juniormarbles
ArboristSite Lurker
By "backing out" you mean CCW, correct? (CW would mean turning the screw to its stop, starving idle fuel.) How many turns "backing out"?
Stihl 026: Idle Speed Too High
- Thread starter juniormarbles
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Chainsaw Jim
CJ Saws, LLC
Yes, ccw..just enough for the idle to come down. It should be less than 1/8 turn. It'll either fix your idling problem, expose a leak, or help you determine a bad clutch.
juniormarbles
ArboristSite Lurker
Turning the idle mixture screw out, as you suggested, dropped down the idle to a "normal" level. Then, pulling the throttle all the way in revved up the engine to the max within a second, and it held at max RPM, and did not go higher if I kept the throttle wide open for five seconds.
But this does not "fix my idle problem". The engine runs too rich if I oversaturate the idle mixture, even if it brings down the idle speed. It should be adjusted with the speed, not mixture screw. So what does this experiment tell you as to the cause?
But this does not "fix my idle problem". The engine runs too rich if I oversaturate the idle mixture, even if it brings down the idle speed. It should be adjusted with the speed, not mixture screw. So what does this experiment tell you as to the cause?
Chainsaw Jim
CJ Saws, LLC
What's too rich? How are you determining this?
juniormarbles
ArboristSite Lurker
Every 2-stroke engine I have ever worked on (this applies similarly to 4-strokes) has a sweet spot for idle adjustment: either side of it the engine runs rough, stinks too rich, stalls too lean or loses power. I's in every owner's manual I've ever read: adjust to highest idle, then add 1/8 to 1/4 turn towards richer, THEN set idle speed with the speed adjustment
In my case, it took about 3/4-1 full turn to bring the idle down with the idle mixture screw (as you suggested for the test), with an idle speed screw that's already non-functional (in its lowest setting). So, I don't regard this method to lower idle speed with the idle mixture screw an acceptable solution, especially with an idle speed adjustment screw that no longer works.
Back to my question: What do you think the test result revealed? What is my engine's problem?
In my case, it took about 3/4-1 full turn to bring the idle down with the idle mixture screw (as you suggested for the test), with an idle speed screw that's already non-functional (in its lowest setting). So, I don't regard this method to lower idle speed with the idle mixture screw an acceptable solution, especially with an idle speed adjustment screw that no longer works.
Back to my question: What do you think the test result revealed? What is my engine's problem?
Another vote here for a bad flywheel side crank seal. Don't use it until it's fixed!
Chainsaw Jim
CJ Saws, LLC
Mentioning how many total turns out on the low would have been a good place to start.
Take Brad's advice, but change both seals.
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Why make guesses on if/where there is an air leak?
It is easy to test on this model.
It is easy to test on this model.
Chainsaw Jim
CJ Saws, LLC
Most saws that old need their seals changed by now. Especially with the introduction of ethanol fuels.
juniormarbles
ArboristSite Lurker
Which seals are suspect? More than one? I can certainly change them if I knew which one(s) to focus on.
Chainsaw Jim
CJ Saws, LLC
The crankcase seals, one on each side, but you'll need a special seal puller and installation punch. Most folks use an improvised method for removal, but the installation is too important to risk without the correct tool.
Sounding like a broken record, but you simply need to strip that saw down to where you can see the crank seals, clean the case up well with degreaser & hot water, and then find/buy the two (flywheel & PTO side) seals for it.
Then take it all to your local Stihl dealer & have them replace the seals. Then have them do a pressure & vacuum check to see if anything leaks.
Seals are 9640 003 1190 & 9640 003 1600.
Call the dealer(s) ahead of time, to make sure that they have the OEM Stihl seal puller & the correct jaws for the 026 first, some do not.
You’ll spend a little, but save a lot of money in the long run.
Then take it all to your local Stihl dealer & have them replace the seals. Then have them do a pressure & vacuum check to see if anything leaks.
Seals are 9640 003 1190 & 9640 003 1600.
Call the dealer(s) ahead of time, to make sure that they have the OEM Stihl seal puller & the correct jaws for the 026 first, some do not.
You’ll spend a little, but save a lot of money in the long run.
juniormarbles
ArboristSite Lurker
Thank you Randy and all for excellent advice. I will proceed and report back.
That would nice, but I've never used a dedicated insulation tool.
With that said, the 026/260 flywheel side seal is one of the most difficult to replace, simply because it's so small.
Chainsaw Jim
CJ Saws, LLC
If you think the 026 is bad without the right tool, you should revisit the fw side on the 044, lol.
