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Adjusting chainsaw carb...

swingset's Avatar

Join Date: Jun 2003
Posts: 26

10-22-03, 02:06 PM   #1  
Adjusting chainsaw carb...

I bought a used Poulan chainsaw off of a neighbor. He thought it needed rebuilt, couldn't get it to start. Paid all of $25 for it. Figured I couldn't go wrong, even if it did need rebuilt. He's had terrific luck with it, but wanted a newer, lighter one.

Well, upon some investigation, I see that the fuel pickup/weight has detached from the fuel line, hook back up, whala it runs.

Only problem is he messed around with all three adjustment screws on the carb and it's all over the place.

I'm pretty new at fiddling with motors, so could you advise me the best way to go about adjusting it? Assume it starts fine and runs, but idles fast and sputters at full throttle. The screws are marked "I", then "L" & "H" (idle/low/high I presume). I've gotten carbs adjusted before, but never knew if I was going about things correctly.

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Terminator20's Avatar

Join Date: Aug 2003
Posts: 865

10-22-03, 02:24 PM   #2  
Hi there!

In order for us to help you adjust that carb properly, we need your modle number of your trimmer, if you can not find that then at least give us the modle of your engine on the trimmer. Usually the engine modle number is directly on the engine block somewhere. I am sure you will find it. The reason we need this information is because every engine has a different kind of carb. We need to know which screw is your idle mixture and air screws. When we recieve the modle number, Cheese and I will help you.

mower17's Avatar

Join Date: Feb 2003
Posts: 365

10-23-03, 12:58 AM   #3  
Going by from what I have learned in the past, the idle adjustment screw will probably have a spring on that screw and will push directly on the throttle linkage. You just adjust this screw until the engine idles like you want it to. I believe on saws, they have to idle to where the clutch will not engauge when the engine is at idle. As for the mixture screws the low speed screw (L) you adjust when the engine is at idle, the high speed screw (H) you adjust while the engine is running with a good bit of throttle. Once you get the idle speed where you like it, then all you have to worry about is the mixture screws. When adjusting the screws, just listen to the engine, to much one way and the engine will run rough and sputter, to much the other way the engine will run rough and maybe start hunting (reving up and down). One thing to check on these small 2-strokes is that the air filter and the muffler are not clogged cause if they are, then you would be having to adjust the carburetor to make up for the air restrictions that these two problems can cause which would mean that the carburetor isn't actually adjusted perfectly. Hope this helps!!!!!!

cheese's Avatar
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10-23-03, 01:15 AM   #4  
Hello Swingset!

There are 2 small screws on the side of the carb. One has an L by it, the other has a H by it. Screw both of them in until they lightly bottom, then back out the L screw 1 1/2 turn, and back out the H screw 1 turn. Then crank it up and set the idle speed with the larger screw that contacts the throttle. Once you get it set properly, fine tune the other 2. The L screw should be adjusted so that the engine idles smoothly, and the H screw should be adjusted while running the engine wide open. Get it to where the engine runs as fast as possible, and back it out a bit more until the engine begins to flutter. Two stroke carb adjustment is something learned by experience, and is tricky if you've never done it before.

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God bless!

DennisG's Avatar

Join Date: Feb 2003
Posts: 153

10-23-03, 07:57 AM   #5  
There is more to tuning a 2 stroke carb than one thinks...a very good link for the beginning person is http://www.madsens1.com/sub8.htm and go to the carb tuning link. There are sound files in there as well as to what it should sound like... If there is something wrong in the carb, one can tune it seemingly correct and inadvertantly cause a lean seizure.

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10-24-03, 10:43 PM   #6  
adjusting chainsaw carb

Go to Yahoo groups, Milling site. Go to message #7945, is the best summary I've seen.

swingset's Avatar

Join Date: Jun 2003
Posts: 26

10-25-03, 12:43 AM   #7  
Thanks guys! Followed the directions and got it running great!

WOW, it's a powerful saw too, much more zip than the old Stihl. I wouldn't have believed it looking at it - neighbor's loss, my gain.

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