026 not playing nice.

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Rockjock

Rockjock

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Gentlemen I have an odd problem with an 026. The unit came to me with great compression and ran once I put fresh mix in it. The issue was I was unable to adjust the idle. The LA screw did nothing, more or less. So it was given a vacuum and pressure test which it passed. The only issue was the tank vent and that was changed out as was the fuel line and carb kit. ( carb was changed out and it did the same thing. Idle is constantly at about 2600 -3000 rpms. ) Saws starts up as it should and all seems ok just the idle. I can back off the LA screw all the way and it does not change the idle. Now I did notice on the crank side the bearing was " wet " this could have been from the cleaning it got int he parts washer but both vacuum and pressure tests were positive. Intake manifold and impulse line also check and they were in good condition.

any ideas gents?
 
HarleyT said:
Can you adjust the idle up/open, with the air filter off, and watch the throttle plate. Then watch it as you back it off,
and watch the throttle plate move. Keep backing it off, and watch the plate, see if it is binding. You might need to loosen and reposition the throttle plate so it is centered better.
Click to expand...


I will try that in the am.. but I did try another carb and it did the same thing. But I will check it again.
 
This is probably a shot in the dark, but if for some reason the air flow is restricted by the air filter it could be a cause and another and the only other thing I can think of would be the throttle linkage is not returning to the correct position. I was going to say that the throttle butterfly was stiff and not closing as it should, but with two carbs. that is not likely. Change the first statment. That would cause it to flood. It takes a while for me to get everything in sync.
When you find out what is wrpng I would like to know since I have two 026 saws. Tom
 
tomdcoker said:
This is probably a shot in the dark, but if for some reason the air flow is restricted by the air filter it could be a cause and another and the only other thing I can think of would be the throttle linkage is not returning to the correct position. I was going to say that the throttle butterfly was stiff and not closing as it should, but with two carbs. that is not likely. Change the first statment. That would cause it to flood. It takes a while for me to get everything in sync.
When you find out what is wrpng I would like to know since I have two 026 saws. Tom
Click to expand...


Will do! the air filter is also new, so I am perplexed . Linkage is also in spec but the saw runs fine it is just I am unable to adjust the idle. Backed out all the way one would think the saw would just stall out and die. Carb is a WT 194, I may swap it with one off my other 026 and see how it runs.
 
Vacuum test the saw for an air leak. Can't diagnose any further until you verify the engine is tight, no leaks. Pay close attention to the flywheel side crank seal and bearing.
 
I know you vacuum tested it, but it still sounds like an airleak somewhere.

Pull your handle cover off (you have to do anyway to swap carbs) and see if it does the same with the linkage wire removed.

Try spraying some WD40 around the carb/boot interface. Could leak there as well.
 
My tip would be check the cylinder screws. And after that the cylinder gasket.

7
 
Thanks gents. The carb linkages were fine, intake boot is good, what is odd is that it holds pressure and vacuum as well without issue. Bolts nice and tight. Seals are cheap so i will swap those out this week.
 
Welder56 said:
Have you tried vac testing while rotating the crank? I'm not really sure if it's an air leak or not but just throwing the idea out there
Click to expand...

Yup tried that as well. I will just order the seals Monday, get them Tuesday and install them. As I said 1 seal did look " wet " so better safe than sorry. Oddly it did run fine after I did the lines and carb kit, was able to adjust the idle but then got it home, and it was acting the same again.. idle 2600 WOT was about 11-12k so it is set to run rich until I sort out the issue.
 
Was the spark plug in it when you vac/pressure tested it? If not, then maybe an air leak in the plug?
 
Chris-PA said:
Was the spark plug in it when you vac/pressure tested it? If not, then maybe an air leak in the plug?
Click to expand...


Plug was in the unit.. also this 026 has no decomp. Soapy spray was applied to all areas that could leak.. I am thinking the seal is the issue. Besides the unit did sit for a very long time and was uber filthy so better safe than sorry. I will re-pressure test it spin the crank and slather it in soapy water as well.
 
I know you stated the linkage was in spec but I once had this problem that carb swapping would not fix, it was the throttle linkage holding the butterfly open, not letting it come down completely closed. I had a few spare linkages and swapped in another, that solved the problem. Looking at them I could not see the difference but there was just enough that the saw could not be brought down to idle.
 
pioneerguy600 said:
I know you stated the linkage was in spec but I once had this problem that carb swapping would not fix, it was the throttle linkage holding the butterfly open, not letting it come down completely closed. I had a few spare linkages and swapped in another, that solved the problem. Looking at them I could not see the difference but there was just enough that the saw could not be brought down to idle.
Click to expand...
I agree with that possibility, which is why I suggested observing the throttle flap while moving the adj. screw. Your eyes are one of the best diagnostic tools available.
 
Looking at the throttle plate on the WT-194 I notice a notch in the plate at the idle ports. Any chance the notch in your plate is large enough to allow for that idle speed with the plate closed all the way?
Next question: How far have you opened up your L needle to get a good clean idle? If it is opened up way past what is recommended for that carb (like, say, 2-1/2 turns in lieu of the recommended start point of 1 to 1-1/2) then I would think you do have an air leak somewhere.
 
HarleyT said:
I agree with that possibility, which is why I suggested observing the throttle flap while moving the adj. screw. Your eyes are one of the best diagnostic tools available.
Click to expand...

couple thoughts:
On some of them stihls you can get the engine warmed up then just pop off the throttle linkage at the handle while it running, or get it warmed up, kill the engine, remove the throttle linkage then restart and test idle. If it's still the same fast idle he has most likely a air leak, maybe a hairline leak at the manifold boot. Also some of them Stihls have a little metal ring behind the carb in the mouth of the intake boot to hold the rubber intake sealed in place at the carb base, make sure it's being used.
He says the cranjk seals are good, maybe. (I usually get or watch for a erratic/rough idle when crank seals are bad)
 
Used a different linkage same result. It looks like the buttery does move so that is ok. I have the seals on order so I am sure that will solve it. I have a spare manifold I can try as well. Clamp nice and tight. fun fun
 

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