porting Stihl 361 pros and cons

[smith2bj]

What are the pros and cons of porting the muffiler on a Stihl 361?  And does it really give the saw that much more power?

[Troutfisher]

The pros would be a gain in performance, maybe 10% or so, and it will get rid of some heat. Some Cons would be more noise, it will get louder. you will have to re-tune the carb, and It may use a bit more fuel.

[Troutfisher]

I have before and after videos of a muffler mod on a MS361 on --Photos MUST be in the Forestry Forum gallery!!!!!--, I would link them, but can't figure out how

[smith2bj]

Does it hurt the longevity of the motor though?   I don't want to have to rebuild the motor every 5 to 10 years.

[Rocky_J]

All the EPA regulations requiring saw makers to make the saws run super lean with ultra high exhaust temps will make the saws last forever. Removing those exhaust restrictions and providing the saw with adequate fuel and lubrication will cause the saw to burn up quicker. 

[chevytaHOE5674]

If the carb is retuned it should not hurt the longevity of the motor, in fact the longevity should be increased. The saw is able to breath easier, and run cooler. All of my saws have ported mufflers and I have no problems with longevity.

All the EPA regulations requiring saw makers to make the saws run super lean with ultra high exhaust temps will make the saws last forever. Removing those exhaust restrictions and providing the saw with adequate fuel and lubrication will cause the saw to burn up quicker. 

Hahaha.

[Troutfisher]

My opinion is that a muffler mod will increase the life of the saw, it gets rid of a lot of heat.

[Preston]

I would have to agree al my saws have been ported and I've been doing it for 11 years.

[smith2bj]

Now is this something that I could do my self, have a friend who is good with motors or send it out to someone who is a professional with this?
What am I looking at for a cost and will I notice that much of a difference?

[Troutfisher]

It's pretty easy to do, as long as you're OK with a little welding or brazing, and know how to adjust a carb. Do a Google search, there's lots of info out there.

[Rocky_J]

Welding and brazing are unneccessary IMO. I own a half dozen engine ported saws, all with muffler mods as part of the deal, and only one of them has the stupid little pipe brazed in place. And it's the worst performing of the bunch!

A dremel tool and some thought is usually about all you need. Simply make the existing exhaust opening bigger and remove the internal baffles out of the muffler. A motor is nothing more than an air pump. Unplug the exit so it can pump more air.

[chevytaHOE5674]

remove the internal baffles out of the muffler.

The 361 muffler is not two pieces like many others. So to open up the internal baffles you need to uncrimp and recrimp, and IMO braze it back together.

And to get enough port opening area in the 361 muffler it needs another port added.

[Cut4fun]

I had a 361 once with just 3  holes drilled in the front and the spark arrestor removed. The cage was still intact inside the muffler. Simple redneck mod.
This saw to date has still been the strongest running STOCK 361 I have ran to date.
I have ran several different ones with goofy little pipes with screens sticking out of them etc and it is really not needed IMO, just overkill.
Another easy 361 muffler mod without splitting the muffler (the cage inside the muffler of the 361 seems to flow pretty good with a stock saw), is a dime size hole or tad bigger on the left side (opposite of the other exhaust port) and screw a husky 288 deflector on it. So easy I call it Caveman muffler modding.

[chevytaHOE5674]

If your cutting in dry conditions, or on most state and all federal lands you need a spark arrestor.

[Rocky_J]

Yup. Which means you need to figure out how to put a piece of screen over the hole. Not a big deal unless you get all fancy complicated and try welding a pipe into the muffler can. 

[Al_Smith]

only one of them has the stupid little pipe brazed in place. And it's the worst performing of the bunch!

  

Some people think they look cool but I suppose those same folks like flame decals also . Neither one does a thing to make the saw run better .

Strange how many folks get sucked into buying  a cobbled up muffler thinking it will turn their stock saw into a screamin meany and all it does it make it loud .  

[chevytaHOE5674]

Strange how many folks get sucked into buying  a cobbled up muffler thinking it will turn their stock saw into a screamin meany and all it does it make it loud . 

I have a port on the opposite side of the muffler as the stock port. I used a piece of pipe with a spark screen from a BR400 backpack blower. The port went from ~64 mm^2 to 140 mm^2. Using timed cuts the saw IS faster than stock. Using an infrared heat gun the temps of the muffler and jug were also reduced. It is in no way cobbled together and in fact looks like the stock muffler should have.

[Al_Smith]

 Perhaps and good for you .However numerous people have payed upwards of 90 bucks a pop for a muffler cover with a cute little pipe sticking out of it .

