Porting stihl ms361

[t4driller]

103/134/74. Without base gasket and .018 squish. Was reading up on some other builds and saw 103 to 97 for exhaust and 20/23 for blowdown. I've seen other saws that were mostly 103. So I'm just trying something different. Maybe it will be a turd, maybe not. I don't plan on doing this for the oem jug.

 

[t4driller]

That last post, numbers were for the AM cylinder. Oem is 104/132/74 Squish. 024 with gasket.

 

[jmssaws]

That last post, numbers were for the AM cylinder. Oem is 104/132/74 Squish. 024 with gasket.

361 quads?

 

[Redfin]

Mike, are you going to open the trans progressively?

 

[Redfin]

361 quads?

Yepper

 

[t4driller]

Mike, are you going to open the trans progressively?

Yes.. secondaries are 1.5/ 2 degrees after primaries.

 

[Redfin]

Yes.. secondaries are 1.5/ 2 degrees after primaries.

You could go a little steeper.

 

[jmssaws]

Yepper

You can get by with more bd then.

 

[t4driller]

Will try and get some more work done on it tonight. Lastnight I got exhaust and intake roughed in. Also the lower transfers tunnel was really narrow right where it meets the case. I opened it up to match the oem cylinder. So all I have left is upper transfers.

 

[t4driller]

You can get by with more bd then.

Numbers remind me of the 7910.i just did. Alot of bd.

 

[jmssaws]

Numbers remind me of the 7910.i just did. Alot of bd.

Indeed

 

[Kevin White]

Curious to see how it turns out. I've got 2 360s I'm working on. Good luck!

 

[drf256]

Sounds like your saw has a relatively tight case.

I'd leave your exhaust at 104, but that's me.

I'd go 124/126 of the transfers. You've got slightly more volume to fill than a 100 exhaust.

Just my opinion, which can be wrong of course. I like a lower exhaust than 100 on a 60cc saw.

What's your compression at 104? Remember that you'll be lowering it at 100*.

 

[mdavlee]

I only lost 5 lbs from 103 to 99 on a 372. I don't mess with these smaller saws much so I don't really know. I like a higher exhaust for a more free running saw.

 

[Redfin]

Just for comparision. I lost about 7 psi on a 660 going from 99.5 to 95.5

 

[drf256]

Great info guys. That's a lot less loss than I would think

 

[t4driller]

I didn't check comp before teardown. I checked it a year or so ago and was at 160 ish.

My plan for the oem was to get squish tightened up, leave ex/int where it's at and raise Trans just a couple degrees. Widen ports as much I can and see how it does. Hopefully I can get this all done by Saturday. [emoji20] [emoji20]

 

[Canadian farm boy]

@t4driller hows this project coming?

 

[t4driller]

I did end up putting the oem cylinder on it , gutted muffler and timing advance. It runs pretty good. I have all the details at home. Still working on this project though. I want to port the am kit and see how it does. Some other projects took priority over this one but I will get back to it soon

 

[Chainsaw Jim]

Anything rated "FD" is a good oil to use. It must say fd or higher on the bottle.
My first thought when I saw the pic of the piston was Stihl ultra. I don't know all fd rated brands, but Husqvarna, shindaiwa, and echo are and Stihl is not. Stihl must have bought too much fb and refuses to discard it to replace it on the market with higher rated quality.

Stihl super is the only one I've found rated fd, the other oils they sell aren't.