361 muffler mod

boboak · March 01, 2006, 06:29:08 PM

I just picked up a new 361 today and I want to mod the muffler. I"ve seen all the choices between just drilling three holes in the cover plate up to sending it off to someone who specializes in muffler mods. What I'm looking for is longevity more than anything else. Will a muffler mod shorten the life of the saw if its too extreme? Is there a big difference in performance between the 'three hole method" and having someone actually mod the muffler? Noise isn't a factor...I do all my cutting in the middle of nowhere. Also,should I wait awhile before I get the muffler done? Would it be easier for me to tell the difference if I ran it stock for awhile? Maybe I'm being too fussy but this is the first brand new saw I"ve bought in quite awhile (ran an 032 til it flat wore out) and might be the last new one ever if my 066 keeps on going like it has. Thanks...Bob

Kevin · March 01, 2006, 07:29:24 PM

I would order a new modified muffler and always have the option of putting the original back on.

rahtreelimbs · March 01, 2006, 10:26:18 PM

I have modded plenty of mufflers and the results are pretty much the same. Performance is gained and the saw runs cooler. If you feel confident ................then by all means do it yourself. With the right tools it is not that hard!

beenthere · March 01, 2006, 11:49:28 PM

What is the tell-tale sign that the saw is running cooler?

DonE911 · March 02, 2006, 07:54:34 AM

I have done the muffler mod on several saws... It is worth the effort. You can easily do it yourself. If you do it, don't forget to put in some screen for safety.

I think the biggest problem for most people ( myself included ) is welding on the thin metal of the muffler .. if you are adding piping to the mod ( double barrell shotgun look alike or whatever) it is hard to weld the heavier pipe to the thinner muffler metal. I started using JB weld instead and so far there has not been a problem... with jb weld you can smear it around like bondo an grind it down after it hardens up for a nice smooth look.

I can't speak for the longivity of the JB weld ... I have a small echo that I did this to about a year and a half ago and its holding up fine. I've run about 2 gal's of fuel through it in that time, but thats not alot of fuel for a working saw... If it lets go next time I use the saw I can JB it again ... it's not expensive.

Bill · March 02, 2006, 05:44:25 PM

Boboak

I may be running a modded muffler by accident - rust did all the work. I am just careful about making sure the mixture doesn't get so lean it burns something ( maybe a piston ? ) . . . FYI - There's several links to tuning spec's for stock/modded saws here in the FF site.

If I had a new saw and my first saw mod I'd be tempted to experiment on a used or cheap second muffler - a> so I have a saw I can take to the dealer if say the handle falls off under warranty and b> when I done practicing I could do it right one time on the good new muffler. Of course you'd have to have the $$$ or rummage around for the second muffler.

FWIW - I've also seen some posts here about spark arrest screens being required in alot of places in Ca. although I don't recall who's checking ( maybe after the fire they come looking for the guy in the next valley that was cutting right before the fire ? ).

Good Luck

rahtreelimbs · March 02, 2006, 07:42:41 PM

I never "gauged/measured" the temp difference between modded and unmodded mufflers. But..........since alot of the EPA mufflers employ alot of backpressure it is not a great leap to realize that operating temps go down when backpressure is relieved!

beenthere · March 02, 2006, 07:57:51 PM

rah
Thanks, I can handle that answer.

parrisw · March 03, 2006, 10:15:35 AM

What is done when a muffler is modded, just drill two holes and weld on a couple of pipes??

rahtreelimbs · March 03, 2006, 06:37:28 PM

Quote from: parrisw on March 03, 2006, 10:15:35 AM
What is done when a muffler is modded, just drill two holes and weld on a couple of pipes??

You are on the right track. Pipes look nice but can cause clearance problems. Holes are the best way IMO. Just that they are easier to do. The biggest concern is to make sure that the muffler is modded off the saw ( It has been done) and that all the newly cut edges are deburred and shavings completely removed.

boboak · March 03, 2006, 07:21:24 PM

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You are on the right track. Pipes look nice but can cause clearance problems. Holes are the best way IMO. Just that they are easier to do. The biggest concern is to make sure that the muffler is modded off the saw ( It has been done) and that all the newly cut edges are deburred and shavings completely removed.

Quote

I've been told that this saw has a catalytic converter. What happens if I do the old "drill three holes in the cover plate" trick? With the catalytic converter still unmodded would I realize any gain? Would it be better to increase the size of the existing exhaust port instead? Also (as long as I'm asking for all this free advice) can you get the muffler apart to drill the cover plate holes from inside out or just drill from outside and airblast afterward? Thanks, Bob

Kevin · March 03, 2006, 08:07:25 PM

Quotejust drill from outside and airblast afterward?

