Christmas Exchange Echo 620

[exSW]

Freight service your good asking as your above 90? Properly working air dryer should prevent that. Although some new software on air dryer cycling could contribute. Although the ole' shaft driven might pose a problem. You working the holiday?

Maybe. I'm on the only stay at home job left in my terminal. Hopefully the one guy older than me that's qualified stays on his extraboard at the autoplant.

 

[Stihlbro]

I hear ya! UPS season.... dot dot dot

 

[exSW]

I hear ya! UPS season.... dot dot dot

Do tell. You'd swear it was Santa himself coming through. I work on NS track as well.So I get it from yours and ours.

 

[Stihlbro]

Most here won't understand, but the 202 come thru Roanoke the other night with a ditch light out. We was sitting there like a NASCAR tire change out, but unfortunately for blue flag protection, one hour of protection for 15 minutes of work. Unfortunately it is the rules we live by that cost a 1 hr 10 minute delay on a tops train. Guess who had to answer for that?


Yep!! That be me!!! Victim of the system!

 

[exSW]

Most here won't understand, but the 202 come thru Roanoke the other night with a ditch light out. We was sitting there like a NASCAR tire change out, but unfortunately for blue flag protection, one hour of protection for 15 minutes of work. Unfortunately it is the rules we live by that cost a 1 hr 10 minute delay on a tops train. Guess who had to answer for that?


Yep!! That be me!!! Victim of the system!

Hand the tools and the bulb to the Engineer. It's happened to me more than once.

 

[Stihlbro]

Tried that, it was a crew swap.

 

[Stihlbro]

Back on track here. Spent a few hours digging into this echo. I'm measuring a factory squish of .036 thousands of .91mm. The base gasket is .012 thick or .32mm. So with no gasket the squish is roughly .026ish.

I put the degree wheel on it and by my method the timing is....
Exh 104
Transfers 121.5
Intake 80

I have spent most of the time studying the port shapes and piston positions thru out. Here is where I'm scratching my head.


I marked the piston at tdc thru the exhaust port . I have very little room here to drop the jug. This is with just the base gasket removed. Hmmm?????

 

[Stihlbro]

Few pics of the topend. Beautiful shapes, bevels look good, very different chamber than I'm use to, I don't understand the piston coloring.

 

[Mastermind]

If you allow for the thickness of your pencil......I see at least .040" you can drop it.

 

[Nitehawk55]

NightHawk, I know what you mean about the seal.....I just put an o ring over the flange from an assortment pack and it seemed to do the trick.

Thanks , I was thinking of trying that

Just making up a parts shopping list for limiter caps , exhaust outlet covers and the like for some Echo muffler mods in the new year .

 

[Stihlbro]

If you allow for the thickness of your pencil......I see at least .040" you can drop it.

I'm gonna mock it back up and make sure my mark is right. Gotta study it more.

 

[Stihlbro]

I've went over this saw a few times. Here is where I am at. The piston skirt is going to limit this saw. The bottom ring is exposed in the intake port from the factory. The ports width do have some room to widen. I've been looking for ways to improve flow and I see a lot in this cylinder that use to be done for improvements over the years.
With saying that, we must have echo engineers on these chainsaw forums.
The tighter squish, the larger intake duration, the transfers openings. The piston is cut on a taper. The bottom ring is towards the exhaust. The top ring pin is center of the bore.

 

[Four Paws]

I think the 590/600/620 is a Shindaiwa design

 

[Stihlbro]

There is some wicked stuff going on with this design. I like it.

 

[exSW]

I think the 590/600/620 is a Shindaiwa design

First thing I thought when I handled one.

 

[Four Paws]

I like how thick the cylinder base is!

 

[Mastermind]

I like everything about the 620..........but I like the 590 piston in it.

 

[Red97]

I like everything about the 620..........but I like the 590 piston in it.

This ^^^

Muh hewo.

 

[Deets066]

There is some wicked stuff going on with this design. I like it.

That's an impressive stock cylinder. I wouldn't have the first clue what to do with it besides shape ports a little

 

[Stihlbro]

I won't touch the transfers. I may widen the exhaust. Intake will end up where setting squish leaves it. This saw is like playing chess, I need every move to count.

I ordered a base gasket, it will probably take a few days to get.