Stihl MS170 chain brake cover

[Hobart]

Hi guys: I ‘ve lurking in the background of your really great forum and I finally got myself registered.
Recently received a MS170 from an elderly neighbor who can no longer use it. Waiting on some parts, but the little saw seems to run pretty well. Question#1: any fix for a chain brake cover that comes off every time the saw is running (should I pop for a new cover) ? Pins are intact but won’t stay put once they’re snapped in.
Question #2 is how does one adjust the low mixture screw if he doesn’t have watchmaker tools? Do I have to remove handles and right side covers to get to the little screw? The saw bogs somewhat when increasing rpms. Thanks ahead of time for any helpful input.

 

[Vintage Engine Repairs]

Hi,

The 170 is a non adjustable carby so you can’t tune them sadly. A few extra dollars by Stihl on putting in an adjustable carb would make an already good saw great. As for the chain brake cover, is it just one that clips in? My memory isn’t serving me well and pictures would help. If it clips in, see where it’s worn, it may be the housing side and then a new cover won’t help.
If it’s screwed in and they are stripped, either put a coil insert in and replace with machine screws, or easier is to use some strimmer line or cable tie in the hole then screw the screw in.

Enjoy the 170, I had a 180 and they are such fun to use. Little screamers that weigh practically nothing.

 

[MagraAdam]

Hey mate, the 170 is a great saw for the money. I run mine with a 3/8LP full chisel chain (14 inch) in 043. I also highly recommend a set of dogs for it (not for help felling or to bury the bar, but to keep wood off the saw and help it run cooler and last for longer). They are $10aud and you'll need a set of screws and a t27 driver. I run some oversize dogs because I never cut 14 inch logs with it, and they keep me well off the wood, the chips fly freely, and I've got plenty of control.

Also spend $30aud on an ms250/211 side chain tensioner. It slots right in and you'll love it.

If the bar nuts are coming off the threads, that sounds like they just aren't being done up tight enough. If the studs are coming out you probably need some thread locker.

Lastly, these saws tend to clog up the spark arrestor screen and the exhaust with spot. Take them both off and soak them in a sealed container of unleaded, then if the screen isn't clean you can scrub it with a brass brush, but they are also cheap to buy. People remove them, but I've set enough trees on fire to know to leave them in.

 

[HarleyT]

It is just a cover that kind of snaps on. Put up a pic of the inside of your cover, and I'll scrounge one up too and put up a pic off a new one.

 

[J D]

With regards to the running issues, I'd suspect the saw has been left to sit with old fuel in it. Best bet in that case is to strip & clean the carb & put a kit in it if necessary.
These saws were factory jetted pretty lean (the newer the worse). You can get replacement jets in 0.05mm increments so if you have the carb apart anyway it may be worth ordering one that's a size bigger than you have. Alternatively you can just drill it out by 0.05mm, but I'd be reluctant to do that unless you had the carb behaving as it should with the exception of WOT RPM being high

 

[Hobart]

Thanks to all of you! I definitely will be following up on all your helpful recommendations!
I’m so glad I finally join up…this forum provides some really great advice to problems etc that would not be addressed anywhere else.
Thanks again (I,ll be back)
Harley: I found a new chain brake cover on eBay for $8. Probably will go that route unless I determine the cover’s pin holes are worn.

 

[HarleyT]

Hold on, I'll go out to the shop now.

 

[HarleyT]

here....

 

[Hobart]

here....View attachment 925847

 

[Hobart]

That’s the chainbrake cover I need for my MS170.
I don’t do PayPal, but I could purchase it with a USPS money order.
How much is it?
My email is [email protected]

 

[HarleyT]

Take the carb apart, and clean, and there is a little brass jet that can be removed and cleaned, uses a flat tipped screwdriver. And check your lever height.

 

[rupedoggy]

Hobart, melt the little tits with a hot screwdriver a little so they are a little wider. Snap them into place. If they are to far gone drill them and insert screws to hold them.

 

[Hobart]

Hobart, melt the little tits with a hot screwdriver a little so they are a little wider. Snap them into place. If they are to far gone drill them and insert screws to hold them.

Thanks for thr tip re. a loose chainbrake cover…I will give it a try and hopefully melting the tits will do the job; if not I’ll screw the cover on.

 

[Hobart]

Take the carb apart, and clean, and there is a little brass jet that can be removed and cleaned, uses a flat tipped screwdriver. And check your lever height.

Thanks Harley…can probably get to carb clean out this weekend