361 muffler mod w/ spark arrestor.

Here's the 361 muffler I just did, with the addition of a spark arrestor. The race guys will slam me for having that on there, but working in dry timber, and especially on gov't land, you need to have it on there.

I did the three holes in the front cover, and took the screen out of my 200T, modified it, and riveted it onto the front of the muffler with two Cherry Max 6-3's.

Haven't run it on the saw yet, but hope to this weekend sometime.

Just passing along ideas...

Jeff

Man, I'm followin' you all over the place. That looks good Jeff. Post your results after you run it.

Gary

I put a screen over mine also, with brads. The quality of the screen left something to be desired; burnt out after a few hours of operation.

West texas, Did Dave ever make good on your 361 that blew?

Happy ending. Was never a problem.

Thats great.

fishhuntcutwood said:

Here's the 361 muffler I just did, with the addition of a spark arrestor. The race guys will slam me for having that on there, but working in dry timber, and especially on gov't land, you need to have it on there.

I did the three holes in the front cover, and took the screen out of my 200T, modified it, and riveted it onto the front of the muffler with two Cherry Max 6-3's.

Haven't run it on the saw yet, but hope to this weekend sometime.

Just passing along ideas...

Jeff

Click to expand...

This looks like a pretty easy way to mod the muffler. I was wondering Jeff did you also do any modding to the original outlet hole in the back?

How did the saw perform after you added these holes? Did you have to mess with the limiter caps at all and readjust the carb?

stump doctor said:

This looks like a pretty easy way to mod the muffler. I was wondering Jeff did you also do any modding to the original outlet hole in the back?

How did the saw perform after you added these holes? Did you have to mess with the limiter caps at all and readjust the carb?

Click to expand...

Outlet hole of the cylinder? No, didn't touch it. Maybe later, but not now. Nor did I touch the inlet of the muffler. There's a baffle there, but I don't think worth messing with. Others may disagree. Still haven't had much chance to run it, so I really can't make a substantial claim. I had a modded muffler on it beforehand, so it's not like day and night from what I had, but from stock, yeah, it's better.

And yeah I had to pull the caps when I first put the original modded muffler on. Like I said, I haven't run this muffler that much yet, and haven't tached it. Sounds good, and runs good, but havent' gotten after it yet. Been too busy splitting wood. I leave Saturday for Christmas, so it may be a while before I get to it.

Jeff

Outlet hole of the cylinder?

Click to expand...

I actually ment the original outlet hole of the muffler. Sorry for the confusion.
If you already had it modded before, it would probably be hard to make a direct comparison. I'm sure any mod you do to open up the muffler would be an improvment.

Have a great Christmas Jeff!

fishhuntcutwood said:

Here's the 361 muffler I just did, with the addition of a spark arrestor. The race guys will slam me for having that on there, but working in dry timber, and especially on gov't land, you need to have it on there.
Jeff

Click to expand...

The screen is over th hole to keep crap out too. I don't know about you, but I don't want a direct opening straight into my combustion chamber.
What if some gravel or something got accidentally kicked in there?
Also, some guys don't know there is a small suction into the exhaust port at one point during a revolution of the motor. It is possible for stuff floating around inside, or in front of, the exhaust, to get sucked in the motor.

stump doctor said:

I actually ment the original outlet hole of the muffler. Sorry for the confusion.

Have a great Christmas Jeff!

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DUH!! You're right, the original outlet hole is in the back. That was my misunderstanding. No I didn't touch it either. No way to get to it without tearing something up.

Merry Christmas to you as well!

Jeff

Absolutely correct Mike. I originally made the mod, and looked into the front of that muffler and was like, "whoa, that's a big empty space in front of my cylinder!"

Jeff

If you think about it, an exhaust hole should allow the same flow with a screen over it, if you make it slightly larger.
For example, a one square inch exhaust hole without a screen, should breathe the same as an 1.2 square inch hole with a screen.

Mike Maas said:

If you think about it, an exhaust hole should allow the same flow with a screen over it, if you make it slightly larger.
For example, a one square inch exhaust hole without a screen, should breathe the same as an 1.2 square inch hole with a screen.

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That's what I was thinking when I put the screen on. I made the holes in the casing a bit larger than what I would have in the first place to make up for the screen.

Jeff

Wire Cloth

Mike and Jeff , if you'll look up wire cloth on McMasters website and look at the brass screen that comes on factory mufflers you'll see that it varies from about 50% open area to about 71% open area . What is a Cherry Max 6-3 ? Is it a stainless rivet ?

http://www.arboristsite.com/attachment.php?attachmentid=11502&d=1080243525

Here is a picture of the new opening on 372 husky. The stainless screen comes from a flour sifter and is just sandwiched between the support and the body. If I want to quiet it down to original sound level I just have to pull the screen and slip in a piece of sheet metal. Opening about 5/8 X 7/8 inch

scottr said:

What is a Cherry Max 6-3 ?

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It's a blind rivet. Anyone who's worked in aviation will be intimately familiar with them. A conventional rivet requires you to buck it from each side. This isn't always doable-like say you wanted to replace one rivet on an aircraft wing. You're not going to dismantle the whole wing to get to the backside of one rivet. A Cherry Max has a post running through it, which is pulled from the head side by a manual or airpowered gun. It bucks the rivet and breaks off, leaving a standard or countersunk head and a cleanly bucked rivet. All the while you never having seen the back side of it. I coulldn't pull the muffler apart, so I used a Cherry Max. They're great!

Jeff

fishhuntcutwood said:

It's a blind rivet. Anyone who's worked in aviation will be intimately familiar with them. A conventional rivet requires you to buck it from each side. This isn't always doable-like say you wanted to replace one rivet on an aircraft wing. You're not going to dismantle the whole wing to get to the backside of one rivet. A Cherry Max has a post running through it, which is pulled from the head side by a manual or airpowered gun. It bucks the rivet and breaks off, leaving a standard or countersunk head and a cleanly bucked rivet. All the while you never having seen the back side of it. I coulldn't pull the muffler apart, so I used a Cherry Max. They're great!

Jeff

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It sounds similar to a pop rivet, yes? But higher quality?

CNYCountry said:

It sounds similar to a pop rivet, yes? But higher quality?

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Yeah, but definately higher quality. They're obviously FAA approved and we use them in the CG.

A screen over the exhaust purpose is to prevent sparks. It wont stop much from getting into the cylinder unless its pretty large, so its usefullness in that capacity is limited.
I remove the screens as soon as I get a saw and have always done so. I also orientate my muffler mods to minimise exposure to things entering the outlets.
As for the the old wives tail of exhaust suction occuring in some part of the motors cycle. This isnt true unless you have a tuned pipe.