ECHO Echo, Echo, Echo

[thedude74]

Just farting around the other night and was curious about swapping parts and compatibility....mainly swapping the 490 to a 4910 recoil start...

CS4910 coil



CS490 coil

 

[thedude74]

As many know the 490 coil is limited to a lower rpm vs the 4910. Flywheel part #s are the same. The flywheel air shrouds also appear identical.

 

[thedude74]

I've got a postage scale somewhere.... exact location escapes me. But by feel alone the 4910 recoil is substantially lighter. It's also a standard type vs the 490s dual spring start assist type....not needed on a 50cc saw in my opinion.


The lighter 4910 recoil starter is a direct bolt on with no alterations or apparent binding/clearance issues

 

[thedude74]

Both of these are ported but run different numbers. The 490 bumps the rev limiter pretty easily while revving/limbing. In the cut bucking it's a non-issue.

Went ahead and ordered a 4910 coil for the 490....Will probably swap the carb at some point too. . Mostly just curious how it will run with the updated parts. I'd imagine the timing curve is probably different and will have an effect.

Anyway, just thought I'd share my findings with those who might be interested.

Edit: Anyone ever put a timing light on these comparing the two ????

 

[Gullet]

Brisco builds some pretty spicy Echos. He pushed a 4910 to 7.4 HP on Joes Dyno.

I agree.
Donnie Walker does also.
There is a video on utube of Buckin Billy felling trees with a Walker full comp 28" 620p that impressed me!

 

[thedude74]

I agree.
Donnie Walker does also.
There is a video on utube of Buckin Billy felling trees with a Walker full comp 28" 620p that impressed me!

Echos decision to go with a long stroke (37.7mm) on the 590/620 makes for a very nice general purpose saw with good low end grunt for a 60cc.

 

[FergusonTO35]

Does a rev limiter really matter on a saw? I would think that you wouldn't be anywhere close to max rpm when cutting anything over the size of a green twig.

 

[thedude74]

Does a rev limiter really matter on a saw? I would think that you wouldn't be anywhere close to max rpm when cutting anything over the size of a green twig.

The 490 coil is limited to a fairly low rpm for a modern 50. It's probably a couple thousand less than the 4910? Stock it was never an issue. My particular 490 will occasionally hit the limiter while limbing spruce.
Does it really matter? Probably not. It's tuned in the cut bucking. Mostly curious what no load rpm it's hitting, what performance difference, if any, the 4910 coil makes. The next step will be the 4910/501 carb..... Experiments for science n stuffs.

 

[old 040]

Recent pick-up, early model Echo 601.......

 

[Ketchup]

The 490 coil is limited to a fairly low rpm for a modern 50. It's probably a couple thousand less than the 4910? Stock it was never an issue. My particular 490 will occasionally hit the limiter while limbing spruce.
Does it really matter? Probably not. It's tuned in the cut bucking. Mostly curious what no load rpm it's hitting, what performance difference, if any, the 4910 coil makes. The next step will be the 4910/501 carb..... Experiments for science n stuffs.

I can’t guarantee it, but I think the 501 has a higher or unlimited coil. I put one on my 490 and have never hit the limiter.

 

[mainer_in_ak]

Ive never put a tach on any saw, ever. Always tuned by ear, in the wood and occasionally check color of spark plug after a long day of cutting

Just checked a CS 620pw and a cs 590 and a mildly ported cs 8000 with larger HDA 45 carb.

Neither the cs 590 nor the 620pw are ported, but have the fully adjustable fuel nozzles in the carbs:

CS 590:13,300 RPM
CS 620pw: 13,900 RPM
CS 8000: 13,500 RPM

Only thing done to the cs 590:
Walbro fixed fuel nozzle
Timing advance
Base gasket delete
Muffler opened up.

Only thing done to the cs 620pw is a gear head muffler deflector.

If a CS 590 is free revving to 13,300, which is right near the rev-limit and running 8 hours a day, resulting in a nice chocolate brown plug color, I don't think it needs to be ported.

I also don't think a cs 590 needs a 620 carb, nor the expense of a 620 coil. Folks are free to set up a saw the way they want, but it makes more sense to just simply buy a 620.

I don't expect a 590 to be a 620p. Here's where modest improvements should be made:
$ 4 for the fixed walbro nozzle
$15 for the oem clutchside felling spike
$15 for a rebeard stihl bar to echo 590/620 adapter
$57 for a 24" versacut bar
$20 for an EXL chain.
Timing advance
base gasket delete
muffler opened up.

The LPX chain that comes on a cs 590 is quite a bit slower than a loop of EXL. In timed cuts, about 3-4 seconds slower in 18"-20" diameter wood. The stock timberwolf bar n chain makes a decent back-up though.

 

[mainer_in_ak]

Checked a couple more saws with the tach:
Cs 6700 13,400 RPM
This 6700 is set up exactly like the cs 590:
Base gasket delete, ignition advance, muffler opened up.

CS 900 EVL 12,000 RPM
The 900 has had the muffler opened up. She's slightly rich. And with such an old saw, I won't spin er up past that.

Again, these are all tuned in the wood. Ran this way for many hours and never retuned. Just figure I'd share what the tach "told me", which is nothing really.

I'll report back what rpms they're pulling in the wood.

*update:
Freshly sharpened exl, rakers set aggressive.

The cs 590 is pulling 11,800 rpm in a 14" diameter birch.

Rpms settling into 11,600 rpm if I put a bit of feed pressure on er.

Non-stop cuts in the hot summer weather, the saw is now hitting 13,500 rpm free revving.

So 13,300 rpm is ideal. Saw restarts easy.

This dmn 590 don't need any 620 innards in er. Be a foolish waste of money. Let the budget saw be a budget saw.

I am darn impressed with this 590!

The cs 6700 is pulling about the same 11,800-11,600 rpms in the cut.

Non-stop cuts in the hot summer weather, free reving it hits 14,000 rpms which I don't like. But it's still "4-stroking" when you lift it out of the cut.