What did I do to my CS-4910?

[lukebuz]

Joe Homeowner here. Novice saw user, moving on the way to intermediate...

Anyways, I recently purchased my 3rd Echo saw. Have a CS-590, a CS-400 that's seen quite of bit of abuse from a learner, and a NEW CS-4910 to replace the CS-400. All totally stock.

The 4910 has been a good saw, but it would occasionally die out after a cut. It would be cutting well, and at the end, it would just quit. Before taking it back to dealer, I figured I'd try a few things.

Not having a clue about carburetors, and what I could find on the internet only giving me partial information, I decided to play with the adjustment screws. Tried a few minor adjustments to see if it would make a difference:
-Turned the "L" clockwise 1/4 turn
-Turned the "H" clockwise 1/8 turn

Amazingly, the saw not only stays running, but I swear it has more power. Just blasted through an 18" red oak trunk.

What impact did my adjustment have? Rich? Lean? Could I screw something up or run it overly rich or lean?

Thanks from a learning lurker!

 

[Chevboy0167]

Turned clockwise or "in", leans out... =less fuel. If tuned too lean, you can burn up the piston and cylinder.

 

[lukebuz]

Thanks! Any suggestions for the original problem? This seems to have fixed it.

How do you know if you are too lean?

Will check out videos in AM

 

[Chevboy0167]

Most 2 strokes tuned leaner will run harder. But go too lean and it will self-destruct. Like you experienced, saw is running faster with more power. Too lean equals less fuel and oil mix to lubricate and cool down the engine and its parts.

Owners manual will have the max wide open rpm stated in it. You can buy a small engine non-contact tachometer to measure this or tune by ear with the saw in a log cutting.

Search YouTube vids for tunning chainsaw in the cut or log. Watch a few and note what to listen and feel for. Never tune too lean that the saw just screams high rpm. That isn't more power... it's your engine crying for help!

 

[lukebuz]

OK, I've reviewed those videos, and I'll tell you there is no way I could "tune by ear" that wouldn't be completely hit or miss. Like, I hear a difference, but not fine enough that I could dial it in better than leaving it near stock settings.

I'll say it doesn't seem to run insanely fast - just seems more solid and steady at WOT, and hasn't (yet) cut out.

Could such a minor adjustment from stock potentially cause a issue? I mean, L was from "1 o'clock" to "3 o'clock" and H was from "1 o'clock" to "2 o'clock". I thought I read stock settings were usually rich?

 

[Chevboy0167]

Tune by ear does take some time getting to know how your saw sounds and feels while cutting.

In past years, most Echo have been lean from factory unless a good dealer fuels it, starts it, and tunes right there in front of the buyer. I do hear that every now and then, some saws show up rich now.

Saw builders set them rich to break in the piston and cylinder until the rings seat, Then we can lean things out a bit.

Those minor adjustments may be fine or may be right on the edge of starting to do engine damage. I don't have your saw in hand and can not tune it over the internet of course.

If your worried , turn the needles back about half what you moved them at the first time.

 

[echomeister]

Turn the H counter clockwise until performance drops ( too rich ) . Then slowly clockwise in small increments until it cuts good.
This is guaranteed to be a safe adjustment

 

[lee_the_wyrm]

Joe Homeowner here. Novice saw user, moving on the way to intermediate...

Anyways, I recently purchased my 3rd Echo saw. Have a CS-590, a CS-400 that's seen quite of bit of abuse from a learner, and a NEW CS-4910 to replace the CS-400. All totally stock.

The 4910 has been a good saw, but it would occasionally die out after a cut. It would be cutting well, and at the end, it would just quit. Before taking it back to dealer, I figured I'd try a few things.

Not having a clue about carburetors, and what I could find on the internet only giving me partial information, I decided to play with the adjustment screws. Tried a few minor adjustments to see if it would make a difference:
-Turned the "L" clockwise 1/4 turn
-Turned the "H" clockwise 1/8 turn

Amazingly, the saw not only stays running, but I swear it has more power. Just blasted through an 18" red oak trunk.

What impact did my adjustment have? Rich? Lean? Could I screw something up or run it overly rich or lean?

Thanks from a learning lurker!

I have a Shindaiwa CS4910 and it is sweet! I recently pulled the restrictor tube and opened the deflector a bit and it's noticeably more snappy. Your adjustments would have made it run leaner, which isn't ideal unless you know what you're doing.

I believe stock tuning is:

1 1/2 counterclockwise on the L
3 1/8 counterclockwise on the H

Remove the limiter caps and seat both screws gently before unscrewing to the above if you are keen on trying.

 

[sundance]

@lukebuz
4910 carb settings from Service Data Sheet:

 

[lukebuz]

∆∆∆ Very helpful, thanks!

 

[Joseph W Santora]

Two strokes run best when leaned out...But not for very long.

 

[tJKrider]

I have a Shindaiwa CS4910 and it is sweet! I recently pulled the restrictor tube and opened the deflector a bit and it's noticeably more snappy. Your adjustments would have made it run leaner, which isn't ideal unless you know what you're doing.

I believe stock tuning is:

1 1/2 counterclockwise on the L
3 1/8 counterclockwise on the H

Remove the limiter caps and seat both screws gently before unscrewing to the above if you are keen on trying.

Do you recall where you are at now with the restrictor out? Assume you opened up the H a bit... Just curious how much. Thx