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Thread: 2 Cycle Fuel Question.......

  1. #41
    Boolit Master
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    2 stoke engines typically don't have an oil sump or pressurized lubrication system. The only lubricant available in the crankcase is the oil/gas mixture. That oil/gas mixture has a lot of demand placed on it; it must lubricate the big end of the connecting rod, the wrist pin, the rings, the piston skirt and the two outer crankshaft bearings. The good news is because it's constantly being replenished; that gas/oil mix only has to work for a brief period of time. More oil improves the lubrication but it comes at the cost of less efficient combustion and less power. Like most things in life - it's a compromise.
    If the bearings can stand a thinner oil mix then there's an advantage to running more gas and less oil. It comes down to what the engine can tolerate. A little more oil doesn't hurt much but it comes at the cost of smoke, plugs that foul easier and slightly reduced power.

    As for alcohol and gasoline - The ethanol causes more problems in small engines than it's worth. It also causes huge problems with storage of fuel. Fuel stabilizer certainly helps but pure gas is even better.

    Octane rating: this is probably one of the biggest scams around and it's easy to sell because people want to believe it's true.
    High compression engines need high octane gas to run without detonation [knocking or pinging]. Increasing the compression ratio (to a point) is one of the ways to increase power but high compression requires high octane fuel to take advantage of that higher compression ratio.
    Using high octane fuel in an engine that doesn't need it to operate; DOES NOT PRODUCE ADDITIONAL POWER. Putting high octane fuel in a low compression engine doesn't magically make it run better, stronger or more efficiently. In fact, it may even be less efficient.
    When people buy high octane fuel and tell themselves that they are getting: more power, better gas mileage or some other perceived benefit - they are just engaging in a self fulfilling prophecy. They want to believe they are getting better performance so they do believe they are getting better performance. The fuel companies are happy to sell you more expensive gasoline and they are not going to educate you.
    Now, there are some high compression engines that have the ability to produce maximum power on high octane fuel and compensate for lower octane fuel when necessary. Those engines have knock sensors and computer controlled ignition and fuel systems that reduce power output when they are fed lower octane fuel. However, a low compression engine that runs fine with 87 octane fuel will not magically produce more power if you supply it with 93 octane fuel.
    Last edited by Petrol & Powder; 04-18-2017 at 07:17 PM.

  2. #42
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    Ethanol free gas is not available within 50+ miles of where I live, because of the Clean Air Act, so that's out. Home Depot has Tru-fuel for $9.55/qt+ Tax and that's out too! Guess I will mix to manufacturers recommendation an just keep 'em seperate. Or I could continue to use my bigger saw and give this one to someone I don't like.
    Yes I can spell, I just can't type!

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  3. #43
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    Quote Originally Posted by dragon813gt View Post
    Lone Star Mobil in Allen, TX is the closest one I could find north of Dallas. But it's not exactly close by.
    Thank you sir! Just noticed your post. I will try to give them a call.
    Yes I can spell, I just can't type!

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    "To disarm the people is the best and most effectual way to enslave them." George Mason Co-author of the Second Ammemdment

  4. #44
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    2 Cycle Fuel Question.......

    Puregas.org or get the app.

  5. #45
    Boolit Master dkf's Avatar
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    Quote Originally Posted by km101 View Post
    Ethanol free gas is not available within 50+ miles of where I live, because of the Clean Air Act, so that's out. Home Depot has Tru-fuel for $9.55/qt+ Tax and that's out too! Guess I will mix to manufacturers recommendation an just keep 'em seperate. Or I could continue to use my bigger saw and give this one to someone I don't like.
    VP is also making several premixed small engine fuels. My local farm/hardware store has been carrying it, they also carry the Stihl canned premix fuel.

