Echo CS-590 Timberwolf Muffler Mod - Flow bench Measurements
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bmwpowere36m3
ArboristSite Operative
Chris-PA
Where the Wild Things Are
Agreed
I saw a very steady 9k stepping through with a 2s window. Using a shorter window I saw a small amount of 4-stroking before the 2.5s mark but none afterwards. The OP's saw 4-stroked much more.
So I think it's fair to say that a stock 590 is a low rpm engine, which makes sense given the timing. Of course it's an entirely conventional engine so it will respond in the normal way to the usual mods
Red97, I really like the exhaust tone of that saw.......especially at idle!!!!!MEAN!
bmwpowere36m3
ArboristSite Operative
Found a vid of me felling/bucking with the CS-590 (simple deflector MM and limiter delete)... I'm getting about 8400-9600 in the various cuts, mostly around 9000 RPM in ~12-15" of this:
bmwpowere36m3
ArboristSite Operative
First cut before the surging 10,100 RPM and the middle of the second cut 9300 RPM (leaned out it).
I don't think my saw is out of tune. It is slightly rich, but its still being broken in. It sounds like the guys who have done some porting are seeing more RPM. Did you somehow raise the ports to alter the port timing to achieve this? I certainly appreciate all the impressive analysis! I will install a tach on it and get more info when I cut some more dead trees we have. That won't happen for a few weeks though. Work is getting in the way.
bmwpowere36m3
ArboristSite Operative
Mine only has 6 tanks thru it... probably not even broke-in yet. No porting, same mods as yours.
Since I'm an amateur when it comes to saws, I started super rich... burbled thru the whole cut and slowly leaned it out. I found a stick almost as big as the bar and start cutting. Released the top handle and let the saw slowly self-feed. Adjusted till it burbled, back and forth (4-stroke, 2-stroke, 4-stroke, etc). As soon as pressure was applied to the top handle it clears out and 2-strokes.
Initially I had it a little rich when cutting is would burble every so often during a cut. Now it rarely burbles during the cut.
Since I'm an amateur when it comes to saws, I started super rich... burbled thru the whole cut and slowly leaned it out. I found a stick almost as big as the bar and start cutting. Released the top handle and let the saw slowly self-feed. Adjusted till it burbled, back and forth (4-stroke, 2-stroke, 4-stroke, etc). As soon as pressure was applied to the top handle it clears out and 2-strokes.
Initially I had it a little rich when cutting is would burble every so often during a cut. Now it rarely burbles during the cut.
The ported 590 has less than 3 tanks on it. Full rebuild. The Christmas 590 is still on the first tank full rebuild too.
Yes, these 590's take a lot of grinding to get the ports right.
Exhaust and transfers need to come up a lot.
Seems porting is close to a 2k gain in cut rpm. That was why I asked to have everything checked with the software. Just to see how well they gain over stock.
Chris-PA
Where the Wild Things Are
If you are used to fuel systems (carbs, injection, etc.) from other types of equipment then it is good to keep in mind that these all-position carbs do not work the same way at all. In most carbs when you set the fuel/air mixture for an operating range (L or H, for example), then within that range if the air flow changes the fuel will change proportionately so the mixture is approximately constant. With these carbs that is not the case. As the air flow increases the amount of fuel increases drastically - this is why your engine misfires (4-strokes) with only a small increase in rpm from lifting. So when you tune a saw you are trying to set a particular point on a steep curve to some set of load/rpm conditions - just a small change in WOT rpm and the mixture is now much different.
My purpose for writing that is because the concept of being properly "in tune" almost doesn't apply to a saw at all. At best the mixture can be correct for some particular load/rpm operating point only. The mixture can be consistent in how it varies with air velocity/rpm, but it can never be constant. Generally we use the obvious sound of the 4-stroke misfire as a marker for proper tuning for some specific conditions - when you hear that it is firing evenly under load but when you lift and the mixture gets rich and misfire, then that is as good as you can do.
Using a spectrum analysis from the audio recording you can sometimes see that 4-stroking misfire even when it's barely audible - yours was doing it more readily than the other recording of a stock CS590, and I suspect that is the reason for the couple hundred lower rpm it is turning.
Merc1973
Newly infected with CAD
Wow, excellent thread. Any updates?
That's what mine looks like too with not much use. Easy switch to rim drive, remove the c-clip?
That's what mine looks like too with not much use. Easy switch to rim drive, remove the c-clip?
Chris-PA
Where the Wild Things Are
This was the video I used for this analysis I posted elsewhere, showing the plots at the saw gets into the fattest part of the wood:
nitehawk55
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Easy switch , new drum and rim sprocket , put them on my 590 . Just the C clip .
motoguy
ArboristSite Member
My CS-620 arrived today. Based on what I read here, all I need to do is remove the deflector, correct? I think I'll keep the screen. I'm also going to keep the black intake insert.
My CS-501 arrived a couple of days ago. I removed the restrictor, screen, and opened up the deflector (essentially chopped one side off for an exit port).
Carb limiters removed on both.
Does that sum up the "most bang for the buck" mods on these two saws? Neither have been tuned, or even fired yet. My tach arrived a couple of days ago. Would you suggest tuning by ear, or tuning to a tach?
My CS-501 arrived a couple of days ago. I removed the restrictor, screen, and opened up the deflector (essentially chopped one side off for an exit port).
Carb limiters removed on both.
Does that sum up the "most bang for the buck" mods on these two saws? Neither have been tuned, or even fired yet. My tach arrived a couple of days ago. Would you suggest tuning by ear, or tuning to a tach?
James Miller
Addicted to ArboristSite
If you opened the muffler up tune by ear. The 590 is easy to hear 4 stroking. My 490 isn't near as obvious to hear 4 stroking. Iv never used a tach so no idea what either turns but they cut good.
James Miller
Addicted to ArboristSite
Nothing to add. Been running my ported 590 for going on 3 years with no problem.
