Muffler Mod Critiques. Too Much, Too Little . . . ?

[GitWood]

OK, I have a bad habit of "fixing" things brand new out of the box. The new Solo 694 is no exception. I have just modded the muffler and wanted some opinions on too much, too little, etc. before I weld it back together.

I cut the welds with a dremmel cut-off disk, added some openings to the inner box, and opened up the outlet. I believe that the outlet is now about 75% of the exhaust port area.

I did it this way because I couldn't find a place that I really liked to add another exhaust port. Also, this way, the factory screen will still go back on if I choose to replace it. Anyway, I will attempt to post before and after pics. Any comments before I weld her back together?

 

[manual]

Looks good to me . I like the stock look.
everything I have read says 85% max opening.
Like to know how she runs afterwards.

 

[UrbanLogger]

Looks fine to me too. I have a really cool Craftsman 42cc saw (hey, it was dirt cheap and almost new, only 1 hour on it when i bought it - $40.00) I opened my muffler up and found a very stupid, completely removable piece(basically a pipe with a lot of holes machined in it) that the exhaust gas had to pass through to get into the open chamber that is the mufflers outer case. There was also a spark arrester screen wrapped around the baffle. I removed only the screen at first, and noticed vary little improvement, then I removed everything inside the muffler, wow what an improvement, it really woke up the saw. I also removed everything associated with the choke, and plugged the holes left in the carb with epoxy, and sanded it smooth, it seems to be a whole new saw. I probably shortened its life somewhat, but for now its actually a decent saw.

 

[Patrick62]

I have done that...

I don't open them up quite as far, and I have to keep a screen functional.

But brand new, still under "warranty", and I am drilling out a muffler!!! You bet. My 046 is opened up a touch,
My 026 was opened up some,

Recently I even opened up my weed wacker! :yoyo:

Nice work on your saw, it should wake it right up :hmm3grin2orange:

-Pat

 

[RED-85-Z51]

Looks fine to me too. I have a really cool Craftsman 42cc saw (hey, it was dirt cheap and almost new, only 1 hour on it when i bought it - $40.00) I opened my muffler up and found a very stupid, completely removable piece(basically a pipe with a lot of holes machined in it) that the exhaust gas had to pass through to get into the open chamber that is the mufflers outer case. There was also a spark arrester screen wrapped around the baffle. I removed only the screen at first, and noticed vary little improvement, then I removed everything inside the muffler, wow what an improvement, it really woke up the saw. I also removed everything associated with the choke, and plugged the holes left in the carb with epoxy, and sanded it smooth, it seems to be a whole new saw. I probably shortened its life somewhat, but for now its actually a decent saw.

So how do you start the Craftsman?

 

[UrbanLogger]

Pump my primer bulb 3 or 4 times, hold it wide open, pull once, then let go of the throttle, pull once, maybe twice, and its running. I've never needed the choke on that saw...It probably helps that this is not my primary saw, it ususlly only gets used when I have to.

 

[ShoerFast]

Just another .02 cents worth, but it seems finding that fine line, that size between the hole size not making any more gain and the going too big increasing unnecessary noise.

If it will stop raining here and dry out a little, I can test an adjustable opening on a stock single port MS-660 , it's my guess that a lot of muffler holes are favoring too big, good for the saw, bad for the ears.

 

[Freakingstang]

Just another .02 cents worth, but it seems finding that fine line, that size between the hole size not making any more gain and the going too big increasing unnecessary noise.

If it will stop raining here and dry out a little, I can test an adjustable opening on a stock single port MS-660 , it's my guess that a lot of muffler holes are favoring too big, good for the saw, bad for the ears.

Why do you think the dual port muffler cover doesn't come on the saws these days? With the single outlet, it will pass many sound requirements for differant countries...

 

[Lakeside53]

Just a word to the wise (that was passed to me by someone that "knows") on modding the mufflers for the likes of the 441 type engine (don't start another rave thread, please...), throw out all the notions of 75, 85 125% or whatever you've heard. Start small, and sneak up on the size... and if you increase the muffler flow, figure on making air-box mods (holes) also - take off the air filter cover while making the muffler end adjustment, then work back onto to the air box... and don't forget the carb jetting. It's not your granddad's saw:monkey:

It won't take long AS guys to figure out what works and what doesn't... but start with a fresh sheet of paper.

