Tuning help please, Stihl 031

[Jules083]

The 031 is a pretty old saw, maybe 80's I would guess from looking. It wouldn't idle when I first touched it and ran like crap. I messed with the carb and right now it idles great, cuts great, 4 strokes right out of the cut but runs clean in the cut. The only problem is when trying to hold the saw at a lower RPM. If you hold the throttle at 1/8 to 1/4, like if you are trying to warm it up or something, it will run fine for 2 or 3 seconds then cut out and die. Tuning problem still? I would think it would be since it runs good everywhere else.

Compression seems very good, it's tight on the pull cord. Overall the saw seems to be in good shape and lightly used for the age. My cousin is an auctioneer, and bought it at an estate sale.

I'm still learning how to tune carbs. I had good luck on my little 021 that would barely run, but it never gave me this issue.

 

[lone wolf]

Try turning the L a 1/16th of a turn out and see if that richens it up. If that has no effect you may have an air leak.

 

[Jules083]

Try turning the L a 1/16th of a turn out and see if that richens it up. If that has no effect you may have an air leak.

That's what I did to make it idle last night. It was running way too lean off the bottom, to the point of dying out fairly quickly. I went left and right on the L, noted where the saw dropped revs off each end, then went basically in the middle, maybe a tad rich.

Try to go more you think? It idles to the point where the chain 'almost' tries to turn, I've heard that's about where you want it.

Maybe the 'LA' is off, and the L is trying to compensate for it? Is it true that if one is wrong the other can compensate for it, but only at certain throttle openings?

Hopefully it isn't an air leak. I helped a guy try to fix one on a Husqvarna once, it didn't turn out very well. Actually I just watched him and drank his beer, but you get the idea.

 

[lone wolf]

That's what I did to make it idle last night. It was running way too lean off the bottom, to the point of dying out fairly quickly. I went left and right on the L, noted where the saw dropped revs off each end, then went basically in the middle, maybe a tad rich.

Try to go more you think? It idles to the point where the chain 'almost' tries to turn, I've heard that's about where you want it.

Maybe the 'LA' is off, and the L is trying to compensate for it? Is it true that if one is wrong the other can compensate for it, but only at certain throttle openings?

Hopefully it isn't an air leak. I helped a guy try to fix one on a Husqvarna once, it didn't turn out very well. Actually I just watched him and drank his beer, but you get the idea.

Try what you said ,then carb or vac leak is highly likely. Prob vac / pressure test it get it out of the way first if problem wont stop.

 

[blsnelling]

I see no symptoms that point to an air leak. It idles down fine and 4-strokes out of the cut. Both of those are indicators that it is not an air leak. I'd start with a kit in the carb and good ultrasonic cleaning.

 

[Jules083]

I see no symptoms that point to an air leak. It idles down fine and 4-strokes out of the cut. Both of those are indicators that it is not an air leak.

That's what I thought. I'm new at this though. I got my Stihl 021 and my Husky 372XP to run better after tuning, but neither one gave me this particular issue.

 

[Fish]

Remove your pull starter and see if your flywheel has the two moon shaped access plugs. If it does, remove them, and clean and adjust your points. Set them at .016, see if the running improves.