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.