# Echo CS-590 Timberwolf Muffler Mod - Flow bench Measurements



## Team FAST (Aug 18, 2016)

I recently acquired an Echo CS-590 Timberwolf Chainsaw. As promised, I intend to measure the muffler on my flowbench and then measure the incremental improvements as a result of the common "muffler mod" alterations.


Here's my saw. I purchased it last week at Home Depot. It was a "return" basically brand new. I purchased it for $275  Piston skirt looks factory fresh. Probably hasn't had a tank thru it yet.


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## Team FAST (Aug 18, 2016)

I had to machine an adaptor plate to install the muffler onto my Superflow SF-110 flowbench,

The plate allows me to install the muffler directly onto the flowbench.


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## Team FAST (Aug 18, 2016)

Here's the muffler installed on the flow bench.

I'll post flow results later on today. I burnt a lot of midnight oil getting everything installed and tested.

Test plan so far is:

1. Stock
2. No screen
3. No screen, no deflector
4. Modified Deflector and screen
5. Modified deflector, no screen

This will show the incremental changes and effects on exhaust flow from altering the muffler.

I may also drill holes, but that depends on the results....


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## 7sleeper (Aug 18, 2016)

VERY NICE!!! Exited about the results. 

7


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## GrassGuerilla (Aug 18, 2016)




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## James Miller (Aug 18, 2016)

Will be watching this one as I just pulled the 90 out of the deflector on mine the other week but left screen in.


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## Team FAST (Aug 18, 2016)

Here are the initial muffler flow results. 

I went as far as modifying the deflector. I haven't drilled any internal holes into the muffler yet.

For those that care, here's the atmospheric data during the test session (which was about one hour).




Here's the Flow results. I am reporting Raw (uncorrected) airflow numbers. Since the test conditions are more or less constant over the hour of testing, these flow values can be directly compared with each other.


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## GrassGuerilla (Aug 18, 2016)

Interesting... The screen makes less difference than I would have guessed.


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## Team FAST (Aug 18, 2016)

Here's how I modified my deflector. I machined the inside baffle away on the mill. I removed as much material as I could. I also completely deburred the part. In original factory condition, there are quite a few burrs and raised edges everywhere on that part. I don't like burrs and edges, so I deburred it (the machinist in me). 











And here it is installed on the muffler:


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## cedarshark (Aug 18, 2016)

I did the exact same thing w/ a foredom grinder and although a retune made the saw much better, I had no idea how much better the muffler flowed. Thanks for the flowtest and the effort involved.


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## hi-fi (Aug 18, 2016)

Very interesting. Thanks for the effort. 

Subscribed.


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## Team FAST (Aug 18, 2016)

Thanks.

There is another piece to this puzzle which I wanted to consider when making changes to the exhaust: The carb and air filter. 

I already had a carb adaptor plate machined, so I went ahead and flowed the carb as well. Two stroke engine tuning is really best accomplished with a "total system" approach. I wanted to see if the intake limits the available airflow. Common sense thinking says that if the muffler flows more than the intake, there probably isn't any benefit or further gains to be had. We all understand that a certain amount of exhaust backpressure is required to prevent short circuiting of the incoming fresh fuel mixture. Exactly how much is highly dependent on several factors. 

The throttle butterfly was held in the wide open (WOT) position for these measurements. I did test the air filter with and without lithium grease applied around the seal surface to the orange air filter base (the area suspected of leakage of dust by members on this forum). Not surprising to me, it did not reveal any changes to the airflow numbers. However it still may be a sealing issue for dust. The air filter restriction will only grow (get worse) as the saw is operated and debris is trapped in the filter media. Carb tuning will definitely be affected by the presence of the air filter

I didn't install the outer cover, due to clearance issues to the bench.




With air filter installed:





Here's the flow data for the carb and air filter assembly:


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## 009L (Aug 18, 2016)

TF,

This is a very freaking cool thread!!! I can't believe one of you chainsaw hicabilly's actually rolls with a Flowbench...Lmao!   Have you done this with other mufflers/carb's? (390xp, 261, 550, etc.) It really takes all the guess work out of the equation.

Thanks,

Pat


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## Big Block (Aug 18, 2016)

this looks to be an awesome thread !


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## Chris-PA (Aug 18, 2016)

Interesting tests! A couple of random thoughts:

19.5 CFM is 552,179 cc/min. A 60cc engine at 10,000rpm is only 60,000 cc/min even at 100% volumetric efficiency, which is 10X less. 

On the other hand the intake and exhaust ports are only open for about 1/3 of a cycle. 

On the other, other hand the flow is not constant, and the peaks may suffer more significantly from restriction.


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## GrassGuerilla (Aug 18, 2016)

Team FAST said:


> Thanks.
> 
> There is another piece to this puzzle which I wanted to consider when making changes to the exhaust: The carb and air filter.
> 
> ...


So... Can we assume you'll be further modifying the muffler looking for a few more CFL of flow? And did you by chance do any test cuts befor the mods or are we sticking with follow bench numbers? 

And thanks for a great thread by the way. Love to see more flow numbers on different mufflers. Those as how are obviously pretty stuffed up from the factory. How's about say Husky 346xp, 545, 555, 550, 562 mufflers? Love to see those quantified.


