Echo cs 590,600,620 porting/mod/build thread

[Red97]

Layed out where I wanted things.

Exhaust was only 50%. Wanted a lil bigger, but not too big this time round.

 

[Red97]

Exhaust roughed in, trying to keep a stright shot out.

 

[Red97]

Transfers raised. Messed up the collet on my rt angle, only had 1 burr that fit, gnarly single cut... I may end up going back in at some point anyway.

Now just waiting for my coil, and a new ring.

 

[Red97]

Nothing?

This is supposed to be a discussion. With hypothesis and bacon and stuffs...

 

[jmssaws]

I've never worked on one, what numbers you got in her now? I didn't read page 2 if you said already I apologize.

How many cc's?

 

[rburg]

Don't know enough about porting to discuss but I do enjoy seeing the work and the finished product

 

[Czed]

Haven't been in mine yet I have 3 288s a 017 and 025 to fix for a friend of mine before I can start on my saws thanks for all the pics and info though.

 

[Red97]

I've never worked on one, what numbers you got in her now? I didn't read page 2 if you said already I apologize.

How many cc's?

60cc
In 78
Ex 113
Tr 130

Where would you go?

 

[Red97]

After the base cut
In 80
Ex117
Tr 136

 

[jmssaws]

Intake is good I think but the exhaust and transfers seem really low.
I'm no 60cc expert but 104 118 sounds better

 

[jmssaws]

After the base cut
In 80
Ex117
Tr 136

Holy *s-word!
Those are the lowest exhaust and transfers I've seen.

 

[Red97]

Intake is good I think but the exhaust and transfers seem really low.
I'm no 60cc expert but 104 118 sounds better

Holy *s-word!
Those are the lowest exhaust and transfers I've seen.

Yes,
Those # would work well in most other 60cc
Seems these run bout 13k stock, but comp is only round 180, with a gasket delete. 022-25 squish.

Really want to raise the torque curve 1000-1500. And keep the comp 190+

I went with 110 and 124. The case seems really tight, didn't widen the transfers just raised them in hopes of keeping velocity up. Same with widening the exhaust to only 60%. (Has plenty of skirt to get 70%).

That was my thoughts on this particular saw, we shall see how it works out. I have a spare jug, and another one coming to play with...

 

[Red97]

45mm bore 37mm stroke, is what complicates things

 

[jmssaws]

You can raise in baby steps until it's where you like it.

 

[Red97]

You can raise in baby steps until it's where you like it.

Yep, I have .015 ish till free port, so I want to see where the comp ends up with these numbers. Really think it would be sweet 205-210psi.



The jug off the saw cleaned up nice so I have a spare if I need to bring them back down.

 

[jmssaws]

Strange combustion chamber design, tiny band.

 

[Red97]

Strange combustion chamber design, tiny band.

The chamber is fairly small, and tear drop shaped. The plug is pretty much at the point.

Very small band, and tapered to match the one cut in the piston.

Definitely very different than most other 60cc I have seen.

 

[jmssaws]

The chamber looks huge but I guess it's that tiny band making it look that way.

 

[drf256]

Interesting build, those uppers are the biggest I've ever seen on a quad.

On a quad with a small tight case, I woulda personally kept the transfers physically lower in the jug. Plus with that super long stroke, the piston is moving much faster than other saws would at the transfer opening point. I bet if you toss a ring in there, there's not much physical distance between the exhaust roof and the transfer opening. And Quads fill a cylinder faster, so they generally like more blowdown.

Did the factory transfers open evenly or did the small exhaust transfer open first? It's an odd setup, is usually see the bigger port being the one closer to the exhaust and opening first.

I'm not trying to insult you bud, the grinding looks great. I just like talking theory. You have a second jug to play with anyhow. I'd consider raising the exhaust roof.

 

[Red97]

Interesting build, those uppers are the biggest I've ever seen on a quad.

On a quad with a small tight case, I woulda personally kept the transfers physically lower in the jug. Plus with that super long stroke, the piston is moving much faster than other saws would at the transfer opening point. I bet if you toss a ring in there, there's not much physical distance between the exhaust roof and the transfer opening. And Quads fill a cylinder faster, so they generally like more blowdown.

Did the factory transfers open evenly or did the small exhaust transfer open first? It's an odd setup, is usually see the bigger port being the one closer to the exhaust and opening first.

I'm not trying to insult you bud, the grinding looks great. I just like talking theory. You have a second jug to play with anyhow. I'd consider raising the exhaust roof.

This is what I was hoping for, some (what if) discussion thank you.

As for the transfer port size, it is rather deceiving. The small port, is still smaller than the factory 357 ports. The lage one is now on the big side.
From factory the large transfer entered the port at a 45* angle. Had a pinch point at the top of the tunnel. It is currently flat.

With the way the lowers are cut out, I belive the transfers will flow in a loop similar to a 2 port engine. Where a true quad flows higher velocity in this shape >> ( 7 )

On the exhaust height factory with gasket is 113, cut the base brought it to 117, I raised it to 110, which is only 3 higher than stock.
I wanted to keep the compression up, since these are fairly low compared to other 60cc saws.

Ex 357 is roughly 200psi with an ex at 104.

On the transfer height, factory blow down was 17* factory was 130 after the cut ended up at 136, I set them to 124 with is 3* less blow down and 6* higher than stock. The durations were throwing me 100* stock, and 80* after the cut.

Wanted to get the duration up. Currently setting at 112* duration.

Also hard to gauge where to go without running one stock either.