Husky 394 Muffler Modification

[Clanski]

I'm new to this site and impressed with all of the knowledge and helpful people who post here.

Two years ago I bought a used Husky 394XP on eBay and used it quite a bit. The muffler was bashed in about 3/8" by the previous owner and it has a small split in it. I got it running good and put about $50 in parts into the saw, but did not buy a new muffler since they cost about $70. All in all it was worth the $220 I paid for it.

I decided to straighten the dent and fix the split in the muffler. Since i got the muffler off, why not modify it?

There are posts on lots of different saws but can anyone explain the best way to modify the 394 muffler? Pictures would be appreciated.

Thanks

 

[romeo]

First, will you be using this saw on public land (National Forrest, etc)? That does matter. If so you must have an ANSI approved spark arrester screen.

As far as modding, the best you can do for a work saw is make two ports, the sum of which equals 70% to 80% of the exhaust port. That has always worked well for me. Make sure you richen her up accordingly.

 

[Clanski]

394 Muffler Mod

First of all, I am on private property.

Regarding the holes; is there a specific location that works best for directing the exhaust etc.? Do i need to braze in some pipes?

 

[romeo]

First of all, I am on private property.

Regarding the holes; is there a specific location that works best for directing the exhaust etc.? Do i need to braze in some pipes?

I have found that it doesn't really matter much where they are located but I like to do them cross corner of each other anyway. Just make sure you don't aim your ports toward the handle bar (ouch). I weld tubes in just to be pretty or to direct flow away but its not necessary.

 

[adkranger]

Spark Arrestors.....

First, will you be using this saw on public land (National Forrest, etc)? That does matter. If so you must have an ANSI approved spark arrester screen.

This is partially accurate. If your saw causes a wildfire because you modded the muffler so that it no longer meets USFS specs you may be held liable for incurred suppression costs regardless of property ownership where saw was operated. This includes such minor tinkerin' as removing the spark arrestor screen. Ever rented an Ericson Sky Crane for a couple of hours? You may find out how much they eat out of Uncle Sam's pocketbook if you are not careful.

Am I opposed to muffler mods? No, but feel the uninformed masses should KNOW the territory they are treading into...... I know of a case where a logging outfit was forced to repay suppression costs to the tune of seven figures because someone on one of their crews removed a spark arrestor on one saw that caused a fire.

Not trying rain on anyone's parade, Mod On!! But leave your properly maintained screens in place, or add them to your newly modded holes. When cleaned on a regular basis, probably no more than yearly for most operators with good mix and properly running saw, they do no harm to performance.

 

[stihl 440]

modded mufflers

When I mod my mufflers I Braze in spark arrersting screen just in case I get a logging job on state or national forest land, I don't have to worry about it. They can just look down my muffler "pipes" LOL, and see the screen is in there. Besides it keeps the sparks down.:greenchainsaw: :hmm3grin2orange: :chainsawguy: :biggrinbounce2:

 

[Lakeside53]

If you mod them correctly, leaving/adding the spark arrester has no effect on the performance of the saw.

The biggest problem is not sparks - it's the 1400F exhaust directed forward and catching bark on fire... Even my 361 mod can do that. USDA approved mufflers don't have this problem, and if you start a fire with a modded muffer, spark screen or not, you'd better hide (or whatever).

Great way to start a campfire if you're out of matches...

 

[adkranger]

If you mod them correctly, leaving/adding the spark arrester has no effect on the performance of the saw.

The biggest problem is not sparks - it's the 1400F exhaust directed forward and catching bark on fire... Even my 361 mod can do that. USDA approved mufflers don't have this problem, and if you start a fire with a modded muffer, spark screen or not, you'd better hide (or whatever).

Great way to start a campfire if you're out of matches...

You're right, of course, it's not sparks but Carbon Particulates or minute pieces from the muffler itself(older equipment) that are the actual cause. Sure direct convection from exhaust gasses could start a fire in prolonged exposure, but the particulates that are expelled from poorly maintained equipment are more likely to ignite in dry litter because they hold heat longer. Imagine that particulate heated to 1400F spit out on the forest litter on a hot, dry day. It may not ignite for minutes taking longer for Conduction tranfer to take place. The Convection from exhaust gasses is imediate, you should see that taking place while cutting.

 

[Lakeside53]

Yep... But it's not always prolonged - a 10-20 seconds on high power and the bark lights up - depends on the tree, temps etc... but it can be pretty quick.

Ask Rbtree about his saws

 

[adkranger]

Ask Rbtree about his saws

Nope, don't want to know. See no evil, hear no evil..............:crazy1: