CS400 tuning

[EchoCS400]

Stock before muffler mod was 1.75 low, 1.5 high.

After muffler mod, still 1.75 low but had to turn down the idle 1/4 turn. Low is set 1/4 turn rich from midway between lean/rich stumble. Used a tach to set idle to 2400rpm. Seems to have good throttle response.

Started 4 turns out on the high but it was puking, barely pulled 8000rpm. Tried tuning it in the wood, ended up 3 turns out. How does this sound? Birch was kinda dry, limited to what I have at home. I'll test it this weekend at the lake. Took about 8seconds stock, 4seconds after. Not leaning on the saw. Also has a brand new oregon S62 chain.

Stock:
https://youtube.com/shorts/52GG5UdEoZY?feature=share
Modded:
https://youtube.com/shorts/QQsITDz2Ovo?feature=share

 

[TLG]

I'm no expert Michael. Those CS400's are a little tricky on the L and idle screw adjustments. Always went by Echos procedure and it works well for me. I also think you are at too fat on the H. I would bring it in a quarter turn at a time for at least 1/2 total and then see how it cuts and sounds in and out of the cut. BTW those are decent little saws and relatively cheap.

 

[EchoCS400]

Yeah tuning the high seems a little hard, found some old poplar to run it in after. 3 turns out seems like its revving really high out of the wood, but almost sounds like its 4 stroking when i bury it. 3.5 turns and she'll just stumble on herself when I put it in wood.

I'd like to lean it out a little more but i don't want to fry it haha.

 

[TLG]

Kinda the opposite of what you want. You want it to 4 stroke out of the cut at full throttle. With a tach it should be around 12,000-12,500 with the four stroke sound. In the cut the four stroke sound will go away and it should settle down a fuzz and pull through the wood. Without a tach you could be off 300-600RPM by ear. That's why I said in and out of the cut. Basically balls to the walls in the cut and pulling just bring the bar up a little out of the cut. Then you should hear the four stroking sound taking over.

 

[mountainlake]

If before the muff modd the high was at 1 1/2 turns out it was way lean maybe going up against the rev limiter. These saws like somewhere around 3 turn out on the high. Steve

 

[EchoCS400]

If before the muff modd the high was at 1 1/2 turns out it was way lean maybe going up against the rev limiter. These saws like somewhere around 3 turn out on the high. Steve

That I'm not 100% sure, the limiter caps were still on... the screws mave have turned when used a deck screw to pull them out. The stock limiter was all the way out. Wherever that sits.

 

[EchoCS400]

Had the saw out this weekend... cut down a bunch of birch.

Seems to be working great, definitely ripping a lot harder than stock. Only issue I have is sometimes after a lot of cutting and running wide open it'll shut off when I finish the cut if I dont blip the throttle a few times.

Does that sound like my low jet is off? I feel like I'm slightly rich on the high, but its cutting good and I'd rather be too rich than lean. Starts and idles fine, just after burying it when I finish the cut and let off the throttle it will occasionally die.

 

[Vintage Engine Repairs]

If you’re cutting and it’s 4 stroking out the cut and cleans up in it and then when you finish your cut and the saw returns to idle but dies, although L and H work together, in this case it’s your H that’s too rich. If it’s idling but loading up and dies it’s the L that’s too rich. You could try either leaning the H slightly or bringing the idle up a bit to open the butterfly. I’ve seen lots of people keep their idle just slightly below chain engagement, I don’t but it may help your situation slightly. It’s quite normal for an engine to drop a few hundred RPM below idle spec after returning from WOT and then gradually coming up to spec. All my saws do that. I do run mine on the rich side, only just cleaning up under good load self feeding and the slightest amount of weight l lift up it 4 strokes. That way, when I’m using the bucking spikes and putting a little load and lifting on it a little, it runs really nice and clean.

Ben demonstrates this nicely.

