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50:1 oil mixing ratio...

Discussion in 'Chainsaw' started by BBush, Apr 23, 2010.

  1. BBush

    BBush ArboristSite Lurker

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    I know that most of the saw manufacturers recommend a 50:1 ratio of gas to oil. With the fact that the manufacturers are making their saws run leaner and leaner, I was wondering if there is a downside to making the oil ratio a little lower. I was thinking of mixing a 2.6 oz. bottle of oil to 0.9 gallons of gas which would yield a ratio of 45:1. I understand that my saw will smoke more, but will it cause any abnormal motor problems such as carbon build up? Also, will the increased amount of oil help to protect the motor if I happen to have the carb leaned out too much?
     
  2. GASoline71

    GASoline71 Mr. Nice Guy (Moderator)

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    Uh... don't lean out the carb.

    Less oil means more fuel... hence fuel charge is richer, not leaner.

    Run 50:1 in your saws with quality brand name mix oil and it will be fine. If it gives you the heebie jeebies, then use 40:1...

    I use Stihl Ultra synthetic mix oil at 50:1 in all my saws... whether they are 4 months old or 40 years old. no probs mang...

    Gary
     
    Last edited: Apr 23, 2010
    teatersroad likes this.
  3. TRI955

    TRI955 I'm the man in the box

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    :agree2:

    :cheers:
    Mike
     
  4. HittinSteel

    HittinSteel Addicted to ArboristSite

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    87, 89 or 93 octane Gary?
     
  5. peterc38

    peterc38 AboristSite Guru

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    Gary,

    Not trying to be wiseguy but I'm not following you. The OP stated/proposed he would mix 2.6 oz oil with .9 gallons gas (in lieu of the typical 1 gallon of gas).

    So he would be using more oil not less, correct?
     
  6. Jtheo

    Jtheo Addicted to ArboristSite

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    I run all my saws at 40:1.

    You won't have to adjust the carb with 45:1, or even at 40:1, and I don't see any smoke at 40:1.
     
  7. GASoline71

    GASoline71 Mr. Nice Guy (Moderator)

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    I don't go by all these oz. numbers and stuff. I buy oil in larger containers and use a Ratio-rite mix cup to determine how much oil to use. Then go to the gas station and fill up the amount of fuel I need.

    Anyways... more oil in the mix means less gas mixed in... there for a leaner charge of fuel.

    less oil in the mix means more gas mixed in... there for a richer fuel charge.

    Clear as mud? :)

    Mix ratios are not rocket science... but for some reason people always wanna make it like they are?

    Gary
     
  8. howellhandmade

    howellhandmade Addicted to ArboristSite

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    It's a common confusion resulting from the practice of referring to a mix with more oil in it as "richer." More oil does not make the saw run richer, and it MAY make it run leaner. More oil per unit of gas may result in better lubrication and lower temps and less wear resulting from less friction -- or it may not, depending on the formulation of the oil. But the more precise use of "rich" means more fuel in the fuel/air ratio. More fuel per unit of air results in more unburned fuel carrying away more combustion heat, but also more unburned hydrocarbons, which the EPA hates. So, if you want your saw to run "richer," adjust the carb. If you feel that more oil in your mix offers better protection, add more oil, but you may have to adjust the carb still richer because more oil in a given volume of mix means less fuel for the available air, thus a leaner burn. Same thing Gary said, just different words in case it make a difference.

    Jack
     
  9. cmarti

    cmarti AboristSite Guru

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    Too keep it simple I follow the Scarecrow's advice with my mix ratios..."The right side of an isosceles triangle is equal to the square of the remaining two sides.":dizzy:

    More importantly Gary what oil should I use in a 46.3/1 ratio?:dunno:
     
  10. BBush

    BBush ArboristSite Lurker

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    So, if my saw has been set up at the dealership when I bought it, to run on a gas to oil ratio of 50:1 and then I run it on a gas to oil ratio of 40:1 or 45:1, the saw may run too lean? I guess I learn something new everyday. I would have thought that a saw was running to lean when the carb in not mixing enough fuel (whether it be plain gas or a gas/oil mixture) to the amount of air that is entering the motor. I can't remember the correct ratio, but engines run at a ratio of like air to fuel of 14:1 or something like that. I was thinking that a motor was running too lean when the ratio becomes 15:1 air to fuel. I would make since to me if your carb is in fact mixing the air to fuel at a ratio of 15:1, the extra oil in the fuel would at least make the motor get enough oil so that the pistons are lubricated. The main downside that I thought was that the saw may not quite as responsive because the fuel charge doesn't have enough gas in it to make quite as powerful of an explosion when it is set off by the spark plug, but I didn't realize that it may hurt the motor. The reason is that gas is a much more powerful explosion than oil. So back to the original comments...I may not be helping my motor to run more oil in the gas than is recommended?
     
