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Stihl MS250 Too High of Compression?

Discussion in 'Chainsaw' started by parrishturf, Dec 13, 2011.

  1. parrishturf

    parrishturf ArboristSite Operative

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    Has anyone ever seen a stock MS250 or any stock stihl with 190psi of compression?

    The saw is about 2 years old, light use. The piston and rings are very shiney. No carbon on top or on roof of cylinder. The exhaust is black but no build up. The exhaust side of the piston is a warm gold. Stihl oil has been used.

    The owner is complaining of hard to pull start. The saw runs and starts great.

    Is it possable an incorrect piston could have been installed?

    If it is I would love to put one in all my 250's!!!

    Thanks for any assistance.
     
    Last edited: Dec 13, 2011
  2. Saw Dr.

    Saw Dr. Junk Collector

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    I have plenty of engines with REALLY low compression that I'll be glad to swap him. I'll even do the labor for free. I can probably find one with at most 65 PSI.
     
  3. jus2fat

    jus2fat Two Harley Fatboys

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    Nope..!! 160-170 Max..!!

    Is this thread a farce..?? I guess I'm just too gullible..:msp_huh::dunno:
    :cheers:
    J2F
     
  4. parrishturf

    parrishturf ArboristSite Operative

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    No farce, the saw my blow tomorrow, but it cuts like crazy now. I have no clue...
     
  5. albert

    albert Addicted to ArboristSite

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    Too much carbon will do that, check the piston top and combustion chamber.
     
  6. sps3172

    sps3172 ArboristSite Member

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    He checked....it clearly says that in the OP.
     
  7. SawTroll

    SawTroll Information Collector

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    It wasn't that clear, quite easy to misread actually.......:smile2:
     
  8. Brian VT

    Brian VT Addicted to ArboristSite

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    Ask him if he's drop-starting it. If so, show him how to start it on the ground with his foot in it or with the rear handle between his thighs.
     
  9. sachsmo

    sachsmo Addicted to ArboristSite

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    Could be sucking bar oil?
     
  10. albert

    albert Addicted to ArboristSite

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    I missed the "no carbon". What ratio mix is he using? Could your gauge be off a little? Sounds like it was broken in "right", show the guy how to start it and tell him to be happy.
     
  11. homelitejim

    homelitejim Full of Scrap

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    I just picked up a well used 025 that runs like a champ and has quite a bit of compression, I have not put a gauge on it but it will pull the starting handle out of my hands if I'm not paying attention.
     
  12. parrishturf

    parrishturf ArboristSite Operative

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    Thank you for the responses. I agree the saw runs great, but when your helping old men with ideas of their own its hard to say I wish I had 190 pounds of compression.

    The oil tank statement is interesting. I can see where that might up compression if it made it up onto the rings. The muffler was oily and wet. The fuel oil is 50:1 Stihl, last thought if it was bar oil in enough quantity to get on the rings the saw should smoke.

    Any way thanks for the thoughts!
     
  13. RAMROD48

    RAMROD48 Addicted to ArboristSite

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    That would have to be some puddle of oil for a MS250 to have a "bar oil leaking in and causing high compression problems"...

    Like enough for the seals to be swimming in it...(its a clamshell, ladies)...
     
  14. parrishturf

    parrishturf ArboristSite Operative

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    Your right!:hmm3grin2orange:

    6 beer's no supper and a keyboard! My bad...
     
  15. DarkTimber

    DarkTimber ArboristSite Operative

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    What kind of Stihl oil regular or synthitc, had an 025 years ago that was a real knuckel buster never checked compression but was using regular Stihl oil. I changed to synthitic
    oil and this made it much eaiser to start and ran great and still runs great as far as I know ( I gave it to my dad when his cheapo Mac top handle died on him.)
     
  16. parrishturf

    parrishturf ArboristSite Operative

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    Orange bottle Dino' oil.
     
  17. BiodieselNC

    BiodieselNC ArboristSite Member

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    Maybe this saw has a popup :)
     
  18. parrishturf

    parrishturf ArboristSite Operative

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    Now its happening to me!!!

    Ok. This is how my life goes.

    I had a large petrified maple to block down today and chose to climb with an MS250 with low miles. This is one of my saws. I was curious about the compression and just grabbed it. It always cranks on the first pull, but, OMG that thing is hard to pull in a tree, I sware it has the same high compression as the saw in my OP. It cuts great for a homeowner saw but I had become spoiled at the ease of other saws. :hmm3grin2orange:
     
  19. homelitejim

    homelitejim Full of Scrap

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    everything is harder in a tree, not a conclusive test.
     
  20. parrishturf

    parrishturf ArboristSite Operative

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    And I weigh more in a tree too...:biggrin:
     

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