Anatomy of a quiet muffler

[ohiofarmer 3,157]

i have a honda CB750 bike with a kerker 4 into 1 exhaust systen that is welded from one end to the other. The perforated pipe failed inside the muffler and the washer  welden on the pipe to the right side cut through the expansion chamber due to vibration. i decided that $400 or so would better e spent elsewhere. You can see the washer to the right of the hose clamps. The second picture shows where the expansion chamber was cut through and forward from that the rest of the chamber and the header pipes form the complete system. The repair was simple in that the perforated pipe was simply hose clamped to solid pipe inserts to restore its integrity and function. Total cost was less than ten bucks--and yes--that is a piece of aluminum spouting holding the severed expansion chamber together on a temporary basis. This is a very quiet muffler that I would compare to Honda factory noise level.

 

 I am posting this because the design is so simple that what appears to be a straight through design is actually a two chamber muffler that could be incorporated for small engines with perhaps throw away propane bottles as the expansion chambers.

 

 First, the 4 header pipes combine into one and they enter the expansion chamber. The gases expand and hit the solid washer and are turned back toward the open end of the SOLID exhaust pipe, creating all kinds of turbulence. They pass through the solid pipe past the washer to the perforated pipe and can either run straight out the back or expand further into the increasing diameter cone-shaped expansion chamber. All that passing through the screen and back also creates more sound attenuation and it works very well. I did not even replace the glass pack material and if anything, the muffler was quieter than before.

http://www.ebay.com/itm/1m-Stainless-Steel-Exhaust-T304-Perforated-Tube-Pipe-3-76mm-Diameter-1-metre-/271048358248

the link shows the appearance of the perforated tube inside the muffler in case my pictures are not clear enough.

 

 If i ever get another " short-fat " propane bottle for the build, you guys will be the first to see it

Edited June 12, 2017 by ohiofarmer