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Chainsaw Carburetor Tuning 101

Post in 'The Gear' started by MasterMech, Mar 1, 2013.

  1. MasterMech

    MasterMech Guest

    Had to tune the MS460 anyways after a carb cleaning. Good opportunity to show how it's done from scratch.

    OldLumberKid, JoeyD, ScotO and 5 others like this.

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  2. DexterDay

    DexterDay Guest

    What about that DP Muffler?? ;) (stock... No thanks) :cool:

    That looked and sounded good. Great job MM. Loved that rebuild thread. Now run the chit out of that thing
  3. Nixon

    Nixon Minister of Fire

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    Sounds really healthy ! She's oiling well too .
  4. kenskip1

    kenskip1 Member

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    I would have made a cut or two in order to make sure the engine got to full operating temperature prior to making adjustments.However that is my personal preference, Ken
    ScotO and n6crv like this.
  5. Boog

    Boog Minister of Fire

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    Nice job MM. I need to get a tach...............I try to do the exact same thing by ear.............only I'm totally deaf in one ear since "78". Its obviously touch and go!

    Your oiler is working good too :p.
  6. HDRock

    HDRock Minister of Fire

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    That's great :cool: Now now do one , explain and use no tach ,please :)
    n6crv likes this.
  7. ArsenalDon

    ArsenalDon Minister of Fire

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    Talent....It honestly is talent. I coach soccer for a living and talent is not easy to find..you are a natural
    ScotO and MasterMech like this.
  8. Senatormofo

    Senatormofo Member

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    I'm impressed! You really know your chit about tuning these saws!
    ScotO and MasterMech like this.
  9. MasterMech

    MasterMech Guest

    I'm not done with that thread yet. And yes, the DP muffler is on there. Final pics are coming if the starter I want to use ever gets here.

    And that's with the oiler @ roughly 50%. ==c
    Nixon likes this.
  10. MasterMech

    MasterMech Guest

    Why no tach? You can tune by ear only too. Forget I'm using a tach and listen to what's going on.
    ScotO likes this.
  11. MasterMech

    MasterMech Guest

    That saw was "pre-warmed". ;)

    EDIT: I had run the saw a bit before the carb was cleaned. Cleaned the carb, ran it again but it was way lean. Went back inside to answer the call of nature, and apparently it had cooled enough to require the choke. Normally I would do a tune with the saw warmed up more bu this one was far enough out (lean) that I didn't want to cut with it for very long.
  12. HDRock

    HDRock Minister of Fire

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    I here ya ::-);)
  13. HDRock

    HDRock Minister of Fire

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    The new Husky 445 refurb
    Don't know if I am very good at tuning, also at the time I couldn't see in the holes , is the idle adjust screw the same head as the H and L ?
    I will check things out some more tomorrow, got dark on me, anyway, the vids



  14. MasterMech

    MasterMech Guest

    The audio breaks up too much for me to really hear whats going on. Can your hear it four-stroking at WOT? It should have a rough tone that will smooth out as soon as you put it in the wood.
    ScotO likes this.
  15. HDRock

    HDRock Minister of Fire

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    Ya your right the audio is breaking up, yes I can hear it four-stroking at WOT, before I adjusted it it was four-stroking almost the whole throt range.
    I tuned my 2 older smaller saws and it seems it was easier to tell the difference while adjusting, the 445 ran smooth cutting, just don't want to have it running lean.
    I have to spend more adjusting it, at end of second vid I think I had it idling to fast.
    On the L needle I could here the difference good,and I think, I got it in the middle ground pretty good ,but at WOT with H needle hard to tell
  16. STICK

    STICK Member

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    I FOUND THIS ADVICE
    It seems to work well without a tach. But, what do I know, I am just a cowboy with a bag of tools.
    This is routine operator maintenance.
    1. Start your saw and run it for a few minutes to warm it up.
    2. Set your saw down, let it idle for 30 seconds, and then pick it up and tip it forward (handle up and bar down).
    3. If it keeps running, go to Step 4. If it stalls, tighten the Low Speed screw. This will reduce the amount of fuel entering the carburetor. Repeat Step 2 as necessary.
    4. Rev (accelerate) the idling saw.
    5. If it accelerates fine, go to Step 6. If it “dogs,” loosen the Low Speed screw. This will increase the amount of fuel entering the carburetor. Repeat Step 4 as necessary.
    6. Rev the idling saw for about 5 seconds (never rev it for 10 seconds or longer).
    7. If it “flutters” while being revved, this is good, so go on to Step 8. If it “screams” while being revved, this is bad. Loosen the High Speed screw. Repeat Step 6 as necessary.
    8. If the chain is stationary while the saw idles, you’re finished.
    9. If the chain rotates around the bar while the saw is idling, adjust the Idler Screw as necessary to make it stop. This situation can be fixed in a matter of seconds and is extremely dangerous if not corrected.
    That’s it. Less than five minutes of your time can make a big difference in how well your saw runs. Two additional tips are 1) use hot water and dish soap to clean a paper-type air filter (let it dry before using), and 2) use chainsaw gas to clean a wire-type air filter (you don’t need to let it dry before using).
    This information will help your saw run more effectively and efficiently.
  17. MasterMech

    MasterMech Guest

    Then perhaps there is something to be learned from the professionals. ;)
  18. brian89gp

    brian89gp Feeling the Heat

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    What if you have a saw that otherwise runs perfectly but it will die when you let off of the throttle after in a cut. Doesn't die if you are just revving. Also it doesn't die after a cut if you feather the throttle once or twice before letting it idle.
  19. osagebow

    osagebow Minister of Fire

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    Question for ya Mech - will the spline tool for a MS 290 (I know I'd have to fool with the tabs to get to it) be the same one as a Husky 350?
  20. HDRock

    HDRock Minister of Fire

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    I think I got the 445 dialed in pretty good, starts good, idles fine, revs up good, four strokes at full throttle, and I put it in some 15" di ash, using the dogs it only bogged out when I pushed it too hard, and the saw did cut pretty well, as long as I let the saw do work, and that is with a low Pro chain on it that came with it, I will use that until it gets dull then put the new chisel chain on, or maybe I should take the low Pro off now and just use it for backup

    Edit: I still think am going to get me a tech tac tt 20k
  21. HDRock

    HDRock Minister of Fire

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    I do like the splined tool, very easy to slip In and onto screw head, used a marker and put a line down the shaft so I could tell how far I was turning it, but mostly just did it by ear
  22. STICK

    STICK Member

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    Surely so. That is why I am here.

    Please, Do tell.
  23. OldLumberKid

    OldLumberKid Feeling the Heat

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    Dumb question but can it be done with the bar and chain off, or does it have to be under load (of a rotating chain)?
  24. MasterMech

    MasterMech Guest

    I supposed there is no reason you couldn't do it sans bar & chain, but adding the B&C would change the load and I would check it by ear at least before trusting it. I haven't done one that way but I would expect it to significantly affect the top end RPM setting.
  25. MasterMech

    MasterMech Guest

    There are a couple things that could aggravate that but I'd definitely try a retune. For a quick test, back the L screw out 1/4 turn and run the saw. If it stops stalling or significantly reduces how often it does stall, then clean the muffler screen and air filter thoroughly and re-tune as I did in the video. Take your time getting the L and LA settings correct.

    If backing the L screw out 1/4 turn doesn't improve things, then I'd make sure the engine doesn't have any air leaks (crank seals, impulse line, intake boot, etc.) before messing with the carb any further.
    OldLumberKid likes this.

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