  11. Gologit

    Gologit Mostly retired

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    You're over-thinking this. Unless you have major changes in elevation where you cut I doubt if you, or your saw, will be able to tell the difference between 45:1 and 50:1. Just use good oil, good fuel, mix it thoroughly...and go.

    I mix somewhere between 45 and fifty to one. It varies...and it doesn't matter.
     
  12. JayC

    JayC ArboristSite Member

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    That's actually a myth. The oil DOES burn, and oil even contains more energy than gas (140KBTU/gal vs. 125KBTU/gal), so adding more oil will not create a lean condition. Higher oil ratios also increases power output up to ~16:1. The only real downside of excess oil is spooge. Personally, I run 32:1 in everything - dirtbikes, saws, etc. I'm running some 24:1 mix in both of my saws right now, and they run terrific, with the exception of a little extra smoke.

    While saws run relatively low performance motors, they are awfully teeny and high-revving, so I wouldn't ever run less than 32:1, regardless of what the manufacturer recommends - call me superstitious. You also have to be careful - a 50:1 recommendation might be for a specific manufacturer branded oil - many of them are semi-synthetic and can run lesser-ratios.

    JayC
     
  13. StihlyinEly

    StihlyinEly Addicted to ArboristSite

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    :popcorn:
     
  14. rmihalek

    rmihalek Addicted to ArboristSite

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    Does anyone have SAE data or data from some other source on the claim that the pre-mix oil actually contributes to the energy of the burning fuel/air charge? I've heard/read anecdotal claims on both sides: some say the pre-mix oil burns and others say the pre-mix oil does not burn.

    If it burns, and has higher BTUs than gasoline, then more oil should result in more power.

    Nevertheless, I also run everything at 32:1 using Mobil Racing 2T with 100 octane Avgas. Makes a nice purple color and smells great.
     
  15. 7sleeper

    7sleeper Addicted to ArboristSite

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    Come on guys! Threads like tihs are becomming annoying!

    I repeat:

    For the answer to all your questions use the search function! Don't be ashamed, it's been asked before!

    Good luck & never fprget your ppe!

    7
     
  16. Gypo Logger

    Gypo Logger Timber Tramp

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    What alot of people seem to miss about oil ratios is how the carb has been set and how the saw is used.
    A saw using 32:1 with the carb set up to factory max RPM and used WOT is infinitely superior and longer lasting than a saw set up rich on the carb at 50:1 and used at partial throttle for extended periods of time.

    A modded saw could probably use 20:1 with no ill effects if it was used WOT and adjusted right.

    Ironically, some of the 50:1 er's like to richen the carb more than need be, especially during breakin. Why not just run a fatter mix and set the carb H where it should be? It's all about complete combustion and lube.
    Gypo
     
    Last edited: Apr 28, 2010
  17. AKDriveSprocket

    AKDriveSprocket AboristSite Guru

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    Do you think running 40-1 compared to 50-1 would help on a lower compression saws? Would compression determine your the ratio of your mix?
     
  18. JayC

    JayC ArboristSite Member

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    Must be a New England thing. Hey - where are your getting Mobil 2T? It's disappeared around here (and most other places) from what I understand.

    JayC
     
  19. Cedarkerf

    Cedarkerf Known to some as....

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    Great oil thread ,from what I have read in this thread 2 parts kerosene,1part oil, 1 part nitro glycerin and 1 part cordite should be the best mix.
    Maybe ill just stick with 93 octane 50-1 which gave me over 3000 hours on an 044 and has worked great on all my other saws
     
  20. GASoline71

    GASoline71 Mr. Nice Guy (Moderator)

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    Saws have a lubrication requirement... not an oil amount requirement. Unless you're using inferior oils... you have to use more. Modern 2 stroke oils lubricate just fine at 50:1...

    Gary
     

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