Bob, if you attempt that, metal particles will enter the cylinder through the exhaust port and your saw is cooked.

rahtreelimbs · March 03, 2006, 09:06:00 PM

Anyone that would drill a muffler on a saw instead removing it is lazy and a few cards shy of a full deck!!!

The trick is to get a free flow for the exhaust............cat or no cat! A combination of holes roughly 100-125% of the exhaust port size is about right. If you want to err on the side of caution make the port/ports the same size as the exhaust port. You can go too big in some cases and power goes down because of lack of any backpressure!

boboak · March 03, 2006, 10:09:51 PM

Kevin and Rich....Relax! I just didn't explain myself well enough I guess. Whatever I do to the muffler happens AFTER the muffler comes off. Thanks for your prompt replies and cautions. I'm pretty sure I'm playing with a full deck but the lazy part....well,sometimes. No way do I want to fry a brand new saw...had enough of a problem justifying the expense to my wife. Thanks, Bob

Rocky_J · March 04, 2006, 08:38:38 AM

I've modded plenty of mufflers myself and never used a welder on any of them. The whole idea is simply to allow exhaust to flow easier and welding is not necessary. Simply remove the baffles inside the muffler and open the outlet hole bigger. If you're careful you can still use the same spark screen to cover the bigger outlet hole. There will be no outward visible evidence that you even did anything but you will feel the difference in the cut.

Please avoid the redneck 'drill 3 holes in the front' method which looks horrible and will embarrass you if anybody sees it.

parrisw · March 04, 2006, 10:46:32 PM

Can you take mufflers apart to remove the baffles?? or is it cut the muffler apart remove them then reweld together??

Thanks

Will

rahtreelimbs · March 05, 2006, 08:51:53 PM

Quote from: parrisw on March 04, 2006, 10:46:32 PM
Can you take mufflers apart to remove the baffles?? or is it cut the muffler apart remove them then reweld together??

Thanks

Will

The muffler is solid. Either cut the muff in half or put the 2nd port in such a manner that you can access the baffle.

boboak · March 06, 2006, 01:52:58 AM

I pulled the muffler off the 361 today. Its one piece and looking into it from the back all I can see is baffles. Baffles EVERYWHERE! Never saw such a *DanG mess. Even if I went with the redneck special (three holes in the front cover...sorry Rocky) mod I don't know how I'd ever be sure I blew all the shavings out afterward. The stock exhaust hole is tiny and all but impossible to get to with a Dremel. This is one I think I'll leave to the experts. Anybody know about what a whole modded muffler would go for?

minesmoria · March 06, 2006, 12:14:17 PM

Walkers saw shop charges 30.00

fishhuntcutwood · March 06, 2006, 12:34:54 PM

I modded my 361 with the redneck method, but I riveted on a spark arrestor from a 200T and I think it looks quite professional if I do say so myself. I was able to clean the muffler out really well with air and and a shop vac. Works great.

Jeff

woodhick · March 06, 2006, 08:50:51 PM

What percentage gain in power would you say you get by running a modified muffler? Does anyone sell aftermarket muffler that are already modified? After reading this post I'm thinking of putting one on my stihl 390, would it be worth it
/ ???

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fishhuntcutwood · March 07, 2006, 08:38:20 AM

Hmmm. I'd say depending on the saw model, you could expect 10% or so, give or take. Newer saws that are more restricted by OSHA and EPA have more to gain. The 029 series of saw benefits really well from muffler mods. They're easy to do yourself. But if you're looking for one to buy, I think Walker's sells complete muffler that they've modded. Or you can send them your existing muffler for them to mod. There's quite a few modders out there, rahtreelimbs being one.

Jeff

West Texas · March 18, 2006, 02:55:11 PM

I put 3 3/16" holes in the front of my 361 muffler. When I sent the saw off to have it modded for use in the 'woods' they had made the center hole larger to 15/64" and had gutted the baffles inside the muffler. On another 361 I have, they added a rather large side port that vents forward with the noise and gases. On all my other saws, I've made sure there was some back pressure remaining; so I've been on the conservative side with my holes, letting them total out to about 80% of the engine exhaust port. I'm no engineer, but it works for me. Tom 8)

fishhuntcutwood · March 19, 2006, 03:03:22 AM

Welcome Tom. Glad to see you here. I modded mine along the same lines. I don't recall the measurements I used, but I went conservative and it works great. My buddy and his stock 361 are day and night to mine. The cuts, the sounds, the powerband are markedly different. This saw really responds well to muffler mods, like the 029 series does.

Jeff