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Northlander

Premium Gas in 2 Strokes

22 posts in this topic

Ive heard varying reports on this. Is it good to run premium gas in your 2 cyl. motor? I have a 25 horse Yamaha oil injected and wonder if premium will help it run smoother and cleaner or does it burn too hot?
My motor recently started running a bit ruff and at times stalls out when idling. New plugs and seafoam ran threw it. Anyone got ideas? Fuel Filter? Can I mess with the idle speed and if so how do I do it?
Thanks for your help.

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I always (and have heard many Xs that you should) run the premium non-oxygenated gas in my motors. Works great and I have never had a fuel problem.

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My 90 HP 2 stroke Yama specifically says to run premium... I personally ahve not noticed a difference between premium and teh few times Ive had to put regular in, but have been told by dealers that yes, premium is important for boats...

For what its worth...

Wally

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North, I have the exact same motor as you, a 91, and have the same problems with it. I have been running nothing but premium for 2 years or so because I heard it was the thing to do, can't say as I notice any difference. The stalling is getting a little annoying, but it always restarts instantly so I haven't done anything about it.

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Its not the higher octane thats required with premium its because its un-oxygenated. Around five years ago all gas for autos were required to have a percentage of ethanol(corn alcohol)to lower emissions. Anyway we call the new gas oxygenated, we don't want that in small engines or engines that are used seasonal because oxygenated gas breaks down fast. When this added corn gas came about we new there would be a lot more gummed carbs showing up in a couple years. Also the alcohol in oxygenated gas makes it burn hotter. Most engines are jetted over so this isn't a problem. If you do run oxygenated gas in a snow machine don't add a fuel deicer because it has alcohol in it already. Now if you use your boat or sled a lot go ahead and use regular gas. If the engine is going to sit then use un-oxygenated with a fuel stabilizer.

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Walleye GFA, I think you may want to read your manual again. I was a marine sales manager for about 12 years and have sold Yamaha, Honda, Merc., Johnson and Evinrude. Through the 2001 model year I have never seen an outboard manufacturer that has called for premium fuel to be used in any of their products.

As far as the ethanol breaking down in the fuel. I can tell you I was given a bottle of 18 year old single malt Scottish ethanol that was purchased approx. 20 years ago. This particular ethanol has held up beautifully!! grin.gif

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I checked and ur right... yet another thing to add to the things I will look for in my next marine dealer... knowledge.

I did notice in my reading that they say to use "Ring Free Fuel Additive"... it somehow makes teh detergents, oxidants, and "aromatics" more safe for 2 cycle engines ???

Is this a good thing to use or is it sales talk ????

Thanks for bringing that up, if its not specifically called for I can prob save quite a bit next year !!!!

wally

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Kwfsh pour you 18 year old scotch into a open container and an unstable environment for 3 months then taste it.
Fact: oxygenated gas breaks down faster the un-oxygenated. Varnishing is a result of old gas. Number one cause of carb failure is varnish and your lucky if all you end up is an engine that runs bad and not a burnt piston and scored cylinder walls.
Tell me how that saves money.

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Surface, oxy fuels have been used since the 70's. This term encompasses ethanol,MTBE and ETBE. As far as I know there is no documentation to support the notion that a fuel with ethanol will break down faster than one without.

This link covers many of the issues that come up in regard to oxy fuels.
www.epa.gov/otaq/regs/fuels/ostp-3.pdf

Oxygenated fuels were mandated by the EPA for winter use in Anchorage in the mid 90's. At that time I spoke to the national service directors of OMC, Bombardier, and Polaris. The only concern came from Bombardier and that was regarding the issue of carb jetting. They recommended that when jetting for altitude you should be conservative and jet one size larger than you would with a non-oxygenated fuel due to the increased operating temperature that an oxy fuel runs at.

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Cut and Paste from Chevron
But what do they know.

Deterioration During Storage

If a gasoline is of poor quality or if the storage conditions are adverse, gasoline can oxidize and form gums over the period of several months. These changes can increase engine deposits and filter plugging. There are reasons to suspect that oxygenated gasoline may form gums more readily than conventional gasoline, but actual evidence is limited.

