Just general MS170 info:
I'm working on two MS170's with fuel issues! One is bogging, other one would not idle until several CW turns of the idle adjustment.
Carb is easy to remove! 8mm socket and a torx to remove plastic cover on handle for throttle linkage access then remove kill wire and the plastic choke shaft and you are there.! OEM Zama carb C1Q 057A is bogging.
Ordered a Zama carb replacement yesterday from STIHL DEALER. 1130 120 0603@ $28 and a fuel hose 1130 358 7701@ $5.99. I can see damp gas on the outside of the old fuel hose.
See cheaper parts on flea bay but, Cannot bring myself to trust ebay for parts when it says from China.
I have purchased the real cheap ebay China chainsaw carbs
just as a test carb to see if a expensive OEM Stihl chainsaw carb is the problem and if Chainsaw responds ok I go to work on the OEM carb, usually run it thru a ultrasonic leaner and then kit if replacement carb is costly. If carb happens to be one of the harder ones to remove and install I'll go for replacement rather than taking chance of having to kit, re-install, test and possibly remove again. (time repairing vs cost of complete carb replacement)
I don't leave a cheap China $10 carb on a high priced good saw.
There is a small hole thru the side of the black handle to adjust the idle speed with a very small screwdriver on these two MS170's. The idle adjustment is kinda slow to respond. Several turns of the screwdriver to get a throttle response. No H and L adjustments.
You need to look at the spark arrestor screen. (remove the 8mm nuts on the front of the muffler and it's right behind the little front plate) These two saws screens were clean but I've heard rumors of the 170 screen clogging mainly due to mixing too much oil in the gas. Saw will start bogging after it gets warmed up similar to carb/fuel issues.
Here is a link for the MS170 owners manual with some good info! The idle adjust says it Left hand thread, but the idle adjust instructions indicate it's RH thread??? (pg 41)
https://www.stihlusa.com/WebContent...TIHL-MS-170-180-Owners-Instruction-Manual.pdf