- Joined
- Jan 4, 2007
- Messages
- 1,079
I just finished basically destroying an already beaten up Rotax muffler. I just had to see what was inside. I quite honestly was expecting something much more sophisticated.
Just inside the muffler body there is a tube about 3" diameter that is welded to the megaphone headpipe. At the inlet that tube has a series of holes about 1/4" or 5/16" drilled around it's diameter. The tube extends about 10" into the body of the muffler but is just open ended.....no reverse taper cone as I had expected, like on what I've seen on tuned expansion chambers. Other than that, there are 3 hole-riddled baffle plates and 3 (I think it was) tubes that have holes in various places. The outlet is merely a tube that's closed on the end opposite the actual exhaust outlet, but the tube is full of holes to let out the exhaust gases. Basically tho whole muffler is just a maze of sorts to give the exhaust various paths to the exit and thereby softening and quieting the exhaust pulses.
The only possible "tuned" part of the pipe, as far as I see it, is the taper of the "headpipe" and the length of it. I would say those two things are quite important, but is there anyone well-versed in two strokes that could unveil any other tuning in the design that I don't see?
I actually worked for a company a short time that did a lot of expansion chamber design, and I'm quite familiar with what difference an actual expansion chamber can do to a 2-stroke motorcycle's power, but I just don't see any of that similarity in the Rotax muffler.
Generally when 2-stroke questions are asked the typical response is something about them being very sensitive to length, diameter, etc., and quite honestly I expected to see the straight section and reverse tapered cone of an expansion chamber "hidden" in the muffler body, but it was pretty un-impressive.
Lynn
Just inside the muffler body there is a tube about 3" diameter that is welded to the megaphone headpipe. At the inlet that tube has a series of holes about 1/4" or 5/16" drilled around it's diameter. The tube extends about 10" into the body of the muffler but is just open ended.....no reverse taper cone as I had expected, like on what I've seen on tuned expansion chambers. Other than that, there are 3 hole-riddled baffle plates and 3 (I think it was) tubes that have holes in various places. The outlet is merely a tube that's closed on the end opposite the actual exhaust outlet, but the tube is full of holes to let out the exhaust gases. Basically tho whole muffler is just a maze of sorts to give the exhaust various paths to the exit and thereby softening and quieting the exhaust pulses.
The only possible "tuned" part of the pipe, as far as I see it, is the taper of the "headpipe" and the length of it. I would say those two things are quite important, but is there anyone well-versed in two strokes that could unveil any other tuning in the design that I don't see?
I actually worked for a company a short time that did a lot of expansion chamber design, and I'm quite familiar with what difference an actual expansion chamber can do to a 2-stroke motorcycle's power, but I just don't see any of that similarity in the Rotax muffler.
Generally when 2-stroke questions are asked the typical response is something about them being very sensitive to length, diameter, etc., and quite honestly I expected to see the straight section and reverse tapered cone of an expansion chamber "hidden" in the muffler body, but it was pretty un-impressive.
Lynn
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