I'm guessing (again) that some of the disappointing mods on the 575 is because they were "over done".

 

[Lakeside53]

Why do you think the dual port muffler cover doesn't come on the saws these days? With the single outlet, it will pass many sound requirements for differant countries...

It does on the 460 magnum wrap, but he primary reason you don't get them as a bolt on option is emissions.

The only factory discontinuation of dual port in the USA was the 066 in 1995. OHSA said was too loud.. and it was, but..

 

[ShoerFast]

Why do you think the dual port muffler cover doesn't come on the saws these days? With the single outlet, it will pass many sound requirements for differant countries...

Yes, it stands to reason, and angling the exit (if you weld in a pipe) makes another favorable adjustment to the sound-wave. As for me, way too many years of ear abuse, and there are places that I cut that I don't need an extra 50 db of "unnecessary noise" ,,,,setting up drop-camps for one.

I should post a picture of a 660 single port cover I have that someone had drilled 4 , 3/4" holes in, sort paired and over-lapping, but it should be an easy audible.

 

[Kneejerk Bombas]

Why do you think the dual port muffler cover doesn't come on the saws these days? With the single outlet, it will pass many sound requirements for differant countries...

Closing off the exhaust ports does make it quiter, but the main reason is it reduces the amount of unburned gas that blows past the top of the piston and out the exhaust. That's how the emisions are kept down.
The new saws (575, 361, 441) have one version, or another, of strato charging. It puts a blast of fresh air between the exhaust gases and the incoming fuel. This keeps most of the incoming fuel in the motor.

 

[Lakeside53]

Closing off the exhaust ports does make it quiter, but the main reason is it reduces the amount of unburned gas that blows past the top of the piston and out the exhaust. That's how the emisions are kept down.
The new saws (575, 361, 441) have one version, or another, of strato charging. It puts a blast of fresh air between the exhaust gases and the incoming fuel. This keeps most of the incoming fuel in the motor.

Not the 361... That just a nice 4 port design.

 

[rahtreelimbs]

I added a 2nd port to my 694 after opening up the inner baffle as you did.

 

[GitWood]

I finally got the chance to try the 694 yesterday. I adjusted the carb a little richer and cut up a little camp fire wood. It seemed to cut pretty well, but I don't think that the 3/8 full skip chain and 7 pin sprocket that I currently have installed are going to let me actually use the saw's available HP. With the 28" bar that I am using, I suspect that full comp chain and 8 pin sprocket would make a difference. Any opinions as to the accuracy of this assumption? If this is the right way to go, will it make much difference?

Thanks,
Mark

 

[rahtreelimbs]

I finally got the chance to try the 694 yesterday. I adjusted the carb a little richer and cut up a little camp fire wood. It seemed to cut pretty well, but I don't think that the 3/8 full skip chain and 7 pin sprocket that I currently have installed are going to let me actually use the saw's available HP. With the 28" bar that I am using, I suspect that full comp chain and 8 pin sprocket would make a difference. Any opinions as to the accuracy of this assumption? If this is the right way to go, will it make much difference?

Thanks,
Mark

On a 28" bar go with full comp full chisel chain!

 

[GitWood]

rahtreelimbs,

I see from your photo that you have your saw in a case. Looks like the case was modded a little. Does the saw fit in it? If so, what type of case and what did you have to do to get it in there?

 

[rahtreelimbs]

rahtreelimbs,

I see from your photo that you have your saw in a case. Looks like the case was modded a little. Does the saw fit in it? If so, what type of case and what did you have to do to get it in there?

That case is a standard Stihl case. The inner walls ( both top and bottom ) had to be removed. I also had to cut a slot in the top for the chain brake handle!

 

[GitWood]

Here is the completed muffler mod. I'm pretty happy with everything except the welds. I haven't used a mig welder in about 25 years. Looks like a little birdie stopped for a visit.

BTW, I did reinstall the screen. At least for now. I'll probably leave it in unless it causes a problem.