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Author Topic: Muffler mods  (Read 4880 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?
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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
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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.
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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
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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
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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.
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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.
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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
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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
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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 naïve 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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Offline realzed

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Re: Muffler mods
« Reply #20 on: April 06, 2018, 11:09:52 AM »
I fully realize any good system requires feedback to make it optimal over a wide range of conditions - especially variable ones - but with present and past saws with their regular carb setups that has never been the case in that most always usually were set for a rough average condition and a user realized often by feel, that he was  living with a certain amount of 'off peak' performance as the nature of the beast as real World conditions changed in a practical sense.
With an M-Tronic type deal as I understand it, while that is still somewhat the case, it is largely improved since it tries to automatically adapt (33 times/sec) to cover a wider range of operational variables..  the carb mixture being just one of those variables - and in the case of modding an exhaust to produce more power, one of the more important ones.
A true system that completely monitors and adjusts for everything I suspect will never hit something as small or cheap as a chainsaw for logic, cost, size, and weight considerations, as somewhat seen by how many buyers resist any electronic interventions at this point now and swear to continue to, until there is no choice left.
We know a tuner can compensate well with carb adjustments for most mods in rudimentary ways - but my curiosity remains at just how good or how far something like an M-Tronic module can mimic or even improve on that to adjust the carb not only to outside operational parameters - but especially in this case, internal or modified parts that certainly change the saw's 'personality' and run safety factors.
I'm sure that in the case of a C-M version, the factory full well knows - but you'd never get that part of the story..
 

Offline woodsdog2015

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Re: Muffler mods
« Reply #21 on: April 06, 2018, 11:14:31 AM »
My original concern is for the condition and longevity of the saw.  If you use a modified muffler and it isn't completely crazy, will these mods hurt or help the long term use of the saw?  I heard Stihl does make a tuned muffler but my dealer said it would be about $136 USD and he didn't feel the cost would warrant the moderate gain in performance.  My dealer does not like muffler mods and feels that they will eventually burn the saws up quicker then using a stock muffler engineered specifically for your model saw.  
I'd rather be in the woods.
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Offline realzed

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Re: Muffler mods
« Reply #22 on: April 06, 2018, 12:24:57 PM »
I concur with the long term part of what you said fully!
Interesting that Stihl offers another muffler as an alternative - never heard that - but I guess it does to a point suggest there is more in many of these saws considering all, to be brought out if the wish is there..
I'm sure you could get many who might chime in on the dealer's take on the reliability aspect of muffler mods being detrimental to saws in the long run considering how long many may have had modified ones working for them - but when done by often different methods and ways, I'm sure the variables mean there will be a lot of different long term results as well.. which is exactly why we both are seeking the same type of info I guess..  
Thanks - Randy

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Re: Muffler mods
« Reply #23 on: April 06, 2018, 01:32:43 PM »
Yep Stihl does offer a dual outlet muffler, well here in Canada anyways.
A couple of years ago I bought a brand new Magnum dual outlet front cover for my 066 from Stihl Canada. The old cover was all banged up from a quarter of a century of use :laugh:

But in the US in early 1995 OHSA forced the discontinuation of the dual outlet muffler. I believe the 046 Magnum was effected too.


 

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Offline mike_belben

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Re: Muffler mods
« Reply #24 on: April 06, 2018, 09:52:31 PM »
A hot jug is the most detrimental thing you can do to a chainsaw.  Many ways to get it but they all result in scoring,  aluminum transfer from piston to jug, and a bound up ring land.  

Get your IR temp guns out.  A muffler mod expels hot gas quicker, thus standing temps will drop from the muffler mod.  This is always to the saws benefit in terms of life span.  It means that the threshold of melting a piston has a little more buffer under all conditions.  