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## James Miller (Aug 18, 2016)

So with just the deflector opened up the spark screen isn't a big restriction? Nice to know as mine stay in to keep the stink bugs out of the muff.


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## Rio95 (Aug 18, 2016)

Chris-PA said:


> 19.5 CFM is 552,179 cc/min. A 60cc engine at 10,000rpm is only 60,000 cc/min even at 100% volumetric efficiency, which is 10X less.



Isn't 60cc x 10,000rpm = 600,000cc? Not 60,000. Or am i missing something?

Seems like the carb has been matched fairly well if this is the case, maybe just a slight restriction.


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## Chris-PA (Aug 18, 2016)

Rio95 said:


> Isn't 60cc x 10,000rpm = 600,000cc? Not 60,000. Or am i missing something?
> 
> Seems like the carb has been matched fairly well if this is the case, maybe just a slight restriction.


Lol, you are of course completely correct. I apologize in general - that's what I get for throwing something out in a spare moment at work. Naturally it makes much more sense too. 

If we take 600,000 and multiply by about 2/5 that the port is open we get 240,000 cc/min, which is still much less than 552,000 but by a more reasonable factor than 10:1.


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## Rio95 (Aug 18, 2016)

Chris-PA said:


> If we take 600,000 and multiply by about 1/3 that the port is open we get 200,000 cc/min, which is still much less than 552,000 but by a more reasonable factor than 10:1.



If the ports aren't open, the carb wouldn't be flowing either, as the carb only flows when a vacuum is created in the crankcase. Therefore matching the flow of carb to the displacement as closely as possible is desireable. We must remember that the flow measurements are done at and arbitrary pressure, which may be different to the pressures/vacuums that the engine draws through the carb.


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## Chris-PA (Aug 18, 2016)

Rio95 said:


> If the ports aren't open, the carb wouldn't be flowing either, as the carb only flows when a vacuum is created in the crankcase. Therefore matching the flow of carb to the displacement as closely as possible is desireable.


The swept displacement corresponds to the piston falling each cycle and is the most the engine could pull in each cycle with 100% volumetric efficiency. At a given rpm it won't be anywhere near that high as a flow rate but I don't have any figures handy so I just used the port open time as a back-of-the-envelope guess. It's probably not that high either. 

I also don't know how much averaging of the flow is happening, but the intakes are very short so probably not much. So the carb has to be sized to accommodate the peaks. 

Anyway it looks to me like the carb is adequately sized. Anyone know how big the venturi is?


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## bmwpowere36m3 (Aug 18, 2016)

Rio95 said:


> If the ports aren't open, the carb wouldn't be flowing either, as the carb only flows when a vacuum is created in the crankcase. Therefore matching the flow of carb to the displacement as closely as possible is desireable. We must remember that the flow measurements are done at and arbitrary pressure, which may be different to the pressures/vacuums that the engine draws through the carb.



+1

The CFM numbers are relative... don't put too much stock into their absolute values. They are influenced by setup of flow bench.


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## Chris-PA (Aug 18, 2016)

bmwpowere36m3 said:


> The CFM numbers are relative... don't put too much stock into their absolute values. They are influenced by setup of flow bench.


Sure - just ballparking anyway. I looked up some Delivery Ratio numbers and it looks like they can get up to 75% of the swept volume, which is better than I remembered. So 600,000 * 0.75 = 450,000 - so the carb & filter are pretty well matched if the flow bench data is representative.


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## Team FAST (Aug 18, 2016)

GrassGuerilla said:


> So... Can we assume you'll be further modifying the muffler looking for a few more CFL of flow? And did you by chance do any test cuts befor the mods or are we sticking with follow bench numbers?
> 
> And thanks for a great thread by the way. Love to see more flow numbers on different mufflers. Those as how are obviously pretty stuffed up from the factory. How's about say Husky 346xp, 545, 555, 550, 562 mufflers? Love to see those quantified.



You're welcome.

I am not sure how much further I will take it based on the intake (carb) flow numbers. I haven't even run the saw, other than a 30sec start to make sure it worked. I won't be doing any serious tree work until the fall. It will definitely get tested then.

I only test what I have personally or what has been provided to me. I do not have access to all those other mufflers. That would also require additional work to machine adaptor plates plus my personal time.

What I am planning is to build a dyno. I've had that in the works for a few years for my trimmer project. That's the best way to quantify changes.


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## Team FAST (Aug 18, 2016)

I would love to flow the ports on the cylinder by itself. If anyone has a dead cylinder, let me know


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## Team FAST (Aug 19, 2016)

Here's one other little interesting thing I discovered during testing. If you leave the screw out that holds on the cover, you gain an additional .5CFM flow (over stock)
Stock =10.5 CFM and stock with that screw removed = 11 CFM

Easy quick little fix


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## James Miller (Aug 19, 2016)

Team FAST said:


> Here's one other little interesting thing I discovered during testing. If you leave the screw out that holds on the cover, you gain an additional .5CFM flow (over stock)
> Stock =10.5 CFM and stock with that screw removed = 11 CFM
> 
> Easy quick little fix
> ...


 Is that bolt hole open to the inside of the muff I never looked when I had mine off. The saw does pick up noticeably with the deflector opened and a retune.


