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My saw doesn't like 50:1

Post in 'The Gear' started by Big Donnie Brasco, Jun 15, 2013.

  1. Big Donnie Brasco

    Big Donnie Brasco Feeling the Heat

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    After a new cylinder, piston, rings etc I was running 40:1 mix in my saw for 4-5 tanks, then switched up to 50:1. It didn't seem to run as good and would bog on occasion when in big wood. Today she was acting up with that $10 small can of STIHL premix 50:1 then I ran out. I figured I'd use up the 40:1 that I had from a few weeks back and that b1tch came alive and screamed like a ***** ape!! With a brand new chain we were slicing through 24" red oak like a nothing! Chips everywhere!!

    Make any sense?

    BDB

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  2. Bigg_Redd

    Bigg_Redd Minister of Fire

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    Not really.

    There's not enough difference between 40:1 and 50:1 to effect jetting/carburation. Is the only difference the ratio? Same gas? Same oil?
    jeff_t and smokinj like this.
  3. smokinj

    smokinj Minister of Fire

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    Rings may not be completely seated yet maybe?
    ScotO and Thistle like this.
  4. bogydave

    bogydave Minister of Fire

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    Nothing wrong with 40:1.
    Check the plug occasionally , should look clean.
  5. MasterMech

    MasterMech Guest

    I'm betting Dex had that fresh rebuild running pretty fat to begin with. Redd is generally right on there not being a big enough difference between 40:1 & 50:1 to noticeably affect how the engine runs. But if it was set super rich to begin with.... If you've run more than 6-7 tanks of fuel through it, I would give it 50:1 and re-tune for best performance.
    ScotO likes this.
  6. Big Donnie Brasco

    Big Donnie Brasco Feeling the Heat

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    yea, FANTASTIC machine and I LOVE it!!!!!
    Dex did a PERFECT job and I would run her all day every day if I could!

    I just need to learn how to tune! I did SLIGHTLY tweak the H screw and that helped but I am terrified of leaning it out too much and wrecking the piston.

    The gas that gave her the most problems was that 50:1 premix EXPENSIVE stuff!

    She runs BEST on 92 octane and STIHL synth oil..................... BUT (just hit me) I added blue Stabil before she started getting finicky !!!

    * everyone that sees my sweet 036 (even small eng mechanics) ask me if it's brand new! DEX ROCKS!
  7. StihlHead

    StihlHead Guest

    Stabil should not make any difference, though I use the red formula and not the green marine stuff. I also only use non-ethanol E0 gas in my saws. Lots of information out there about 2-stroke motorcycles running better with more oil in the fuel mix. Reason being a better ring seal and more compression. I still run my saws at about 45:1 for that reason. But in your case your new rings & cylinder are likely not seated in yet, and so the saw is running better with more oil in the premix because of the micro-gap in the P&C. Typically saw engines take about 10 tanks of gas to seat right.
  8. DexterDay

    DexterDay Guest

    I would def run the saw a lil longer on a richer mix. Although you have ran a few tanks, it may need a few more.

    I didn't use OEM parts in the cylinder rebuild. I didn't use the Cheapest chit either, but there are definitely good aftermarket kits out there, the Meteor, Hyway, etc kits have been proven on AS to hold up well. I just bought anther Hy Way kit from Weedeaterman on AS for an 026 I just picked up.

    Again, if there does come to be problem. I told him to pay shipping and I will personally go through it and run it myself. Although a tune from the local dealer would be cheaper. I would stand behind the saw.

    And MM. I did have it running fat n 40:1 when it shipped, as I had about 2 tanks ran when I sent it. Wanted it to be a little thick for break in (always cautious). Also, told him to check muff screen (can't remember if I reinstalled it??) it may have been carboning up?
    Joful likes this.
  9. Big Donnie Brasco

    Big Donnie Brasco Feeling the Heat

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    Just to be clear... Dexter did a STELLAR job on this saw, and I could not be happier!!!! Any "issues" I have are purely due to my inexperience with chainsaws and their tuning. :)
  10. lukem

    lukem Minister of Fire

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    Probably still breaking in. You should feel the saw get progressively stronger after each tank (not much but a little)...when that peaks (7-10 tanks) switch to 50:1 and re-tune the carb.
  11. Boog

    Boog Minister of Fire

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    I would totally expect that the saw would need a little re-tweeking after a breakin period. Keep your fuel/oil mix the same so you can compare apples-to-apples performance. Sounds like you've run 3 different "Mixes" in it so far, so its hard to say for sure what's the cause of your problem. Tuning your carb screws is not that difficult. There are some good postings here on doing it, and on YouTube too. I'm sure Dex will make things right if you do develop any significant issues in the near term.
  12. Big Donnie Brasco

