In loving memory of Kenis D. Keathley 6/4/81 - 3/27/22 Loving father, husband, brother, friend and firewood hoarder Rest in peace, Dexterday

the mix thread

Discussion in 'Chainsaws and Power Equipment' started by splitoak, Jun 13, 2014.

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  1. splitoak

    splitoak

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    Ok guys..i didnt want to hijack another post so ill start my own..here goes....
    i have two stihl saws ms 290 and 441c according to the book and dealer i am to run a 50:1 mix....am i getting bad info?..i know its for emissions..should i be running richer??..i want to get a long service life from my saws...if not 50:1 what then?.if not hp ultra what oil?..i know you guys know your stuff so enlighten this redneck:D:popcorn:
     
    splitoak, Jun 13, 2014
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  2. lukem

    lukem

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    50:1 should be fine on a stock saw if you're using good oil. 40:1 isn't going to hurt anything either.
     
    lukem, Jun 13, 2014
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  3. mdavlee

    mdavlee

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    I won't run 50:1 in a wild thing. I use 32:1 in all 2 stroke stuff. I can't use ultra any way as it gives me headaches. Maxima K2 is a good oil as is motul, klotz, belray, and a few more.
     
    mdavlee, Jun 13, 2014
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  4. MasterMech

    MasterMech The Mechanical Moderator

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    This is a tough topic to get good advice on. Some will tell you that you're going to h-e-double-hockey-sticks if you deviate from the manufacturers specs and what not. Others are convinced you should have never left 1953 behind and should be running the same mix grand-pappy's pappy did. So what is the truth? Is there a "best mix"? The answer is no. There is no best mix ratio. Every type and class of two-cycle engine is different and what is absolutely necessary for one is total overkill for the next.

    My current mix is AMSOIL Dominator @ 40:1. It's more available to me than other top-shelf synthetics and much less expensive than Stihl HP Ultra. Why 40:1? Because I have been inside my engines that run this mix and there is plenty of oil in that bottom-end, even for my modified pro-saws. The math is easy for 40:1 and 32:1 as well. Dump 4 oz oil into your can, add 1 gal for 32:1 and 1.25 gal for 40:1.
     
    MasterMech, Jun 13, 2014
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  5. nate

    nate Banned

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    (disclaimer... I am talking about stock/stockish saws. Hogging out a muffler or a bit of porting is stockish)

    I run 50:1. My thoughts are that Stihl wouldn't recommend a mix if it destroyed the saw. They have done more testing than everyone in this forum combined many times over.
    Also you'd be hearing about burned up saws left and right if it was an issue.

    For all we know the min oil needed might be an 80:1 mix and 50:1 is erring on the safe side.

    More oil makes a leaner mix, not richer since there is less gas. The oil is for lube, not for fuel. If you decide to run more oil, you need to adjust the carb to richen the mix.

    Stihl Ultra does stink if mixed too heavy. Not sure why? My buddy cut with me a few days and his saw exhaust smelled like burning vomit. I don't get that smell with a normal mix in my saws. I'm not sure what he mixed, as he just did the "eh... 3-4 "glugs" should do it"

    Ratio is not hard to figure out. Just take 128 and divide by the mix (ie 50) to get ounces of oil per gal of gas. Multiple by amount of gals... (so 50:1)... 128/50 is 2.56oz. x 5 is 12.8 oz for 5 gals.
     
    Last edited: Jun 13, 2014
    nate, Jun 13, 2014
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  6. splitoak

    splitoak

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    So i should just stay @ 50:1 with hp ultra then?..lol..or should i mix .9 gallon of 93 with a bottle of hp ultra?:headbang:
     
    splitoak, Jun 13, 2014
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  7. DexterDay

    DexterDay Administrator

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    Seeing 1st hand inside of a saw running 50:1 is what changed my mind. Plus, I don't need a few different mixes lying around. So for my ported saws, stock saws, weed eater, trimmer, and blower all get the same diet.

    Stihl does know what they are doing and running 50:1 in your stock saws won't hurt.

    The 93 octane is another story. I just posted a response in the muff mod thread.
     
