Aggrevation with ms170 project

[Mouthfulloflake]

PIcked this little clean saw up it was locked up.
opened it up piston and cylinder look great, crank bearings were rusty, I guess someone washed it?

oh well, ordered a chinese engine from amazon, looked decent bolted it all in.
cranked on the second pull idles and oils well, bogs when revved.

clean the carb, replace the fuel line, same.

order a new ( aftermarket) rubber manifold and that little white plastic ring.
remove engine again, install new manifold boot.
starts right up and runs perfect!

next day pick it up, and it starts right up, then wont rev starts bogging again.

what in the world am I missing here?

the one time it was running well ( after the new manifold) it was revving clean, and 4 stroking with bar and chain installed and held WOT.
I am stumped, sympathy and ideas are welcomed.

 

[Tomos770]

Clogged spark arrestor in its muffler?

 

[trains]

I would put new bearings in the original stihl motor and get rid of the chinese junk.

Also, my guess would be the carb still needs a bit more cleaning.

 

[Jasonrkba]

MS170. The only saw I have literally thrown across my yard. I've had two of them and both would run great one day and like crap the next.

 

[SawTrash]

MS170. The only saw I have literally thrown across my yard. I've had two of them and both would run great one day and like crap the next.

The air filtration system on those leaves a lot to be desired, sawdust can get into carb very easily.

See filter improvements -

https://www.arboristsite.com/threads/ms180-air-filter-mod.352461/

 

[Mouthfulloflake]

Clogged spark arrestor in its muffler?

It was pretty clear, but I cleaned it once, same issue, so I eventually removed it make sure.

 

[Mouthfulloflake]

I would put new bearings in the original stihl motor and get rid of the chinese junk.

Also, my guess would be the carb still needs a bit more cleaning.

Do you think that is why it will run once day and not the next?
the machine work and porting on the chinese engine actually look pretty good.

I really do not think that is the issue.

 

[Mouthfulloflake]

The air filtration system on those leaves a lot to be desired, sawdust can get into carb very easily.

See filter improvements -

https://www.arboristsite.com/threads/ms180-air-filter-mod.352461/

Ok, This makes sense to me, I knocked the large particles out of the "filter"
but did not do much beyond that.

I will blow it all out and go through the carb again.

thank you.

 

[HarleyT]

While apart, remove the boot and look at it. Sometimes that little tit gets pinched.

 

[Tomos770]

And in meantime... If you are bored...

 

[cookies]

simply get a new carb

 

[Mouthfulloflake]

While apart, remove the boot and look at it. Sometimes that little tit gets pinched.

the intake manifold? I replaced it. it doesnt seem to be pinched or twisted.

 

[Mouthfulloflake]

simply get a new carb

I have an aftermarket carb for it, but I was trying to make the OEM work.
If i do replace it will be with the Walbro 215, best price im seeing is right under $30, does that sound right?

 

[anlrolfe]

I was given a roasted MS170 and then upgrade to 180 Chi-Com and replacement carb.
It's the 1-saw that I can't hear POP and have to judge the choke through experience.
If the bearings were rusty, I wonder the change the crank seals could be shot?

 

[cookies]

I have an aftermarket carb for it, but I was trying to make the OEM work.
If i do replace it will be with the Walbro 215, best price im seeing is right under $30, does that sound right?

yea their under 30 bucks for oem and their so tiny its very likely you will never get it cleaned out and functioning properly so i just get a new one and clean out the fuel tank and use a new filter.

 

[HarleyT]

the intake manifold? I replaced it. it doesnt seem to be pinched or twisted.

I have seen folks put it together with this tit pinched together and causing problems.

 

[Snowchaser]

The walbro 215 knockoff turns it into a whole new beast. Albeit a small beast. Never a problem since. 3 years now. And a basic muff mod.

 

[Mouthfulloflake]

yeah its real fun putting that dang thing in there. and the aftermarket one I got doesnt seem as good as the OEM, so I will be back in there at some point.

I have seen folks put it together with this tit pinched together and causing problems.View attachment 966883

 

[Mouthfulloflake]

The walbro 215 knockoff turns it into a whole new beast. Albeit a small beast. Never a problem since. 3 years now. And a basic muff mod.

so, its ok to use the knckoff 215 carb? its like $10, versus $35 for the OEM
not that it really matters, but at some point I will end up with so much money I could have bought a brand new ms 170 haha

 

[Snowchaser]

My knock off was probably $15. I would say i got lucky and i enjoy tinkering with saw carbs so if it didn’t work, I would have fixed it. I would spend the $30 if you got it. My funds were a lot tighter a couple years ago.