Muffler Mod-Rookie Mistake

[hokiebob1]

I tried to open up the muffler hole on my Husky 353 today. I removed the screen and using a carbide burr, opened up the hole and in the process opened up the shroud over the hole. Well, most of you pros probably know this, and if I'd have taken my time, I would have too, but when you open the hole and the shroud, you have to make sure that the shroud still covers the entire hole, otherwise when you're into your first cut, you burn a hole through the top plastic cover. Needless to say, its back to the drawing board with either an addition/extension to the shroud or I'll blank off the stock opening and add either one 1/2" hole with tubing nipple extension, or possible two 3/8" holes/nipples. Anyone have thoughts on the best way to go.

You know, I'm pretty good with big block chevy's but these little two strokes are a tad different!

thanks
bob

 

[tony marks]

did the same thing once.. didnt hurt the saw ,but didnt help its looks.. all i know to tell u to make sure the port doesnt chanel exhaut on to plastic..nor in the direction of where u hand is gonna be..
use to have a kees walkbehind mower..it was excellent machine except for the fact that the exhaust was channeled strait in to the face of the operator. wasnt hard to fix it ,but i just thot somebody who never used one musta desighned it..

 

[Doug01]

I suppose that muffler isn't much different than the 350's muffler. When I did my 350 I had to get rid of the factory deflector to get the hole bigger. I took a muffler from a dead homelite and cut in half, filed on it so it fit like I liked and had a guy at work braze it on for me. No more melted plastic.

Doug

 

[rbtree]

hokiebob,

I make your port area a bit larger. My 346 by Dennis Greffard, has two 9/16th id ports. Together they aren't as much area as the cylinder exhaust, so they could be larger. No need though as the saw is a screamin' demon! I'd go with two 5/8 ports with the larger displacement of the 353.

But I'd stay away from tubes, unless you can angle them sideways. They can impact the wood and break the muffler. And disrupt exhaust flow. Instead, install the second port in the bracket area, and use a screen.

 

[hokiebob1]

Thanks guys. RBtree, it sounds like your 346 doesn't have tubes-were the new exhaust holes covered by a stock-appearing shroud, or something else? I assume that one of the 9/16" utilized the stock opening?

 

[jokers]

Hey Bob,

I did the exact same thing on a muffler that I did for a freind when I was in too much of a rush. Don`t beat your self up over it.

Nothing ventured, nothing gained.

Russ

 

[rbtree]

No, mine has tubes. But I've done some of my own, more in the current style of builders, utilizing the original port and one new one, and keeping screens.

Here's a good old thread, including photos of Ken Dunn's work. Subject here is 372/385 mufflers, a bit easier to wrok on than the smaller 346 one.

http://www.arboristsite.com/showthread.php?s=&threadid=5127&highlight=372+muffler+mods

 

[hokiebob1]

Thanks to all for your inpute. I completed my muffler mod and no joke, it really peps up the saw. I ended up opening up the stock outlet pretty much to the same size as the screen. I fabricated and tigged on a new shroud to deflect the exhaust out rather than up through the plastic. Its hard to judge the area of the outlet, but its pretty close to the cylinder port size-I figure the screen adds sufficient backpressure to make the 2 stroke happy.

In short, it runs much better, the revs stay up much better in the cut, and the owner (me) is very happy....well, except for that unsightly jagged burn hole in the plastic!

bob