ms361 teardown - "while I'm in there"

[jrobie79]

Long time lurker, first post. Been reading a bunch and just picked up a new to me ms361, it is absolutely filthy, so far I've probably picked off, wiped, scraped about a full pound of crap. So i started stripping it to clean it. See below:

Before I started tearing it apart I took a compression reading, and got just under 120psi. Is this acceptable? Haven't run the saw at all so I never took a warm reading:

The Piston looks ok from the exhaust and intake side (I'll get some pictures of that later).

My question is, what should I change while I'm in the process of putting everything back together since it'll be most stripped down? When I work on my car if I have to take a bunch of parts off I might as well swap in new smaller parts (hoses, plastic bits, etc...). I was thinking maybe some seals, rubber bushings, hoses, etc.

I've been using the factory service manual and this forum to take it apart and look forward to my new addiction and bring more active on this forum.

p.s. does anyone offer powder coating services? I'd like to get all the Stihl grey pieces refinished as I'm going to tackle the orange plastic restoration myself.

 

[cuinrearview]

Fuel and impulse line. Piston rings. Possibly piston if the skirt wear is excessive. Crank seals. Check the crank bearings for play.

 

[cuinrearview]

@glock37 for powdercoat if he still comes around this place.

 

[blsnelling]

Compression should be 160-170 on a 361.

 

[BuckthornBonnie]

Fuel and impulse line. Piston rings. Possibly piston if the skirt wear is excessive. Crank seals. Check the crank bearings for play.

Yep.
Check intake boot and oil worm gear as well. Been into a few of these 1135s, worst one had bad bearings and a cracked flywheel (extremely unlikely). Others had typical fuel line/filter and carb issues.

 

[drf255]

Make sure your tester has a Schrader valve at the end. Traditional auto testers will show a low reading on saws.

 

[jrobie79]

Make sure your tester has a Schrader valve at the end. Traditional auto testers will show a low reading on saws.

on the end that gets inserted into the cylinder correct? If so, yes my tester does have it, it is an automotive one though.

 

[drf255]

It can be bad. Ive had them be off quite a bit. Try a dab off oil in the valve.

 

[jrobie79]

It can be bad. Ive had them be off quite a bit. Try a dab off oil in the valve.

will do, I'll borrow another from a buddy of mine

 

[jrobie79]

so I never got the compression over the 120 from my first picture.

I stripped it a little more, took the cylinder off and snapped a few photos (is this piston cooked?) I will snap a few photos later on tonight of the inside of the cylinder.

I also noticed there is side to side play in the rod at the crankshaft (shown in photos below), is this normal?

Took a few other photos of the clutch side, lot of worn out powdercoating, so I'm gonna split the case and get it done by Glock37

@cuinrearview
@drf255
@BuckthornBonnie

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[jrobie79]

Assuming the piston is cooked, should I get a genuine Stihl, good used OEM one, or any recommended aftermarket brands (I've seen people suggest meteor?)

Should I use upgraded (ceramic) bearings? Also, in the IPL it lists two size cylinder gaskets, what's the deal behind one or the other?

 

[cgraham1]

Side to side play on the crank is okay. Meteor makes a good piston... otherwise go with OEM. If you can find a good used OEM one, I don’t see why it wouldn’t work just fine with a new set of rings. I usually get Cabers.

 

[cuinrearview]

I would get a meteor or OEM piston, clean up the cylinder you have, get new rubber lines and gaskets, and run the piss out of your new to you saw.

 

[Van462]

The base gaskets are of 2 different thickness. .5 mm and 1mm. It will depend on your squish measurement on the piston/cylinder. Many remove the base gasket and use sealant to bump compression up a bit.

 

[ChoppyChoppy]

If the cylinder looks fine, I'd just put new rings and run it. Polish the piston a bit if need be.

If it ain't broke, don't mess with it.

 

[drf255]

The side play is normal, like Clint said.

As long as you plan on keeping the saw, I’d reuse that piston with some cleaning and new rings. The sides of it look great and that looks like carbon scoring to me.

You’re gonna have to clean the jug up good. They definitely like a compression boost, so you can try custom gaskets to get to .017 squish. Use good oil that won’t ash a lot, like Motul800 or Belray H1R.