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Chainsaw repair question

Post in 'The Gear' started by truck243, May 2, 2011.

  1. truck243

    truck243 Member

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    I took apart my 5 yr old poulan chainsaw(no surprise there) because of low compression (110psi) and found, yes, you guessed it, a scored piston, and cylinder. My question is, What are the removable plastic pieces inside the cylinder? I dont know much about 2 stroke engines.

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  2. CTYank

    CTYank Minister of Fire

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    There should be nothing plastic "inside the cylinder" presuming you also mean above the piston. Sounds like the engine sucked in some debris, or stuff went adrift on disassembly.

    What plastic bits are missing near the carb inlet, and how do they match up with the bits in the innards?

    I hope you know that you don't have to pull the cyl to inspect the innards- just pull the muffler. Also, compression checking for little 2-strokes can be tricky. Normally, it works like this (if you have fuel, spark, and fresh plug): 1) engine is hard to start; 2) comp. check done with known-good tester, engine warm, as many cranks as it takes; 3) a/r pull muffler and inspect piston & innards; 4) for such engines if ok, run it, else toss it.

    In fact, 110 psi would NEVER cause me to pull the cyl. (Might stimulate shopping for a replacement, though.)

    Sounds like you have a parts saw, at least for b&c. I hope you got lots of miles out of it.
  3. Mt Ski Bum

    Mt Ski Bum Member

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    I'd sell it for parts & go find a nice new Stihl saw. ;)
  4. Beetle-Kill

    Beetle-Kill Minister of Fire

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    What model Poulan? Did you like it?
  5. wkpoor

    wkpoor Minister of Fire

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    Don't know about plastic pieces inside Cyl but the P&C for some saws can be had cheap and maybe you could find them on Epay. That might be a 300.00 saw new so a 30.00 repair would be worth it. Other wise pitch and get a new one. Also depending on what the cyl actually looks like you might be able to save it with emery paper and then just put in a new piston with rings and pin. I just saved a Dolmar 5100S that way. Worked like a new one.
  6. smokinj

    smokinj Minister of Fire

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    +1 no plastic going to hold up in any jug and slug!
  7. southbound

    southbound Minister of Fire

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    any chance for some pic's????
  8. truck243

    truck243 Member

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    Its a poulan model pp4218avhd, and the parts I'm asking about are inserted into the cylinder, one on each side, below the piston. They are made of plastic or something similar.
  9. oilstinks

    oilstinks Feeling the Heat

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    Had one of them saws and it was nothing but trouble. I put almost as much money into it working on it than i paid for it. When it ran i loved it but it was a shotin the dark everytime i fired it up. Dont know what your refering to but if theyb are "plastic like" thay are probably the material that phenolic pistons in brake calipers are made of i would think
  10. HittinSteel

    HittinSteel Minister of Fire

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    I am at a total loss. Nothing is inserted in to a piston/cylinder/crankcase that is made of plastic. Gonna have to second Southbound's request for pictures.
  11. TreePointer

    TreePointer Minister of Fire

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    Maybe something broke off at the carb and/or intake tube/boot and ended up inside the cylinder. As others have stated, pics are needed on this one.
  12. southbound

    southbound Minister of Fire

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  13. truck243

    truck243 Member

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    Thanks for the "link" southbound. Strange name for those parts "transmission inserts" I'm wondering how to inspect them. and what their function is. I dont know much about these engnes, but I'm determined to learn. Where can I get repair/rebuild info. I'll fix it in my spare time, but I agree, I'm gonna buy a Stihl! Whats a good model for a home owner?
  14. truck243

    truck243 Member

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    P. S.- I'm having problems posting photos, I've tried at various resolutions, but no luck, I'll have to work on that too!
  15. HittinSteel

    HittinSteel Minister of Fire

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    Well I'll be darned.....what in the heck are those things for?

    Truck, a 250 Stihl is a nice little saw for a homewoner.
  16. fyrwoodguy

    fyrwoodguy Feeling the Heat

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    just another reason to stay away from the big box stores and support your local servicing dealer
  17. mecreature

    mecreature Minister of Fire

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    Keep this thread updated Truck. I use a PoulanPro... cause I have one
    same saw.. it works fine for me, at the time.

    I have used the diagrams on below for ref.




    ereplacementparts.com
  18. Mt Ski Bum

    Mt Ski Bum Member

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    +1- i recently bought a 250, & it's a great saw! Great power/weight ratio. I also love Stihl's "master control switch"- one switch controls cold start (full choke), warm start (partial choke/half-throttle), run, & stop.

    Just make sure to switch the control to "warm start" after 3 pulls on cold start- even if the saw didn't "sputter" or "cough" (or whatever you prefer to call that sound)- if you keep trying to get it to "cough" on cold start after 3 pulls, you'll flood the engine (I learned that the hard way after pulling 5 or so times on cold start when it wouldn't "cough" :red: )
  19. heat seeker

    heat seeker Minister of Fire

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    My guess is that those "transmission" parts are to guide the piston skirt and reduce friction. Years ago, a friend of mine bought Teflon coated pistons for his motorcycle. He claims that it ran faster after that. The skirts of the pistons were coated with green Teflon, and we had to hone the bores out to accommodate the oversize.

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