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Tuning carb question.

Discussion in 'Chainsaws and Power Equipment' started by mrfancyplants, Apr 7, 2021.

  1. mrfancyplants

    mrfancyplants

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    When my new/used saw starts up it bogs down just on acceleration when you first pull the trigger. This seems to go away once the saw gets warmed up.

    Last weekend I attempted to tune the carb by adjusting until idle, low and then high were within rpm range of the manual specifications for the saw. It was adjusted after the saw was good and warmed up. Now this week, the saw is having the same issues taking off. If I barely feather the trigger it will get going nice and strong.

    Do I just need a five minute warmup every time I start the saw? Should I righty-tighty (a little)the L adjuster to emulate the feathering of the trigger?
     
    Last edited: Apr 7, 2021
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  2. M2theB

    M2theB

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    I’ve had a couple Husqvarna 435’s act that way. Maybe with warm up it gets tighter gaps and better primary compression for the impulse.
    It doesn’t take 5 minutes to get passed it though. 10/20 seconds most with some pizz revs.
     
  3. buzz-saw

    buzz-saw

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    Try adding a little fuel. Counterclockwise on the screws.
    Maybe just a little more on the High screw ? ( or both ? )
    The high side screw has no effect on the low side and idle.

    Fatten it up just a hair and see.
     
  4. Ronaldo

    Ronaldo

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    It sounds crazy but less fuel and too much fuel on the low side can sound and act the same. Try giving it a little more fuel (screw counter clockwise) and see, then you can always go the other direction if needed.
     
  5. huskihl

    huskihl

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    I’d turn each (L and H) about 1/8 turn out (ccw).
     
  6. mrfancyplants

    mrfancyplants

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    Pardon the double post, but I think this belongs in this thread...

    I’ll try fattening H and L a hair and see if it any better. I’ll wait two minutes idle and try it as is and then Lefty-loosy a bit on each of it is still bogging on acceleration.

    It is going to take a while to get this thing “wired” I think. And probably will need to take a second shot at tuning it with my brother-in-law’s tach:

    Idle, shoot for manual’s RPM, or just slow enough for the chain to stop moving?

    For adjusting L, there is no need to touch the throttle, right?
    Lean until it starts to race
    Rich until it starts to sputter
    Set it half way between just on the rich side where RPM just starts to drop.

    Readjust Idle
    Readjust L?

    H- make sure RPM within specs at full chained but unloaded throttle.
     
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  7. huskihl

    huskihl

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    I usually turn the L in until it lopes, and then back out around 1/4 turn.
     
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  8. mrfancyplants

    mrfancyplants

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    “in” is righty tighty right? At idle?
     
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  9. huskihl

    huskihl

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    Yes
     
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  10. mrfancyplants

    mrfancyplants

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    I leaned out the idle and fattened the L and H a little, and the bogging on acceleration seemed to have gone away. Thanks for the help. I probably will tune with a tach soon before I try my hand at that big locust log that had been singing to me.
     
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