ArboristSite.com Sponsors
 
 


  1. Please see this post Click Here Please ask questions if you have them!! I hope this is going to great for us all.
    Dismiss Notice

Stihl MS 170 throttle linkage keeps coming loose at carburator end

Discussion in 'Chainsaw' started by godfreydanials, Mar 31, 2012.

  1. godfreydanials

    godfreydanials New Member

    Joined:
    Mar 31, 2012
    Messages:
    3
    Likes Received:
    1
    Location:
    Upstate NY
    I have a Stihl MS 170 that is about 4 years old, with very little useage. Recently the hooked end of the throttle linkage started popping out of the slotted lever on the carburator. I have reconnected it twice and it just popped out again. I don't see any retainers or anything to keep this linkage captured. I thought I would just bend the open slot closed on the carb lever, but that metal is very hard and would probably break before it bent.

    How can I prevent this rod from coming loose?

    Does anyone have a diagram of this linkage, or a PDF service manual?
     
    Dan_IN_MN likes this.
  2. jbqwik

    jbqwik ArboristSite Lurker

    Joined:
    Jun 11, 2006
    Messages:
    44
    Likes Received:
    6
    Location:
    MA
    If there's any plastic in the linkage chain then the opportunity for wear is always present. I can't visualize this setup but here's one cheap band-aid: Cinch a small plastic tie wrap (a.k.a. cable ties, come in sizes from tiny to huge, at any auto parts /Radio Shack /etc.) around the two parts. If no binding, then maybe a reasonable fix?
     
    Dan_IN_MN likes this.
  3. Dan_IN_MN

    Dan_IN_MN Addicted to ArboristSite

    Joined:
    Dec 15, 2008
    Messages:
    4,268
    Likes Received:
    518
    Location:
    FORMERLY Manyhobies
    PM (private message) sent
     
  4. Fish

    Fish Account Hold

    Joined:
    Apr 22, 2001
    Messages:
    13,967
    Likes Received:
    1,292
    Location:
    Loretto/Manton Ky.
    Sounds like someone has bent the throttle rod already....
     
  5. bennn*e

    bennn*e ArboristSite Guru

    Joined:
    Apr 3, 2009
    Messages:
    857
    Likes Received:
    1,366
    Location:
    In a Stihl Shop or my shed...so Stihl shop's :)
    there was a revision done on these probably 2-3 years ago, they re designed it to hook the other way and we haven't had a problem since. ill have a look tomorrow if there was a change in part number or just a running change over
     
  6. Fish

    Fish Account Hold

    Joined:
    Apr 22, 2001
    Messages:
    13,967
    Likes Received:
    1,292
    Location:
    Loretto/Manton Ky.
    Never heard of any revision, been parting them out for 5 years now, working on them a lot longer

    View attachment 231725
    [​IMG]

    The return spring on the throttle rod on the carb and the spring on the trigger keep the rod tight

    View attachment 231726

    [​IMG]
    To remove the throttle rod, squeeze the trigger, and hold the throttle on the carb open.
     
    Last edited: Apr 1, 2012
  7. Fish

    Fish Account Hold

    Joined:
    Apr 22, 2001
    Messages:
    13,967
    Likes Received:
    1,292
    Location:
    Loretto/Manton Ky.
    While holding the throttle open with a screwdriver, release the trigger.

    View attachment 231728

    [​IMG]

    And move the throttle rod to the right
     
  8. Fish

    Fish Account Hold

    Joined:
    Apr 22, 2001
    Messages:
    13,967
    Likes Received:
    1,292
    Location:
    Loretto/Manton Ky.
  9. Fish

    Fish Account Hold

    Joined:
    Apr 22, 2001
    Messages:
    13,967
    Likes Received:
    1,292
    Location:
    Loretto/Manton Ky.
    The only changes/revisions I have noticed are in the plastic ring expander in the intake boot, and the real recent change to the better quality green fuel line.

    View attachment 231730


    [​IMG]
     
  10. godfreydanials

    godfreydanials New Member

    Joined:
    Mar 31, 2012
    Messages:
    3
    Likes Received:
    1
    Location:
    Upstate NY
    Tell me more...

    Fish,

    I do have a return spring on the carb throttle shaft, but the linkage is just flopping around. Do you have a picture, or can you describe what I am looking for on the trigger end of the linkage for a spring? I will go out to the barn in the morning and have a look. I took down a big willow today with the Husky and don't have enough left in me to go back out tonight. I would like to use the 170 to cut the small stuff up.

    Thanks for your help, I really appreciate it.
     
  11. Fish

    Fish Account Hold

    Joined:
    Apr 22, 2001
    Messages:
    13,967
    Likes Received:
    1,292
    Location:
    Loretto/Manton Ky.
    The spring on the trigger end is in the black plastic handle part, you need a new throttle rod if both springs are working....

    Folks like to bend chit before thinking...........................................
     
  12. bennn*e

    bennn*e ArboristSite Guru

    Joined:
    Apr 3, 2009
    Messages:
    857
    Likes Received:
    1,366
    Location:
    In a Stihl Shop or my shed...so Stihl shop's :)
  13. Fish

    Fish Account Hold

    Joined:
    Apr 22, 2001
    Messages:
    13,967
    Likes Received:
    1,292
    Location:
    Loretto/Manton Ky.
    Wow, been parting them out for 5 years, never noticed the difference, kind of a subtle change, but the change makes sense.
     
  14. godfreydanials

    godfreydanials New Member

    Joined:
    Mar 31, 2012
    Messages:
    3
    Likes Received:
    1
    Location:
    Upstate NY
    Thanks guys for the jpegs. I took the throttle rod out and sighted down the end of it. The flat link that goes through the trigger was about 15* off of perpendicular to the vertical end below the hook at the throttle plate. I grabed both ends with pliers and twisted the rod clockwise until they appeared to be square. I ran the saw for a couple of hours yesterday with no problems. If it comes off again, I will find a new style throttle rod to replace this one.
     

Share This Page