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## Team FAST (Aug 19, 2016)

James Miller said:


> Is that bolt hole open to the inside of the muff I never looked when I had mine off. The saw does pick up noticeably with the deflector opened and a retune.




It does go into the internal cavity of the muffler. When removed on the bench, airflow escapes through the hole.
I'm probably going to leave mine installed.


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## blsnelling (Aug 19, 2016)

Very interesting results.

My concern is this. Without dyno testing, you won't know what affects incremental changes have on actual power made. At some point, more flow won't make more power. 

Over the years, I have found that a modest muffler mod gives most of the gain, without the excessive noise that comes with more radical muffler mods.

I'm sure your well aware of all this, but just wanted to point it out for everyone.


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## Team FAST (Aug 19, 2016)

blsnelling said:


> Very interesting results.
> 
> My concern is this. Without dyno testing, you won't know what affects incremental changes have on actual power made. At some point, more flow won't make more power.
> 
> ...




I completely agree. Which is why, based on the carb intake flow numbers, I am not inclined to make any additional changes to the muffler, based on the flow gain I measured just from modifying the deflector.

I need to install it on the saw and tune it up.

Dyno testing a two stroke...if I ever get there...is a HUGE can of worms. Many Many variables.


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## Team FAST (Aug 20, 2016)

Here are the corrected airflow results. This data has been corrected for test flow calibration (using a standard flow orifice calibration plate from Superflow), and temperature differences caused by the adiabatic heating of the air through the bench.

What this means, is that if someone took these same parts and repeated the measurements on their own calibrated flow bench (applying their own corrections based on test conditions) then you should get very similar results. Think of this like SAE Corrected Horsepower numbers on a dyno.

The values changed a little but the basic relationships of the test configurations and conclusions remain unchanged.


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## RedFir Down (Aug 20, 2016)

Thanks for taking the time to test this muffler, interesting findings!
I think there is a small error. In post 7 you have Screen and deflector remove @ 20.5 and in post 31 it's @ 10.6.
Again, kudos!


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## Team FAST (Aug 20, 2016)

Good catch! I fat-fingered it onto the powerpoint slide. I've made the correction. Should be 19.6


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## svk (Aug 20, 2016)

Great work. Do you have any intention to do this with different models?


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## Chris-PA (Aug 20, 2016)

Does anyone know what venturi size that carb is?


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## c5rulz (Aug 20, 2016)




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## Team FAST (Aug 20, 2016)

Chris-PA said:


> Does anyone know what venturi size that carb is?



Chris,

Best I can measure without disassembling the carb, it is 15.5mm

Walbro HDA 268a 547


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## Chris-PA (Aug 20, 2016)

Team FAST said:


> Chris,
> 
> Best I can measure without disassembling the carb, it is 15.5mm
> 
> Walbro HDA 268a 547


Hey thanks! I've got an HDA that size on my 62cc Chinese clone, and I have often considered putting a larger carb on it. Given this data though I don't think it's something I will bother with unless one falls in my lap.


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## Team FAST (Aug 20, 2016)

Just for giggles, I installed a velocity stack on the carb and tested it. Despite looking Bad-ass, and despite my hopes and dreams....alas...it provided no benefit. The carb flows exactly the same with or without the velocity stack. 

*BUT* with a Velocity stack installed, and a blanking choke plate (the kind that swings completely out of the carb throat) I could remove the stock choke butterfly and install a K&N style air filter (which has very low restriction) and make some pretty hefty gain on intake airflow. So the velocity stack can improve flow....






I also managed to install the Echo air filter cover, to better simulate the exact flow that the carb experiences when everything is installed on the saw.

The plastic cover reduces flow to the carb by 0.3CFM as compared to flowing the carb with the air filter and no orange cover. So that's probably a negligible amount. Plus, there may be some dynamic pressure effects from the engine fan and the swirl filtration scheme they use.


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## Chris-PA (Aug 21, 2016)

Team FAST said:


> *BUT* with a Velocity stack installed, and a blanking choke plate (the kind that swings completely out of the carb throat) I could remove the stock choke butterfly and install a K&N style air filter (which has very low restriction) and make some pretty hefty gain on intake airflow. So the velocity stack can improve flow....


Did you try no choke plate and no velocity stack? My bet is that simply removing the choke plate is where the gains are.


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## Big Block (Aug 21, 2016)

Try removing the black intake....stack for lack of a better word from inside the air filter. It takes 30 seconds. Just pop the air filter apart and the black piece just falls out.


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## Team FAST (Aug 21, 2016)

Big Block said:


> Try removing the black intake....stack for lack of a better word from inside the air filter. It takes 30 seconds. Just pop the air filter apart and the black piece just falls out.




Wow. I had no idea that thing was inside there! Good catch and thanks for the tip!





Out it goes. And back to the bench I go.



Here's the quick results (corrected flow data).

Carb + air filter, with black insert = 17.2 CFM
Carb + Air Filter, without black insert = 18.4 CFM

The black insert costs you 1.2 CFM!

Carb + air filter + orange filter cover with black insert = 16.8
Carb + air filter + orange filter cover without black insert = 17.6


So installed on the saw you gain back .8 CFM (the cover still has a detrimental effect)

I retested the carb+filter_cover with insert to compare to last night and I am within 0.1 CFM so the tests repeat well.


