Need help adjusting idle and revs on Husqvarna 128LD trimmer


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Old 09-21-22, 01:31 PM
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Need help adjusting idle and revs on Husqvarna 128LD trimmer

I have Husqvarna trimmer (week whacker). Model 128LD. I put a new carb on it but I need help adjusting idle and revs. I have viewed few YouTube videos and tried few things but unsuccessfully. Local shop wants to perform full carb maintenance for $60 which I think is not needed given the carb is new. Are there any instructions on how to reset the carb to default settings and then how to adjust for best performance? I am afraid that after I messed with it, the defaults are long gone (high and low screws plus the idle revs). Any help is appreciated.
 
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Old 09-21-22, 07:56 PM
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Set both H and L screws 1 turn out from lightly seated, start it. If it won't idle without working the choke back and forth, back the l screw out until it idles. Then give it full throttle. Back the H screw out until the engine starts fluttering and slowing down, then turn it back in until it screams, then back it out again until it slows down and stop just before it starts fluttering again. Then go back to idle and see if it still idles well. If it stumbles and smokes, turn the idle back in until it idles smoothly and leave it out enough that it doesn't hesitate when you give it throttle. Set the idle speed screw low enough that the clutch disengages and the trimmer head doesn't turn when idling.
 
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Old 09-22-22, 03:27 AM
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Thank you. Will try the instructions later today. I do have one question. How about the idle speed screw? Is there a setting the screw should be at before I start zeroing out and adjusting the H and L screws? I am afraid that after my numerous attempts to adjust all three screws are way out of their default setting.
 
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Old 09-22-22, 06:13 PM
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Just figure it out as you go. The idle speed screw should be contacting the throttle stop at least, and probably a turn or two more than that in.
 
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Old 09-23-22, 03:04 PM
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I have tried to make the adjustments per your instructions but unfortunately, I have failed. I was able to adjust the L screw and idle but I am unable to adjust H screw to get anywhere near a good running trimmer. It looks like it is working as intended until about 90% of the throttle. Then the last 10% the engine dies. I have a weird feeling that the H screw is not making much of a difference. Also, when the throttle is fully pressed the revs go down and engine dies.
 
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Old 09-26-22, 07:40 PM
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If the H speed screw isn't doing much then there is another problem(s). Could be air leaks, blocked exhaust, or most likely internal carb problems.
 
 

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