about it,, I just ran reg. Reg ended up being 89 octane and I popped my motor.

Lesson learned,,, pay attention to the octane level you require,,,,, not if it's High test or reg.

I do notice a differance with my sled when I run reg (accelerates faster,,, seat of pant meter),,,,, I have also been told that running high test will rob you of a couple of HP but will also provide you with a safety factor if you get bad gas (below 87). ie: if you get bad high test chances are you will still be above 87 octane,, no danger to the motor,,,,, if you get bad reg chances are you are below your recommended octane..... bad for the motor
 

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And look at it this way from a cost standpoint.

Most of us lately have been lucky to get 1000 miles a season. 1000 miles at 10mpg is 100 gallons of gas using Wisconsin math. The cost difference between 92 octane and 87 octane is generally 20 cents a gallon or less. Once again using Wisconsin math that equates to a dismal $20 or less per SEASON spent on the premium fuel. That's a half gallon of oil at todays prices!

Race fuel in a stock sled is junk. Try putting 110 octane in a stocker sometime and be prepared to pull it over MANY times just to get it to start. It's like putting ice in your gas tank!
 

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I think it's kinda funny that when it comes to injection oil most snowmobilers will only run what the dealer says and nothing else and in some cases people actually sound like they afraid to run anything else because of warranty concerns or whatever.

But when it comes to gasoline people think higher octane is better in some way and that they are doing thier machine a great favor by putting premium in it. (mmmmmm, so the snowmobile manufacturers have the oil injection thing figured out but don't have a clue on petrol)

If you go to a mom & pop station and your concerned about the quality of the regular (87 octane) I would be even more worried about the premium.

Some people recommend running premium for the first tank of the year. Does the premium have some magic cleaning agent that the regular does not?
 

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I have always used premium just as an added safety factor, in case a jet is slightly varnished / plugged, or a little ice in the air is freezing up the mains, etc. But if your engine is designed to run on 87, you will make slightly less hp with higher octane grades. At my university we demonstrated this with an old Ford straight 6 designed to run on 87. On the dyno, it made a few less HP with 92 octane. With detonation sensors, some engines can take advantage of higher octane fuels (but only if preignition is detected at lower octane levels). To my knowledge, there is no 2 or 4 stroke consumer snowmobile designed to run on anything greater than 87. Yes, it is a waste of money to run premium in a stock sled, but not a huge waste. It might be able to save you if your jetting is right on the verge of a meltdown with 87.
 
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