Right behind the oil pan and under the transmission is my first attempt ever at making a muffler. I wanted the bike to be quiet. The quieter the better, in my book. The muffler is made of some sheet steel I bought for the purpose. Each side is pretty similar as far as to how it enters the muffler. Originally I had put flanges onto the muffler and the elbow that joins the headers to it. Then I realized that it would be simpler and nicer to braze them directly on and the only joint needed is the slip joint.
Inside the muffler, it goes like this: Where the pipes come into the muffler (they are staggered) they are attached to pipes that I scalloped. That is, I made short cuts and dimpled one side down into the pipe. You've seen pipes made like this commercially as baffles. I had bought two sets of R1100S mufflers. Stock ones are cheap. One of them I took apart to see better how mufflers work. From that set, I used the perforated lining which is basically sheet metal full of holes. The way it is used in my muffler is as a lining that is held about 1/4-1/2" off the walls of the muffler box.
I had also hoped to make a better and better looking muffler to occupy the same space. Actually, the newer style of mufflers as on Buells, Hondas (I think) and BMW 1000RRs inspired my thoughts along this line. Anyway, in my mind, the muffler would look a lot like a belly pan and come to kind of an elliptical point on the bottom with the long axis running front to back. If that muffler cavity could be made to do the whole quieting job, I had planned to run bare pipe up and have it exit where the R1100S pipes do. It could look kind of raw and would mean a lighter weight up high in the back. On subsequent bikes, I'd just probably exit it near the rear tire. Recently, Matt Richards linked on facebook to a site that had some really cool Moto Guzzis and there was one with my vision of a muffler and it was executed just as I had planned to do on my next attempt with the exception of the pipes going up under the seat hump.
I think it is a good sign that I can cleanly end this post with the word hump.
Chuey
