Lakeside53's --361 muffler mod w/photos

[timberwolf]

No harm in leaving existing outlet. Yes, you can clean the muffler screen with a brush, but if it's welded in it's not easy to replace without cutting and redoing the work.

 

[Darton2]

OK - I have searched and read abunch trying to figure out what the best size hole to open my 2171 muffler up too. I have seen the 80-85% rule but allot of guys put the double barrel 3/4 pipe or double barrel 1/2" pip coming out. Both are way more than that rule.

Who has done the modification and is happy with it on the 372 or 2171? What size did you end up with?

I have a 6 month old saw that needs to breathe better but dont want to screw it up. Some guys mention that the saw doesnt idle well after the mod, I assume thats from going too far with the mod. Any advice?
:deadhorse:

 

[timberwolf]

Even on a bone stock 026 two 1/2 inch pipes will be fine. Problems start when the total area of the outlet is over about 125% of the exhaust port area measured at the port.

I have saws here that will run fine with 150 to 200%. It ok if you are after every last bit of power, but it's stupid loud and hard on fuel.

That said, it easer to make a hole bigger than smaller, and most of the gains will be found in the first 75% increase in area after that it's a dimminishing return.

 

[K9-Handler]

Shrek -- another version of a 7900 muff

This is my version of the double-barrel mod shown in the beginning of the thread. It is for my Makita 6400/7900BB project.

I call this muff "Shrek". Do I need to explain farther? :hmm3grin2orange:

On the saw:

 

[AR200]

I got my muffler mod done last night. The saw is a Jonsered 630 I left the existing port in the muffler and added this 5/8" dia hole. I ran it in some small stuff last night but can't wait till this weekend to put it in some bigger stuff to see if it made much difference.

[/IMG]

[/IMG]

 

[(WLL)]

This is my version of the double-barrel mod shown in the beginning of the thread. It is for my Makita 6400/7900BB project.

I call this muff "Shrek". Do I need to explain farther? :hmm3grin2orange:

On the saw:

looks like the port is blowing right on the cutter hand

 

[JONSEREDFAN6069]

I got my muffler mod done last night. The saw is a Jonsered 630 I left the existing port in the muffler and added this 5/8" dia hole. I ran it in some small stuff last night but can't wait till this weekend to put it in some bigger stuff to see if it made much difference.

[/IMG]

[/IMG]

LOOKS GR8!!! what'd you use for screen?

 

[K9-Handler]

looks like the port is blowing right on the cutter hand

It's not. Just a camera lens anomaly. The handle is well behind the exhaust flow (or at least half of it)! :hmm3grin2orange:

 

[moose42]

Well after reading all 18 pages of this thread I just had to go and do it to my saw. I decided to do it to my Stihl 064. The muffler was simple and seemed like the perfect choice. I started by opening the hole from a small half inch hole to about 3/4. I left the stock diverter on at first to see if there was much of a difference. WOW! After some test run (and re-tune) it ran awsome. I knew I had to make it just a bit better. So I took the stock diverter off (that stupid angle piece on the outside) so I can put a pipe on it. I went with a 3/4" conduit coupler. I cut an angle on it and then matched the hole to fit the oval. I didn't go all the way because the part that holds the screen gets in the way. I just welded the coupler on and then cleaned up the welds. The only thing I did the cage on the inside was drill 2 1/2" holes in the front. Gave it another re-tune and gave it a test. The saw is louder and a nice deep tone. The power increase is well worth the time and effort.

 

[820wards]

ok to be honest I haven't looked to find spark aresting mesh..thought it would be easier just to ask the people that know what they are doin...so..where do you find this stuff???

I like your Wildthang...

Here is mine.

.17 Ackley Bee

jerry-

 

[K9-Handler]

Big pipe

so I can put a pipe on it. I went with a 3/4" conduit coupler.

Are you sure the Public Works Department isn't going to miss that piece of culvert pipe??? :hmm3grin2orange: :hmm3grin2orange: :hmm3grin2orange:

 

[moose42]

It's not all about the size of the pipe that matters, it is how well it works for ya!

 

[AR200]

LOOKS GR8!!! what'd you use for screen?

Just some stainles steel screen we had laying around at work. I think we get it from mcmastercarr.

 

[JONSEREDFAN6069]

SOME PICS OF THE 630 MOD, JUST FINISHED TONITE

[/IMG][/IMG]

 

[biggenius29]

I just took my muffler of my 460 to do the mod. Do I drill out a hole in the cover of the muffler, or do I widen the side by the spark arrestor? I think it would be easyer to drill out the cover instead of the side of the muffler.

 

[windthrown]

Why are you modding a 460? You can go buy a dual port muffler cover from Stihl for that for about $30. Part number 1128 140 0801.

 

[mole1982]

What size hole do I drill in the muffler 1/2, or 5/8.

 

[Lakeside53]

Neither... drilled holes are round; you read the thread and it will tell you to trace around the angled pipe - a weighted oval....

 

[windthrown]

Neither... drilled holes are round; you read the thread and it will tell you to trace around the angled pipe - a weighted oval....

But but but... where can I get a drill bit to cut an oval? Madsons? Harbor Freight? Does Stihl make one? :greenchainsaw:

 

[weimedog]

The one thing I see in these mods is emphasis on reduction of back pressure. Coming from the motorcycle world..and having tweaked, tuned, and raced motorcycles since the 1970's...I wonder if anyone has done research past less flow restriction and towards tuned mods. I realize expansion chambers are not practical but maybe improvements in other ways...maybe length of pipe or increased volume within practical limits. Possibly working the location of exhaust exit along with different length pipes to effect actual "tune". I think the newer Strato or X-Torq designs will require thought in that area from what I understand about their theory of operation.