Lakeside53's --361 muffler mod w/photos
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Lakeside53
Stihl Wrenching
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Reply to artie bc
It applies to the total area of the exhaust (existing and added openings).
It applies to the total area of the exhaust (existing and added openings).
Four Paws
Addicted to ArboristSite
artie__bc said:
If you would have read the entire thread, you will see that it was covered in post 6. Don't mind helping, but when the information is easily obtained in the thread you are posting in...SEARCH. It doesn't get much easier than that!
Welcome, and remember, 80-85% is a 'safe' guideline...some saws can be taken well beyond this without any ill results.
Hey Josh, he did say "Please." 
Four Paws on one post you said the new hole should be 80 - 85% and on another you said combined SA of all holes. Just wanted some clarification before I start hacking at my muffler! Anyways, my 044's muffler already has a hole that equals about 80% of the cylinder port SA, so maybe I won't gain anything with a muffler mod? Has anyone here done an 044?
I disagree that 80-85% is optimal, as measured against the port at the cylinder wall. Ken Dunn, venerable saw builder, used 125-150% as his baseline.
most of my saws are probably at 100-125%, but have also been woods ported, which may allow for more opening. One, was muffler ported by Ed Heard way too much. It's a 346, and is very fast, but way too loud. Definitely no power fall off from too much port area. I do need to quiet it down though!!
most of my saws are probably at 100-125%, but have also been woods ported, which may allow for more opening. One, was muffler ported by Ed Heard way too much. It's a 346, and is very fast, but way too loud. Definitely no power fall off from too much port area. I do need to quiet it down though!!
Lakeside53
Stihl Wrenching
artie__bc said:
IMO... any number bandied around is just a WAG starting point, and will vary depending on whether you just do the muffler, make changes to the airbox/carb, or make other more radical changes.
On the very old 044 there is only a little to be gained. On the later 044, lots... If you're worried, make your hole adjustable with metal slide then do timed cuts. You'll quickly figure out "optimal", and trade off sound level... If you have a spare muffler front this is very simple... cut a long slot say 1/4 inch wide and have a screw-on on cover strip. Once you've figured out your optimal opening area you make make something more desirable - and either dual port the muffler or enlarge the existing hole.
Four Paws
Addicted to ArboristSite
artie__bc said:
Yes, I see that now. I should have said 'holes' and not hole. Even then, I could see how it might be confusing. I will edit the initial post for clarity. And, as Andy pointed out, these numbers are somewhat of a WAG. You can take a muffler too far - beyond the point that you gain any power and just make it louder (like rbtree said). rahtreelimbs opened up a Shindaiwa 488 muffler to the point that it wouldn't run well. The point here is more is not always better. Since the muffler mod is one of the first things (and maybe only thing) a new comer may do to their saw, the 80-85% was thrown in as a safe baseline. A woods ported saw will benefit from more surface area for the exhaust as the engine is now flowing more fuel and air. Also, as Andy mentioned, an older 044 will not benefit as much as a new 440 as the older saws have pretty free-flowing mufflers from the box.
Anyhow, good luck, and post up some pictures of your mod when you are done!
Josh
Freakingstang
Doctor Freakinstein
rbtree said:
I agree with you RBTree. I have never had power fall off from too much opening. Most of mine are 100-130% of the exhaust port at the cylinder (piston).
A 372 works real good with a 1/2 x 1" oval hole. theory would say, based on the 80-85% that that is too much, but works extremely well.
While a saws needs some back pressure to run, it also needs to be able to breath.
My 346 has been opened up with two 3/8" holes in addition to the stock outlet. This wasn't done by me, but the builder who built the saw. It is entirely too loud, but hey, that is what muffs are for!
The 80% rule is a guideline so you don't hack your muffler up. But don't be afraid to open it up a little at a time and check the results. You could be quite surprised.
An 044/046 breathes extremely well with the dual port muffler and both holes opened up. The last one i did, I believe was about 150% of the exhaust port and it could have taken more, but I was trying to be conservative.
Modded saws respond well to a bigger opening also.
Keep in mind, that you should put a spark screen in the new hole. This will also affect airflow up to 50% depending on the screen size. So sometimes the hole has to be bigger than one would think with a screen in place to get the best gains.
Lakeside53
Stihl Wrenching
Freakingstang said:
The best way to do this is make your outlet the size you need, and arrange the screen so it's several times the area of the actual opening. This is what Stihl does on their pro saws and to some degree on all saws/OPE - and if you do, you can pretty much just forget its effects both initially and over time. It's not just the new screen occlusion that matter - the wires get coated with fuel additive debris (that tan stuff - not just "soot") and get significantly thicker.
I showed one way of doing this on on the 361 muffler mod thread.
Yeah Andy, I saw the thread on your 361 mod, and I've got the parts to do it to my 044. I also have a big bore cylinder kit for it, and plan to install a Maxflow air filter, so maybe it'll benefit more from a little better exhaust flow. I guess if it doesn't work out it won't be too hard to weld the hole shut again.
As far as whether it's an old or new 044, it's late 90's; does that make it old or new? It has the 12mm wrist pin.
Cheers, artie
As far as whether it's an old or new 044, it's late 90's; does that make it old or new? It has the 12mm wrist pin.
Cheers, artie
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Lakeside53
Stihl Wrenching
artie__bc said:
With the 12mm it's "newer", but the big muffler strangle didn't come until about until the 1999 production.
Yeah, this muffler is just a tin box with an inlet and outlet, no baffles or anything. Just a spark screen on the outlet. I've been considering, and I think the easiest thing would be to enlarge the outlet a bit. There's a lot of room to do that.
Lakeside53
Stihl Wrenching
artie__bc said:
The easiest thing to do is slap a factory dual port front on it..
Lakeside53
Stihl Wrenching
artie__bc said:
1128 140 0801
Lakeside53
Stihl Wrenching
musch said:Does anyone have photos of a MS260 muffler mod?
And yes, I did search the archives....
Take off the front cover, remove the screen. You'll have one round hole about 3/8" in the center (back). Drill a 5/16 hole above it and one below it (don't go too deep). Debur the holes, re-insert the screen and it's done. Adjust your carb.