I am definitely removing that part from inside my air filter! I will likely machine a spacer for the stud to prevent collapsing the air filter when I tighten the cover.


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## Big Block (Aug 22, 2016)

Team FAST said:


> Wow. I had no idea that thing was inside there! Good catch and thanks for the tip!
> 
> I will likely machine a spacer for the stud to prevent collapsing the air filter when I tighten the cover.



Your welcome! ^^^^^ that is exactly what I did


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## Team FAST (Aug 22, 2016)

Based on what I learned from these measurements, my approach to improving the performance on the Echo-CS590 saw will be:

1. Modify the exhaust deflector as shown to improve airflow
2. remove the air filter black plastic plenum insert
3. re-tune the carb
4. sharp chain!


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## James Miller (Aug 22, 2016)

Sounds about right. And now there's numbers to back it up


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## hatfield (Aug 22, 2016)

Team FAST said:


> Based on what I learned from these measurements, my approach to improving the performance on the Echo-CS590 saw will be:
> 
> 1. Modify the exhaust deflector as shown to improve airflow
> 2. remove the air filter black plastic plenum insert
> ...




Thanks for taking the time to do this. I appreciate it. So, based on your testing, do you think removing or drilling a few holes into the inner tube will make more improvements ? I know you just modified the deflector. Just wondering how much more one can go, and maintain appropriate back-pressure ?
I would like to do a MM, but don't want it so loud that I irritate my neighbors. We all get along.


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## hatfield (Aug 22, 2016)

Did you add new liquid gasket to the back of the muffler where it mates to the steel back-plate ?


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## Team FAST (Aug 22, 2016)

hatfield said:


> Thanks for taking the time to do this. I appreciate it. So, based on your testing, do you think removing or drilling a few holes into the inner tube will make more improvements ? I know you just modified the deflector. Just wondering how much more one can go, and maintain appropriate back-pressure ?
> I would like to do a MM, but don't want it so loud that I irritate my neighbors. We all get along.




You are welcome.

More holes will improve airflow. But it will make it much louder, and reduce the back pressure. At some point you will surpass what the intake tract is capable of flowing. That would be too much, in my opinion.

Without a dyno, its very tough to quantify. You can over do it.


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## Team FAST (Aug 22, 2016)

hatfield said:


> Did you add new liquid gasket to the back of the muffler where it mates to the steel back-plate ?



The aluminum backing plate has the gaskets on it and they are intact. So I am re-using it. I just reinstalled everything tonight.


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## James Miller (Aug 23, 2016)

hatfield said:


> Thanks for taking the time to do this. I appreciate it. So, based on your testing, do you think removing or drilling a few holes into the inner tube will make more improvements ? I know you just modified the deflector. Just wondering how much more one can go, and maintain appropriate back-pressure ?
> I would like to do a MM, but don't want it so loud that I irritate my neighbors. We all get along.


My 590 is noticeably louder with just the deflector opened up. These saws get obnoxious fast when you start drilling holes inside the muffler. Maybe @Big Block still has some of his videos of the different muff mods he did on his 590.


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## Chris-PA (Aug 23, 2016)

Team FAST said:


> More holes will improve airflow. But it will make it much louder, and reduce the back pressure. At some point you will surpass what the intake tract is capable of flowing. That would be too much, in my opinion.
> 
> Without a dyno, its very tough to quantify. You can over do it.


I don't like really loud, wide open muffler mods either, and usually try to keep the longest path length through the muffler I can while reducing restriction. Without a dyno you can get some guidance from the non-linear fuel delivery characteristics of the carbs.

It's known that just increasing air velocity a small amount by lifting in the cut will cause the mixture to go so lean it missfires (4-strokes), so it follows that anything which increases the air velocity through the venturi will also cause it to get richer. Since increasing air flow (and velocity) through the carb is the goal, then an effective muffler mod will do the same. So if your mild muffler mod is successful then you will likely need to lean out the H slightly, and possibly make the L slightly rich to allow for faster acceleration (yes, I know this is counter to the standard advice about MM tuning).

If you open the muffler up far enough, you begin to pull fresh air back into the cylinder before the exhaust port closes. This is air that has not passed through the carb or picked up fuel, so you will need to enrich the H to compensate. This probably does make more power, but at this point also there is not much of an enclosed can so that any fuel lost out the open exhaust port due to scavenging losses is not recovered and fuel use goes up quickly. And it will be loud as hell.


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## fordf150 (Aug 23, 2016)

@Chris-PA Iirc 620 is 17.5mm venturi compared to something like 16mm for the 590, I get some time i will dig up carb numbers and verify those measurements.




Very interesting thread


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## chuckwood (Aug 23, 2016)

GrassGuerilla said:


> Interesting... The screen makes less difference than I would have guessed.



In winter, under cold/wet/snow conditions you could run a saw without a screen with no worries. But I took the screen out of one of my saws during a hot, dry period in summer, testing to see if I could get more power. I was cutting some dry pine and started a fire in the sawdust. It had the potential to have started a serious forest fire had I walked away from the cutting site without noticing the sawdust fire. With no screen the hot sparks coming out of the muffler are easy to see.


