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026 Stihl surging and bogging.

Discussion in 'Chainsaw' started by Ryan_289, Mar 13, 2019.

  1. Ryan_289

    Ryan_289 ArboristSite Lurker

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    My new to ne 026 Stihl developed an issue this afternoon. This saw sat up for a while before I bought it. I put fresh gas in and it ran like a top cleaning some fence rows out for an afternoon. This evening after running perfect for a bit I noticed the idle creeping up faster than normal and bogging and surging in wood. I found this YouTube video that sounds like mine.

    .

    Carburetor? The only thing that's changed from the other day was I put a brand new stihl OEM air filter on it.

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  2. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    Take the carb out and at least clean it internally, suggest you install a new kit in it but it may just need a cleaning, fine screen inside may be getting clogged up with debris.
     
  3. brock1994

    brock1994 ArboristSite Operative

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    You'll have to adjust the carb for the higher air flow that it's now getting. I would imagine the old filter was gunked up.

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  4. Ryan_289

    Ryan_289 ArboristSite Lurker

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    I'll take it out and give it a cleaning. The only other thing I could think of was on the new filter when I got it, some of the flannel had been glued to the mounting surface. I scraped off the majority of it but there is still some left. Could this not be sealing up properly?
    Anyone have the initial carb settings for this saw?
    [​IMG]

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  5. brock1994

    brock1994 ArboristSite Operative

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    I would try running the old filter to eliminate that causing it. I would bet that you have the non adjustable H jet carb, correct?

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  6. brock1994

    brock1994 ArboristSite Operative

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    The reason I say that is I had the same issue and you cannot get the carb to tune correctly since the H jet is fixed. I changed the whole set up to a wt194 but before I did I just ran the older filter and it worked fine dont ask me why but it did.

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  7. raybow1

    raybow1 ArboristSite Operative

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    Take your air filter off once it is warmed up and try running it without. If there is a huge difference then what you have is a soft or stretched choke spring on the air filter and it is partially closing when more air flow is required. It would also surge and cause it to run faster as it may be partially closed meaning its like a half choke. It may be that it came unhooked also. Just a thought.
     
  8. SteveSr

    SteveSr ArboristSite Guru

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    Be careful! Unstable idle and surging can be the sign of an air leak, which if left uncorrected, will burn-up the saw. This saw is old enough to need crank seals, impulse line, and/or intake boot. Best to do a pressure/vacuum test before going much further.
     
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  9. Ryan_289

    Ryan_289 ArboristSite Lurker

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    The carb does have an H adjuster screw. I hate to run the old filter, the reason I bought a new one was when I was trying to clean the old one I blew a tiny hole in it.

    Where is the choke spring? I'm fairly mechanical but have never been into one of these saws.

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  10. Huskybill

    Huskybill Addicted to ArboristSite

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    Note, I wash my older filters with ether if there gummed up that bad. Oiled wood chips can clog them up on the older saws. I shake them in the wind to dry.
     
  11. raybow1

    raybow1 ArboristSite Operative

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    It is inside the air filter. But try the no air filter test first and make sure it is the air filter before messing with any of that. You can also move the lever on the air filter by hand and make sure it has full open and close travel with sufficient tension.
     
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  12. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    The air filter not sealing tightly would not cause a surging problem, might let fine dust into the carb throat but a good cleaning of the mating surface should fix that up. The inital setting is one turn out on both needles on a 026 carb, the L will usually tune in at less than one turn out, the H usually at just slightly more than a turn out. Mine run best at L=7/8 turn out, H= 1 1/8 turn out. The OEM filters do not have a problem with the choke flap springs like the aftermarket filters do but a check on it seating properly won`t hurt.
     
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  13. raybow1

    raybow1 ArboristSite Operative

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    It is an easy test to pull air filter and run without. The reason I suggest this is because in the post he suggests that is the only thing that changed and it was running good before the swap. Also don't overlook the tank vent. When it starts acting up, crack the fuel cap and see if it settles back in.
     
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  14. drf255

    drf255 BAD CAD

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    Could be anything.

    Change spark plug. Run without air filter next. See what happens.

    Could also be the fuel line/filter/carb. Tank vent possible, but rare.

    Air leaks usually cause idle issues. If the saw idles just fine and has no issues coming down to a regular idle after a cut, I doubt it’s an air leak.

    Sometimes it’s just quicker to pull muff, check piston and do a vac test just to eliminate that whole set of problem. Over the years the symptoms of an air leak have never ceased to amaze me.
     
  15. Wood Doctor

    Wood Doctor Edwin

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    My carb soak idea might work here also. Remove the carb and soak it submerged in mixed fuel inside an empty jar for about 36 hours with the lid on loosely. Then see if that makes a difference. Many times I have found that it does. Also, be sure that the fuel filer (pickup body) isn't blocked up. Replace that also.
     
  16. Ryan_289

    Ryan_289 ArboristSite Lurker

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    I went by the dealership today and picked up a new fuel line and filter. I'm going to replace that, clean the carb, and see what happens. They told me they could pressure test it for me but don't usually replace crank seals. I'm sure its costly to have them do it.
     
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  17. Ryan_289

    Ryan_289 ArboristSite Lurker

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    Well I went to change the tank line but they sold me the wrong line. Mine is the smaller straight line instead of the larger bent line. The guy said it would work but the grommet is to big on the new one. Either way, my old one looks fine and is still very pliable. Took the carb off and cleaned it. It looked pretty clean. I fired it up and lowered my idle some. It will be tomorrow before I can cut anything. This thing is super clean, I may have been the first one to take the top cover off. All the carb boot lines and impulse lines look good and soft. Piston looked brand new looking in from the carb throat.[​IMG][​IMG]

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  18. SteveSr

    SteveSr ArboristSite Guru

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    The best thing to do with these is to just drill out the tank with a 15/32" bit. There is access through the top of the carb box once you remove that metal cover. I have done several like this. The old fuel line is likely NLA while the new one is the same as used on the 260 and should still be available for a while.
     
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  19. sb47

    sb47 Addicted to ArboristSite

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    Try some VP fix-it-fuel. It worked for my 290 and made it run like new again. Replace the plug as well.
     
  20. SteveSr

    SteveSr ArboristSite Guru

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    Future upgrade... Compensating carb (Wt-426) and the bigger , wider air filter. Your carb is convertible if it is a Wt-194 to a WT-394 if you can find a metering cover with the snorkel.
     

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