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Bogging under load

Discussion in 'Chainsaw' started by Dale, Dec 19, 2011.

  1. Dale

    Dale AboristSite Guru

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    Hi guys. Been a while since I posted on the forum. Well I have an issue with my 028 Super. It's bogging in the cut, or "under load" as I call it. Pull it out of the cut, and it revs and responds as expected. Was just wondering if there were some simple things I could/should check prior to taking it to the Doctor. I must add, I already had the carb apart to check the diaphragm/gaskets etc...., but no change. Something has me thinking "H" side carb. adjustment if it bogs in the cut ??? I could be wrong though. Thanks fellers.
     
  2. deye223

    deye223 Addicted to ArboristSite

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    check fule line for cracks . is your air filter clean
     
  3. Brian VT

    Brian VT Addicted to ArboristSite

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    I would 1st check compression and/or remove the muffler and inspect the side of the piston and cylinder. If all looks well, then check your fuel line and filter. A small split in the fuel line will draw air and cause the lean condition you describe. Also, a soft fuel line may collapse under load and restrict fuel flow. Another fuel restriction can be the fuel tank vent not venting properly.
     
  4. redunshee

    redunshee Addicted to ArboristSite

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    In addition to other suggestions try richening the Hi speed needle a bit(counterclockwise). You want saw to kinda burble(4 stroke) out of the cut at wot then clean up in the cut. Sometimes if the H screw is too lean saw will bog in the cut.
    Bob
     
  5. Dale

    Dale AboristSite Guru

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    I'm confident on all the upfront and easy checks... fuel line soft (not brittle), clean air cleaner/fuel filter, etc... My HOPES are that the saw is not on it's "last leg" as far as the cylinder/piston. This 028 has been a real gem. I bought it used in 1991, so my guess is that it's an early/mid 80's vintage. Reckon a compression test may be in order.

    I've changed impulse line on a couple occasions also.
     
  6. Fish

    Fish Account Hold

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    When "under load" you are in the cut, so look at loose/worn out av mounts, which when under load will flex fuel/impulse line/boot etc.
    and small tears can become large when flexed, making it only starve while in the cut.
     
  7. alderman

    alderman Addicted to ArboristSite

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    Hasn't been mentioned but is easy to check. Make sure the spark screen on the muffler isn't plugged. I once fixed a saw with these symptoms by cleaning the screen. It would run like normal until I put it to the wood.

    Most likely not your issue, but worth a look anyway.
     
  8. Dale

    Dale AboristSite Guru

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    Interesting theory Fish. It is indeed and Anti-Vib (AV) which I don't think I mentioned, as I didn't think it was pertinent, but I will def. check out.
     
  9. Dale

    Dale AboristSite Guru

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    Alder.... Spark Screen is free and clear. Thx.
     

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