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Stihl 34MM Piston Help!

Discussion in 'Mechanic and Repair' started by Hydrauk, Mar 27, 2008.

  1. Hydrauk

    Hydrauk LawnSite Member
    Posts: 2

    Hello, I am trying to re-build a Stihl FS 80 Trimmer. The cylinder wall is fine. But the Piston and Rings are scorched. I am trying to locate a 34MM Piston Kit. I need the Piston, Rings, Wrist Pin, and Wrist Pin Keepers. This Engine is the 4137 series, found on many Stihl models.
    34MM Piston, 28MM stroke. 1.55 Cu In. The E-bay search and Google are not getting many results. Can anyone give me some better leads? Thanks in advance for your time.

  2. jkason

    jkason LawnSite Senior Member
    Posts: 548

    You also need to get the cylinder (jug). If you don't, you wasted your time. Don't try to "polish" the cylinder, it won't work. (20 yrs experience).

    Try searching for "cylinder kit" and your model.

    Compare parts price and your aggravation vs. buying a new one. You may be right on the border.
    Usually, smaller trimmers (i.e., the homeowner units) aren't worth the trouble.
  3. sawman65

    sawman65 LawnSite Senior Member
    Posts: 751

    the fs 80 is a pro unit and you can buy the parts you need sans the jug and i have built many with good results but you need to go to a dealer for parts. but with the time and cost of parts sthil offers a short block for the unit. i think it would cost like 20%more but well worth the cost. frist thing you need to do is find out why it tore up in the first place no use throwing money at it just to have it happen again
  4. kayeproperties

    kayeproperties LawnSite Member
    Posts: 141

    Try J-thomas.com they have a lott of parts and might have yours but it is expensive to put a shortblock on and the unit still has a lott of miles anyway so ya might be better just gettin a new one and having a parts spare. Good luck
  5. Hydrauk

    Hydrauk LawnSite Member
    Posts: 2

    Thank you for the responses. Yeah, I realize that just getting a new Trimmer is another route, or even a Short block. But now that Iam into it, I want to finish it. I have everything cleaned and laid out, It just screams..to be put back together. I did order the parts from a Stihl dealer. It's just amazing to me that there are no aftermarket Pistons for this Model. I will let you guys know how it works out. Have fun doing Spring clean ups fellas!
  6. mkkauriga

    mkkauriga LawnSite Member
    Posts: 1

    I have the same problem. sorry to hear that polishing the cylinder doesen't work.
    Also cannot find a 34 mm piston with retainer springs for the wrist pin one went flying away across the garage.

    How did it happen...only one way ..poor lubrication mix. Had some young guys work for me (cheap labor) ran the machine with no mix (about 3 minutes) then you know what happed next :no no:

    If you find a good price on a short block let me know and vis a v.

  7. BigFish

    BigFish LawnSite Gold Member
    Posts: 3,248

    Polishing the cyl. won't work 'cause it's hard chrome plated! Try using the Foose method: Mothers polish and ball LOL.

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