 Naturally, a number of muffler modded saws will be burned up at the hands of oblivious operators and the muffler will be wrongly convicted for it in the operators ignorance.   Thats just life.  
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Offline Al_Smith

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Re: Muffler mods
« Reply #25 on: April 06, 2018, 10:22:29 PM »
I acquired a Stihl 024 from a dealers dead pile that wasn't dead .Evidently the owner sent it in for repairs and they found a scalded piston and sold him another saw .These plus the 026 models had three different mufflers and this one was the most restrictive .All I did was gut the muffler and rebuild the carb,never did a thing to the piston .It has ran flawlessly ,toasty piston and all .So in so many word what I'm saying if you know what you are doing you're not going to ruin a saw by altering the muffler .Further more a Stihl dealer by franchise rules is not allowed to alter a saw in any way including the muffler .Oh before I forget,I run it on 32 to 1 mix ratio . 8) <I just had to throw  that in.

Offline woodsdog2015

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Re: Muffler mods
« Reply #26 on: April 08, 2018, 01:44:41 AM »
Thanks fellas sounds like most feel that the saws will run better and cooler with a reasonable muffler mod.
I'd rather be in the woods.
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Offline wild262

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Re: Muffler mods
« Reply #27 on: April 08, 2018, 09:46:07 AM »
Thanks fellas sounds like most feel that the saws will run better and cooler with a reasonable muffler mod.

               It absolutely does in my opinion.  Downside is more noise sometimes.  As was said, the extra heat is what  is detrimental to the saw, esp. when using in summer months.  Some will argue, but to each his own. ;)

Offline Bandmill Bandit

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Re: Muffler mods
« Reply #28 on: April 08, 2018, 10:29:04 AM »
Used to be saw engines were fairly decent out of the box and I still did mods because having raced snowmobiles you just have the know how to get them running BETTER! BUT now they require a near tear down and rework just to get them to idle decent never mind perform any where near the theoretical maximum. Any thing with a new 2 cycle hits the bench for a rip down and rework before I ever pull the cord. I even swapped the carbs on my most recent saw and blower to new "older model" carbs that you can actually adjust properly before I put gas in the tank the first time.

Mufflers get reworked and I adjust the exit orifice size to achieve best back pressure too. Its a real PITA but well worth it.        
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Re: Muffler mods
« Reply #29 on: April 08, 2018, 11:39:06 AM »
Thanks fellas sounds like most feel that the saws will run better and cooler with a reasonable muffler mod.

               It absolutely does in my opinion.  Downside is more noise sometimes.  As was said, the extra heat is what  is detrimental to the saw, esp. when using in summer months.  Some will argue, but to each his own. ;)
Yes they absolutely last longer. :)
As I showed before my 27 year old 066Mag that I just rebuilt recently for the first time still has lots of life in the piston/cylinder.  Only had to replace a loose PTO bearing.
Thanks to its factory installed dual outlet muffler long before EPA and OSHA they built the saws to last.


 

 

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Offline Woodcutter_Mo

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Re: Muffler mods
« Reply #30 on: April 08, 2018, 11:57:06 AM »
 Here's the muffler mods I did on my 455, I drilled a hole in the side and made a weld on deflector and have added a spark arrester as well. The saw is a little louder but not by too much, actually similar to my stock 372xp. After the 372xp's warranty is over it will get some muffler work as well as my 550xp.

- WoodMizer LT25, Kohler, all manual, old "drag" style WoodMizer sharpener, cat claw single  setter
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Offline teakwood

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Re: Muffler mods
« Reply #31 on: April 08, 2018, 12:03:19 PM »
Thanks fellas sounds like most feel that the saws will run better and cooler with a reasonable muffler mod.

               It absolutely does in my opinion.  Downside is more noise sometimes.  As was said, the extra heat is what  is detrimental to the saw, esp. when using in summer months.  Some will argue, but to each his own. ;)
X2 and what you guys call summer months for us its 12 month per year and ad 20%.
Now its 27 degrees in the morning and 34 after mid day. Just nasty  
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Offline wild262

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Re: Muffler mods
« Reply #32 on: April 08, 2018, 12:52:41 PM »
Thanks fellas sounds like most feel that the saws will run better and cooler with a reasonable muffler mod.

