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Tearing down my JMSSAWS, one by one...

Discussion in 'Chainsaws' started by SOS Ridgerider, Aug 24, 2017.

  1. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    Ok guys, I have started tearing down the saws I had done by JMS. I'll try and tear one down every night after work. I have 6 of them... Ugh...
    I know what you all think by now: "Who's dumb enough to have 6 saws done by him?" Well, that's me. I'm that guy who was way too naive and had just gotten into saws.

    I'll tear them down, and share both the good and the bad. I'll need some help I'm sure, as I'm no professional saw mechanic. I'm also looking forward to constructive criticism, help and suggestions.
    If all you're going to do is to tell me how dumb I was, please refrain from doing so, as I already know that, and it is in no way helpful to anyone.

    The first saw I've torn down is my Dolmar 7910. A favorite saw for me.
    I bought the saw new about a year ago, and ran about 2 tanks through it before sending it off.
    It came back running good, and was stronger than before I sent it away. I was happy.

    The first pics are of the piston, and shows a few small streaks on both the intake and exhaust side.
    I can feel them with my fingernail. What are some of you guys' opinions? This is after 2 tanks by me, maybe a few tanks by him, then followed by probably 2-3 tanks again by me after I got it back.

    IMG_3671.JPG IMG_3672.JPG IMG_3673.JPG IMG_3674.JPG IMG_3681.JPG
     
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  2. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    The next pics are of the cylinder. There are only a couple of small things I can feel with my fingernail in there. Intake and exhaust side look about the same.
    The base has been "treated", in some way. Saw still had a base gasket.
    IMG_3676.JPG IMG_3679.JPG IMG_3682.JPG
     
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  3. dall

    dall Soon to be banned fart knocker.

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    sondre what is the area below port in second cylinder picture ?
     
  4. RI Chevy

    RI Chevy Stihl Runner

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    Sorry Sondre. On the positive side, at least you caught it early enough to still fix.
    I am not liking those streaks.

    Sent from my SM-G930V using Tapatalk
     
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  5. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    Other than that, the only things I noticed were a sloppy muffler mod with burrs hanging off of it, and a bolt for the chain brake that was way too short, and the whole brake flag was loose. Threads are stripped in the front of the hole, but I can fix that easily with a longer screw.

    I did the muffler mod myself, except for the second outlet, before sending it off, so he had less work to do than usual.
     
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  6. Lightning Performance

    Lightning Performance Knuckle dragger swinging member

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    Tool marks.
     
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  7. Lightning Performance

    Lightning Performance Knuckle dragger swinging member

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    Gasket match the jug and case. The sander struck again. True it up.
     
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  8. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    I assume you're thinking about the black spot in this pic?
    IMG_3679.JPG

    The 7910 has an SLR muffler, and has a tube sticking into the exhaust port from the muffler. There is a guide channel in the top and bottom of the port, with a ridge on the piece that sticks into the port. The black spot you see there is what's left of the upper channel from opening the exhaust.
     
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  9. dall

    dall Soon to be banned fart knocker.

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    inside the cylinder sondre about 1/2 to 3/4 inch theres a horizontal line
     
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  10. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    Gotcha. Not sure what it is, but it can't be felt with a fingernail. Completely smooth. There are also some wavy lines from a burr hitting the plating there. The only streaks I can feel are on the pto side of the exhaust port.
     
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  11. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    The jugs on all the saws will be sent out to be checked and trued, unless they're garbage.
     
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  12. Lightning Performance

    Lightning Performance Knuckle dragger swinging member

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    What do the port edges feel like?
     
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  13. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    They feel ok. Most are smooth, and seem beveled. None are real sharp.
     
  14. Lee H

    Lee H ONE OF THE GREATEST!

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    Sorry to here about your saws Sondre. Glad this whole JMS thing
    was found before any damage occurred.
     
  15. SOS Ridgerider

    SOS Ridgerider Pinnacle OPE Member

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    Thanks Lee. I hope the other 5 are ok too.
     
  16. tree monkey

    tree monkey ONE OF THE GREATEST!

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    [​IMG]

    this is not normal
     
  17. huskihl

    huskihl Just an ordinary member

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    7910 has an extension on the cylinder , so it was probably done on a lathe. Piston looks fine to me.
     
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  18. tree monkey

    tree monkey ONE OF THE GREATEST!

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    it has been posted that he can't cut them true on a lath either, best to have it checked.
     
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  19. Deets066

    Deets066 AKA Deetsey

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    There is something goin on with the cylinder wall, as Tree Monkey said... it's not normal
     
  20. Frank bierce

    Frank bierce Pinnacle OPE Member

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    What causes the cylinder bore to look like that? The plating to me almost looks "uneven". I see
    The light reflecting at different angles...

    IMG_3298.JPG
    This is what I'm used to seeing...but I haven't gotten into a smidge of the cylinders most of you fellas have...
     
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