MS170 x 2 fuel run issues, need repair advice?

[Okie]

Have two MS170 chainsaws in for repair.
I've never been around a MS170 and need few tips?

Both saws have been stored for quite awhile, but gas in tanks still seems good, but I drained all and added fresh mixed gas.

One will start up and idle good for about 10 seconds, won't accelerate, bogs when throttle opened will come back to idle and then after about 10 seconds with good idle just die. Can choke and same thing again. Spark arrestor screen is ok on both saws.
Installed another spark plug, same, can see wet liquid fuel along the rubber fuel line under carb, but not dripping just wet. Do not see any carb adjustments at all except for small hole thru side of plastic cowling.
I'm thinking fuel line and carb or carb kit?
See a new Walbro adjustable carb on flea bay for like $15 or a Zama not adjustable for like $13 with two gaskets??

The second saw starts and accelerates good and no idle at all. If I hold the throttle advance it will idle good without the chain moving. Appears it just needs carb idle advanced somewhat. Can see a small hole going thru the side of the plastic for maybe a idle adjustment???
What is strange to me about this saw is when I first pulled the cord it appeared the compression is real weak and it will fail the drop test, weight of saw will uncoil the pull rope. When I removed the spark plug to check compression the end of the spark plug at the tip end was very rusty. Compression checked 100psi after about 5 pulls on a good 2 cycle comp gauge and the other ms170 checked 120psi and sharp compression jerks feel when pulling the rope.
I primed the saw and it started on about 3rd pull and accelerates good but won't idle. (acts like LA idle screw needs adjusted. When saw dies it will start right back up at advanced throttle.
Just going by compression feel I would have bet this saw would never start/run and sound good.

Summary:
#1: Carb replacement (walbro or Zama) and fuel line as a start?? (or kit the existing carb)

#2: Is there a LA idle adjustment for these saws?
and wonder why the weak pull thru feel for compression , but runs great and sounds strong????????????

 

[Boomer 87]

You mite be as well off buy a new carb from stihl, they're only about 30 bucks for an oem carb

 

[Boomer 87]

The idle adjust on those I think goes through the black part of the handle there's a small hole to stick a long thin screwdriver through

 

[LoveStihlQuality]

The stock carbs are non-adjustable. Only idle speed adjustment. Carb kit for a few bucks. I bought a adjustable carb with plan to mod the muffler but couldn't get throttle linkage attached (at least without bending around). I got it running well stock and sold it.

Sent from my SM-N900P using Tapatalk

 

[LoveStihlQuality]

Good YouTube video Donyboy73. Fuel line was bad. Easy to replace step by step.

Sent from my SM-N900P using Tapatalk

 

[Boomer 87]

I didn't recommend the aftermarket adjustable carbs, bc i have no experience with them. Are they decent?

 

[Okie]

I looked at the one MS170 that needed LA idle adjust and I held the trigger at idle and with as small screwdriver thru the small side hole after several turns of a screwdriver the idle stayed at where I was holding the throttle and the adjustment was very slow to make a difference in the idle speed. Several turns of the screwdriver would be required to slow down the idle and maybe like five turns of the screwdriver to make any difference in the idle speed. Idle speed just don't feel right. I'm thinking that no way that a Bubba could turn the idle screw 10 or more turns slowing the saw idle down to where it was initially set. I'm thinking something might be wrong with the idle adjust screw on this carb????
I seen on a ms170 parts list that two different carb's were OEM but both carbs take the same kit number of 1130 007 1061 @ few bucks and a carb 1130 120 0603 at around $22 list from Stihl.
Aftermarket clone carbs dirt cheap on flea bay.
I see a advertised Walbro carb on flea bay that has adjustable jets, but their are no holes in the existing plastic case for access adjustments. (I prefer Walbro carbs, but???)
Probably requires mods to the saw for a test when using a Walbro??????

Anyone had any carb experience with the MS170?????????? (suggested replacement carb or kit, etc????

Here is the Walbro carb listing on flea bay:
http://www.ebay.com/itm/for-Walbro-...312167?hash=item43cedbada7:g:5l8AAOxyWmxSXD7e

Item number: 291233312167

 

[Boomer 87]

I could be wrong but don't some of those idle adjustment turn backwards of what you would think like u would turn it left to speed it up instead of the normal right turn. I know I've run across that I just don't remember what saw it was

 

[HarleyT]

Here is a new carb off of the ms170.

 

[HarleyT]

I looked at the one MS170 that needed LA idle adjust and I held the trigger at idle and with as small screwdriver thru the small side hole after several turns of a screwdriver the idle stayed at where I was holding the throttle and the adjustment was very slow to make a difference in the idle speed. Several turns of the screwdriver would be required to slow down the idle and maybe like five turns of the screwdriver to make any difference in the idle speed. Idle speed just don't feel right. I'm thinking that no way that a Bubba could turn the idle screw 10 or more turns slowing the saw idle down to where it was initially set. I'm thinking something might be wrong with the idle adjust screw on this carb????
I seen on a ms170 parts list that two different carb's were OEM but both carbs take the same kit number of 1130 007 1061 @ few bucks and a carb 1130 120 0603 at around $22 list from Stihl.
Aftermarket clone carbs dirt cheap on flea bay.
I see a advertised Walbro carb on flea bay that has adjustable jets, but their are no holes in the existing plastic case for access adjustments. (I prefer Walbro carbs, but???)
Probably requires mods to the saw for a test when using a Walbro??????