My work is done here. smile.gif

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Quote from Chevron " actual evidence is limited "

I am not trying to start a [PoorWordUsage]ing contest here but I have tried to find anything that would indicate that there are some inherent dangers or pitfalls with oxy fuels. I have not found anything to indicate that this is the case.

I am a firm believer in using fuel stabilizer to keep gas fresh. I have not ever seen anything to indicate that an alcohol/gasoline blend has a shorter or longer shelf life than 100% gasoline.

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Where is my fuel filter on my 1997 25 horse Yamaha oil injected outboard? Could that be part of my problem? What are people gapping their plugs at with these?

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Northlander If it was a plugged fuel filter, air leak, un-vented tank, weak pump or any other fuel related problems the motor would act up under high RPMs long before the symptoms would show up at idle and low speeds. Its cold out and the motor uses more gas when cold. Could be that with warmer temps you wouldn't notice anything unusual. I'd say your low speed is a little dirty. I'm not sure if you have a eternal low speed adjustment, if not pull the cover off and look at the carb, you'll see a L and a H. With the engine running turn the L out(counter clock wise) 1/4 turns. If you do a search theres a post that goes into the procedure in detail but remember if the carb is dirty adjusting it is a temporary fix. Seafoam wont clean a carb. Its purpose is to remove carbon and as a fuel stabilizer. Nothing will remove varnish and gum except carb cleaner.

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ST, my motor is a 91 25 yammy, same problem as North's. But it does it warm in midsummer as well as lately, in the cold. Same adjustment worth a try?

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traveler, yes. Before you make any adjustments turn you low speed in till it just stops. Count the turns so you have a reference point from its original setting. Then come back out to that setting and go from there. If you don't get any results bad or good you can count on the carb being dirty.

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If you talk to the tech reps from all the O/B, snowmobile, atv, and watercraft companys they will tell you to save your money and run regular. Premium is just harder to burn and will not gain you any performance advantage in consumer products.

The ring free type additives are a great product to use as they will help keep your rings, cyl's and pistons clean. This will help your rings from sticking and your engine from losing performance. The buildup of carbon is also very abrasive so it is best to keep it to a minimum if at all possible.

Alcohol in and of itself is not a bad thing in an engine. In 1872 when Nichlolas Otto invented the internal combustion engine there was no such thing as gasoline and 180-190 proof Ethanol was the specified fuel. Even the Model T Ford was designed to run on crude gasoline, alcohol or any combination of the two.

Alcohol is much cleaner burning than gasoline, raises octane, produces less carbon monoxide, and contains no sulfur or additives.

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S.T. whats the best carb cleaner to buy? Or should I just go get a good tune up?

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You can try the Miracle Cure method first, using a carb cleaner like Gumout added to the gas and running it. If your lucky that might work. If not get a quart can and a spray can of Gumout when your ready to take off the carb and clean it.

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We ran across something at the shop that blow all the other carb cleaners out of the water. I'ts an alcohol-based cleaner called "Bonefide". It's made by Drummand-American. I've never seen it in any stores, but there are Drummand-American reps all over and I'm sure their HSOforum could hook you up as well. It's over ten dollars a can but MAN does it work on carbs!!!
On another subject we had a guy in the shop who had put oxygenated gas in his lawn mower in the fall. It's a John Deere with a clear plastic tank, and in the spring it had literally seperated just like oil and water. There was about a two inch layer of clear liquid in the tank. Derndest thing I ever saw!

------------------
Steve @ Bakken's Boat Shop www.bakkensboatshop.com

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Good info ST! I have always used Non O premium for that exact reasons. Even though people laugh at me for using it.

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Steve I'll keep and eye out for that brand. Plastic tanks seem to be the worst thing for storing gas in.

Markel I see your from New London,nice town. I made my first trip to NL 27 years ago on a pheasant hunt. Been going back every year since.

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Fuel Degradation In Storage By Ralph E. Lewis Power Research Inc.

The problem begins with today's modern fuels. These so-called "clean" fuels typically deteriorate at much faster rates than fuels made 20 years ago. While all fuels suffer from the problem, most at risk are the EPA mandated reformulated gasolines (RFG) that contain oxygenate additives, derivatives of methyl alcohol and ethyl alcohol. We've seen gasoline have shelf life as little as a month--particularly if it is subjected to heat and moisture.

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