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## Big Block (Aug 24, 2016)

James Miller said:


> My 590 is noticeably louder with just the deflector opened up. These saws get obnoxious fast when you start drilling holes inside the muffler. Maybe @Big Block still has some of his videos of the different muff mods he did on his 590.



As soon as I get a good Internet connection I'll post some vids


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## James Miller (Aug 24, 2016)

Big Block said:


> As soon as I get a good Internet connection I'll post some vids


 You keep late hours its 20 of 2 in the morning here. Thanks in advance for the videos.


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## Team FAST (Aug 25, 2016)

I machined a spacer to replace the back plastic plenum insert for the air filter tonight and put the saw back together. All done! Now to tune it in some wood....






Ready to go with the companion CS-400.


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## Big Block (Aug 26, 2016)

James Miller said:


> You keep late hours its 20 of 2 in the morning here. Thanks in advance for the videos.


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## Big Block (Aug 26, 2016)

All of those are the eardesplitterloudenboomer mod lol


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## James Miller (Aug 26, 2016)

Big Block said:


> All of those are the eardesplitterloudenboomer mod lol


At the end of the first noodleing cut is it hitting the limiter. Iv heard mine do that a few times. Its a different sound then the saw 4 strokeing when you lift.


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## Red97 (Aug 26, 2016)

@Team FAST

If I sent you a modified 590 muffler would you be willing to test it?

I just got done porting my 590, still fighting some carb issues. But with a hole punched around the tube. Roughly 3/4" area and a new deflector on top, I feel it gained a good bit. Other than being real loud.





I added one of my large deflectors, and opened up most of the area around the tube.
I have 2 mode 590's to port, would be nice to Taylor port timing to flow bench numbers. Similar to selecting an auto camshaft to match head flow.


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## Big Block (Aug 26, 2016)

James Miller said:


> At the end of the first noodleing cut is it hitting the limiter. Iv heard mine do that a few times. Its a different sound then the saw 4 strokeing when you lift.



Sure sounds like it huh. I never caught that before.


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## Team FAST (Aug 26, 2016)

Red97 said:


> @Team FAST
> 
> If I sent you a modified 590 muffler would you be willing to test it?
> 
> ...




Sure. PM me.


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## James Miller (Aug 26, 2016)

Big Block said:


> Sure sounds like it huh. I never caught that before.


Mine would do that now and then in a long cut with the bar buried befor I trimmed the limiters and gave it some more fuel.


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## James Miller (Aug 26, 2016)

@Team FAST what's done to your cs400? Just muff mod and retune or is there more to it?


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## Chris-PA (Aug 26, 2016)

Big Block said:


> Sure sounds like it huh. I never caught that before.


Surprisingly you can sometimes tell the difference between 4-stroking and rev limiting by looking at the spectrum plot. If it is visible, 4-stroking actually does show up as an every-other revolution firing at 1/2 rpm. But the rev limiter appears as a every 3rd revolution firing at 1/3 the fundamental rpm. It's hard for me to hear the difference.

If I can find some time this weekend I'll see if I can tell from your video.


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## James Miller (Aug 26, 2016)

Chris-PA said:


> Surprisingly you can sometimes tell the difference between 4-stroking and rev limiting by looking at the spectrum plot. If it is visible, 4-stroking actually does show up as an every-other revolution firing at 1/2 rpm. But the rev limiter appears as a every 3rd revolution firing at 1/3 the fundamental rpm. It's hard for me to hear the difference.
> 
> If I can find some time this weekend I'll see if I can tell from your video.


 I'd like to see what you find. It would be nice to know what that distinct burp I'll call it is as that's the second 590 iv heard do it.


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## Red97 (Aug 26, 2016)

Just got this one finished. With a 620 coil, needs a 620 carb too.

Gonna test it tomorrow


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## Team FAST (Aug 26, 2016)

James Miller said:


> @Team FAST what's done to your cs400? Just muff mod and retune or is there more to it?



That one just had a carb tune and muffler mod per my own instructions in the CS-400 muffler mod thread I stated a few years ago. 

Actually that is my second saw. I have two CS-400s


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## Big Block (Aug 26, 2016)

James Miller said:


> Mine would do that now and then in a long cut with the bar buried befor I trimmed the limiters and gave it some more fuel.



I had it fairly lean in that video as I was ~8,000 feet above sea level


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## Chris-PA (Aug 26, 2016)

James Miller said:


> I'd like to see what you find. It would be nice to know what that distinct burp I'll call it is as that's the second 590 iv heard do it.


I can't see all that much because those are pretty short burps. There are two events I can make out at around 1:05 and 1:06, and both have a noticeable spike at 1/2 rpm, so I would guess it's just 4-stroking (rich). That's hardly very conclusive though. Listening to it the whole cut sounds a little like it's 4-stroking, but it doesn't look that way in the spectrum plot - I suspect it's some sort of reverberation in the audio track.

Then again, it _*is*_ an Echo........


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## Matt Hogden (Aug 27, 2016)

Great thread. I love Echo and Shindaiwa stuff. Last of the good quality saws. Fully Japanese. Not chinese. I modified the muffler on my Shindy 757 and it made a real big difference.


