IMO there are two basic ways to modd a 572 muffler, with variations in each method. I have a picture handy of this modd. It's pretty simple and easy to do. This is dual 3/4" ID tubing ports from the front of the muffler.
This method completely bypasses all baffling. When I do this, I blank the OEM port with a piece of sheet metal.
The variations within this method would naturally be the size and positioning of the ports.
In this example, care must be taken to keep the exhaust port nearest to PTO side short enough that it does not obstruct access to the lower crankcase muffler mounting bolt.
It's a bit loud, but a breather.
For those that may ask if it's overdone, my response is no. Saw runs great.
Second method is to do all the modds inside the muffler and keep it spark arrested. Again, there are variations in the basic method.
Sorry, but no pics on this. Look at your muffler and it's easy to understand.
Use a die grinder/Dremel with cut off wheel and cut the exhaust deflector nearly all the way just above the muffler. Leave it connected just a bit in the center so repositioning is easy. Bend the deflector back out of the way.
Use die grinder/Dremel with various carbide burrs to completely open the top portion of the muffler under the spark screen. Completely remove the exhaust venturi attached to the top of the muffler.
Then from the newly opened exhaust port, as well as from the cylinder side port, cut and remove the baffling that surrounds the oem exhaust port. I try to remove as much of the baffling as possible.
After that is completed, and this step applies to the first method I mentioned as well, be absolutely sure all burrs are removed and blow out muffler with compressed air until all chips and dust are eliminated.
Then fold the deflector back into position and braze it into place.
This method is a bit loud also, but because of the spark screen restrictions, it does seem to be a bit more quite. Unless you make a new spark screen from larger mesh material to increase flow. In that case it's quite loud.
The noise level can be reduced by leaving more of the baffling in place. It depends on an individuals preference.
A variation of this method would be to completely remove the oem deflector, make a new one of sheet metal that would be a bit taller, or higher off the muffler in order to gain more clearance for a larger exterior opening for the exhaust to escape.
IMO the later step is unnecessary, especially on a non ported saw.
I use the brazing method over tig or mig because it leaves no welding splatter. A little flux to chip off, but not a problem.
In either case, before paint, use a high pressure hose from each port to be sure all chips and dust are removed and then back with compressed air.
Either method works well and helps the 572 wake up a bit.
Thanks Mike