               It absolutely does in my opinion.  Downside is more noise sometimes.  As was said, the extra heat is what  is detrimental to the saw, esp. when using in summer months.  Some will argue, but to each his own. ;)
X2 and what you guys call summer months for us its 12 month per year and ad 20%.
Now its 27 degrees in the morning and 34 after mid day. Just nasty  

    I actually prefer to cut in cooler months or early spring.  Gives the wood time to season some, no humidity to deal with, and no bugs, ticks, poison to deal with.  I'm actually burning 2 wood stoves as we speak here in NE Missouri.  Winter keeps dragging on.  Just bought a new Echo 360P, but I doubt I will wait till the 5 yr. warantee is up before I muffler mod it and adjust to 40:1.   Its very restrictive.

Offline moodnacreek

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Re: Muffler mods
« Reply #33 on: April 08, 2018, 05:07:26 PM »
Put a high compression piston in a 261 epa husky. That gave it considerably more torque. Then I put the xp muffler on and that increased the acceleration.

Offline woodsdog2015

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Re: Muffler mods
« Reply #34 on: April 08, 2018, 05:53:13 PM »
Now you’re the second person in this thread to mention not only modifying the muffler but also switching to a less lean oil to gas mixture. Specifically 40:1 gas/oil mix instead of the factory 50:1 mix. What is the reason for that? Again, my concern and issue is for saw life not speed or saw testing. Also can advertised “test mufflers” be used for wood cutting and timbering operations? It appears that the model I’m interested in is always publicized as a test muffler only not for wood cutting but why would you invest in these mufflers just for saw testing purposes? The other thing I heard is that the stock mufflers ensure greater torque than speed and this is more important than speed in  the wood cutters world, all else being equal.
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Offline woodsdog2015

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Re: Muffler mods
« Reply #35 on: April 08, 2018, 05:59:13 PM »
Btw, I too prefer to cut now while I can see everything in the woods and  you can work like a bull and stay relatively cool with no bugs etc. to me this is prime time for wood cutting.
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Offline wild262

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Re: Muffler mods
« Reply #36 on: April 08, 2018, 07:52:07 PM »
Now you’re the second person in this thread to mention not only modifying the muffler but also switching to a less lean oil to gas mixture. Specifically 40:1 gas/oil mix instead of the factory 50:1 mix. What is the reason for that? Again, my concern and issue is for saw life not speed or saw testing. Also can advertised “test mufflers” be used for wood cutting and timbering operations? It appears that the model I’m interested in is always publicized as a test muffler only not for wood cutting but why would you invest in these mufflers just for saw testing purposes? The other thing I heard is that the stock mufflers ensure greater torque than speed and this is more important than speed in  the wood cutters world, all else being equal.
I don't know if your referring to me or not.  And I certainly don't want to hijack this tread with the "mixture" debate, but yes I do prefer 40:1 or more oil.  If I am milling, it gets dropped to 32:1. That milling puts a lot of stress on them.  But those days are pretty much over for me.   I've been inside lots of saws over the years and have seen several bottom end failures with bearings and such ran on 50:1.  Not saying that was the cause, but the saws I have been into that were ran with 32 & 40 to 1, had more oil film coating on the lower internals, and they were in the shop for new top ends.  That's just my observation.  Thus that's why I now run 40:1 in all my 2-stokes.  The 50:1 was mostly a EPA thing as I understand it in order for the saws to make the feds happy.  If you have been running the leaner mix, then stick with what works for you. :)

Offline Rebarb

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Re: Muffler mods
« Reply #37 on: April 08, 2018, 10:00:52 PM »
My muffler modded saws cut wood more efficiently and they run cooler.
I also run 40:1 in all my saws.

Offline teakwood

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Re: Muffler mods
« Reply #38 on: April 09, 2018, 07:50:32 AM »
I have always run 50:1 with stihl oil, first the orange jugs and since 2 years the semi synthetic stihl oil. never ever had a scored piston and i did hundreds of hours of chain saw milling in tropical hardwood in very hot temps with a 088.  
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Offline Drifter27

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Re: Muffler mods
« Reply #39 on: April 09, 2018, 11:10:46 PM »
I'd like to hear about this also. I don't have the experience a lot of people here do but I've always thought muff mods keep saws cooler and that's good for everything

Offline woodsdog2015

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Re: Muffler mods
« Reply #40 on: April 10, 2018, 12:30:11 PM »
Thanks fellas sounds like most feel that the saws will run better and cooler with a reasonable muffler mod.

