Saw dies after 8-10 seconds of idle time

So, is there a sure-fire way to diagnose a welch plug?

 

http://www.zamacarb.com/pdfs/TechGuide_2007.pdf

Note: It is often un-necessary to remove the welch plug. Test for plugged progression holes by spraying carb cleaner into the L needle hole. If cleaner sprays out the progression holes there is no need to remove the welch plug.

 

That's a nicely done pdf - thanks for the link pullin. My earlier post was focusing on the Idle Operation figure on page four - with closed throttle plate an obstruction in the idle passage would lead to the idle problem. This pdf also gives a nice trouble-shooting chart including possible causes of a no-idle condition. Cheers!

 

Never had to mess with a Welch plug but I recall reading clear nail polish as a sealer?

Please educate us as you figure it out...

 

L screw too rich? Thats my guess if everything else checks ok

 

MY 041 would do this years back without any of the diagnostic checks that you've already performed.
A small amount of fine saw dust had worked its way into the carb and no matter what setting the L or LA it would die after 10-15secs when warmed up. I'd guess either the float needle is sticking or the fine screen inside is partially plugged. Once the screen is cleaned retune is in order as it was set fat to compensate for the restriction

 

I had a saw that did the exact same. Was the L needle.

Had another saw that was all wonkey idle and wide open. There was saw dust all in the I thermal screen like Basod says. That one was a bit different from your symts though. It starved at WOT as well.

 

Well, I've made quite an improvement, but I don't really know exactly what it was, so that sucks. I had a little time this evening, so I pulled the carb off and disassembled it for a good cleaning. The pump diaphragm looked like it had seen better days, but for the sake of science I went ahead and completed the cleaning and reassembled everything. The metering lever was just a tad low, so I set it correctly. Nothing else looked suspicious; no buildup anywhere, screen was clean, etc.

I put both screws at one turn out. It fired and started quickly, but died almost instantly when I blipped it to the 'run' position. I tried it a couple more times and it would rev great and stay going if I gave it just a little throttle, so I turned the LA screw up and it would then do what it had previously done and ran for a short while and then die. The next time I adjusted the L screw CCW and it responded well. I ended up with the L screw at about 1.5 turns out and the saw seems to idle, rev, and return to idle in a pretty healthy manner. The idle is just a tad erratic, but nothing major. Unfortunately it was too late/dark to go out & do some test cutting, so I just put a bar & chain on it and reluctantly shelved it for the evening. Tomorrow I'll try some cutting and will report back.

 

I would of rebuilt the carb. You were already in there!!!
And sounds like it just needed an L adjustment. The 1 turn out is just a starting point to a perfect brand new saw. Yours is used. Maybe the filters are a tad dirty. Maybe the compression is not what it was new. Many factors effect tune. Including as I have found temperature. A 30 degree difference can make a huge difference.

 

I would have rebuilt it if I'd had a kit, but the 15 minutes it takes to pop it off and clean it is worth an experiment. Typically, I'd put the carb body in the US cleaner, but I was in a hurry this evening. The L screw made virtually no difference previously. Also, the compression is acceptable at 155 psi. Sort of looking like it might just have had a partially clogged low jet...

 

To me it sounded like the L was too rich at first and was loading up the saw and flooding out at idle.

But turning OUT the screw shoots that idea down?? anyway glad your making headway on thia issue.

 

Beau,
Do you know what carb is on the 064. I have a few w-69's off of o66's I can send you if you want to try them.

 

Thanks for that helpful offer! I don't know if the WJ-69 carb will work or not though. MediaCAT it shows a WJ-65 for the 064 and on this saw the carb is stamped WJ-6B?

I'll continue to try this one out and if I get to the end of my rope I may take you up on that offer. Thanks again!

 

I have a 69 on my ms650

 

Wj69 will work for an 064

 

Does stihl list the wj65 as a carb for this saw? Maybe thats an issue? How long have you had saw?

 

Yes, they list only the WJ-65. Not to get into the whole backstory, but I purchased it from an AS member who purchased it from a reputable member of both AS & FHC. They both ran the saw and didn't have this same issue I was having with the idle.

Anyways, as I mentioned it's doing well now, so I think the problem is licked.

 

I bet a kit clears up any wonky operation.

I have had some saws or weedeaters just flat out not run or act up. New kits solved the problem. Never was able to see anything wrong with old diphrams or gaskets, needle??

 

Any of the carbs from the 064-066 will interchange. The 044-460 series is the same way. Some of the 394 carbs will fit also on the 1122 series. Just have to swap shafts to get the right throttle connections.