    Big Donnie Brasco Feeling the Heat

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    Like I said Dex is AWESOME, any problems I may experience are simply ME and my inability to tune a carb! :p
  13. Freeheat

    Freeheat Minister of Fire

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    Im no expert but it sounds like old fuel.
  14. StihlHead

    StihlHead Guest

    Stabil will keep fuel fresh, for up to a year at least.
  15. StihlHead

    StihlHead Guest

    Of course, Stabil will not freshen up old fuel, it only keeps new fuel fresh.
  16. clemsonfor

    clemsonfor Minister of Fire

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    I run every thing at 40:1. All my 2 cycle stuff including stihl saw. I use husky oil as i get it at lowes. The boats are all labled for 50:1 but i run 40:1, every now and then i go to 50:1 and cant tell a difference. Well thats premix boats i forgot i have one boat with oil injection on it. Its run at whatever the thing tells it based on rpms. I want to pull that out and put a regular fuel pump on it and get rid of the oil injection so i can go to 40:1 fuel.
    Big Donnie Brasco likes this.
  17. Joful

    Joful Minister of Fire

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    You enjoying cleaning carbon deposits out of muffler screens and combustion chambers?
  18. clemsonfor

    clemsonfor Minister of Fire

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    Nope, the screen had very little carbon on it when i pulled it out when i rebuilt my saw. the cylinder looked clean and my plug was a nice color when i pulled it out. About this time last year i totally tore my saw down due to the decompression valve falling apart and the actual valve falling into the cyl and locking the piston on the up stroke to the cyl head. could not move it. took it apart the piece fell out and all it did was make small dents in the piston and a few in the top of the head, no damage to the piston edge or cyl walls. No carbon very slight wetish carbon in ring areas but nothing that alarmed me. Looked normal clean to me. thats with running maybe 5 gallons of fuel through the saw in th e12 months prior and maybe 3 gallons the previous years to that since new. And untill that incident smashed the ground strap on the plug closed, and i figured i would just get a new one as i had regapped it once and could see some wear on it. That was the original plug that came with the saw, no carbon problem on it.
  19. Joful

    Joful Minister of Fire

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    Nice! I had always been told running rich on the oil mix would accelerate carbon build-up. Perhaps there's more to it.
  20. clemsonfor

    clemsonfor Minister of Fire

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    It will carbon up if ur running richer than say 32:1. But at 40:1 u don't even notice its just a bit more oil. To me I rather it be slicker in there. I know there designed for 50:1 for a reason blah blah.
  21. Bigg_Redd

    Bigg_Redd Minister of Fire

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    1) Running rich (as in carb adjustment) will accelerate carbon build up

    2) More oil actually leans out carb tuning because it displaces gasoline

    3) With the possible exception of these fancy new computer chipped saws, no carb can tell the difference between 40:1 and 50:1

    4) Synthetic and synthetic blend oils greatly reduce carbon build up at any mix ratio
  22. jensent

    jensent Member

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    Red is right again!
  23. jharkin

    jharkin Minister of Fire

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    Actually, I was suprised to learn that the type of oil makes more of a difference in carbon buildup than the mix ratio. Interesting writeup from oil testing done by UAV guys:

    http://www.geistware.com/rcmodeling/articles/oil_test/index.htm

    What especially shocked me was how bad the "miracle synthetic oils" like Amsoil carbon up in just a few hours run time - and the synthetics make a hard carbon glaze thats harder to remove tahn the soft buildup from dino oil.

    Ever since I read that article I run nothing but 32:1 Pennzoil dino oil in every 2 cycle engine I have - saw, trimmer and my giant scale RC planes. Never had any issues with carbon, never worry about burning up from a lean run. (Note that Pennzoil is also one of the most popular oils among Ultralight pilots. If they trust their life to it, I trust my gear).

    [For the cars its another matter, I use only synthetic - mobil1 and redline trans fluids]
    Joful likes this.
  24. clemsonfor

    clemsonfor Minister of Fire

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    I use the husky semi syn oil from lowes, but its the same oil you would get anywere. it also has a fuel stabilizer in it. I use premium 100% gas to mix it with and have never had a problem with 1 year old fuel.
  25. MasterMech

    MasterMech Guest

    I'm not seeing that. Running Amsoil Sabre Pro at 80:1 and nothing has blown up, and it all runs clean. I might pop the top-end off one of the MS460's I have to see what's up in there since that top end has seen nothing but AMSOIL. Could be interesting.

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