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Stihl 090 on the inside

Discussion in 'Chainsaw' started by fourfivefour, May 10, 2009.

  1. fourfivefour

    fourfivefour ArboristSite Operative

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    My 090 was down on a power and compression. I knew there was no scoring from previous inspection through the exhaust port. I thought the rings were worn.
    I decided to take a look at it tonight. I first fired it up and got it warm and did a compression check, 90 psi was all I got hot. I had previously saw 125 psi cold.
    I pulled the cylinder off and this what I found:
    [​IMG]

    [​IMG]

    [​IMG]
    This saw is VERY clean!!! I may have to raise my asking price now.
    Not a mark on the piston and normal looking wear in the cylinder. I checked the ring end gap and found both rings at .024 in.. I had a new Woodlands Pro piston kit so I contemplated changing the piston. I tried the new rings in the cylinder and found them at .010 in.. I measured both the old and new piston's skirt and found them both to be the same, so I decided to just install the new rings only.

    I got it back together and on the second pull it ripped the starter handle out of my hand, WOW (what happened?) it never done that before. Pushed the choke in and it fired off, idling noticeably faster so I had to back it down. It seems it's making a little more power at idle now with the new found compression. Fired it back up and warmed it up then let it cool down. I ran it again and made a quick cut through some oak, it ripped it apart. Shut it off and walked back to the shed laughing out loud. My old lady wanted to know what was so funny. LOL
    I checked compression 125 psi hot now.

    I let it cool off then fired it back, cut a cookie off a 30" oak log, this thing is unstoppable now.:chainsaw:

    Now I have to confess I did notice a slight exhaust leak noise when it was running before I took it apart. Also there was some soot around the compression release. I found the compression release valve loose. I cleaned it up and and tightened it, sprayed some brakekleen on it and the leak stopped. After I put it back together and ran it the I didn't hear the leak anymore. The slight compression leak and worn rings coupled together, I'm surprised It even ran.
    I would have taken a video but I ran out of light. I'll try tomorrow to get the video.:cheers:
     
  2. Trigger-Time

    Trigger-Time Guest

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    NICE!!!...............I will be Waiting on Video :)
     
  3. gonecountry

    gonecountry ArboristSite Operative

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    Dang that thing is clean hard to beleive the rings could be worn out, you sure the culprit couldnt just have been the compression release.
     
    bump_r likes this.
  4. blsnelling

    blsnelling Site Sponsor

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    That's what I'm thinking. I would love to have that saw, but it's just no in the cards right now.
     
  5. Bill G

    Bill G Addicted to ArboristSite

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    You said you were raising the asking price. So please elaboate.

    Bill
     
  6. fourfivefour

    fourfivefour ArboristSite Operative

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    No I'm not raising it. The price is still a $1000..:clap:
     

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