Chainsaw Repair

Pics?  Sounds like you could dremel or drill through the wire or baffle to bypass for flow?

IPL of muffler on page F?  http://www.ereplacementparts.com/echo-cs400-c09011001001-c09011999999-chainsaw-parts-c-35043_35970_36727.html

if you really want to wake that saw up you need to split the muffler open and remove EVERYTHING!
then mod the deflector. i used two 3/8"o.d. X 3/4" long stainless tubing silver soldered into the deflector

 it's louder than an old xl12, but pulls very good.
i have done about 10 of these saws and this is by far the best way to do it

  that pic was taken last winter while a friend and i were taking apart a big elm. we brought the echo along for branch detail and was quite impressed on how well it did. even with the stock safety chain it was pulling through the wood very good, made my 025 look down right crappy. now, after close to probably 20 tanks through it, that little echo really hauls a$$ for a 40cc saw. at the time it was on it's 3rd or 4th tank. frozen elm isn't the nicest wood to cut and that little saw did a fine job of it. so much so i went out to potters and bought my self one. no idea why they get so loud after this mod, i mean LOUD! the only way to explain it is to compare it to an xl12
leaves you ears ringing.

Actually I saw later version of that 440 today,a 4400 .Sitting in the back  room of a Stihl dealer .I think I could have landed it on the cheap but I neither want nor need  a 40 some cc saw .

It looked good ,tag said a scorched piston but it had great compression .Now had it have been closer to 3 cube I'd have given it a go .Are those a removavble cylinder or clamshell ?

the "newish" cs440 is a 3 piece case. crankcase bottom, top and seperate cylinder. very easy to get some compression out of them. they get strong too
you could throw a cs510/520 shortblock in there as well. but it aint as easy to make power as they are a "true" clammy. better power can be made from the 440.