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## Ranchers-son (Aug 27, 2016)

Thank you @Team FAST for your time, effort and attention to detail. I'm curious how my 620p carb and muffler would perform.


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## Big Block (Aug 28, 2016)

It'll haul ass is what it'll do

Sent from my SM-N900T using Tapatalk


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## jdvsn83 (Aug 30, 2016)

Matt Hogden said:


> Great thread. I love Echo and Shindaiwa stuff. Last of the good quality saws. Fully Japanese. Not chinese. I modified the muffler on my Shindy 757 and it made a real big difference.



Shindaiwa 757, great saw!


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## tsiawalatowa (Sep 25, 2016)

I've had my 590 for two years and 00 months and I really like it!. I haven't done anything to it yet but I will be doing the mentioned mod to it manana (means tomorrow to those east of the New Mexico). Personally I like Echos, they have been reliable and get the job done, maybe not as glamorous as my Stihl or Husky but they are reliable and faithful... akin to someone you would take home to meet mom. Thank you Team FAST for putting your information out! I look forward to reading more info put out by you!


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## bmwpowere36m3 (Oct 7, 2016)

@Team FAST @Red97 

Any updates testing those modded muffs?


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## Team FAST (Oct 9, 2016)

bmwpowere36m3 said:


> @Team FAST @Red97
> 
> Any updates testing those modded muffs?



Funny you should ask! On Friday, we lost a red oak in our backyard to storms. So I got a chance to use the saw for the first time since I did this muffler mod!

@bmwpowere36m3 @Cliff R @Big Block @Chris-PA 

Impressive power. I dialed in the carb settings. I will post a video.


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## Team FAST (Oct 9, 2016)

Here's a video of the CS-590 with the muffler mod cutting in red oak. It was a tad rich in this video.




In the second video, I leaned the hi speed screw slightly. Pretty happy with the way its running! I am seeing some chain stretch. How much is typical? Seemed to get more frequent the more I cut.


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## James Miller (Oct 9, 2016)

Team FAST said:


> Here's a video of the CS-590 with the muffler mod cutting in red oak. It was a tad rich in this video.
> 
> 
> 
> ...


The stock chain on mine stretched some adjusted once or twice and it was fine. I had the 20" bar on mine buried in red oak noodling Friday they cut well above there price point. @farmer steve likes it and he's a stihl guy so it must be a good saw.


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## ANewSawyer (Oct 9, 2016)

Team FAST said:


> Here's a video of the CS-590 with the muffler mod cutting in red oak. It was a tad rich in this video.
> 
> 
> 
> ...




Is that just muffler modded and retune?


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## Team FAST (Oct 9, 2016)

ANewSawyer said:


> Is that just muffler modded and retune?



Yes. Its my saw with the muffler you see modded in the beginning of this thread. I removed the caps from the mixture screws and I also removed the black plastic intake plenum from the air filter.


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## Red97 (Oct 9, 2016)

Team FAST said:


> Yes. Its my saw with the muffler you see modded in the beginning of this thread. I removed the caps from the mixture screws and I also removed the black plastic intake plenum from the air filter.



I would reccomed putting the black plastic back in, the fuel spit back will saturate the filter in no time, causing chips to stick, restricting the air flow more than the plastic piece.


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## Team FAST (Oct 9, 2016)

I'll keep an eye on it. I went thru a little over a tank today with that tree, and didn't see any issues with the filter. My bigger concern in the chain stretch. How much wear is normal on the drive spur?

This is what mine looked like after that tank of gas:


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## bmwpowere36m3 (Oct 9, 2016)

Team FAST said:


> I'll keep an eye on it. I went thru a little over a tank today with that tree, and didn't see any issues with the filter. My bigger concern in the chain stretch. How much wear is normal on the drive spur?
> 
> This is what mine looked like after that tank of gas:
> 
> View attachment 530531



!!!! WOW

Same pattern, just polished after 6 tanks...


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## James Miller (Oct 9, 2016)

I'll get a pick of mine tomorrow and compare I have more then 10 tanks on mine and feel like it looks about the same as yours still. I wish the spur would ware out so I have an excuse to replace it with the 600p rim drive.


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## Chris-PA (Oct 10, 2016)

Team FAST said:


> My bigger concern in the chain stretch. How much wear is normal on the drive spur?
> 
> This is what mine looked like after that tank of gas:
> 
> View attachment 530531


That seems like a lot for one tank. I've had some that barely showed a mark after many tanks. 

I had one on my Earthquake that had a slightly high tooth, which I ground down and then waited for it to wear in - it seemed like it took forever.

As for the saw performance in the video - it's very hard to tell much from one short cut. It sounds to me like it is still 4-stroking until about half way through the cut, so I'm not convinced the mixture is right. I downloaded the video and did a spectrum plot last night but only a had a couple of minutes to look at it. From what I could tell the saw was only turning 8000-8500rpm, but this might be caused by a too rich mixture. I will try to look at it again this evening and pay more attention to the second half of the cut after it cleans up. 

I understood the stock exhaust duration is only around 134deg, and if this is the case then it may be more of a limiting factor than the muffler flow. Although the RedMax GZ400/4000 has about the same exhaust duration, and while they are not high rpm screamers they will rev higher than that under load, so maybe it's something else.


