024 Stuck Ring?

[nedsim]

Several months ago I'd been using my Stihl 024 for a few hours. I shut it off for perhaps 1/2 hour while hauling brush. When I went to restart it -- nothing. I set it aside and used another saw for the rest of the day. I got back to it a few days later, and still no sign of life, and it seemed to pull over awfully easily. I don't have a small engine compression tester, but used what I had by comparing readings to an 026. The 024 was less than half the 026. Set it aside again and when I came back to it a week or two later, it started right up, and though I didn't try cutting with it, it seemed to run fine. Next time I tried it wouldn't start. Decided today it would be a good cold weather project, so brought it into the shop and tried again -- started with a couple pulls, sounds OK, idles, though I still haven't tried putting a load on it.

Peeking into the exhaust port, the piston and cylinder look pristine. I bought the saw new around 1987 and it's never been abused, except perhaps a little fuel neglect. It's been fed only canned fuel, 100LL, or ethanol free fuel for the last 5 or 10 years.

My questions:
-Is it unusual/possible to have an intermittently stuck ring?
-What are the typical causes?
-Is there anything else that I should be looking for before tearing it down?
-Any reason not to test it under load if it'll run tomorrow?
-I'm not a fan of elixirs like Seafoam, etc., but, if it is a stuck ring, is there anything worth trying before I start tearing into it?

 

[Mad Professor]

Post a picture of the piston/rings through the ex port.

If it is reading 1/2 the compression of a running 026 something is up.

 

[Chevboy0167]

No idea if all this stuff works but......

https://xado.us/collections/automob...roducts/anticarbon-anti-carbon-engine-cleaner

https://www.liqui-moly.com/en/us/valve-clean-p000041.html#2001

http://www.motorvacsalesandservice.com/MV4.html

The idea here is to remove sparkplug, bring piston up to top dead center and drop some cleaner through plug hole and let it set for a few days or even a week. Dump out or flush out, then repeat the process a few times.

Or cheaper yet, try a mixture of ATF, (automatic transmission fluid), mixed with diesel fuel to the same method as above. Plus, you could add a bit of ATF in your mixed fuel and 2 stroke oil. Run it hard and hot for a few tanks.

Kind of just spit balling here...... results may very!