 

[GeorgiaVol]

If you’re cutting and it’s 4 stroking out the cut and cleans up in it and then when you finish your cut and the saw returns to idle but dies, although L and H work together, in this case it’s your H that’s too rich. If it’s idling but loading up and dies it’s the L that’s too rich. You could try either leaning the H slightly or bringing the idle up a bit to open the butterfly. I’ve seen lots of people keep their idle just slightly below chain engagement, I don’t but it may help your situation slightly. It’s quite normal for an engine to drop a few hundred RPM below idle spec after returning from WOT and then gradually coming up to spec. All my saws do that. I do run mine on the rich side, only just cleaning up under good load self feeding and the slightest amount of weight l lift up it 4 strokes. That way, when I’m using the bucking spikes and putting a little load and lifting on it a little, it runs really nice and clean.

Ben demonstrates this nicely.

Great way of explaining it!

 

[EchoCS400]

If you’re cutting and it’s 4 stroking out the cut and cleans up in it and then when you finish your cut and the saw returns to idle but dies, although L and H work together, in this case it’s your H that’s too rich. If it’s idling but loading up and dies it’s the L that’s too rich. You could try either leaning the H slightly or bringing the idle up a bit to open the butterfly. I’ve seen lots of people keep their idle just slightly below chain engagement, I don’t but it may help your situation slightly. It’s quite normal for an engine to drop a few hundred RPM below idle spec after returning from WOT and then gradually coming up to spec. All my saws do that. I do run mine on the rich side, only just cleaning up under good load self feeding and the slightest amount of weight l lift up it 4 strokes. That way, when I’m using the bucking spikes and putting a little load and lifting on it a little, it runs really nice and clean.

Ben demonstrates this nicely.

Thats a great video, so to my understanding the echo cs400 has a rev limiter so should it hit that at WOT out of the wood? I thought I didn't want it revving that high.

I think its a little fat on the High side, its not quite cleaning up when i lean on it in the cut. It's close because i can hear it 4stroking in and out, maybe I'll lean out the high a little and see how it runs.

 

[FlyingDutchman]

What muff mod did you do?

My CS400 runs like trash, really need to get the limiter screws off of it.

 

[EchoCS400]

What muff mod did you do?

My CS400 runs like trash, really need to get the limiter screws off of it.

Removed muffler, opened up the muffler to match exhaust port, removed deflector and opened it up, drilled a hole on an angle to straight shoot exhaust gas out.

 

[Vintage Engine Repairs]

Thats a great video, so to my understanding the echo cs400 has a rev limiter so should it hit that at WOT out of the wood? I thought I didn't want it revving that high.

I think its a little fat on the High side, its not quite cleaning up when i lean on it in the cut. It's close because i can hear it 4stroking in and out, maybe I'll lean out the high a little and see how it runs.

Rev limited coils need to be tuned in the wood. Set the saw way rich, make a cut, tweak H screw, repeat over and over until it only just clears up in the cut, then you are safe. This video should help. A tach is useful too to make sure you are under the limited RPM.

 

[Ittybittyfitty]

I have an unused CS400…I’m waiting until I have time to muff mod it before trying her out. Rather than using a drill or whatever to auger out the insides, has anybody had luck separating the muff into 2 halves to remove the guts and then putting it back together?

 

[FlyingDutchman]

tried it for a bit... Gave up and drilled out. Extremely hard to remove the catalyst regardless... Was not fun.

 

[EchoCS400]

I have an unused CS400…I’m waiting until I have time to muff mod it before trying her out. Rather than using a drill or whatever to auger out the insides, has anybody had luck separating the muff into 2 halves to remove the guts and then putting it back together?

Drilling was pretty simple, but I have seen guys seperate the 2 halves, gut the muffler and then weld it back together.

I wanted a little back pressure and was trying to not make it too loud... not sure how much of a difference it makes though.

On another note, I tuned the saw again and ended up leaning it out a little more. Starts perfect, idles, and doesn't stumble. It's like a completely different saw, I can't believe it.