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#Post#: 52516--------------------------------------------------
Echo cs670 Porting for Work
By: awol Date: January 14, 2015, 5:42 pm
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These are a very well designed saw, and dependable in the
woods, but seem to be lacking in performance. They use a full
skirted piston with windows, and all transfer flow must pass
through these windows, to get to mid fed lower quad transfers.
The original piston is also domed. I found that a Husky 268
piston makes a good replacement, it is slab sided but not
windowed, and has enough skirt length and width to allow
widening of the EX port. It is also much lighter, and has a flat
top, requiring a lot of squish band and combustion chamber work.
Here is the saw stock.
HTML https://www.youtube.com/watch?v=hIIFMow_69I&feature=youtube_gdata_player
And here it is after mods with the same untouched chain.
HTML https://www.youtube.com/watch?v=AMlxrbizvo8&feature=youtube_gdata_player
#Post#: 52517--------------------------------------------------
Re: Echo cs670 Porting for Work
By: aclarke Date: January 14, 2015, 5:49 pm
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Sounds good!!
#Post#: 52520--------------------------------------------------
Re: Echo cs670 Porting for Work
By: awol Date: January 14, 2015, 6:09 pm
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Thanks!
In order to help out the restricted transfers, I added
fingers at the end of the bridge.
#Post#: 52521--------------------------------------------------
Re: Echo cs670 Porting for Work
By: Chainsawrepair Date: January 14, 2015, 6:13 pm
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Nice.
You have measurments of the 268 piston and 670 piston? If not I
will dig later.
I know all to well about the stock video. Own a 6700. Reminds me
of a husky 365 weight and handling but less power then 365.
#Post#: 52524--------------------------------------------------
Re: Echo cs670 Porting for Work
By: awol Date: January 14, 2015, 6:50 pm
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I have the 670 piston in the scrap bucket, I will get pics
and measurements of it and post the results. I do know that the
268 piston was around .080 taller, as that is how much material
I removed from the squish band. This brought compression up to
250psi, so I had to remove a little material from the combustion
chamber. Comp is now 190psi after about two gallons of gas.
#Post#: 52533--------------------------------------------------
Re: Echo cs670 Porting for Work
By: aclarke Date: January 14, 2015, 8:39 pm
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Cool. Are the finger ports separate from the mains or do they
connect on top?
#Post#: 52538--------------------------------------------------
Re: Echo cs670 Porting for Work
By: awol Date: January 14, 2015, 9:31 pm
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The fingers are connected to the intake side uppers.
I tried to attach a photo, it shows up when I look at the
thread, hope everyone else can see it.
#Post#: 52539--------------------------------------------------
Re: Echo cs670 Porting for Work
By: aclarke Date: January 14, 2015, 9:51 pm
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Good deal nice work
#Post#: 52572--------------------------------------------------
Re: Echo cs670 Porting for Work
By: Chainsawrepair Date: January 15, 2015, 5:45 pm
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[quote author=awol link=topic=4526.msg52538#msg52538
date=1421292705]
The fingers are connected to the intake side uppers.
I tried to attach a photo, it shows up when I look at the
thread, hope everyone else can see it.
[/quote]
I can see them and when clicked on pic it enlarges to giant
size. Like this.
HTML http://chainsawrepair.createaforum.com/index.php?action=dlattach;topic=4526.0;attach=10906;image
#Post#: 52588--------------------------------------------------
Re: Echo cs670 Porting for Work
By: awol Date: January 15, 2015, 9:08 pm
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Here are the measurements of the stock Echo piston:
Pin boss width 17mm .667"
Pin diameter 12mm .472"
Comp height 22.2m .871"
Total ht. 40.4mm 1.586"
Dome ht. 2.29mm .090"
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