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Best way to tune a Carb...?

Discussion in 'Chainsaw' started by Geal, Sep 20, 2009.

  1. Geal

    Geal ArboristSite Operative

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    has anyone got a simple but effective way of tuning a carb, i have had a look on here but havent had much luck, does any one know of a good link or site thanks.
     
  2. garmar

    garmar ArboristSite Operative

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    That's surprising considering how many threads there are here about this. This is a very comprehensive article and if it doesn't explain it well enough for you I don't know what will. So I hope it helps. http://madsens1.com/saw%20carb%20tune.htm
     
  3. Geal

    Geal ArboristSite Operative

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    thanks for that. look like il be needing a tach, what the best type and where can i get one.
     
  4. ShoerFast

    ShoerFast Tree Freak

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    Geal

    All you really need is a good straight knot free log and a stopwatch.

    An 'H' setting that gives you the best timed cut is your best bet.


    Set the 'L' for the best idle , quick and smooth acceleration, with out loading up on extended idles will be all you need.


    There is a ton of info using the search function.

    Welcome to the site! :cheers:
     
  5. edisto

    edisto Spelling/Reality Check

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    I put some of it together as part of an FAQ thread here.
     
  6. garmar

    garmar ArboristSite Operative

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    Bookmarked. Thanks, buddy. :cheers:
     
  7. smilin possum

    smilin possum Addicted to ArboristSite

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    Just run both screws in until they just touch the seat, don't go to far. Now Back them both out 1 1/4 rounds and it'll be so close it ain't funny then fine tune it by ear. Good smooth idle and four stroking at WOT.

    If the saw has a muffler mod. be sure to richen up the high speed to allow for it. Saw Safe.
     
    Jtheo likes this.
  8. nmurph

    nmurph ArboristSite.com Sponsor

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    +1 for most carbs.......a very good starting point.
     
  9. garmar

    garmar ArboristSite Operative

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    Yup. This is how I tune my saws. Might not be scientific but I haven't burnt one up yet.
     
  10. Geal

    Geal ArboristSite Operative

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    so from what i have read L for the right mix and H for rpm, so if i turn up H clockwise to get more rpm for my saw will i have to adjust the L? and if i get my saw to idle smoothly with the L needle then just adjust the h needle for the rpms? is this right?
     
  11. redunshee

    redunshee Addicted to ArboristSite

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    Not exactly. Lo and Hi typically operate independently. Once saw is warm turn Lo screw counterclockwise until saw starts to stumble. Then turn clockwise until same thing happens. Midway between both were you set Lo screw. Now you set idle screw. Test settiings by seeing whether saw revs smoothly w/o stumbling. Next you set Hi speed as discussed in earlier posts. However don't lean out too far(turn clockwise) or you'll burn up saw. I listen for fourstroking sond and then rev saw up and shut it off under WOT. This way I can check color of plug. You're looking for a light brown color. If its more white in color your Hi speed needle is set too lean. Turn it counterclockwise and retest.

    Bob
     
  12. blsnelling

    blsnelling Site Sponsor

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    Use a screwdriver:greenchainsaw:
     
  13. nmurph

    nmurph ArboristSite.com Sponsor

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    can you tuna piano with the same screwdriver?
     
  14. outdoorlivin247

    outdoorlivin247 Addicted to ArboristSite

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    No but you can eat tuna w/ a fork...:jester:
     
  15. Geal

    Geal ArboristSite Operative

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    i was thinking a crack bar or something like that :greenchainsaw:
     
  16. Geal

    Geal ArboristSite Operative

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    thanks for that will try on my 361
     
  17. redunshee

    redunshee Addicted to ArboristSite

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    If you have limiter caps on your 361 you may not be able to tune exactly as I've described.
     
  18. Former Saw Builder

    Former Saw Builder AboristSite Guru

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    :hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:
    Brad,

    I was thinking that but just could not bring myself to type it...
     
  19. willsaw4beer

    willsaw4beer Addicted to ArboristSite

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    The l is the low speed/ idle jet and the h is the high speed jet.

    How I tune a saw is warm it up then turn in the idle screw till the chain spins, then tweak the l screw till you get the spot where the chain spins the fastest. From there blip the throttle and adjust for best throttle response. Turn the idle screw out till the chain stops and/ or to manufacturers recommended rpm (if you have a tac.)
    H you hold the saw wot and richen (turn out) the h screw till it burbles. Put the saw in wood, make some cuts and richen/ lean slightly for fastest cutting. If you're really extreme adjust the h while the saw is in the cut, lol.
     
  20. Nathan75

    Nathan75 ArboristSite Operative

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    Set it to stock settings and go from there. Put it in wood and listen. It is pretty obvious what the saw wants. If you are unsure on this take it to someone who knows and will teach you. A good dealer or someone on this forum who is local to ya.
     

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