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Author Topic: Muffler mods  (Read 4875 times)

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Offline woodsdog2015

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Muffler mods
« on: April 04, 2018, 07:34:51 PM »
Fellas what is your opinion of muffler mods for chainsaws? Mufflers like the “Buckshot” and others to let the saws breath and run cooler. Do you pros who are running saws all day use them? What are the detriments besides warranty exclusion? I was the joint about making this modification to make my saw run better, cooler, and more efficiently but I don’t want to reduce the longevity of my saw(s). Opinions?
I'd rather be in the woods.
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Offline Woodcutter_Mo

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Re: Muffler mods
« Reply #1 on: April 04, 2018, 08:34:27 PM »
 I did muffler mods to my Husky 455 Rancher and my Stihl 024. They're just a little louder (would greatly depend on how you mod them), and they seem to use a little more fuel which would make sense because I had to richen the carb settings a bit after opening the mufflers. They do seem to be a little stronger in the cut and snappier revving. That's my only experience so far.

 
- WoodMizer LT25, Kohler, all manual, old "drag" style WoodMizer sharpener, cat claw single  setter
- Husqvarna 372XP X-Torque/24" bar, 455 Rancher X-Torque/20" bar, 550XP/20" bar, Stihl 024AV/18" Oregon speedcut
- Kioti DK45, '92 Dodge Cummins with Cannonball  bed, '07 Honda Rancher

Offline woodsdog2015

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Re: Muffler mods
« Reply #2 on: April 04, 2018, 09:27:21 PM »
Thanks, any concerns about there not being any back pressure and burning the saw up?  I just figure if it can breath better it’l run better and cooler but I’ve also heard the mufflers are engineered the way they are for a purpose and part of an nyegrated system and helping one thing may in fact cause other unanticipated problems. Some guys just do these things to make them run faster but I want to keep my saw for a long time.
I'd rather be in the woods.
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Offline Woodcutter_Mo

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Re: Muffler mods
« Reply #3 on: April 04, 2018, 10:01:37 PM »
 The more experienced guys will be able to tell you more, and there's alot of reading on the subject. But there does need to be a certain amount of back pressure. The total amount of opening can only be a certain percentage of the size of the exhaust port on the cylinder. I can't remember off hand but I want to say around 70%, so you don't want to open it up too much. Also, if you do an exhaust mod, remember you have to retune the carb or it will likely run lean and burn it up.
- WoodMizer LT25, Kohler, all manual, old "drag" style WoodMizer sharpener, cat claw single  setter
- Husqvarna 372XP X-Torque/24" bar, 455 Rancher X-Torque/20" bar, 550XP/20" bar, Stihl 024AV/18" Oregon speedcut
- Kioti DK45, '92 Dodge Cummins with Cannonball  bed, '07 Honda Rancher

Offline Rebarb

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Re: Muffler mods
« Reply #4 on: April 04, 2018, 10:04:57 PM »
I strongly believe with EPA Restrictions that newer saws simply don't run to there potential. 

I've modded the last 3 saws a bought and my last, actually gained 1000 rpms from stock form via tachometer. 

Some do a simple flap mod by cutting a flap in the top of muffler using a cutting disk with Dremel tool.

I actually remove the arrestor plate and then remove restrictor tube but also while i have the arrestor plate off, cut front side open with Dremel depending on model.

But as mentioned, i do have to richen up the saw to get 4 stroking back.
But you will have to remove the limiter tabs " wood screw works" and you'll need proper spline tool to adjust high-low.

If your not comfortable with properly tuning a saw and possibly risking running to lean then simply trust factory settings. 
I personally want optimal performance and piles of saw dust. Lol 

Offline teakwood

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Re: Muffler mods
« Reply #5 on: April 04, 2018, 10:25:39 PM »
In my opinion it's a great and simple modification. i did all my 260s about 3 years ago. since then i sold 2 and have just one left.

My all day saw, 361: 1/2 year old, opened her up after the first tank and richened the carb. and she runs great. i have at least 150 tanks thru it and i love the saw. bought a second 361 (70 tanks thru) two month ago for the help and didn't do the mods.  What a difference!!! mine is at least 15% faster and stronger.

