Un-Muffler Modding a CS590

[Johnwell]

Recently picked up a CS-590 Timberwolf for $180 (which I thought was pretty reasonable). Unfortunately, the previous owner decided to get a bit aggressive with a dremel on the muffler.



My goal is to maintain reasonable exhaust flow while reducing the noise this thing puts out.

First thing I did was remove the pipe from the baffle in the exhaust. Previous owner just flattened it out.



Next, I tried my best to remove the dents in the muffler. Didn’t turn out how I was hoping, but sits better on the saw now.



It was around this time I found a perfectly sized piece of tube stock.





Compared to the original, the new pipe is much larger diameter and shorter.

And fits nicely.

At this point I ran out of midnight oil—more to come later.

Planning on welding it to a piece of flat stock that I can sandwich between the top of the muffler and the deflector.

 

[singinwoodwackr]

Recently picked up a CS-590 Timberwolf for $180 (which I thought was pretty reasonable). Unfortunately, the previous owner decided to get a bit aggressive with a dremel on the muffler.
View attachment 1108654
View attachment 1108655

My goal is to maintain reasonable exhaust flow while reducing the noise this thing puts out.

First thing I did was remove the pipe from the baffle in the exhaust. Previous owner just flattened it out.

View attachment 1108659

Next, I tried my best to remove the dents in the muffler. Didn’t turn out how I was hoping, but sits better on the saw now.

View attachment 1108660

It was around this time I found a perfectly sized piece of tube stock.

View attachment 1108667

View attachment 1108669

Compared to the original, the new pipe is much larger diameter and shorter.
View attachment 1108673
And fits nicely.
View attachment 1108674
At this point I ran out of midnight oil—more to come later.

Planning on welding it to a piece of flat stock that I can sandwich between the top of the muffler and the deflector.

So, weld that up and bolt the top deflector back in place? The final opening might be too much. I usually shoot for about 75% of the exhaust side opening.

 

[Johnwell]

So, weld that up and bolt the top deflector back in place? The final opening might be too much. I usually shoot for about 75% of the exhaust side opening.

I was planning on welding the new pipe to a piece of flat stock with a smaller hole drilled into it. That way I can work my way up slowly to try to find the sweet spot by removing the whole assembly and drilling/boring the plate a bit at a time. As it is currently, I feel fairly confident that it was taken too far..

 

[singinwoodwackr]

I was planning on welding the new pipe to a piece of flat stock with a smaller hole drilled into it. That way I can work my way up slowly to try to find the sweet spot by removing the whole assembly and drilling/boring the plate a bit at a time. As it is currently, I feel fairly confident that it was taken too far..

That’l work

 

[Breckinridge Elkins]

A lot of work for a $25 muffler.
Remember to use a new gasket.

 

[singinwoodwackr]

A lot of work for a $25 muffler.
Remember to use a new gasket.

But more fun

 

[coffeebrk]

But more fun

Especially when the OP includes pics!!

 

[Johnwell]

Especially when the OP includes pics!!

Yeah, the OP should post more pictures….

A lot of work for a $25 muffler.
Remember to use a new gasket.

Wasn’t too bad for work, if I could actually ever find the tools I was looking for or the stock I need I probably would only have about 30 minutes in this. Also, I priced out a new muffler at $50. If it were $25 I probably would’ve done that, but I couldn’t justify nearly a third of the price of the saw for a new muff.

So had a slight change in plans last night after remembering I’m terrible at welding. Instead of welding my ‘stack’ to the plate, I decided to weld it into the muffler itself. That way, the stack to plate alignment isn’t critical and no one has to see my awful welding.. Oh, you still want to see my awful welds? Okay, well I guess you’ll understand why I didn’t pursue a career in welding.. I couldn’t get the welder down to a low enough setting for me to be comfortable on this thin of metal, so I just tacked it and figured it should be plenty strong enough.

Yeah, I know it looks awful, so no laughing. I’m sure my wife will pick on me enough…

But, with the cover on I can’t see it, so I’ll call it a win. Now just to get a gasket and re tune the saw. Started out with a 15mm drilled hole, I may have to increase it for flow.

