Chainsaw Muf Mods

[Homer6679]

Good morning, at least in the PNW. I’m wanting to get into muff modding. I have a few chainsaws that I have laying around for practice. Here are some question for some of y’all that are familiar with the topic.

How do you split the muffler to cut out the baffles? I assume a rotary tool with a cut off wheel but I was just curious if you guys do something different.

After doing all the work you want inside the muffler, how do you put it back together? Brazing? Solder? What do you use for heat?

To run a screen or not run a screen and the reason why?

Any other advice or tips welcome.

 

[Evan]

I use a 6" suicide wheel on 4.5" grinder.

Carbide burrs on 1/4" die grinder to gut the muffler ounce apart.
Miller 235 wilder and metal to put it back together with a 1" spark tube. Through factory outlet location or if I dont like that location plug it and run port in location I want.

 

[Bob Hedgecutter]

If you only buy Stihl saws with two piece mufflers- taking them apart is no longer a problem!
Otherwise- do as above.
It is generally accepted to aim for around 70% of the area of the exhaust port for the new exit port of the muffler- can be one big hole- or two, maybe three smaller ones- placed in positions of your liking.

Spark arrestor screens- yes if required by law where you cut, or if you buck up firewood in tinder dry conditions with the bar buried, exhaust exiting directly on to dry softwood bark (like beetle dead Pine).
Fairly easy to start charring up the bark of some species when repeat hot cutting firewood rings- will smoulder for hours- you get home, the wind pick up where you were cutting- you see reports on the news about a forest fire.......

 

[Tomos770]

Aint the rule of the thumb is 60% of exhaust port?

 

[Bob Hedgecutter]

Aint the rule of the thumb is 60% of exhaust port?

If you like, I do not think it is chiselled in a stone tablet anywhere as to the precise exact percentage- maybe I should have worded it as not more than rather than around?

 

[hwrdpromac7900]

This guy would know.

 

[ballisticdoughnut]

Aint the rule of the thumb is 60% of exhaust port?

You have to take into account the spark screen when modifying mufflers on chainsaws. The 60-70% rule apples to tuned pipes not mufflers. Having said that, it’s entirely possible to “over do it” on a muffler mod. As far as the outlet is concerned, you can go quite large if your running a spark screen. Something like 50% larger than the exhaust port since the screen will detract from the surface area.

 

[Tomos770]

This guy would know.

A 2stroke priest? Sorry dont have a clue who that is...

 

[esean]

Depending on the muffler design, you may not need to cut it open. With fairly open cans you might only need to enlarge the outlet. I've also drilled through baffles from the cylinder side. Just be sure to wash out all shavings. I screen the outlet to keep mud daubers and other bugs out, but don't need spark protection here so use a larger stainless mesh for better flow.

 

[Homer6679]

Thank you for all the replies, couple questions however:

In the event I would like to cut one open, do I need a welding set up to put it back together or will some propane/map gas and some brazing rod do it?

What stainless mesh will work? Will expanded metal work? I know I can buy that by the sheet

Best way you guys have tested to see which set up is better for a certain saw? For instance on an 026 is a 60% opening better than a 75% and what’s the best way to test that?