               It absolutely does in my opinion.  Downside is more noise sometimes.  As was said, the extra heat is what  is detrimental to the saw, esp. when using in summer months.  Some will argue, but to each his own. ;)
Yes they absolutely last longer. :)
As I showed before my 27 year old 066Mag that I just rebuilt recently for the first time still has lots of life in the piston/cylinder.  Only had to replace a loose PTO bearing.
Thanks to its factory installed dual outlet muffler long before EPA and OSHA they built the saws to last.

(Image hidden from quote, click to view.)
 
(Image hidden from quote, click to view.)
 
(Image hidden from quote, click to view.)

Holmen Tree, did you adjust the carb when you utilized the dual ported muffler so that the saw wouldn't run leaner and thereby have concerns about frying the piston and cylinder or was this all set from the factory?  It appears that most here enjoy the muffler mod but also do something on the other end, like switch to a less lean oil to gas ratio etc.  I guess I'm wondering if I purchase a muffler for my saw, they call them "test" mufflers, and do nothing to the carb or continue to use the factory 50:1 fuel to oil mixture ratio, will that be detrimental to my saw just by opening up the muffler.  The stock MS 362C muffler is just an open can with no baffle in it whatsoever so just adding a couple of more holes doesn't seem like it would lean the fuel mixture too much would it????    I'm throwing all of these scenarios out there sorry fellas.
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Offline HolmenTree

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Re: Muffler mods
« Reply #41 on: April 10, 2018, 01:07:09 PM »
Woodsdog, yes my 066 mag with dual outlet muffler came from the factory that way and from my information it also came with carb jetted richer.
To be honest I have no plans to do a muffler mod to my new MS261CM. I do residential tree removal and I think the extra noise would only be  detrimental to my business.
Out in the wilderness make all the noise you want.

Earliest Stihl factory dual outlet mufflers I can remember was an option for the 038 Magnum around 1985. But the 038 Super around 1983 may have got them first in the PNW.
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Offline mike_belben

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Re: Muffler mods
« Reply #42 on: April 10, 2018, 01:52:05 PM »
Fellas, a 2 stroke's lifespan is heavily correlated to being tuned correctly for the current operating condition.  There is no set it and forget it in a saw thats used in both summer and winter.  Every 10 or 15* temperature change really does need a little turn on the screws to run optimally.  Maybe a 70cc saw isnt too noticeable but on a tophandle you cant miss it. Theyre way down on power if out by 1/2 turn. 


 If tweaking screws isnt your bag then the Mtronic stuff may be the ticket for ya. 
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Re: Muffler mods
« Reply #43 on: April 10, 2018, 02:06:44 PM »
Some of my saws lose that sweet spot at WOT with just a 10th of a turn on H.
Up here in the great white north, temperatures can vary big time. Go from 40 below and a few months later 110 above.
Cold temps needs the carb to be richer if set with summer adjustments. 
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Offline woodsdog2015

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Re: Muffler mods
« Reply #44 on: April 10, 2018, 04:35:53 PM »
Woodsdog, yes my 066 mag with dual outlet muffler came from the factory that way and from my information it also came with carb jetted richer.
To be honest I have no plans to do a muffler mod to my new MS261CM. I do residential tree removal and I think the extra noise would only be  detrimental to my business.
Out in the wilderness make all the noise you want.

Earliest Stihl factory dual outlet mufflers I can remember was an option for the 038 Magnum around 1985. But the 038 Super around 1983 may have got them first in the PNW.
I believe I'm going to leave mine well enough alone too.  On another subject, and this is for anyone.  Does anyone know where I can get a full service manual for my Stihl Saws.  I did a quick google check and one popped up for the MS 362 and 362C (which is my saw) and it says 2010-9 so I'm assuming it was put out that year?  Is there anything a little newer?  My saw I believe was Manufactured in 2012 (I think) even though I bought it new in late 2015.  
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Offline Al_Smith

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Re: Muffler mods
« Reply #45 on: April 10, 2018, 07:06:36 PM »
I've never tried but I think you can get them through Stihl .Might just be the operators/ users  manual though come to think about it .If not you might be able to find one on flea bay .

