Stihl MS361 Build

[drf256]

Found a bit of time to do my favorite thing, finally.

Figured it was time for a build thread around here. When this saw is complete, I'm doing a thread on SVT's 046.

This is my first 361 build ever. The owner is well aware of that, I'm still not sure why he sent it to me after the disclosure.

The saw was a bit puzzling and I spoke to many of the more experienced fellows about it. Like @Mastermind @Stihlbro @blsnelling .

Anyhow, here it goes, dot dot dot

 

[drf256]

She's a dirty girl. I hate dirty saws.

 

[drf256]

The wash on this 47mm piston is excellent. I've got some transfer to remove here.

 

[drf256]

Like,most Stihl models, there is a lot of variation in jugs. This saw had the Stihl Branded jug on it. @dall , one of the most generous people I've met (he's a tightwad about capitalization and punctuation though) sent me a Mahle 361 jug.

The Mahle has a smaller lower opening than the Stihl Branded jug. The tunnel ar the same. The uppers are smaller and tighter on the Mahle. Both jugs have some odd angles in the upper with large bevels. The bevels open squarely, but the actual port opening open at angles. It makes me fear playing with them.

Sans gaskets:

Mahle 103/128/74

Stihl 103/130/76

Pics of both jugs below. It's very hard to see in pics, but the Mahle has much smaller ports.

I decided to go with the Stihl Jug. The squish was 20 with a 20 gasket. It was a headslapper without one.

 

[drf256]

 

[drf256]

After a lot of thought, I decided against a popup slug. It woulda been less work, but I didn't like the tiny stock squishband.

At 47mm and cooling fins the width of an 066 jug, I figure this jug has a lot of cooling potential. These saws run about 170 psi stock. My target is about 225. How did I figure out the amount to take out? 3 beers and my guestimatometer.

I took .030 from the band. .030 from the cylinder extensions (gasket thickness + base cut) and .010 from the base.

 

[paragonbuilder]

The wash on this 47mm piston is excellent.

View attachment 80381 ]

That is fantastic!


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[drf256]

Here's the stock band.

 

[drf256]

Here's what 30 out looks like. I finished it with a 150 grit sanding.

 

[paragonbuilder]

Like,most Stihl models, there is a lot of variation in jugs. This saw had the Stihl Branded jug on it. @dall , one of the most generous people I've met (he's a tightwad about capitalization and punctuation though) sent me a Mahle 361 jug.

The Mahle has a smaller lower opening than the Stihl Branded jug. The tunnel ar the same. The uppers are smaller and tighter on the Mahle. Bot jugs have some odd angles in the upper with large bevels. The bevels open squarely, but the actual port opening open at angles. It makes me fear playing with them.

Sans gaskets:

Mahle 103/128/74

Stihl 103/130/76

I decided to go with the Stihl Jug. The squish was 20 with a 20 gasket. It was a headslapper without one. View attachment 80383View attachment 80384View attachment 80385View attachment 80386View attachment 80387

How much does the port timing stagger Doc? It's enough that I can see it clearly in the pic!


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[Brewz]

 

[drf256]

Squish target hit. .021-.022 with .026 solder, which means about .019-.020 true squish.

The lower ring pin rides along the Flywheel side exhaust, so many tell me they just leave the port stock.

Major appliance malfunctions at my house. The worst is the fridge in my garage which stores the MOFO fuel . A new one is coming today, so half of my garage needs to be moved to get it placed.

That's it for now. I'll post more when I get some grinding time in.

Hope you guys are enjoying. This is what this site was for IMHO.

 

[drf256]

How much does the port timing stagger Doc? It's enough that I can see it clearly in the pic!


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Believe it or not, the opening in the plating occurs at the same time for both uppers.

The true ports open nearly at the same time, inside the big bevels. They both open intake first and the secondaries are tighter and smaller. They do open maybe 1* later than the primaries.

I'm a bit perplexed. I would prefer not to touch them, but I have to.

The jug numbers came out at 104/132/75 after machining. I'm gonna raise them 6-8* and be very careful to match the opening angles the factory engineered into the jug.

A popup would have required me raising them less, but I needed to cut the crappy band out anyway. I also wanted a bit more compression than I feel the popup woulda given me.

 

[Brewz]

I have a tecomec 361 cylinder here and it has a WAY larger primary lower compared to the secondary.
The OEM jugs look to be about equal.

I am wondering what would be better?

 

[drf256]

The secondaries are smaller than the primaries Tony. It's just hard to see in the pics. They're tighter too.

 

[Brewz]

Im thinking of attacking the uppers similar to a 661 cylinder with the primaries feeding in at almost 90* and the secondaries opening a couple degrees later and feeding in at a more slopped angle flushing up along the rear wall of the cylinder towards the top.

 

[Brewz]

The Farmertec cylinder has almost equal spaced and sized.



By the looks of it, the OEM cylinders are in between the 2

 

[drf256]

I'll try to get a pic later Tony. The jug is soaking in the USC.

The lowers split much deeper into the jug than the 2 AM you are showing.

 

[PA Dan]

View attachment 80394 View attachment 80395 View attachment 80396 View attachment 80397 View attachment 80398

Squish target hit. .021-.022 with .026 solder, which means about .019-.020 true squish.

The lower ring pin rides along the Flywheel side exhaust, so many tell me they just leave the port stock.

Major appliance malfunctions at my house. The worst is the fridge in my garage which stores the MOFO fuel . A new one is coming today, so half of my garage needs to be moved to get it placed.

That's it for now. I'll post more when I get some grinding time in.

Hope you guys are enjoying. This is what this site was for IMHO.

Pics of new fridge and MOFO fuel please![emoji41]

 

[hseII]

View attachment 80394 View attachment 80395 View attachment 80396 View attachment 80397 View attachment 80398

Squish target hit. .021-.022 with .026 solder, which means about .019-.020 true squish.

The lower ring pin rides along the Flywheel side exhaust, so many tell me they just leave the port stock.

Major appliance malfunctions at my house. The worst is the fridge in my garage which stores the MOFO fuel . A new one is coming today, so half of my garage needs to be moved to get it placed.

That's it for now. I'll post more when I get some grinding time in.

Hope you guys are enjoying. This is what this site was for IMHO.

Hear Here.