Need help Stihl MS170

[barryk]

Hi, im new to the site, ive just bought a Stihl ms170 and i have a problem stopping it, when i put the lever to the stop position the saw keeps running and i have to choke it to stop it, i have taken the cover off and i can see a black wire not connected to anything, it seems the wire can clip into a little plastic piece but im not sure if something else is missing, i will take a photo of it soon and hopefully someone can help, thankyou.

 

[demographic]

The black wire contacts that bent spring when the levers in the up position and that grounds the ignition, is the wire OK at the other end?

 

[barryk]

The black wire contacts that bent spring when the levers in the up position and that grounds the ignition, is the wire OK at the other end?

hi, thanks for the reply, the end of the black wire with a brass like fitting will not reach anything in the stop position, do you think something else has broken off the end of the wire that makes contact with the spring?

 

[Stihlofadeal64]

Hi, im new to the site, ive just bought a Stihl ms170 and i have a problem stopping it, when i put the lever to the stop position the saw keeps running and i have to choke it to stop it, i have taken the cover off and i can see a black wire not connected to anything, it seems the wire can clip into a little plastic piece but im not sure if something else is missing, i will take a photo of it soon and hopefully someone can help, thankyou.

The black wire connected to the short circuit switch (black switch) should engage the spring when you attempt to stop it. If the other end of the wire is also connected to the coil properly. You can drain the gas and oil, remove the caps and remove the screws for the pull rop cover and insure that this is properly connected. It's not rocket science, if the wire is in place and everything is functional you should be fine. Send me your email through the personal message system and I'll see if I can round up an individual parts list, and repair manual in pdf format. Happy sawing!
Tommy

 

[barryk]

The black wire connected to the short circuit switch (black switch) should engage the spring when you attempt to stop it. If the other end of the wire is also connected to the coil properly. You can drain the gas and oil, remove the caps and remove the screws for the pull rop cover and insure that this is properly connected. It's not rocket science, if the wire is in place and everything is functional you should be fine. Send me your email through the personal message system and I'll see if I can round up an individual parts list, and repair manual in pdf format. Happy sawing!
Tommy

Hi Tommy, when i adjust it to the stop position the end of the black wire touches nothing, is something else missing from the end off the black wire?

 

[Swinny]

Hi Tommy, when i adjust it to the stop position the end of the black wire touches nothing, is something else missing from the end off the black wire?

what the man says above is correct. looks like the wire and part of the connector has broken and slid through the connector and not making contact. all it is is a female spade connector that pushes onto the plastic bar then when you turn it off, i.e the lever to the up position it contacts the spring and stops the spark

 

[Swinny]

like this http://www.jimruffi.com/images/shopping/female_spade.JPG

remove the broken connector, should just push off the plastic bar, cut off the bit of broken connector from the end of the wire and fit a new one of these and slide it back in the plastic bar

hope you get it sorted

 

[barryk]

like this http://www.jimruffi.com/images/shopping/female_spade.JPG

remove the broken connector, should just push off the plastic bar, cut off the bit of broken connector from the end of the wire and fit a new one of these and slide it back in the plastic bar

hope you get it sorted

hi, seems something from the end of the wire needs to bend all the way around to reach/make contact with the spring, a look inside another ms170 would be ideal, thanks for all the help.

 

[Swinny]

hi, seems something from the end of the wire needs to bend all the way around to reach/make contact with the spring, a look inside another ms170 would be ideal, thanks for all the help.

when you turn the lever to the up position that connector turns with the bar and then makes contact with the spring, try it

can get some pic of my 017 if necessary

 

[demographic]

Hi Tommy, when i adjust it to the stop position the end of the black wire touches nothing, is something else missing from the end off the black wire?

Are you sure that your getting the full stop position on it?
In this picture of yours the lever needs to go up about three positions to switch it off.

On mine, I have to put the lever into the on and choke on position to get the top cover off, then in order to get the switch on the normal on position I have to push the lever up and thats then in the full throttle position, pull the trigger and the lever pops into the normal on position where when I let off the trigger it can idle.

From there I have to put the lever UP again to switch the saw off.

Here's the lever in the normal running position where I can let the trigger off and it will idle...

And here's the spring that grounds the wire, on this picture the spring isn't contacting the brass so the saw could run.

Now, in this picture the lever is up as far as it will go (almost touching the airbox if its called that) and the spring is contacting the brass wire end connector.

That springy bit of metal acts as a contact on the brass end of the wire thing.


It could be that the black wire has come off somewhere else but to be honest I've not taken mine to bits to see exactly where it goes, from working on motocross bikes I'm assuming it's connected to the coil and acts as a ground when you stop the saw.

All those pics are of my 017 which as far as I know is just an older version of your 170.
Sorry for the dirt but at least the filters clean and I was cutting some punky wood up the other day.

 

[barryk]

Are you sure that your getting the full stop position on it?
In this picture of yours the lever needs to go up about three positions to switch it off.

On mine, I have to put the lever into the on and choke on position to get the top cover off, then in order to get the switch on the normal on position I have to push the lever up and thats then in the full throttle position, pull the trigger and the lever pops into the normal on position where when I let off the trigger it can idle.

From there I have to put the lever UP again to switch the saw off.

Here's the lever in the normal running position where I can let the trigger off and it will idle...

And here's the spring that grounds the wire, on this picture the spring isn't contacting the brass so the saw could run.

Now, in this picture the lever is up as far as it will go (almost touching the airbox if its called that) and the spring is contacting the brass wire end connector.

That springy bit of metal acts as a contact on the brass end of the wire thing.


It could be that the black wire has come off somewhere else but to be honest I've not taken mine to bits to see exactly where it goes, from working on motocross bikes I'm assuming it's connected to the coil and acts as a ground when you stop the saw.

All those pics are of my 017 which as far as I know is just an older version of your 170.
Sorry for the dirt but at least the filters clean and I was cutting some punky wood up the other day.

Thankyou, yes ive managed to make contact with the spring clip i see now how it works, when the lever is all the way up in the stop position it touches the stop wire, now i have another problem the saw started perfectly before i re seated the wire and now it will not start ive checked plug spark cleaned it etc, is there a chance i have flooded the carb in any way???

 

[barryk]

Thankyou, yes ive managed to make contact with the spring clip i see now how it works, when the lever is all the way up in the stop position it touches the stop wire, now i have another problem the saw started perfectly before i re seated the wire and now it will not start ive checked plug spark cleaned it etc, is there a chance i have flooded the carb in any way???

 

[Danno]

barry, did you figure it out? Mine isn't starting either. Just bought it as a non-runner. Figured best case scenario it was a short in that ground wire, worst case needs a new coil.

Others, am I right that I should be able to disconnect the short circuit wire where it plugs into the coil to test the kill switch?

If I don't get spark after doing that, then it's coil, right?

 

[TommyH]

I had the same issue, unfortunately when i found this answer and went to look at my saw, I noticed the white semi-loop piece that holds the switch shaft was broken, it appears that it can break easily, so be careful working your saw mate!

 

[smitty73]

Hi All,
Ive been following this thread as I had a similar problem to BarryK.
I was finding that the choke lever wouldn't return to the off position without me moving the flat spring manually. The spring was stopping the lever from turning so the spring couldn't make contact with the wire.
I fixed this by removing the choke lever then carefully bending the spring upwards then refitting the choke lever. I tried this a couple of times until the lever moved as it should.
Also, thanks to all that provided photos, they were incredibly helpful.