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"Opening up the muffler"

Started by TexasTimbers, October 23, 2005, 09:59:26 AM

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TexasTimbers

I've seen some references to this but can't find any details in the archives regarding this mod. I have a stihl 025 I'd like to try this with if you chainsaw wizards think it's a good idea. If so, can you point me in the right direction?
kevin.
The oil is all in Texas, but the dipsticks are in D.C.

Tom

If you click on "Search" at the top of the page and enter "muffler" in the search window and only check the Chainsaw section for the search, you will end up with 7 pages of stuff similar to the link below. :)

https://forestryforum.com/board/index.php?topic=6030.msg84117#msg84117

TexasTimbers

Thanks Tom. I did see that thread previously but I still don't know if it's detailed enough for me,; probably because I just can't picture it. Guess the best I can do is print it off and take a stab at it :o
The oil is all in Texas, but the dipsticks are in D.C.

fishhuntcutwood

I can't speak to specifics on a mod for an 025.  But there are some general rules for any muffler mod- 1) Start off small.  You can always make your hole(s) bigger, but can't easily make them smaller.  2) The entire muffler opening should be smaller than your exhaust port in your cylinder-you need some backpressure for the engine to do what it needs to do to run.  Alot of guys say 85%.  I don't know personally.  3) Take the muffler off your saw to do the mod.  This way you keep any metal shavings out of the cylinder.  It seems obvious, but bears mentioning.  4) Richen your carb up after the mod.  And just as an observation, most of the better mods I've seen done are the simple ones.  When someone tries to get too fancey, or someone tries to break new ground just for the sake of doing it, it'll alot of times come out not as good as the guy who just drilled three holes in the front of his muffler.

Jeff
MS 200T
MS 361
044
440 Mag
460 Mag
056 MII
660 Mag

treeboy

hi kevjay probably too late for you but some pics of what I did.
Taking apart the muffler. I also removed the spark arrestor screen shown inside the muffler


Here is the muffler off. I cut the outlet open a tiny bit, ground off the edges, covered it back up. From looking at it all together you can't even tell. Make sure you remove all the little bits of metal, and richen the carb. My saw works great now, nice and loud too 8)

Spencer

floyd

Removing spark arrestors may make saw run better but don't get caught on Crown Land, or USFS land with spark arrestor gone.

You will pay if you start a fire & get caught.

treeboy

Thanks for the info Floyd, didn't know that. I think I liked being ignorant better ;)

floyd

If 1 wants, or needs, to stay in compliance, a good habit to get into is cleaning the spark arrestor on your muffler.

Little known fact of questionable interest...very different muffler on "east"coast sthil vs "west" coast saw.

treeboy

good point Floyd, we do have a lot of "old mans beard" lichen on our acreage. That stuff burn like crazy when dry.

GammaDriver

Quote from: floyd on November 17, 2005, 11:02:56 AM
Little known fact of questionable interest...very different muffler on "east"coast sthil vs "west" coast saw.

And, being an East-coaster, that diffirence is... ?  You've got me curious!  (I'd guess the east coast is wetter, so less spark arrestor screen? - or more crowded, so quiter - one option's good, one's worse i guess)

thecfarm

I'm pretty sure here in Maine you need the spark arrestors too.Game Warden can pitch you for that.Some guys have been known to run without them.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

floyd

Gamma, this was in 80's. Guy from KY had a 30 series sthil. his muffler had a longer "hood" over the spark arrestor. It also ran quieter.

vgbob

Would someone mind explaining the point of backpressure in
a 2 stroke exhaust system? The reason for my question is
that I have a pair of identical Jonsereds 70E's. I suspect you
can guess the next part...
Out in the woods a few years ago one of 2 muffler bolts fell
out of one saw. So I just removed the muffler, retuned it
and kept going.  Both saws had a baffle in the mufflers come
loose in the first few years of use, so are probably somewhat
more open than stock, but I never did any modifications other
than that. The saw without a muffler 'feels' like it
has more power.  But perhaps even a bad modification is
better than the more or less stock muffler.  But since the
saw seemed to run better I never bothered to put the muffler
back on. I only cut in my own woodlot, so it's not a concern
for me other than what is best for performance.

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