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Re: Muffler mods
« Reply #46 on: April 11, 2018, 04:12:17 PM »
Thanks Al yeah I do have the owners manual but I'm talking about the actual service manuals?  I find them very useful for saw maintenance and what not, I have one for my four wheeler and truck too and they have saved me a little $$$ along the way.  Plus, I'm just interested in them.  
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Offline Al_Smith

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Re: Muffler mods
« Reply #47 on: April 11, 2018, 05:30:22 PM »
I don't have the new service manuals because the newest Stihl I have is a pair of MS 200T's .I do however have the older  manuals on micro fitche and the parts lists in a big dealers book that must weigh 10 pounds .
Being somewhat of a collector of a number of things i have a library of service manuals covering everything from chainsaws to Bridgeport Milling machines .They are where you find them is all I can say .

Offline thedoublejranch

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Re: Muffler mods
« Reply #48 on: April 15, 2018, 12:36:48 AM »
You have to be careful, back-pressure actually aids a 2 stroke. So much un-burnt fuel escapes, and a backpressure pushes it back into the cylinder to be burnt. This is the principle in which an expansion chamber uses, the pulses reflecting back pushes un-burnt fuel back into the cylinder, creates a natural supercharging affect. Of course, our saws do not use this expansion chamber (I know hot saws do) and a little in moderation will help, but there is a point of diminishing returns ie power and also fuel consumption. So start with baby steps.

Normal soot and carbon can restrict it over time, boiling hot water clears the carbon/soot right off and a spark arrestor screen too
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Re: Muffler mods
« Reply #49 on: April 15, 2018, 11:29:54 AM »
Wow, what an outstanding thread. I've been inside many, many saws. Very few echos, mostly stihl, husqy, and not quite as many Jonsered. Every one of you guys display acute knowledge of chainsaws and what impresses me is it's practical, applicable knowledge. I have grown accustomed to muffler modifications in conjunction with ten thousands squeeze on the jug. Running the 40:1 mix has proven to be the best mix ratio for me. I should also touch on this point, fresh air as well as vaporized gas runs faster and cooler over polished portals. Oh, please forgive me I started rambling on. My intentions were simply to compliment all of the knowledgeable people who submitted posts to this thread.

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Re: Muffler mods
« Reply #50 on: April 15, 2018, 11:42:33 AM »
Also, my 064 was manufactured in '92. With the muffler modifications and squeeze on the jug it provided over two decades of service before I restored the saw. I consider that to be proven longevity in the field... which is one of our goal as cutters of wood.

Offline HolmenTree

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Re: Muffler mods
« Reply #51 on: April 15, 2018, 12:45:53 PM »
Knuckledragger,  yep my 066mag manufactured in 1991 came from the factory with a dual outlet muffler,  and I do credit its longevity for maybe staying a little cooler.
But I think the main reason was to get the 066's h.p.up to compete with the Husqvarna 394XP.

There is debate on polishing ports. It is a fact that some high performance saws have roughed up surfaces and even screen material inside of intake manifolds to mix up the fuel mix charge a little better.  Even debate on polishing exhaust ports.
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Offline knuckledragger

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Re: Muffler mods
« Reply #52 on: April 15, 2018, 01:21:20 PM »
Holmentree, I'm aware of different thinking on port polishing. I'm also a believer that what may work very well for one doesn't necessarily mean it will work for another. Stihl has a rough intake, I understand why. That only leaves the exhaust. Couple that with muffler modifications, and proper octane, mix ratio, fresh gas and there you go. A066 that provided 27yrs a 064 that provided 25yrs of service. Now then, all of my husqy saws, personal saws, have the intakes polished slick as glass. I will look at the intake about every twenty five hours of run time. The point of muffler modification is to me pointless if other steps aren't taken to facilitate and optimize said modification. Fraunk-n-Steen saws don't receive this type of attention because as a gift most are not appreciated like one that has been purchased with hard earned cash. I know that going in. This thread has become rather in-depth from a seemingly simple subject" muffler mods". In my opinion if one intends to modify the muffler on their saw they should have a direction, a plan so to speak, because like this thread it's really not as simple as it may appear.