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## Team FAST (Oct 10, 2016)

Yep. it was four stroking initially and cleaned up in the cut. No idea what the rpms or port timing is. The saw ran great and it didn't bog down at all. Plug looked great. The CS400 I have feels like a toy compared to this saw.


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## bmwpowere36m3 (Oct 10, 2016)

bmwpowere36m3 said:


> !!!! WOW
> 
> Same pattern, just polished after 6 tanks...



What I meant is the wear pattern is the same, but its not removed any material (can't be felt)... their simply polished areas after 6 tanks. I do run my chain pretty tight... compared to those I see daylight under the bar.


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## James Miller (Oct 10, 2016)

So I took some pictures of my spur drive these are after somewhere between 10-15 tanks.



and one of the muff mod screens stay in my saws to keep the stink bugs out.


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## bmwpowere36m3 (Oct 10, 2016)

James Miller said:


> So I took some pictures of my spur drive these are after somewhere between 10-15 tanks. and one of the muff mod screens stay in my saws to keep the stink bugs out.



Pics aren't the clearest... but yours show very little, not like the OP's.


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## James Miller (Oct 10, 2016)

bmwpowere36m3 said:


> Pics aren't the clearest... but yours show very little, not like the OP's.


lense on my phone is pretty scratched up but its the best I got. I hoped it would ware quickly so I could put the rim on it. But it hardly shows signs of ware.


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## Chris-PA (Oct 10, 2016)

Team FAST said:


> Yep. it was four stroking initially and cleaned up in the cut. No idea what the rpms or port timing is. The saw ran great and it didn't bog down at all. Plug looked great. The CS400 I have feels like a toy compared to this saw.


Well, I was more focused on the quantitative aspects, and a 60cc saw should not come close to bogging in wood that size. 

The 4-stroking appears to end just as it hits the widest part of the wood at 8s, which would make sense. I suspect that the carb with the fixed H jet in addition to the needle is borderline too rich with the opened up muffler, but it depends on how much adjustment range you have left on the H screw. 

I _think_ it looks like the no load rpm is around 11krpm right before the cut.


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## Team FAST (Oct 11, 2016)

Chris-PA said:


> I _think_ it looks like the no load rpm is around 11krpm right before the cut.




Great stuff! I will put a tach on my saw to validate your predictions. I will calibrate your acoustic analysis with measured data.


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## James Miller (Oct 11, 2016)

Team FAST said:


> Great stuff! I will put a tach on my saw to validate your predictions. I will calibrate your acoustic analysis with measured data.


What do you have to do to upload a video I'd love to put one of mine up for Chris to go over to compare to yours since there the same setup except I have the plastic piece in the filter still. Just sounds like yours doesn't have the RPMs mine does.


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## Red97 (Oct 11, 2016)

Vs



Be interested to see how these 2 compare @Chris-PA 

Totally different porting strategy, real similar tune, same bar/chain/wood.


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## bmwpowere36m3 (Oct 11, 2016)

Chris-PA said:


> Well, I was more focused on the quantitative aspects, and a 60cc saw should not come close to bogging in wood that size.
> 
> The 4-stroking appears to end just as it hits the widest part of the wood at 8s, which would make sense. I suspect that the carb with the fixed H jet in addition to the needle is borderline too rich with the opened up muffler, but it depends on how much adjustment range you have left on the H screw.
> 
> I _think_ it looks like the no load rpm is around 11krpm right before the cut.



Tried it out for kicks at work using our analysis software...

@Team FAST
first video (rich): 7700 RPM
second video (leaned out): 8200 RPM during the first half when it sounds like its 4-stroking and 7800 RPM when it clears up

@Red97
590 Christmas: 10,800-10,900 (first - second cut)
590 Ported: 10,400-10,900 (first - second cut)


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## Red97 (Oct 11, 2016)

Thank you sir.

If you have the time.



This one I know is definitely on the lean side, just curious if it showed in the wood too..


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## Chris-PA (Oct 11, 2016)

Red97 said:


> Be interested to see how these 2 compare @Chris-PA


I will look at it later this evening, but it looks like bmwpowere36m3 already got some numbers for you.



bmwpowere36m3 said:


> Tried it out for kicks at work using our analysis software...
> 
> @Team FAST
> first video (rich): 7680 RPM
> second video (leaned out): 8160 RPM during the first half when it sounds like its 4-stroking and 7800 RPM when it clears up


Yes, this is very similar to the numbers I got, depending on how long an interval I looked at. I saw a little higher, around 8k to 8.6k when I had it down to a 1/2s interval. 

The 136deg exhaust duration is likely holding it back in terms of rpm, but as I wrote earlier I have saws with exhaust durations that short and they will rev higher. So I'd suspect it has the ability to rev higher if it were leaner and that the mixture is keeping it from taking full advantage of the muffler mod.


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## Red97 (Oct 11, 2016)

100% stock limiters and all. Just to see if the tune is the culprit on team fast saw.