Of course i didn't go bananas on the mod, opened it about 2-3 times the original hole
National Stihl Timbersports Champion Costa Rica 2018

Offline realzed

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Re: Muffler mods
« Reply #6 on: April 04, 2018, 11:25:28 PM »
Not to hi-jack this thread - but if anyone knows the best way to reliably mod a new version II 261C-M I'd be very interested in knowing what's involved and the best method to do it.. 
I don't want or need to make some kind of race saw out of mine either, as previously stated - just want to improve what already is there and keep it reliable and workable.
I've heard the M-Tronic deal does away with the carb retuning worries afterwards so it seems like a no-brainer since I've heard this model can pick up substantial power all across the rpm range if the mod is done right - Thanks.. 

Offline HolmenTree

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Re: Muffler mods
« Reply #7 on: April 05, 2018, 12:42:26 AM »
I haven't done mine yet Randy but I'll let you know after I take a look at it.  It's a pretty impressive saw as it is.
Making a living with a saw since age 16.

Offline Weekend_Sawyer

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Re: Muffler mods
« Reply #8 on: April 05, 2018, 07:56:14 AM »
I haven't done mine yet Randy but I'll let you know after I take a look at it.  It's a pretty impressive saw as it is.
I'm looking forward to that.
I bought a MS440 from a forum member about 10 years ago that has a moifided muffler.
I don't know how much of a performance upgrade it was but I know it's loud!
It's been a great saw and I'm really happy to have it.
Imagine, Me a Tree Farmer.
Jon, Appalachian American Wannabe. ... and it looks like my dream will come true!

Offline mike_belben

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Re: Muffler mods
« Reply #9 on: April 05, 2018, 08:05:24 AM »
I do them all to lower jug temps and help give a buffer against scoring (or melting the tank on these plastic clamshells.)

The easiest and quietest way is to make a fishgill slit with a dremel and pry it open with a screw driver so that it aims gas BACK TOWARD the powerhead.  Then fashion a little tin louver and weld it on over that which redirects gasses forward and away.  This gives you as much opening as you want, but it still maintains the noise cancelling properties of a reflective wave.  


Throw out anything youve ever "learned" associated with the term "backpressure" from hotrod magazine or wherever.  whether it be for 2 stroke or 4.   There is not eve a lick of performance to be gained (though much to be lost) from a positive pressure present on your exhaust side, it just creates reversion.  Economy is a little more gray, but in saws youd be much better off to work on blowdown and transfer timing and upper transfer port layback toward the intake side.  Using exhaust restriction to keep charge in is not how to make power.

 Exhaust tuning for power is entirely based on manipulating the timing of reflective waves so that a negative pressure arrives at the exhaust valve or port to create a scavenging effect, at the time when you want it.  Its obvious on a dirtbike, pipes and reeds give huge powerbands when the wave arrives. Different pipes deliver the wave at different intervals so you can have powerband at different parts of the rpm band.  On a saw not so much, its just off or on because no reeds and no pipe.  No reflective wave, just a restrictor can to dampen sound and spark.
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Offline Woodcutter_Mo

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Re: Muffler mods
« Reply #10 on: April 05, 2018, 10:41:39 AM »
 If I remember correctly, retaining a little back pressure on a saw was mostly to keep cold air from hitting the exhaust port. Is that correct?
- WoodMizer LT25, Kohler, all manual, old "drag" style WoodMizer sharpener, cat claw single  setter
- Husqvarna 372XP X-Torque/24" bar, 455 Rancher X-Torque/20" bar, 550XP/20" bar, Stihl 024AV/18" Oregon speedcut
- Kioti DK45, '92 Dodge Cummins with Cannonball  bed, '07 Honda Rancher

Offline woodsdog2015

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Re: Muffler mods
« Reply #11 on: April 05, 2018, 10:59:25 AM »
Well my concern is I have ring of carbon around the top of my piston on my stock 362 and don't want it to get worse.  What would you guys do?   I don't cheap out on anything I use the stihl synthetic oil and 90 octane non-ethanol gas.   
I'd rather be in the woods.
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Offline Rebarb

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Re: Muffler mods
« Reply #12 on: April 05, 2018, 11:44:06 AM »
Well my concern is I have ring of carbon around the top of my piston on my stock 362 and don't want it to get worse.  What would you guys do?   I don't cheap out on anything I use the stihl synthetic oil and 90 octane non-ethanol gas.  
Go too a 40:1 mix and run it long and hard,seriously. 
How's the exhaust port look ?