For $0 in material and probably an hour and a half of work (including looking for tools, material, and looking disappointedly at my crappy welds), I’m not disappointed with the final result. Will report back on noise and performance.

 

[singinwoodwackr]

Yeah, the OP should post more pictures….


Wasn’t too bad for work, if I could actually ever find the tools I was looking for or the stock I need I probably would only have about 30 minutes in this. Also, I priced out a new muffler at $50. If it were $25 I probably would’ve done that, but I couldn’t justify nearly a third of the price of the saw for a new muff.

So had a slight change in plans last night after remembering I’m terrible at welding. Instead of welding my ‘stack’ to the plate, I decided to weld it into the muffler itself. That way, the stack to plate alignment isn’t critical and no one has to see my awful welding.. Oh, you still want to see my awful welds? Okay, well I guess you’ll understand why I didn’t pursue a career in welding.. I couldn’t get the welder down to a low enough setting for me to be comfortable on this thin of metal, so I just tacked it and figured it should be plenty strong enough.
View attachment 1108871
Yeah, I know it looks awful, so no laughing. I’m sure my wife will pick on me enough…

But, with the cover on I can’t see it, so I’ll call it a win. Now just to get a gasket and re tune the saw. Started out with a 15mm drilled hole, I may have to increase it for flow. View attachment 1108873
View attachment 1108874
For $0 in material and probably an hour and a half of work (including looking for tools, material, and looking disappointedly at my crappy welds), I’m not disappointed with the final result. Will report back on noise and performance.

As long as it works, who cares?
gring the nasty stuff down to look better and
get some black hi-temp spray paint and it will look great.

for MIG welding mufflers, .023g wire is best but you can get by with .030 if you are more careful. Learn how to make nice, even tack welds in a row. Takes a bit of practice. TIG is better for the thin stuff but most don’t have one.

 

[Johnwell]

As long as it works, who cares?
gring the nasty stuff down to look better and
get some black hi-temp spray paint and it will look great.

for MIG welding mufflers, .023g wire is best but you can get by with .030 if you are more careful. Learn how to make nice, even tack welds in a row. Takes a bit of practice. TIG is better for the thin stuff but most don’t have one.

Yeah, all I have is mig and a cheap harbor freight flux core welder. Don't have 220 in the shop yet, so it was flux core .035" wire--not the ideal setup for sure.

I've never learned to use a tig welder, but my father in law has one. If I decided to modify mufflers more frequently I'd definitely pursue a better way.

 

[singinwoodwackr]

Yeah, all I have is mig and a cheap harbor freight flux core welder. Don't have 220 in the shop yet, so it was flux core .035" wire--not the ideal setup for sure.

I've never learned to use a tig welder, but my father in law has one. If I decided to modify mufflers more frequently I'd definitely pursue a better way.

Oy, don’t think I’d even try with that, lol
good job considering what you used

 

[Sidecarflip]

I modded my CS 590 muff and air cleaner before I ever fired it up and I bought it new. so the gasket was fine. Also put in a larger Walbro carb. I did the muff just like Red Beard modded his and used his velocity stack and oiled foam air cleaner too. It runs like a scalded dog with a 20" bar and full tooth chipper loops. Nice saw and always starts on the second pull. I also did the 5 degree offset crank key and eventually will change out the mag coil to the larger one with no rev limiter. Running Red Armor 50-1 canned fuel and Stihl bar oil. Still prefer my 42 year old 028AV I bought new but the Timber Bear is running a close second. I will say the Stihl's like canned fuel better too. Have 3, the 028, an 090G and an 075. Now 2 Echo's as well. The 590 and the CS top handle arborist saw. The big ones are shelf queens now. Too dam heavy for this old man but not for sale and both are mint too. Some paint chips on the bottom (typical powder coat Stihl paint). My wife can sell them cheap after I pass.

 

[Johnwell]

Ran and tuned the saw for a bit yesterday on a 30” ash log—this saw rips a 20” bar. Definitely much much quieter and better throttle response than before, although I didn’t jet the saw with the open muffler and it was originally rich for my liking.

Still need to work on my log splitter, right now, I’m the log splitter…