stihl 026 problems

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“Tune old saws in the wood.
Adjust the H side so that it burbles (four strokes) at WOT unloaded, and runs clean when under load in the cut. When you lift cutting pressure, it should immediately revert to four stroking. Warm up the saw before tuning it.”-John 3:16-

I’ve read that verse.
I don’t think that is how it reads.
 
I got my o24 AVS working again with a new top end. In Post #29, I promised I would show a couple of Pics, so here they are:
Srihl 024 AVS.jpg
I elected not to do anything fancy with it, just make sure that it ran well. I may have splashed on some paint here and there. After all, this saw must be at least 32 years old, made in West Germany. I measured 145 psi compression after installing the new top end. That's enough for me. She's easy to start and handles the 16" bar very well. I decided not to add an outer bumper spike. Please forgive me for that.
 
Update: looked at pioneerguy600's thread photos at the contact spring.
https://www.arboristsite.com/community/threads/stihl-026-contact-spring.170025/
Indeed my contact spring was bent, I have rebent it and now it works close enough. This thread started back in december when my saw would start but didnt run right. Took it apart, replaced impulse line, cleaned carb and replaced fuel tank line. Started it just now and damn it, same problem. Starts full choke, switch to half choke and it winds up and then dies. I will look for a camera to post a photo of inside muffler at piston, I have a feeling that there is a serious issue here unfortunately.
 
As a follow up, I looked at the plug in the borrowed 026 that I have and it had a ngk bpmr6a, the manual states ngk BPMR7A or a bosch plug WSR 6 F. What is the difference between the 6a and 7a?
 
As a follow up, I looked at the plug in the borrowed 026 that I have and it had a ngk bpmr6a, the manual states ngk BPMR7A or a bosch plug WSR 6 F. What is the difference between the 6a and 7a?
'
the difference between the 6a and 7a is the heat range.the 6 will run slightly hotter than the 7.either one will work. personally i run the bosh wsr 6f. plugs are almost like an oil thread. :surprised3:
 
couple hints:

Fuel, ignition, compression.

See if you can tell if it floods or runs out of gas. I sometimes remove the muffler and I can tell by looking at the piston cylinder if it's flooding or running out of gas and you can run the piston down and give it a little squirt of gas on top of piston and get a re-start with no choke if it's running out of gas.
Sounds like it's running out of gas at initial start or losing ignition.

I use a Briggs in line spark tester to watch the spark while a chainsaw or engine is running. (like this one at this link for $12.55)
https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=Briggs+in-line+spark+tester&_sop=15

Have the room dark for viewing spark through the little clear window. If it's losing fire try setting the air gap at the mag at .012 instead of .010. and remove the kill wire from the mag plug on terminal. If it keeps on running with the wire removed just choke to stop.

How does it act when re-starting? Like does it need choke to re-start or no-choke.

Have you pressure tested the crankcase?
 
couple hints:

Fuel, ignition, compression.

See if you can tell if it floods or runs out of gas. I sometimes remove the muffler and I can tell by looking at the piston cylinder if it's flooding or running out of gas and you can run the piston down and give it a little squirt of gas on top of piston and get a re-start with no choke if it's running out of gas.
Sounds like it's running out of gas at initial start or losing ignition.

I use a Briggs in line spark tester to watch the spark while a chainsaw or engine is running. (like this one at this link for $12.55)
https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=Briggs+in-line+spark+tester&_sop=15
-I dont have one, clearly a good investment. I will put it on the shopping list. Thanks for the link.

Have the room dark for viewing spark through the little clear window. If it's losing fire try setting the air gap at the mag at .012 instead of .010. and remove the kill wire from the mag plug on terminal. If it keeps on running with the wire removed just choke to stop.
-Spark seems good in the dark, my experience is watching various sleds with no spark or weak spark as a comparison the saw seems good in that regard.

How does it act when re-starting? Like does it need choke to re-start or no-choke.
-Only wants to start with choke and air filter, wont start with air filter off. Tried starting with gas cap off and saw sideways, it started with choke, (not a plugged fuel filter or vent)

Have you pressure tested the crankcase?
-I have no idea how to do this or what tool(s) I would need but the more I google its sounding like either the carb needs to be re taken apart and re cleaned or the crankcase has a leak which I am beliving as the carb was went through, flushed out with carb cleaner, new gaskets oem walbaro, new needle and seat. I will youtube how to pressure test the crankcase but I am thinking that I start looking for someone near Thessalon, ON that has more chainsaw experience than I do.

I appreciate your reply and we ll see how it goes as this saga continues, I will fix the saw by golly.
 
Reading back in your posts:

And to clearify it starts with choke and then runs with choke off idles and runs but wont keep a high rpm when going through wood.

Screen in carb clogged if starving for fuel (and you have to inspect closely with a magnifying glass to see such) or as stated below the choke flap in the air filter is not staying open due to the spring inside the filter assembly out of place. You can find a you tube video about the choke flap issues.


Notorious Saw for pulling choke flap closed. I've seen guys go as far as splitting the case when it was the air filter.


Your latest post: Starts full choke, switch to half choke and it winds up and then dies.

This is symptom of the choke flapper closing right after the saw starts instead of staying open.(common problem with those model saws) If you have another air filter install it and test or go to you tube and see how to fix the spring inside the air filter. If you find this is the probelem best to replace the air filter with a new.

Also make sure when it starts with choke that the kill switch wire you were fiddling with is not grounding when in run position.
 
Bought one for a friend and was told runs. I didnt inspect as I always figure something will be amiss.

Like I thought. Tuned lean and exhaust side was toast.

She lives again. Meteor piston kits was sweet. Caber rings are a no brainer. The circlips were just like oem etc so installed those too. $29 for kit


DSCF0148.JPG
s026mxx.jpg DSCF0166.JPG
 
Bought one for a friend and was told runs. I didnt inspect as I always figure something will be amiss. Like I thought. Tuned lean and exhaust side was toast.

She lives again. Meteor piston kits was sweet. Caber rings are a no brainer. The circlips were just like oem etc so installed those too. $29 for kit
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View attachment 644014 View attachment 644015
I'm jealous of your magnetic parts holders. Next time I'm at HF I'll pick up a couple. It always works out that the part I lose on the floor and cannot find is the one I am out of. Good job, JJ. Now and then these little saws are fun to work on. A new 261 runs about $600, so I never feel sorry when I get one of these vintage ones going again.
 
Hello everyone, I just wanted to give a final comment on the thread for now. The 026 that was taken apart in the winter is back together and running properly finally. I caved and took it to a local mechanic. I replaced both fuel lines and cleaned the carb and it wasnt running right. He took the saw and started with the carb, I had put the wrong screen in it, so with the correct screen and a quick once over it is running like a stihl should again.

Just wanted to say thank you for all the advice that I have been given on this thread.
 

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