Anyone had any carb experience with the MS170?????????? (suggested replacement carb or kit, etc????

Here is the Walbro carb listing on flea bay:
http://www.ebay.com/itm/for-Walbro-...312167?hash=item43cedbada7:g:5l8AAOxyWmxSXD7e

Item number: 291233312167

That ain't no Walbro.....

 

[LoveStihlQuality]

I could be wrong but don't some of those idle adjustment turn backwards of what you would think like u would turn it left to speed it up instead of the normal right turn. I know I've run across that I just don't remember what saw it was

Yes. Turn clockwise to increase idle speed. A little finicky to make sure screwdriver is seated in screw

Sent from my SM-N900P using Tapatalk

 

[Okie]

I could feel the screwdriver seated and staying in the idle screw slot good, but it took several turns of the idle screw to make any changes in the idle speed when the saw started idling own it's own.
After I turned the idle screw several turns, like probably 10 turns CW and the saw started idling own it own and the chain not turning, I turned it probably about 5 more turns at least and the engine picked up little speed and the chain slightly engauged and I backed the screw CCW 5 or 6 turns and the engine came back down. (like slow motion and lazy response)

Saw piss rev's real good and comes down to idle good now but the idle adjustment is very slow and lazy responding to any adjustments?????

I'll order new stihl carb and fuel hose for the one that won't piss rev and see how she flys and if idle adjustment is normal acting I'll check the lazy acting idle carb further.



Thanks for the heads up about the ebay carb not being a walbro for these ms170's!

 

[LoveStihlQuality]

Yeah, if you're turning that me

Sent from my SM-N900P using Tapatalk

 

[LoveStihlQuality]

Try new carb and fuel line

Sent from my SM-N900P using Tapatalk

 

[joeblacky]

The idle adjustment on all the ms170's I've worked on have been quite slow to respond, and normally take a good few turns to set it right.

Not much that can go wrong on them though, my standard procedure for one of these that isn't running is fuel filter and line, air filter, spark plug and a fresh Chinese eBay carb for a tenner, I've done dozens of them and this has always cured any of the problems you mentioned

 

[Okie]

I ordered the Stihl carb and fuel line awhile ago.

The carb on the saw has Zama C1Q 057A,
Carb was like $28 and fuel line $5 from Stihl dealer.

I priced a kit for the other OLD running lazy idle adjust carb and it was @ like $20 for a kit.
I thought maybe I might kit it if kit was not any more than $10. I see carb kits on ebay for like $5.
I'll leave the running carb as is, unless the idling becomes erratic.
I did notice that the idle adjust on the bad removed Zama C1Q 057A carb is not like most small carbs because idle adjust screw does not move the throttle butterfly, looks like maybe a air adjust behind the throttle plate throat area which would explain why it's slow adjusting and also noticed on the same side as the idle adjust screw the carb also has TWO very small holes in side marked L and H jet holes but cannot be adjusted with normal tool nor if the carb is on the saw the carb L and H holes cannot be accessed when the carb is mounted onto the saw.

If you look at the pic of the Zama HarleyT posted you can see a plugged H jet area, this bad removed Zama has a hole there and you can see a itty bitty brass stem down deep in both L and H holes.

I'll get back next week with the results.

 

[joeblacky]

I think that's so they can use the same casting of the carb body for several different variations, as the big tollitson on my 090 also has two sets of L & H stamped on the casting in different places, with two of the holes blocked off

 

[trboxman]

I think that's so they can use the same casting of the carb body for several different variations, as the big tollitson on my 090 also has two sets of L & H stamped on the casting in different places, with two of the holes blocked off

Yep, that same Zama C1Q carb body, and subsequently rebuild kits, work on a pretty wide variety of configurations.

 

[Okie]

Installed the new Stihl dealer $29 Zama carb and New fuel line and starts easily and runs and cuts good.
Dropped one of the small carb stud nuts down into the plastic handle bar area and had to completely remove the handle to finally find and retrieve the small nut.

The other saw that would fail the pull cord drop test that only required several turns of the idle adjust screw starts, runs cuts and idles good.

I was surprised at how good the small tooth chains cut and they are at about 1/2 life. Appear the chains would be good for trimming small limbs and brush with getting the ole brush slap in the face from a big tooth chain grabbing the small limbs.
Both MS170 saws appear to have 14 inch bars.

I used the infrared thermometer and checked jug temp of both saws into a full bar cut and both saws max temp was around 325F and took quite awhile (probably around 1 minute of full bar cutting at max throttle) to ever get to this temp.

The upside down air filter on the MS170 is misleading when you first take off the plastic cover, the air filter will look clean on the MS170 but you are looking at the carb intake side. The dirty side of the air filter is not seen until the filter is removed. A air filter could be clogged and appear clean at a casual glance.

Thanks for the tips.

 

[o8f150]

go buy 2 wt215's and put them on and don't look back,, they are fully adjustable