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Saw That Won't Four Stroke

Discussion in 'Chainsaw' started by Freudianfloyd, Feb 14, 2020.

  1. Freudianfloyd

    Freudianfloyd ArboristSite Guru

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    I recently picked up a few 029's that were not running. On the first saw, it was obvious it needed a new fuel line, but everything else looked good. No I did not do a pressure/vac test yet. It was in such good condition and ran somewhat when I got it so it appeared to be an easy fix.

    Anyway, I put a new fuel line and filter on it last night, and the saw fired right up and seemed to run and idle good. However, I could not get the saw to 4 stroke when trying to tune the carb. I put it down and went to work on something else. After it cooled, I tried to start it again, and it fired up on the first pull. However, it still would not 4 stroke. And this time, when revving it up, it would also bog at higher RPMs.

    So my question is, besides a leak test, what do these symptoms most likely mean? I was thinking since the fuel line was in such bad condition, it's possible the impulse line isn't much better, maybe it is sucking air? Carb rebuild needed?

    Also, I did pull the muffler back off to check for any scoring, and it was perfect thankfully.

    Any ideas?
     
  2. MACHINE

    MACHINE ArboristSite Lurker

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    Always vac n pressure test a unknown saw

    Sent from my SM-G955U using Tapatalk
     
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  3. Mad Professor

    Mad Professor Addicted to ArboristSite

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    Did you have limiter caps off when trying to tune? Reach the limit?

    Check for sawdust under carb covers keeping the diaphragms from working, and the inlet screen on the carb.
     
  4. MontanaResident

    MontanaResident A Stihl Fanatic

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    My 461 4 strokes and is easily recognizable. The 290, not at all. The 290 is going into its 9th year of service, SO 4 stroking is not the be'all of diagnosing a chainsaw.
     
  5. cuinrearview

    cuinrearview Red saw lover

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    You need to finish your fuel system overhaul with a carb kit. I've seen some immaculate saws on the outside full of crud inside. And vice versa.
     
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  6. Freudianfloyd

    Freudianfloyd ArboristSite Guru

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    Yeah, it's probably a good idea. I did take it apart and clean it, but it may be worth getting a kit for it as well.
     
  7. Freudianfloyd

    Freudianfloyd ArboristSite Guru

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    Yes, limiter caps are still installed.
     
  8. cuinrearview

    cuinrearview Red saw lover

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    Those gotta go too. Still some work to do on this one FF...
     
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  9. Freudianfloyd

    Freudianfloyd ArboristSite Guru

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    Yeah. I just wasn't in the mood to do too much last night. This weekend I will probably give it another go.
     
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  10. Canyon Angler

    Canyon Angler Addicted to ArboristSite

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    My 361 has those miserable limiter caps and I have the Stihl tool to pull them, but I always put them back on/in when I'm done (fortunately I don't need to adjust carb almost ever).

    I think it was my dealer who told me you need to replace the caps after adjusting the carb (to keep things from moving, maybe?).
    Is that not true? Is there any reason the caps need to be put back on/in? Could save me some hassle...
     
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  11. Brent Nowell

    Brent Nowell Addicted to ArboristSite

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    If your turning the high out almost to the point where it will fall out and it’s still not four stroking it’s either

    clogged h jet
    Or
    Air leak
     
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  12. dmb2613

    dmb2613 Addicted to ArboristSite

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    He hasn't removed the caps yet. after he pulls them I bet he can get it to 4 stroke
     
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  13. Freudianfloyd

    Freudianfloyd ArboristSite Guru

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    Yes, I still need to remove the caps. I will do this next.
     
  14. Totembear

    Totembear WoodAholic

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    Because thats what Stihl tells em. It dont keep anything from loosening up, just from tuning correctly, especially if you have a modded saw. EPA crap...
     
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  15. hardhat

    hardhat ArboristSite Operative

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    While you are in the carb, check out your metering lever. I have overlooked this for years and only recently researched it. If all else is good with carb, if metering lever is set too low (below floor of carb) it can cause saw to starve under high load from needle not opening enough to allow enough fuel into carb. If lever set too high, can flood saw due to needle not closing fully (like happened recently on my 034). I think there is probably a somewhat narrow range of settings that will work properly, but level with floor of carb seems to be right spot for most.


    May just be crap in carb...
     
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  16. aokpops

    aokpops Addicted to ArboristSite

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    Never ran a four stroke chainsaw . Bought a few leaned them to two stroke .
     
  17. rupedoggy

    rupedoggy Addicted to ArboristSite

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    Don't come on here complaining about it not four stroking.............
     
  18. Jkstihl

    Jkstihl Chainsaws make me fap.

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    Well if it idles good i doubt its an airleak. Pull the limiters as mentioned and set it with a tach if you have one.
     
  19. drf255

    drf255 BAD CAD

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    I cut the stop tabs off that limit them and then reinstall. It’s not to stop needle movement, it’s to help guide your screwdriver to the adjustment screws. Carbs with limiters generally have tiny screw heads to fit the limiter tabs. Most are nearly impossible to find with your screwdriver once you pull the tabs and reassemble the saw.

    And to FF, pull them caps. While the carb is off, pull both sides apart and take a peak. If you opened the muffler, you’ll need to fatten her up past what the limiters will allow.
     
  20. Corncob

    Corncob ArboristSite Lurker

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    :mad::chainsaw:
     

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