Echo 620-PW...digital ignition?

[Radu88]

I have been very pleased with my CS-590 that I have beat the crap out of for 4 years with no problems at all, as such I have been eyeing the 620-PW.

Reading through the specs and I noticed "It has a digital ignition system that automatically adjusts the engine timing for optimum performance."

Is that essentially in the same realm as the M-Tronic system/etc? I'm generally a fan of old school saws without additional electronic components so I wanted to figure out what the deal is with these 620's

 

[RED-85-Z51]

Echo has used a digital ignition called Slope Advance Ignition1/2/3...(SAI), for well over 2 decades now. It retards timing for easy starting, then advances it along the power curve for peak power. Mtronic and Atune use a module to play with the timing and fuel trim. Echo uses a non electronic carb

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[Jwilliams]

I own both the 590 and the 620 and think if I would of bought the 590 first and it was now Ide buy the 7310 the 590 is too close to the 620 in my opinion

 

[Piston Skirt]

Echo has used a digital ignition called Slope Advance Ignition1/2/3...(SAI), for well over 2 decades now. It retards timing for easy starting, then advances it along the power curve for peak power. Mtronic and Atune use a module to play with the timing and fuel trim. Echo uses a non electronic carb

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Correction:
Echo has used SAIS and SAIS2 (Slope Advancing Ignition System) ignitions for more than 2 decades. Those are electronic analog systems and SAIS2 slope features ignition retarding for soft rpm limiting.
For around 15 years most ECHOs have digital microprocessor controlled ignition systems called “Digital CDI” with mapped advancing/retarding angles and some of them have separate map for cranking and some additionally have limiting for first 20-24 seconds of warm up (does not spool up despite rock solid idle no matter what)
590/620 has cranking map feature too.

 

[Miles86]

I have a CS-600 from 2010 and the power band is much wider than my grey CS670 from 2008, the 670 you need to really listen to the rpm and not dog it at all, it cuts well when you get used to that.

 

[Cliff R]

My good friend and long time employee of Echo told me at least 20 years ago that some of their coils have "timing retard" modules. I suppose it was his "basic" way of saying that some models used them for rev-limiters vs just cutting out the spark at high RPM's, at least that was my understanding of the design.

This would allow for leaner carb settings to please the EPA but help with not "smoking" P/C's due to increased RPM and higher EGT's plus less lubrication, or at least one would think they would help some?

Not sure but I've owned quite a few different models and both my CS-600P and CS-620PW do not appear to be RPM limited. The CS-590 has a rev-limiter but it's high enough it doesn't really come into play with correct carb settings........

 

[mountainlake]

I have a CS-600 from 2010 and the power band is much wider than my grey CS670 from 2008, the 670 you need to really listen to the rpm and not dog it at all, it cuts well when you get used to that.

You need to give it more fuel on the high adjuster, CS670 saws have excellent torque unless adjusted to lean. If it has limiter cap they need to come off. Steve

 

[Miles86]

Hi Mountainlake - thanks will given it a try.

 

[rmh3481]

God Bless Mountain Lake!

 

[Piston Skirt]

My good friend and long time employee of Echo told me at least 20 years ago that some of their coils have "timing retard" modules. I suppose it was his "basic" way of saying that some models used them for rev-limiters vs just cutting out the spark at high RPM's, at least that was my understanding of the design.

This would allow for leaner carb settings to please the EPA but help with not "smoking" P/C's due to increased RPM and higher EGT's plus less lubrication, or at least one would think they would help some?

Not sure but I've owned quite a few different models and both my CS-600P and CS-620PW do not appear to be RPM limited. The CS-590 has a rev-limiter but it's high enough it doesn't really come into play with correct carb settings........

Normally they avoid spark cutting at any cost as this leads to the carbon build up. There are several techniques of rpm limiting, gradually retarding ignition being one of them.
Ignition retarding is not related to emissions as those are measured at idle and maximum power.
Spark cut is more effective on 4 strokes.

 

[Cliff R]

The only Echo saw I've owned that had an annoying Rev limiter was the CS-360T, it "cut-in" WAY too early for my liking and made the saw difficult to tune on the "H" speed screw. I replaced it last year with a CS-355T and never looked back. The CS-355T is better everyplace, Echo really did their homework when making that saw....IMHO......

 

[Piston Skirt]

The only Echo saw I've owned that had an annoying Rev limiter was the CS-360T, it "cut-in" WAY too early for my liking and made the saw difficult to tune on the "H" speed screw. I replaced it last year with a CS-355T and never looked back. The CS-355T is better everyplace, Echo really did their homework when making that saw....IMHO......

Properly set, almost all Yamabiko engines (except some of the newest ones, like 2511) first reach the maximum RPMs due to the rich mixture limitations. If the engine (I’m still talking Echo) goes into RPMs where the actual limiting starts kicking in - it’s already running lean.
But yeah, some guys advance ignition timing searching for comfort in “retarding area” (12K and above) while at the same time overadvance the max power rpm range. Another misleading point in it - low-to-mid range advancing improves acceleration a bit so there is some impression of better power...

 

[Cliff R]

Agreed, all my other Echo's are fine and easy to set the "H" speed screw when tuning.

The CS-360T was just coming in too early. I'd start out "pig" rich and would try to sneak up on the best tune, and just about where you'd think just tiny bit more and we're perfect the pesky timing retard/limiter would come crashing in. Whatever module they used on that saw it acted like it was actually cancelling spark and mimic "four stroking" but it wasn't quite there yet. They just missed the mark slightly or were worried about P/C failure with that unit and put some more fail-safe into it?

Don't get me wrong it cut great but the last little "tweak" with the "H" speed screw was just a guess as to being perfect you could not tell the module coming into play vs a correct carb setting.

Matters not as I sent it down the road and put a CS-355T on the shelf instead. It has NONE of the negative characteristics of the CS-360T, and just all the way around a better saw......IMHO.......

 

[Piston Skirt]

Yep, here’s one more good thing about 355 (36x for the rest of the world) - it is digital, computerized, mapped more precisely and more reliable than ever since day 1
And It’s already some 10 years since it’s introduction

 

[Cliff R]

+2
It very quickly became my "go-to" saw on the side-by-side and I use it just about every time I check out my property and do any clean-up. Starts in one or two pulls, excellent power, good ergonomics and light weight.......

 

[Piston Skirt]

+2
It very quickly became my "go-to" saw on the side-by-side and I use it just about every time I check out my property and do any clean-up. Starts in one or two pulls, excellent power, good ergonomics and light weight.......

Yup, last time i dropped ‘em on scales, it was a tad lighter than 201 and a lot lighter than 540.