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## bmwpowere36m3 (Oct 11, 2016)

Chris-PA said:


> I will look at it later this evening, but it looks like bmwpowere36m3 already got some numbers for you.
> 
> Yes, this is very similar to the numbers I got, depending on how long an interval I looked at. I saw a little higher, around 8k to 8.6k when I had it down to a 1/2s interval.
> 
> The 136deg exhaust duration is likely holding it back in terms of rpm, but as I wrote earlier I have saws with exhaust durations that short and they will rev higher. So I'd suspect it has the ability to rev higher if it were leaner and that the mixture is keeping it from taking full advantage of the muffler mod.



I did an average over the length of the cut. I agree, where you look at the data (point in time) and how much pressure your applying to the saw will influence the results.


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## bmwpowere36m3 (Oct 11, 2016)

Red97 said:


> Thank you sir.
> 
> If you have the time.
> 
> ...




11,000 RPM but is certainly varies throughout that cut


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## bmwpowere36m3 (Oct 11, 2016)

Red97 said:


> 100% stock limiters and all. Just to see if the tune is the culprit on team fast saw.




8,800 RPM


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## Chris-PA (Oct 11, 2016)

bmwpowere36m3 said:


> 11,000 RPM but is certainly varies throughout that cut


Agreed



bmwpowere36m3 said:


> 8,800 RPM


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


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## Red97 (Oct 11, 2016)

Thank you for taking the time. I felt these saws mod well, seems to prove true given the video analysis. 

Seen a pretty stay range of 10,500 -11k while trying to hold a tach.


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## Ronaldo (Oct 11, 2016)

Red97, I really like the exhaust tone of that saw.......especially at idle!!!!!MEAN!


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## bmwpowere36m3 (Oct 12, 2016)

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:


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## Red97 (Oct 12, 2016)

Curious. This is the same saw before any carb mods. H needle 1/8-1/4 turn from seated. Plenty rich lol.


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## bmwpowere36m3 (Oct 12, 2016)

Red97 said:


> Curious. This is the same saw before any carb mods. H needle 1/8-1/4 turn from seated. Plenty rich lol.




First cut before the surging 10,100 RPM and the middle of the second cut 9300 RPM (leaned out it).


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## Team FAST (Oct 12, 2016)

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.


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## bmwpowere36m3 (Oct 12, 2016)

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.


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## Red97 (Oct 12, 2016)

Team FAST said:


> 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.



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.


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## Chris-PA (Oct 13, 2016)

Team FAST said:


> I don't think my saw is out of tune. It is slightly rich, but its still being broken in.


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.


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## Team FAST (Oct 13, 2016)

Chris-PA said:


> 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.




Agreed....

You've sealed the deal. I'm building a dyno.


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## Merc1973 (Jan 13, 2017)

Wow, excellent thread. Any updates?




Team FAST said:


> I'll keep an eye on it. I went thru a little over a tank today with that tree, and didn't see any issues with the filter. My bigger concern in the chain stretch. How much wear is normal on the drive spur?
> 
> This is what mine looked like after that tank of gas:
> 
> View attachment 530531



That's what mine looks like too with not much use. Easy switch to rim drive, remove the c-clip?


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## Chris-PA (Jan 13, 2017)

Team FAST said:


> In the second video, I leaned the hi speed screw slightly. Pretty happy with the way its running! I am seeing some chain stretch. How much is typical? Seemed to get more frequent the more I cut.



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:


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## nitehawk55 (Jan 13, 2017)

Merc1973 said:


> Wow, excellent thread. Any updates?
> 
> 
> 
> ...



Easy switch , new drum and rim sprocket , put them on my 590 . Just the C clip .


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## motoguy (Apr 11, 2018)

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?


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## James Miller (Apr 11, 2018)

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.


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## Team FAST (Jun 22, 2019)

bump


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## James Miller (Jun 22, 2019)

Nothing to add. Been running my ported 590 for going on 3 years with no problem.


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## eye.heart.trees (Sep 24, 2021)

Team FAST said:


> Wow. I had no idea that thing was inside there! Good catch and thanks for the tip!
> 
> View attachment 520878
> 
> ...



Anyone come up with a good "workaround" for this? This black "insert" inside the air-filter _prevents the carb's spit-back of air/fuel mix into the filter_, which wets the filter's rear wall especially the bottom and it attracts dirt like no other, so having SOME kind of "spit-plate" in there seems pretty requisite....am gonna see if I can order one for next-to-nothing so I can comfortably hack-away at mine, have several ideas for far superior approaches, one is to quite literally just put a sponge fixed inside the filter as the 'plate' so it can take the spitback from the carb and then just evap the gasoline and 'get heavy with oil' I guess? Maybe wring it out once every few sessions ;D 


^that "bonded sealing washer" (#8 size) on the spindle is perfect for filter sealing, it fits so tight on the shaft you have to push it down and can literally "peg the air filter in-place" just using the washer it's an awesome $0.25 fix (I smear a lil marine grease on its bottom/rubber side before installing....also put same grease on interfaces on rear of filter!)


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## RedneckChainsawRepair (Jun 8, 2022)

Nick made a heck of a set up for 590 air filter. https://redbeardsaws.com/products/echo-cs-590-620p-air-cleaner-system


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## North by Northwest (Sep 25, 2022)

RedneckChainsawRepair said:


> Nick made a heck of a set up for 590 air filter. https://redbeardsaws.com/products/echo-cs-590-620p-air-cleaner-system


Now that's a sweet retro fit set up brother !


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