My Echo CS-352 came with no Cat (muffler modded) from Factory

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Charles Bale

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My CS-352 SN is in the Serial Number grouping that starts with C704xxxxxxxx

muf1.jpg muf2.jpg If you have this saw & SN, its comes with the Muff Part# A300000803 with no cat. The Parts Diagram actually shows no matrix for the 5th SN grouping muffler.

My Serial Number grouping is the 5th of 5 different SN groupings listed on Echo's web site. The first four groupings have muffler PN A300000831

Might be how all the Echo saws are, so if your thinking about modding your muff on any Echo saw, and doing a Cat Delete, might be already done, and you might be able to see it not there on the parts diagram.

I got a nice new muffler off ebay, (PN A300000831) and did a dam fine job removing the cat from the engine side, only to find my muff was modded.

Anybody want a modded muff for a CS-352? $15 shipped. But the exhaust guide plate is not included.
 
I just thought it was interesting that the first 4 generations of 352s have cats. then no cat. usually over time they choke/lean the new stuff (whatever it is) out so much, it hurts usability and longevity.
 
You sure that's a brand new s untouched saw? Sure looks like someone took the cat out of that muff. The ridges in the second pic look just like when you take the cat out of a 310-400 muff and clean it up with a flap wheel.
 
The pictures are the ebay muff I took the cat out of. The muff on my saw had no cat. My saw was manufactured March 2018. Strange Echo is doing the "cat delete" from the factory on the saws they are making now. That was my whole point.
 
Removed the muffler to decat it and discovered the muffler had a type of hollow cylinder with several holes inside the muffler housing, but no cat. Chainsaw is also dated March 2018. The saw ran and started terrible out of the box. Decided to enlarge a couple of the cylinder holes and open up the exit deflector. Tuned it and saw starts and runs great now. Perhaps Echo decided to save money using a more basic muffler and to meet EPA/CARB they tune the saw more lean. Just guessin...
 
Yesterday I bought a 352 at a pawn shop. The manufacture date is May 2018. It also doesn't have a cat. Just a round cylinder with some oblong holes cut around it. Guess I'll drill a few more holes, open up the deflector and call it good.
 
I just thought it was interesting that the first 4 generations of 352s have cats. then no cat. usually over time they choke/lean the new stuff (whatever it is) out so much, it hurts usability and longevity.
As a manufacturer You can't just set something overly lean - in that case CO goes down but NOx immediately goes up. Both are strictly regulated in most of the world. US has a bit more flexibility with EPA "banking" system.
 
I've only ran into CAT's on Echo's CS-330/360T's and the CS-370/400's. They are NOT easy to remove from the top handle saws. I cut the muffler in half then MIG'd it back together after the work was complete.

I'm also conservative about the size of the exit holes inside the "can" after the CAT is removed. Pretty sure I go up to 5/16" holes but it's been a while since I've done one and have bad cases of CRS these days. All the ones I've modded have responded well and the ones I kept have been dead solid reliable in long term service.

I don't use my CS-360T all that much as I'm not overly fond of the top handle design for limbing an such, plus the rev-limiting coil on that saw is annoying as it comes it a bit too early for my liking. I've got at least a zillion hours on the little CS-370, it's now in need of a clutch as the drive sprocket is worn down a bit. I'm not able to find one anyplace with a removable sprocket so will end up going back to another OEM part.......Cliff
 
These saws are night and day if you open up the muffler a bit. They are tuned terribly lean from the factory so be sure to give them the fuel they need.
 
I cut the tabs on the limiters. Just wondering how much to open up the muffler?
Pull the deflector off the front. It will be crackly but if you pick up performance you’ll know that it needs more breathing. Then you can put it back on and decide which method you want to do long term.

“Gills” or “Swiss cheese” muffler mods help flow but don’t sound as obnoxious.
 
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