ms170 "rumble"

walhondingnashua

Feeling the Heat
Jul 23, 2016
260
ohio
I put a new stihl bar and chain on my ms170. Its an older saw (10 years old or so) and has the 14" bar. When I free hand the chain around, it has a slight "rumble" to it. If I run the saw, it doesn't do it if I rev it up but when I put it to work, it has a constant rumble under load. Motor is running great and has all its power. Does not bog down either, just the "rumble."
The sprocket has some grooves worn in it. Could this be the cause?
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,403
NE Ohio
Yes, sprocket is worn, chain is not...they don't match...they must match. When you pull the chain around the bar by hand it should feel smooth.
Mismatched chain/sprocket is probably one of the most common un-diagnosed problems with the average persons saw
 
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Does it look like this ..and not like this .
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