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Re: Muffler mods
« Reply #53 on: April 15, 2018, 01:53:46 PM »
Good post knuckledragger, 
That's why I threw in the polishing comment. Like you said lots of variables, throw a tuned exhaust pipe on that saw and you have another whole different scenario with porting.
My 066 factory dual outlet muffler is loud and the saw  performs very well. But there is still a baffle inside the muffler over the cylinders exhaust port, combination is matched for the capacity of the carb.
I left that baffle in and kept the saw stock with no modifications, this very early S code 066 with it's strong port timing ,thin rings etc. was all I needed for what I was doing with  28" b/c. 
She's a keeper too. :)
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Offline knuckledragger

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Re: Muffler mods
« Reply #54 on: April 15, 2018, 06:01:20 PM »
I'm not sure why I never purchased the 066. Hind sight being 20/20 I now believe I should have, but I have way too many saws as it is. I wasn't aware that stihl employed you. Not that I ever doubted your knowledge holmentree, it was easy enough for me to know you had vast amounts. The stihl thing makes everything come to light. Exceptional picture btw.

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Re: Muffler mods
« Reply #55 on: April 15, 2018, 06:29:59 PM »
I didn't stay with Stihl long though, big city and rush hours to the office wasn't my thing. But I did do field testing for them after when I got back into the woods.
Making a living with a saw since age 16.

Offline Al_Smith

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Re: Muffler mods
« Reply #56 on: April 15, 2018, 08:05:56 PM »
The back pressure or what might seem to be from a pressure can muffler doesn't really back charge like a tuned expansion chamber .Once the muffler pressure equals the outgoing transfer charge coming up on compression the flow stops .It's just about like shutting a valve .Some pressure build up is good because of both crankcase volume and carb size of a chainsaw as oppossed to say a dirt bike .
The reason old kart engines could run on huge megaphone exhausts was because they often had multiple carbs ,very large ones at that .If you megaphoned the average chainsaw engine you'd over run the carb at some point .Not to mention blowing your eardrums out .They most likely would not idle very well either if at all .

Offline mike_belben

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Re: Muffler mods
« Reply #57 on: April 15, 2018, 11:02:23 PM »
A rough, dimpled or screened intake conduit will have more surface area for liquid fuel droplets clung to the walls, to mate with air molecules passing by.  These points will wick fuel onto them.    However in a two stroke it wont matter nearly as much as say, a fuel injected 4 stroke, because there is plenty of time for mixing.  The charge goes into the crankcase then through the transfers so the travel path is very long and turbulence is high.  On the 4 stroke, injectors are typically spray right at the back of the intake valve so there is very little time for atomization. 


I agree with AL on the can muffler back pressure.. A little pressure will help prevent all the intake charge from flying out the exh @ blowdown but a lot is going to limit the saws ability to pump air out, which will translate into high frictional horsepower.  FHP is subtracted from BHP so youd be down on power output from too much backpressure.

  As for tuned pipes pushing charge back in, i dunno.  Im having a hard time with that.   Ive long been under the impression that Inert, spent gas always contaminates a fuel charge and cools peak cylinder temp which means less cylinder pressure, thus less torque.  Manufacturers use the cooling effect of EGR to get temps down and dial in nox emmissions.  It always seems to cost power.

Conversely, a negative pressure wave vaccuums everything out of a cylinder, both spent and fresh gasses.  This scavenging effect always makes additional power by removing the inert gasses that limit cylinder pressure.  I know this is the case on 4 strokes making power by exh length tuning, negative pressure wave rarefraction travels back up to the port, caused from sound wave exiting the tailpipe.  P.H. Smith wrote a book full of pressure graphs from a machine that could look at exh pressure by crank angle.  I have it somewhere but its been almost 20 yrs, i dont recall if it covered 2 strokes.   

I have to wonder why dirtbike pipes arent glowing cherry red on every straightaway if theyre feeding that much fuel into the pipe.  Surely it would burn in there.. The pipe is beyond the fuel's auto ignition temp, no?
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