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fuel grade for small 2 stroke engines?

Posted by cowboyandy (My Page) on
Thu, Aug 28, 08 at 7:54

I didn't know it, but apperantly husquvarna recommends mid grade or higher gas in the chainsaw I have. So I started putting in 91 octane in the chainsaw, weed whacker, boat ('66 merc 50 hp OB) and riding mower.

I seem to notice a big difference in the chainsaw, seems like it doesnt bog down as easy.

Is it all in my head, or does higher grade fuel actually perform better in a small engine?


Follow-Up Postings:

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RE: fuel grade for small 2 stroke engines?

Yes, 2 cycle engines love octane.

I just switched all my OPE to AVGAS 100LL. It's high octane and it doesn't have all the garbage additives (ex: ethanol) that automotive gas has.

It stays fresh for years.


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RE: fuel grade for small 2 stroke engines?

89 octane is all that is needed in most 2 cycle engines. If the manual recommends a higher octane then use it but otherwise it's a waste of money. 2-cycle engines do not love octane like davefr says. That statement is ridiculous. Using AVGAS like davefr is asking for a melt-down. High octane gas burns slower and can cause overheating problems in engines requiring lower octane. Dave, you are wasting your money on AVGAS.


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RE: fuel grade for small 2 stroke engines?

Yes, I'm waisting + $.75/gallon on fuel that lasts years vs. weeks!!! AVGAS doesn't cause melt down. I'll take the miniscule risks of AVGAS anyday over ethanol/oxygenated crap in automotive pumps. Do a search on AVGAS in 2 cycle equipment and you might be enlightened.


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RE: fuel grade for small 2 stroke engines?

davefr, Your crusade for avgas is ridiculous. Avgas shelf life is one year. Big deal. Nothing gained there. High performance 2 cycle engines love the octane they were designed for. Any higher octane rating over that will contribute to overheating and lower power. Higher octane fuel does one thing. It burns slower. So what's the deal?? Do you think you're cool by burning avgas? Do you go tell you neighbors that you're burning avgas? Why not try Nitrogen Tetroxide and Hydrazine. You wouldn't even need spark plugs.


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RE: fuel grade for small 2 stroke engines?

AVgas means nothing. High octane means slower burning (raised flashpoint). You will not gain power by using high octane, but will most likely lose power. Can't say I agree with overheat issues but it's possible.


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RE: fuel grade for small 2 stroke engines?

For home owner, having a gad that don't go bad even for a year IS about the most important thing. I AV gas can do that, I think it is very valuable. It is not about gaining power. You want power, get a bigger 2cycle!!!

The question is whether AV gas will hurt the engine. Any technicle data?


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RE: fuel grade for small 2 stroke engines?

The way I understood this topic, having worked on cars for the last 30 years. Higher octane is only needed for higher compression engines--typically found in older vehicles, hot rods, etc.. Higher octane will not hurt if used where not needed, its simply a waste of money. If you use lower octane gas in a higher compression engine, you will get pre-ignition or pinging. I never heard of higher octane gas lasting longer. I have has a dozen or so 2 and 4 stroke engines for lawn/yard equipment and I never saw any recommendation for anything over 87-89 octane (regular).


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RE: fuel grade for small 2 stroke engines?

Why is it that people say they can store gas for only a few weeks? I have a gallon can for trimmer and I store it for months during the winter. I could maybe believe it if the can didn't have tight fitting cap or something. Few weeks, no way. I use 87 octane, same as I use in my vehichles. ??????????????????????????


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RE: fuel grade for small 2 stroke engines?

Stihl recommend 89 octane gas. It is pretty much known you use more than 87. Only Honda trimmer specified you can use 87.

Shelf live of gad depend on the temperature of storage and how full is the container. People want to push it, it is their choice, don't cry when things happened. I learnt my leason.


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RE: fuel grade for small 2 stroke engines?

I do use 93 in the Echo products because that is what Echo says to use. They run better too on 93 than 87.


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RE: fuel grade for small 2 stroke engines?

I had a friend that ran a Briggs on Av gas and it seized up after about 30 minutes. High octane AV gas in a low compression engine is still burning when it comes out the exhaust. I'm talking really high octane here. There is only one reason this topic started. The dude that promotes the use of avgas likes to tell his buddies, Hey man, My mower runs on avgas. Wooppeee So what?? Waste your money if you want. Shoot...why not use jet fuel in your kerosene lamps??


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RE: fuel grade for small 2 stroke engines?

Higher octane does work better, but is it a racing chainsaw???? Then unless you make your living with it, you could probably squeeze by with the lower octane.

Just use Mobil or Shell to stay away from ethanol. If its a boat or dirtbike I personally would use Mobil Super+ octane level of 93.


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RE: fuel grade for small 2 stroke engines?

Simply use fuel stabilizer in all small engines, as it not only preserves the fuel and prevents shellacking, but inhibits the deleterious effects of Ethanol and other additives. The kid working at our airport made the mistake of using AV gas in their lawn mower, with spectacularly disastrous results.


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RE: fuel grade for small 2 stroke engines?

I personally use Octane 89 for all my Domestic Please Craft Sure have used AV 101 during my early yrs racing snowmobiles and motorcross and enduro 2-strokes , but that was for short term performance gains under extreme conditions and tuning .But my lawnmower and saws and trimmers ..etc just plain old pump gas suffices . It is a good policy to use a fuel treatment occasionally and stabil during storage. I like Lucas Products , but MMO , Duralube or Resilone ..etc are other fine Carb Cleaning additives and lubricants that help reduce carbon . Raystrom recently tabled a Product that was very interesting also . Can not remember the Title , but it had showed some merit for use within OPE and even Diesel Engines. Ray can you enlighten this Old Dude once more Bro ..Thanx :)


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RE: fuel grade for small 2 stroke engines?

When in doubt refer back to your notes lol . I put Rays info within my Favorites . Star Tron is the Product Identifier . I will be trying to locate some this week within local supply Stores in my area . It really has some intriguing concepts .


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RE: fuel grade for small 2 stroke engines?

Just stay away from ethonal if you can, here I can get 91 oct without ethonal. Race gas will most likely make less power in the average small engines. Steve


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RE: fuel grade for small 2 stroke engines?

AV Gas will definitely produce less performance within regular ope units. Only engine performance changes (Porting and Tuning) will provide any significant performance increases within these engines . I suppose if your a Lawn Tractor Racer or a Chainsaw Cutting Competitor you may find use for High Performance Fuel , but not within your everyday gas trimmer or lawnmower's lol .


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RE: fuel grade for small 2 stroke engines?

chainsaw engines are very high performance, you should be using the best high octane gas, stabil, and synthetic oil in every tank. We are talking pennies more for the the better stuff.


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