Stihl ms261 muffler mod??

[Stihlproincky]

Hi all, I posted this in the modded work saws, dunno if it's something I said or what but I never got replies.
So the question is do the 261's benefit from muffler mod's??
Not in to porting yet just looking for advice on muffler mods.
Thanks in advance.

 

[Stihlproincky]

By the way this saw has been burnt up so I'm rebuilding it, its also a m-tronic if that matters.

 

[J D]

Just about any saw will benefit from a muffler mod... the degree depends on where the most significant restriction to air flow is. M-tronic shouldn't make a difference if you dont go opening it up massively.
Be sure to vac/pressure test the saw when you've fixed it

 

[ace4059]

Not sure how much it helped my saw but I added the “WCS universal power port” which is just a universal deflector that you screw into your muffler after cutting a hole in the muffler.
I couldn’t tell large gains.

Maybe someone else will chime in.

 

[J D]

If nothing else it will help get heat out of the saw

 

[Stihlproincky]

If nothing else it will help get heat out of the saw

Exactly, this saw belongs to the neighbor my concern is to keep it as cool as possible to hopefully help offset him running it dull=hot. I understand this won't fix negligence but I have to be respectful.
My personal saws have muffler mods and copper cooling plates.

 

[singinwoodwackr]

Hi all, I posted this in the modded work saws, dunno if it's something I said or what but I never got replies.
So the question is do the 261's benefit from muffler mod's??
Not in to porting yet just looking for advice on muffler mods.
Thanks in advance.

I’ve done a half doz of them. Big gains? Nope, but definitely better than stock. I usually shoot for 80% of the exhaust port itself for “opening up” a muffler. Either expand the stock hole or add a dual port. Go too far and you’ll lose torque.

 

[Sidecarflip]

Even my ancient 028 got it's muff opened up a bit with my trusty Dremel.... Long time ago.

 

[LuDookie]

261’s have a pretty open muffler. Mine did. I’ve done several muffler mods on saws and saw nothing improve on less open saws than a 261, while other saws very much need it. I’d leave it alone.

 

[Sidecarflip]

Both my Echo's got the muff treatment and the Timber Bear got a whole lot more.. Dang Timber Bear sound like a Motocross bike now... Real deep exhaust note, not at all unpleasant.

 

[WI_Hedgehog]

My understanding is opening the muffler to 80% & advancing the timing work together, one without the other doesn't help much, and how much it helps depends on how restricted and timing retarded the saw is. You might want to find information from a builder like @huskihl using Search regarding advancing the timing and opening the muffler.

EDIT: See @huskihl's post below.

 

[huskihl]

My understanding is opening the muffler to 80% & advancing the timing work together, one without the other doesn't help much, and how much it helps depends on how restricted and timing retarded the saw is. You might want to find information from a builder like @huskihl using Search.

80% is a wive’s tale, a guess, as every saw is different. Some are still narrower ported (because of skirt width or flange thickness limitations) than others are stock. In that case, 100-150?% is probably more beneficial.

Hp continues to go up with less restriction until 150-175%. Forgiveness on the dogs (perceived as torque) goes down the bigger you go. It’s all a trade off, gaining in one area without giving up too much in another.

Timing advance is completely separate and the 2 are not related nor required for one another. Advancing timing (if the stock ignition timing allows it) adds torque which usually results in more cutting rpm in a work saw setting. It usually hampers unloaded rpm or high rpm with light work conditions like limbing or possibly in a race saw application. Some saws love 10-12° of advance and some need retarded 5° from stock in order to allow them to rev. So the only “rule” is if you never try, you never learn

 

[guym3]

Good advice from Huskihl. I opened my 261 to 80% and got an 8% speed up on cutting speed. Yes feels better to use but not much change.
Porting it however made it a new saw.

 

[singinwoodwackr]

80% is a wive’s tale, a guess, as every saw is different. Some are still narrower ported (because of skirt width or flange thickness limitations) than others are stock. In that case, 100-150?% is probably more beneficial.

Hp continues to go up with less restriction until 150-175%. Forgiveness on the dogs (perceived as torque) goes down the bigger you go. It’s all a trade off, gaining in one area without giving up too much in another.

Timing advance is completely separate and the 2 are not related nor required for one another. Advancing timing (if the stock ignition timing allows it) adds torque which usually results in more cutting rpm in a work saw setting. It usually hampers unloaded rpm or high rpm with light work conditions like limbing or possibly in a race saw application. Some saws love 10-12° of advance and some need retarded 5° from stock in order to allow them to rev. So the only “rule” is if you never try, you never learn

Interesting. Many years ago I played with opening my already dual port muffler on my 066 RE. I got improvements up to a point and then lost power. That’s where my 80% has come from.
My guess is that there is really no set percentage for all saws.

 

[WI_Hedgehog]

80% is a wive’s tale, a guess, as every saw is different. Some are still narrower ported (because of skirt width or flange thickness limitations) than others are stock. In that case, 100-150?% is probably more beneficial.

Hp continues to go up with less restriction until 150-175%. Forgiveness on the dogs (perceived as torque) goes down the bigger you go. It’s all a trade off, gaining in one area without giving up too much in another.

Timing advance is completely separate and the 2 are not related nor required for one another. Advancing timing (if the stock ignition timing allows it) adds torque which usually results in more cutting rpm in a work saw setting. It usually hampers unloaded rpm or high rpm with light work conditions like limbing or possibly in a race saw application. Some saws love 10-12° of advance and some need retarded 5° from stock in order to allow them to rev. So the only “rule” is if you never try, you never learn

Thank you! That explains what I'm experiencing and corrects my misunderstanding.

 

[JoeMay]

Just received this brand new Dolkita 7300 this month. The box and stickers verify made in Germany 2021. I was astounded how easy the cat was to remove once the muffler halves were separated. It simply slid right out. No cutting or drilling. I have a Dolmar PS 421 that took significant effort with various tools to remove the cat.

 

[Stihlproincky]

Just received this brand new Dolkita 7300 this month. The box and stickers verify made in Germany 2021. I was astounded how easy the cat was to remove once the muffler halves were separated. It simply slid right out. No cutting or drilling. I have a Dolmar PS 421 that took significant effort with various tools to remove the cat.

Yeah those mufflers are a PITA
I did a stihl once but the cage had broke loose already that's why I look it out.

 

[J D]

Just received this brand new Dolkita 7300 this month. The box and stickers verify made in Germany 2021. I was astounded how easy the cat was to remove once the muffler halves were separated. It simply slid right out. No cutting or drilling. I have a Dolmar PS 421 that took significant effort with various tools to remove the cat.

Did you put spacers in to take up the gap that flange left? I would be concerned the muffler would crack or deform around the mounting points if the bolts weren't on something solid all the way through

 

[JoeMay]

The spacers will definitely go back in during reassembly. I will likely have to salvage a chunk of that cat’s bulkhead to close any gap that will result. Still a lot easier than that PS 421 muffler mod.

 

[huskihl]

Just received this brand new Dolkita 7300 this month. The box and stickers verify made in Germany 2021. I was astounded how easy the cat was to remove once the muffler halves were separated. It simply slid right out. No cutting or drilling. I have a Dolmar PS 421 that took significant effort with various tools to remove the cat.

That was easy because it’s the SLR tube from the 7300 and 7900. You’ll want the spacer as soon as you can.

The 6400 has the Cat muffler