    https://vpracingfuels.com/small-engine-fuels/#sef

  6. #46
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    yup octane is a burn retardant. It slows and cools the burning of your fuel. Using it in a motor that doesn't have enough compression to warrant it makes your motor run worse. Snowmobiles are a good example. THey have to start when its real cold out. Take a stock snowmobile and run premium fuel in it and I can about guarantee you that it will be harder to start and foul plugs faster. Petrol and powder is absolutely right. Add octane to a motor that doesn't have enough compression to need it and you are NOT going to gain power. In fact you will make your fuel harder to ignite and burn cooler. Add to that they fact that a lot of pump fuel today uses alcohol to get its higher octane rating and you compound the problem in a 2 stroke.
    Quote Originally Posted by Petrol & Powder View Post
    2 stoke engines typically don't have an oil sump or pressurized lubrication system. The only lubricant available in the crankcase is the oil/gas mixture. That oil/gas mixture has a lot of demand placed on it; it must lubricate the big end of the connecting rod, the wrist pin, the rings, the piston skirt and the two outer crankshaft bearings. The good news is because it's constantly being replenished; that gas/oil mix only has to work for a brief period of time. More oil improves the lubrication but it comes at the cost of less efficient combustion and less power. Like most things in life - it's a compromise.
    If the bearings can stand a thinner oil mix then there's an advantage to running more gas and less oil. It comes down to what the engine can tolerate. A little more oil doesn't hurt much but it comes at the cost of smoke, plugs that foul easier and slightly reduced power.

    As for alcohol and gasoline - The ethanol causes more problems in small engines than it's worth. It also causes huge problems with storage of fuel. Fuel stabilizer certainly helps but pure gas is even better.

    Octane rating: this is probably one of the biggest scams around and it's easy to sell because people want to believe it's true.
    High compression engines need high octane gas to run without detonation [knocking or pinging]. Increasing the compression ratio (to a point) is one of the ways to increase power but high compression requires high octane fuel to take advantage of that higher compression ratio.
    Using high octane fuel in an engine that doesn't need it to operate; DOES NOT PRODUCE ADDITIONAL POWER. Putting high octane fuel in a low compression engine doesn't magically make it run better, stronger or more efficiently. In fact, it may even be less efficient.
    When people buy high octane fuel and tell themselves that they are getting: more power, better gas mileage or some other perceived benefit - they are just engaging in a self fulfilling prophecy. They want to believe they are getting better performance so they do believe they are getting better performance. The fuel companies are happy to sell you more expensive gasoline and they are not going to educate you.
    Now, there are some high compression engines that have the ability to produce maximum power on high octane fuel and compensate for lower octane fuel when necessary. Those engines have knock sensors and computer controlled ignition and fuel systems that reduce power output when they are fed lower octane fuel. However, a low compression engine that runs fine with 87 octane fuel will not magically produce more power if you supply it with 93 octane fuel.
    Soldier of God, sixgun junky, Retired electrical lineman. My office was a 100 feet in the air, closer to God the better

  7. #47
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    Quote Originally Posted by Lloyd Smale View Post
    yup octane is a burn retardant. It slows and cools the burning of your fuel. Using it in a motor that doesn't have enough compression to warrant it makes your motor run worse. Snowmobiles are a good example. THey have to start when its real cold out. Take a stock snowmobile and run premium fuel in it and I can about guarantee you that it will be harder to start and foul plugs faster. Petrol and powder is absolutely right. Add octane to a motor that doesn't have enough compression to need it and you are NOT going to gain power. In fact you will make your fuel harder to ignite and burn cooler. Add to that they fact that a lot of pump fuel today uses alcohol to get its higher octane rating and you compound the problem in a 2 stroke.
    This is true from both of you, it is just a waste of money unless you run a Ferrari. Almost every vehicle says 87 octane. Too much is not good at all.
    The crazy woman down the road had a Subaru, the old one with the flat VW engine and some mechanic told her to use high test so that is all she bought and had nothing but trouble. Now she has a tiny SUV and I bet she still feeds it the most expensive gas.
    All small engines use 87. Either way alcohol is just no good, decreases gas mileage too, eats some rubber hoses, collects moisture and on and on.
    They came out with E85 or whatever, almost all alcohol and car makers void the warranty if you use it.
    My biggest gripe is having to pay road tax when I buy gas for small engines and lawn mowers.
    Long ago Amoco sold good gas, so pure we used it in lanterns, almost white gas. No lead.
    I bought some gas up town one time, Sonoco (spelling) and could watch the fuel gauge drop. I put BP in and am getting 18.5 MPG with a big 4 Runner 8 cyl. Constant 4 wheel. It reads out on the dash. I turn the air on and still get 18.3 MPG. That is on side roads too. 87 octane.
    One thing to watch is the battery, mine was bad and I took it over from Carol when we bought her a newer one, she never got better then 16 MPG. Alternator was working overtime. Changing the battery made the mileage jump.
    My friend has a little car that shuts the alternator off when the battery is full, stores power in a big capacitor for when needed. It sips gas.
    Too much oil is no good in two strokes if it has bearings. If an engine has bushings you better use what the instructions say, if 25 to 1 never put 50 to 1. The engine will seize. The cheap chain saw made in Canada had steel against steel. Not even a bushing. Pullun or how you spell it.
    I have a Husky backpack blower and I could not start it when using Stihl synthetic at 50 to 1. No compression. Rings were carboned in so tight they broke when I could not move them. I had to buy a new piston and rings. Soaking did not help, they were locked.
    Oil is important, even brand.

