Torque Port 357/359. Which jug?

[Zombiechopper]

I have a 357 that I ported myself. It's a little high strung. I never raise exhaust, this is just a basic woods port with widened ports and no base gasket with squish right at .020"

I unshrouded the lowers a bit and opened them to match the case. The saw has a bit of a flat spot reving up and then surges up to max rpm. It does not have as much torque in the cut as my ported MS361 or ported 262XP/261. I want more low end grunt like my 262. That saw lugs down and chugs through anything, where as this 357 will stall in the cut if I don't let it hold the high revs just right. I like my saws set up with short bars, and I like to be able to push on them.

The saw doesn't suck and it's not slow in the cut at all. I just want more grunt

Should I:

1) use the 357 jug and send it off for a cut squish band to lower the exhaust
2) get a 359 jug to work with
3) start with another 357 jug and leave the lowers alone?

The way I did the lowers is from looking at pics of ParrisW and TDI Rick's 372 ports. I don't have any pics as I ported this saw a couple years ago

 

[Zombiechopper]

Option B: trade it. It's a high rev modern saw. I might prefer an older gruntier saw.

 

[sunfish]

1) use the 357 jug and send it off for a cut squish band to lower the exhaust

This should get ya what ya want and is what I plan to do to my 357.

Lower the exhaust and raise the comp.

 

[Zombiechopper]

I guess I'm worried that opening up and unshrouding the lower transfers is causing a problem with the small crankcase volume. I based what I did on the 372 formula

 

[sunfish]

I guess I'm worried that opening up and unshrouding the lower transfers is causing a problem with the small crankcase volume. I based what I did on the 372 formula

Sounds like you didn't do enough to the lowers to cause a problem. From what I'm hearing lately, cutting the cylinder (squish band and base) changes the attitude of most any of these saws. More torque and power.

 

[blsnelling]

There should be no flat spot, regardless of torque. Sounds to me like something's amiss with the saw.

 

[rattler362]

I have a 357 that I ported myself. It's a little high strung. I never raise exhaust, this is just a basic woods port with widened ports and no base gasket with squish right at .020"

I unshrouded the lowers a bit and opened them to match the case. The saw has a bit of a flat spot reving up and then surges up to max rpm. It does not have as much torque in the cut as my ported MS361 or ported 262XP/261. I want more low end grunt like my 262. That saw lugs down and chugs through anything, where as this 357 will stall in the cut if I don't let it hold the high revs just right. I like my saws set up with short bars, and I like to be able to push on them.

The saw doesn't suck and it's not slow in the cut at all. I just want more grunt

Should I:

1) use the 357 jug and send it off for a cut squish band to lower the exhaust
2) get a 359 jug to work with
3) start with another 357 jug and leave the lowers alone?

The way I did the lowers is from looking at pics of ParrisW and TDI Rick's 372 ports. I don't have any pics as I ported this saw a couple years ago

What were your timing #? i did the same thing to a 365 i changed the int port timing and it helped a bunch.The next one i do i am gonna try a single ring instead of two.

 

[Zombiechopper]

There should be no flat spot, regardless of torque. Sounds to me like something's amiss with the saw.

It revs fast hesitates for a split second, then Whoosh up to full revs. It's not really bad at all, but I am noticing it. Throttle response is excellent. It cuts as fast as my other 60cc saws but it needs to be babied a bit to keep the revs high whereas my 361 and 262 will lug much better. I bet that flat spot spooling up coincides with it stopping in the cut when revs drop below a certain point. I'm probably making this sound worse than it is, I can work with the saw all day and it cuts just fine but it definitely has a different attitude than my other saws.

Port timing was not changed. I only widen when I port my saws. Gasketless 020" squish, 3/4" pipe brazed into muffler, ports widened to 1/10th of skirts. Lower transfers matched to case and unshrouded a bit. Upper transfers widened towards intake.

What do you think Brad? Could it be a tuning issue or did I eff it up? lol! I should make a video. I'm not sure if I am exaggerating it in my mind thinking about it too much

maybe it's time for a degree wheel too

 

[mdavlee]

Sounds like we need a video to see what its doing. A degree wheel will let you get all that's there for a work saw.

 

[blsnelling]

Yup. Post up a vid and get a degree wheel on it.

 

[rattler362]

Have you tryed to richen it up a little on the Low side?could be the problem.

 

[Stumpys Customs]

There should be no flat spot, regardless of torque. Sounds to me like something's amiss with the saw.

I agree. Sounds like some carb issues or maybe needs the timing advanced a bit.

What were your timing #? i did the same thing to a 365 i changed the int port timing and it helped a bunch.The next one i do i am gonna try a single ring instead of two.

I agree with this too.

If you left the ex stock then it's not to high. The 359 I built had the ex timing close to stock #'s, but the intake & uppers wern't The lowers got alot of work too. It had lots of grunt to it. I think the issues you're having have nothing to do with the porting unless you went to wide & it's free porting or cross porting somewhere.

 

[Stumpys Customs]

Have you tryed to richen it up a little on the Low side?could be the problem.

That might help some too.

 

[parrisw]

The hesitation doesn't sound right to me. Which carb is on it?

 

[Zombiechopper]

The hesitation doesn't sound right to me. Which carb is on it?

it has a new Zama to replace the bad Walbro. The original carb went bad before the saw was ported.

What do you guys think of this port map? I have never analyzed timing. I always just widen ports and that works just fine for me. I see a degree wheel in my future, but I'll have to order one from somewhere. Or, I might send the saw off for machine work. It's not free porting. The 357 has a full circle piston so the ports aren't too wide. I'm not even sure if the numbers I gave you are any use. I just wanted to look and see what I did for my own peace of mind. It was a long while ago when I ported this and I have since quit drinking....
View attachment 242011

 

[Zombiechopper]

[url]http://i98.photobucket.com/albums/l268/JP3006/357XPPortMap-1.jpg[/url][img][/URL]

trying to get this port map embedded. Does this show any obvious stupidity or obvious room for improvement? A degree wheel will take some time to get here and set up. To me the obvious thing is lack of exhaust duration

 

[mdavlee]

It's hard to say what it needs without figuring the durations. I know someone was measuring and converting it into degrees. You may be able to get it converted if you know the stroke and then maybe the measurement from the top of the exhaust port to squish band.

 

[rattler362]

I am far from knowing what i need to know about porting but i just widen the EXT might clean up the casting marks.i dont bother the roof of the Ext because i don't wont to loose compression you more then likely won't that much some of the other builders will chime in on the subject.

 

[Zombiechopper]

I am far from knowing what i need to know about porting but i just widen the EXT might clean up the casting marks.i dont bother the roof of the Ext because i don't wont to loose compression you more then likely won't that much some of the other builders will chime in on the subject.

yup, that has been my philosophy so far as well. The port map I posted shows just widened ports. Now that I see it on paper, it sure looks like the exhaust could come down towards the intake. I'm taking baby steps towards understanding timing. It hurts my head.

Husky website says stroke is 1.34 and bore is 1.81

squish to ex roof is .9625
ex duration .453
ex floor at 1.415

squish to intake opening 1.635
in duration .530
in floor 2.148

Now, I found a calculator tool but it wants connecting rod length. This was from a kart forum. Is there a better way?

I know port maps translate poorly. I have measured quite carefully with dial calipers. Would like to see what I can come up with since getting a degree wheel will take some time.

 

[Zombiechopper]

blowdown .169

My understanding of blowdown is that it is from when exhaust opens to when transfer opens.