    DexterDay, Jun 13, 2014
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  8. Hedgerow

    Hedgerow

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    You could do either... And your saws will still live a long and happy life...
    Just make sure it's in there...
     
    Hedgerow, Jun 13, 2014
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  9. Cut4fun

    Cut4fun

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    I wont and tell others no to 50:1 epa crap.

    40:1 min and I do 32:1.

    But it's your choice and your saws.
     
    Cut4fun, Jun 13, 2014
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  10. JRSDWS

    JRSDWS

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    I mix 36:1 and use it in all saws and the string trimmer. I was mixing 40:1 but changed when I got my first ported saw. I have a tough time swallowing the 50:1 pill. I always make sure there is no chance of erroring on the lean side, too. Oh...and 87 octane ethanol free gas for me.
     
    JRSDWS, Jun 13, 2014
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  11. Hedgerow

    Hedgerow

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    And 20:1 for play...
     
    Hedgerow, Jun 13, 2014
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  12. mdavlee

    mdavlee

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    I've never run that rich. Maybe with part nitro.
     
    mdavlee, Jun 13, 2014
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  13. Cut4fun

    Cut4fun

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    I did 24:1 with juice. I think my 1 gal cocktail mix can is still marked that way. Then when I went alky/nitro it became my flush can.
     
    Cut4fun, Jun 13, 2014
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  14. Cut4fun

    Cut4fun

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    Pic of can with 24 on it.

    [​IMG]
     
    Cut4fun, Jun 13, 2014
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  15. mdavlee

    mdavlee

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    I forgot about needing to flush those til you posted that. I might one day build a saw to run on that stuff.
     
    mdavlee, Jun 13, 2014
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  16. bogydave

    bogydave

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    My mix is always a little heavy on the oil side.
    I figure I don't get 100% of the oil out of the little bottles so I only add .9 gallons of gasoline.
    Don't know what mix ratio that is, but never saw a 2 cycle engine burn up with to much oil in the gasoline,
    but to little oil can cause expensive bad things.

    IMO some where between 50:1 & 40:1 is good
    .5 oz more in a ( 128 oz) gallon is not earth-shattering, but erring on the safe side makes me fell better.


    Oil:Gas mix chrt.jpg
    Some say the extra oil helps with performance,
    reduces internal heat & friction on the engines ? ?

    I know several 2 cycle outboard guys that have oil injection pumps & oil reservoirs
    mix their gas tanks 100:1,
    Don't seem to hurt t the performance but saves big bucks $$ if the oil pump
    ever fails or reduces the mix.

    One of the first thing checked on a 2 cycle warrantee is the fuel mix, to little oil & they don't pay.
     
    bogydave, Jun 13, 2014
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  17. MasterMech

    MasterMech The Mechanical Moderator

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    That's entirely true Nate, that Stihl has done more testing on this than I will ever care to. But longevity is not the only thing affecting the official 50:1 recommendation either. As a manufacturer, Stihl must adhere to emissions regulations as well. And if 50:1 is what it takes to get an engine to pass, so be it, as long as the engine lasts an "acceptable" period of time. And as long as the compression ratios and power outputs are modest, there's no doubt in my mind that most equipment will live a long time indeed on 50:1.

    However in the case of saws, there is a BIG difference between a pro-grade saw turning 11,000 rpm under load and Joe homeowner's leaf blower chugging away at 6000 rpm. ;)
     
    MasterMech, Jun 13, 2014
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  18. DSS

    DSS

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    It amazes me that people will pay $1000 for a saw but not put a little more oil in the mix. 32 or 40:1 gives me a little extra safety net. It's been shown that ported saws running 50:1 will probably have bearing issues.

    But it's all good. Guys running on the ragged edge of tune @ 50:1 keep a lot of us in cheap saws with fried top ends. :loco: :crazy:
     
    DSS, Jun 13, 2014
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  19. Hedgerow

    Hedgerow

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    That'll buff right out...
     
    Hedgerow, Jun 13, 2014
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  20. DSS

    DSS

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    Meh...
     
    DSS, Jun 13, 2014
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