  8. #48
    Boolit Master
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    Quote Originally Posted by dkf View Post
    VP is also making several premixed small engine fuels. My local farm/hardware store has been carrying it, they also carry the Stihl canned premix fuel.

    https://vpracingfuels.com/small-engine-fuels/#sef
    NAPA carries VP fuels. At least all the ones around here do. Which means if yours doesn't they can get it. They have the small engine cans right at the front door when you walk in, can't miss it. It's not cheap but you can at least buy it five gallons at a time.

  9. #49
    Boolit Master Rick Hodges's Avatar
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    My Stihl owners manual for my weed wacker specifies 50:1 and 91 octane fuel. They warn against ethanol, but do state that it can run on 87 octane but to be careful as it will run hotter with the regular fuel.

    I have a place near me that sells 91 octane ethanol free at the pump for $3.649/gallon at the pump. I use that and mix 50:1 for all my two stroke needs. This after having to have the fuel system rebuilt in my Husqvarna chainsaw due to the lines and plastic getting brittle from the ethanol. I don't use that much two stroke fuel and it makes good sense to me to pay a little more for decent gas.
    Je suis Charlie

  10. #50
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    Quote Originally Posted by 44man View Post
    I had nothing but troubles with oil, carbon and plugged exhaust. I used Stihl synthetic at 50 to 1 along with all other brands. Oil would drip from mufflers all over the garage floor. I was always fixing.
    I found Opti II and all problems went away. It comes in a little pack for a gallon of gas. 50 to 1.
    Every octane gas here has alcohol in it. Have to go to a Liberty station to get rid of it, place is too far and it is expensive.
    Sea Foam seems to take care of it.
    about 10 to 15 (maybe 20?) years ago, I was doing some backyard/redneck wrenching on lawn equipment as a part time business...mostly due to Minnesota's switch to ethanol. There were lots of giveaways, that just needed carb work.

    BUT also, I was given (for free), the nicest gas powered Stihl hedge trimmer, it ran but was problematic...the only issue was oil/carbon filled screen in muffler (spark arrester?).
    The person said they only used Stihl Oil, I suspect he was among the crowd that thinks 50:1 is good and 40:1 is better. I use Stihl chain saws and I quit using Stihl oil about 10 years ago, when I stumbled onto a large box of 2.6 oz bottles John Deere synth 2 cycle oil (maybe a hundred bottles?), it is red like Amsoil...I mix it 50:1 with non-oxy gas, but if I get a little sluggishness and smoky exhaust I add a little Gas, to lean it a bit. I still have a few of those left, when I run out, I'll probably start using Amsoil.

    I am also a big fan of Seafoam, I always give a small engine a dose of Seafoam to the gas (or gas/oil mix) after a storage period...to clean out any varnish that may have 'set' during a season of sitting around.

  11. #51
    Boolit Master

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    Called VP Racing Fuels at corporate in San Antonio. They said that all Walmart stores carry their premix in 40:1. It's in a white can and just says "SEF", but if you look on the back it has the VP logo and info. Still spendy at $6.40-ish a quart, but I won't use too much in my weed trimmer.

    Also supposed to be available at AutoZone and Napa. If it's not on the shelf, they can order it from their warehouse for you. And you can order 1 gal., 5 gal., and 55 gal containers on-line but be prepared for the price!

    just FYI
    Yes I can spell, I just can't type!