Offline realzed

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Re: Muffler mods
« Reply #13 on: April 05, 2018, 02:25:10 PM »
I haven't done mine yet Randy but I'll let you know after I take a look at it.  It's a pretty impressive saw as it is.
Thanks Willard - I would really appreciate that..
Here it is, I haven't even used my new c-m yet (still waiting for the weather to clear and Spring to hint that it might at sometime come - and yesterday we got seriously dumped on 25 cms and all most anyone can think of is snow shovels digging out and nothing to do with saws) and already I'm getting worried about trying to improve it somewhat!!  ;)

Offline mike_belben

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Re: Muffler mods
« Reply #14 on: April 05, 2018, 02:57:11 PM »
If I remember correctly, retaining a little back pressure on a saw was mostly to keep cold air from hitting the exhaust port. Is that correct?
If cold air around the jug was an issue we probably wouldnt have fins and deflector plates to direct maximum cooling air past them from the starter fan.  
Hotter gas does flow faster through a conduit but a saw muffler isnt much of a conduit.  Its a baffle chamber and flow is obviously last on their priority list when you look inside any of these things.  
If i had to guess why manufacturers are choking saws down and running them hot i would say its more likely something youd see on an emissions analyzer.  Tier 4 is probably not an easy thing to pass. 

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Offline Canadiana

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Re: Muffler mods
« Reply #15 on: April 05, 2018, 04:28:04 PM »
Not to hi-jack this thread - but if anyone knows the best way to reliably mod a new version II 261C-M I'd be very interested in knowing what's involved and the best method to do it..
I don't want or need to make some kind of race saw out of mine either, as previously stated - just want to improve what already is there and keep it reliable and workable.
I've heard the M-Tronic deal does away with the carb retuning worries afterwards so it seems like a no-brainer since I've heard this model can pick up substantial power all across the rpm range if the mod is done right - Thanks..
Mt original style 261cm was a great stocker. After a moderate muffler mod it was a bit better but marginal. I didn't remove a lot of metal when i expanded the muffler outlet, deflector, and gasket but i thought it was enough. Maybe this saw has nearly reached its potential before a mod. I hope holmen does his newer version this spring and let's us know the results
The saw is more fun than the purpose of the wood... the forest is trembling 🌳

Offline Al_Smith

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Re: Muffler mods
« Reply #16 on: April 05, 2018, 06:05:17 PM »
I have to laugh because quite frankly I'm not sure if I have a saw with a pressure can muffler that hasn't been altered .It's kind of like the oil wars,some swear by it some swear at it .
You have to look at it like this .A pressure can style muffler is a regulating device as well as a noise reducer .With restrictions you can't transfer a more powerful fuel  charge because it can't get in simply because it can't get out .It takes fuel to make power .Not to worry it's not like dumping fuel into a double A fuel dragster with 3000 HP .It's a little bitty chainsaw engine .The extra fuel it uses won't send you into bankruptcy.

Offline dogone

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Re: Muffler mods
« Reply #17 on: April 05, 2018, 11:59:07 PM »
   My only project was my husky 154. Opened up and polished in and out ports. Opened up the muffler and drilled holes then added fish gills on outside of muffler. Unscientifically it seem to have more power and is certainly louder. Burns more fuel also. I guess you could call drilling holes in the muffler of my $99.00 poulan a project also. Did this as soon as I bought it so nothing to compare with but runs well.

Offline realzed

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Re: Muffler mods
« Reply #18 on: April 06, 2018, 08:31:08 AM »
Is there any valid proof that the M-Tronic has the ability and mixture range to compensate fully for any muffler modifications, in anyone's own actual experience?
It certainly appears that if that is in fact the case as I have heard, and it can and will adjust for freer exhaust flow and thus the leaner mixtures, then any gain on a saw with such a module would be virtually a 'no-brainer' since aside from a bit more noise there really wouldn't be much if any risk or down side to making such a modification..
At least that is my own naďve thinking unless there are other factors that I'm not aware of possibly.. 

Offline mike_belben

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Re: Muffler mods
« Reply #19 on: April 06, 2018, 09:17:35 AM »
Ive never even seen an electronic saw but do know automotive systems fairly well.

If these machines have an exhaust gas temp or oxygen sensor feedback to the computer then automatic compensation may be possible.  If they dont then i cant see how.

In efi cars you are reprogramming the fuel and ignition tables to shoot for a more aggressive operating condition.  Otherwise you could do all you want for hard parts but the computer is still gonna modify values until it arrives at the 14.7 air/fuel or whatever base map the factory installed.  So the real power is in tweaking the map.  The feedback devices are how the computer knows it is following the map.
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