Just ask around about those little pipe things and see what folks say . All along a second port cut in them would have done better .

You want to get serious about a muffler remove everything inside it and just leave the shell .Leave a hole or series of holes equal to about 80-85  percent or so of the exhaust port area .If you want a screen ,make the hole a tad bigger .Richen up the carb until it 4 cycles and get with it .Then tell me  how it runs .

[chevytaHOE5674]

I cut up 5 or 6 mufflers for the 361 before I settled on just a second port on the side. To much port (and opened front cover) and the saw fell on its face and was annoyingly loud, to little and the gain was negligible. A second port of around 9/16" ID was the best gain (also backed up by members on another forum).

And correction the port area with a 9/16" port added is around 215 mm^2.

And where do people by "muffler cover with a cute little pipe sticking out of it" for a 361 that has a 1 piece muffler?

[Al_Smith]

And where do people by "muffler cover with a cute little pipe sticking out of it" for a 361 that has a 1 piece muffler?

Correction on that statement  .I should have specified mufflers in general not necessarily a 361 .

However I have uncrimped that style,gutted them and recrimped . It's kind of a pain in the behind to do but possible ----and no before you ask I've never done a 361 .

I do have a 2100 Husky to do though which should prove interesting and likely to be rather loud no doubt .

[smith2bj]

Is there a web site that has a step by step with pictures that is easy to follow along with?  I tend to be a visual person that needs to see it done.   

[smith2bj]

does anyone know about a website that discribes how to port a muffiler on the stihl 361 that they would recomend?

[boobap]

this one right here...what else do you need?   

[windthrown]

All the EPA regulations requiring saw makers to make the saws run super lean with ultra high exhaust temps will make the saws last forever. Removing those exhaust restrictions and providing the saw with adequate fuel and lubrication will cause the saw to burn up quicker. 

I hope that this was posted tongue in cheek...

Ported saws will typically run better, richer, cooler and last a lot longer. Lean saws that run hotter are sure to burn up faster. Ported saws burn more gas, but that's the price you pay for having more power. They can be louder, but they do not have to be that much louder (if they are done right). As someone else posted above, a larger ports in the muffler does not always mean a better running saw. They need to be done right.

I have found that the shark-gill 361 mod is the easiest. Cut three 1/2 inch slots in the muffler on the side opposite the factory port. Then lever them open with a screwdriver. Add a piece of spark screen, and cover it with a Husky muffler port cover to baffle the exhaust toward the front of the saw. Drill 2 small holes in the baffle cover tabs top and bottom and the muffler and secure it with two small pan head screws. Then remove the limiter tabs on the carb, and open up the H jet and tack it to about 14,500 RPM WOT. It should burple (4-stroke) at WOT. Check the plug after runnig it WOT in a good long cut. The plug should be chocolate brown.

[Rocky_J]

Yes, tongue firmly planted. I'm just sick and tired of trying to convince the naysayers who will beat you to death with their doubts. So I play Devil's advocate and argue their position to show them how ridiculous it is.

[Al_Smith]

  Discussing ported saws can get as controversial as what kind of mix oil to use and at what ratio .

You can fiddle with the muffler and call it ported .You can pull the base gasket and call it ported .Fact is you can go nutty like a few of use and dome the piston,cut the base widden and raise the ex ,widden the transfers ,enlarge the intake and call it what ever you choose to . No matter what you do if you do it correctly and have the correct fuel mixture it isn't going to fly apart like a dollar watch . Chances are really great in addition to all that ,that the saw will last just as long as a factory tuned choked down stocker .------But they aren't for everybody .

[windthrown]

I dunno... once you run ported saws, all you want to do is open up all the stock saws you get your hands on.

I just modded another Stihl 310. Took an hour to do it all; opened up the muffler to match the 'standard' 1127 muffler that they sell in Europe and pretty much matches the stock carb. Then I clipped the carb H limiter and tuned the H screw around to 1-1/4 turn (stock is 3/4 of a turn). What a difference that made. The 310 keeps up with my 361s. The only difference now is the WOT revs; the clamshell 310 engine has a max rev rating of 13k, whereas the 361 is 14k. I run them at 13.5k and 14.5k (factory setting tolerance is +/- 500). Not much else you can do to 'port' a clamshell engine. Cannot squish it, maybe open the intake and exhaust ports a bit. But even with just a muffler mod it has a 10-15% gain in power. Now it has more power than a 390. It runs a 25 inch bar now, no problem. The stock 1127 saws are certainly choked down. They are gasping for air and tuned way too lean!