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    "To disarm the people is the best and most effectual way to enslave them." George Mason Co-author of the Second Ammemdment

  12. #52
    Boolit Master historicfirearms's Avatar
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    You guys in texas should look at your local airport and ask for 100LL, prounounced as "hundred low lead". If they ask tell them its for your ultra lite. It will cost around $5 a gallon. Its great fuel that takes years to degrade. I put it in all my engines that sit for extended time, but dont use it in anything with a catalytic converter. The lead will plug cats up.
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  13. #53
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    Lead was an anti knock additive but the greeny wienies said it was poison and it is true. Then alcy came in to reduce pollution but reduced mileage so more gas is used along with more smog. Then the catalytic to heat more and change exhaust. The thing burns fuel that the engine should use. It all adds to cost.
    Engines are made better so it helps, Oils are better too. Long ago as a mechanic, 50,000 was good but now 300,000 is broken in. Air filters and oil filters are better.
    Much was learned from racing engines but the use of nitro methane for power makes them rebuild an engine after the race.
    This is interesting.
    Nitromethane exhaust

    Exhaust gas from an internal combustion engine whose fuel includes nitromethane will contain nitric acid vapour, which is corrosive, and when inhaled causes a muscular reaction making it impossible to breathe. People exposed to it should wear a gas mask.[15] The condensed nitric acid-based residue left over in a glow-fueled model engine after a model-flight session can also corrode their internal components, usually mandating use of a combination of kerosene to neutralize the residual nitric acid, and an "after-run oil" (often the lower-viscosity "air tool oil" variety of a popular preservative oil) for lubrication to safeguard against such damage, when such an engine is placed into storage.

  14. #54
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    Octane is not a "burn retardant". It is two things. An 8 Carbon atom molecule, and a burn speed rating based on that molecule.

    -HF

  15. #55
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    historicfirearms,

    THANKS for the info. = I'll "call around" to some of the smaller/local FBOs and will pass along your comment to our classic outboard "addicts", too..
    (My 2-cylinder, 18-40HP "Johnnyrudes" don't do well on ethanol "enhanced" gas AND they need a mixture of 24/1 gas to 2-cycle oil, too.)

    yours, tex
    Last edited by texasnative46; 04-21-2017 at 12:40 PM. Reason: typos/clarity

  16. #56
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    Quote Originally Posted by historicfirearms View Post
    You guys in texas should look at your local airport and ask for 100LL, prounounced as "hundred low lead". If they ask tell them its for your ultra lite. It will cost around $5 a gallon. Its great fuel that takes years to degrade. I put it in all my engines that sit for extended time, but dont use it in anything with a catalytic converter. The lead will plug cats up.
    Thanks! I will check with the smaller airports in the area. I know of 2-3 that should have it but don't know if they will sell to "off airport" customers. I will try the "ultra-lite" story.

    Don't think I would have any success at DFW Int'nl. lol
    Yes I can spell, I just can't type!

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    "To disarm the people is the best and most effectual way to enslave them." George Mason Co-author of the Second Ammemdment

  17. #57
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    Quote Originally Posted by HangFireW8 View Post
    Octane is not a "burn retardant". It is two things. An 8 Carbon atom molecule, and a burn speed rating based on that molecule.

    -HF
    True, I think some posters are using the word "Octane" to indicate the Octane rating. That's proper considering the context of this thread but not technically correct. There is a difference between Octane - a class of hydrocarbons and Octane rating - a measure of a fuel's ability to withstand heat & pressure without detonating.

  18. #58
    Boolit Master LAKEMASTER's Avatar
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    I bought a boat years ago that sat for 7/8 years, maybe more. I ran 3 gallons of 40:1 through it off of a gas can.

    Motor was a mid 80s mercury inline 4 cylinder. ( iron duke)

    Pulled the spark plugs after the 3 gallons and they were gray. Not black.

    Modern day 2 cycle oil is every clean burning and very efficient.
    Lee Loadmaster - Lee O-frame - Lee Melting Pot - Lee......... EVERYTHING

  19. #59
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    Long ago before synthetics I ran a popular 2 stroke oil and had problems with carbs all the time. I found particles or what looked like paraffin floating in the gas. It plugged everything.

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BR Bench Rest M Magnum RN Round Nose
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GC Gas Check