Porting Husky 340/345/350's

[isaaccarlson]

I round off the corners and use jb weld to build up areas to smooth flow.

 

[thedude74]

Not that anyone cares to hear about a husky 350, but I thought I would share my findings after porting three of them with varying recipes. The one that that I was happiest with ended up as follows:
Cut 0.050” from the band
Meteor flat-top piston
Ex: 107
Tr: 125, 128
In: 77

Was that with a base gasket?
What was the final squish number?
Did you test compression? If so...
How many psi?

 

[thedude74]

I round off the corners and use jb weld to build up areas to smooth flow.

Nice! I hadn't thought of that.
Adding JB and shaping these areas(blue shading)??

 

[thedude74]

Maybe some JB and shaping here too? Kinda of a sharp angle on the lower transfer cap.

 

[farminkarman]

Was that with a base gasket?
What was the final squish number?
Did you test compression? If so...
How many psi?

No base gasket. Iirc, the squish was 0.018”. I don’t test compression, so I can’t help you with that one.

Edit: I took 0.010” from the cylinder riser to keep from cutting too much off the cylinder base.

 

[thedude74]

No base gasket. Iirc, the squish was 0.018”. I don’t test compression, so I can’t help you with that one.

Thank you sir. Very helpful! As far as not testing compression....no worries.....im guilty of that as well.
I'd imagine with those numbers you build a hard pullin Torquey 350.......kinda what I'm after....a do it all light weight saw that can pull 3/8"(or .325")"18" or 20" in spruce and birch.

 

[farminkarman]

Thank you sir. Very helpful! As far as not testing compression....no worries.....im guilty of that as well.
I'd imagine with those numbers you build a hard pullin Torquey 350.......kinda what I'm after....a do it all light weight saw that can pull 3/8" 18" or 20" in spruce and birch.

I also advanced the flywheel about 8 degrees.

 

[thedude74]

I also advanced the flywheel about 8 degrees.

That's a decent amount of advance. About .035" off the key or so? Thanks! Any shared knowledge is very helpful and most appreciated.

 

[isaaccarlson]

Set the cylinder in place without the piston and see what needs to be smoothed out for nice flow. I didn't cut the squish band and ended up with .018" squish and (180 psi last time I checked). My combistion chamber is quite small. I could cut a couple degrees out of the band and have 200 psi if I wanted it, but it's pretty hard to pull over already. I might do that in the future, but it runs REAL good as it is. I'm running pretty much stock timing. I just found my 2 stroke timing light (powered by the spark, not a battery) so I can check it and see what the timing actually is. My ms390 will yank the rope out of your hand if you sissy-pull it. I have not had my 350 do that, so there may be some timing on the table, but I won't know until I check it. Timing isn't something you take a guess at.

Don't go too big on the muffler outlet. I use 50-75% of the area of the exhaust port for the muffler outlet.

 

[thedude74]

Set the cylinder in place without the piston and see what needs to be smoothed out for nice flow. I didn't cut the squish band and ended up with .018" squish and (180 psi last time I checked). My combistion chamber is quite small. I could cut a couple degrees out of the band and have 200 psi if I wanted it, but it's pretty hard to pull over already. I might do that in the future, but it runs REAL good as it is. I'm running pretty much stock timing. I just found my 2 stroke timing light (powered by the spark, not a battery) so I can check it and see what the timing actually is. My ms390 will yank the rope out of your hand if you sissy-pull it. I have not had my 350 do that, so there may be some timing on the table, but I won't know until I check it. Timing isn't something you take a guess at.

Don't go too big on the muffler outlet. I use 50-75% of the area of the exhaust port for the muffler outlet.

All excellent input! Very much appreciated! Funny you mention that("set the cylinder in place")...ive been staring at the cylinder a)on top the base adapter last couple of days.
Speaking of ms390....ive milled hundreds of board feet on an Alaskan mill with a muffler modded Stihl 039 and 28" bar. It wasn't fast...but it did it without issue....
Anyway, 180 psi is pretty good without cutting the squish. Like you said the factory squish band is nice and wide compared to many other stock saws.

Fom my limited experience ported saws like big exhaust openings....up to My ported echo cs490 made a noticeable gain going from roughly 60% to a measured 80% muffler opening to exhaust port ratio. I'll start on the lower end (60%)and work my way up.

BACK TO WORK!

 

[thedude74]

More husky 350 numbers dimensions etc..piston pin diameter 9.96mm(10mm)

 

[thedude74]

Piston pin bearing width 13.62mm

 

[thedude74]

Small end rod width 14.27 mm

 

[isaaccarlson]

What piston are you using?

 

[thedude74]

Small end rod diameter ID 12.82mm

 

[isaaccarlson]

They pull pretty good when done.

 

[thedude74]

Aftermarket(chinesium) 45mm 353 piston left, stock 350 45mm dished piston right. With the pin connecting the two they are flush(within a few thousandths). The dished piston took about 3.5 ml(1 ml =1 cc) of water to fill flush. No idea how many cc the combustion chamber is...

 

[thedude74]

They pull pretty good when done.

Dang! They sure do get up the rpms and stay there! Very nice saw you built.

 

[isaaccarlson]

Dang! They sure do get up the rpms and stay there! Very nice saw you built.

That's with the rakers filed way down (.035) to put a load on the saw. With the rakers at .025 it was absolutely screaming.

 

[thedude74]

That's with the rakers filed way down (.035) to put a load on the saw. With the rakers at .025 it was absolutely screaming.

Heck yeah. I'll bet it would pull 3/8 no problem.