Ok so here in NZ we don't have heaps of cheap dyna mufflers, and it's not really the look I want anyway.

I want the straight drag pipe look with a slash cut end.

I've got a 16" BSA slash cut muffler to go on the end, but the baffles aren't there. Usually there would be some sort of fibreglass baffle inside secured with a bolt but it's missing.

I don't actually know how to repack the baffle, or how I should go about adding a baffle to achieve the right amount of back pressure the savage needs.

I've read the BCB drag pipe just uses a few discs with holes drilled in. I'd love to know more about this in detail as it sounds pretty easy to add that in. Or if someone can explain how best to repack this little muffler that would be good.

cheers

I built a muffler that uses a megaphone and some perforated pipe.  The system requires the exhaust to flow in and out of the perforated pipe 4 times, and the megaphone area acts as a chamber to even out the pulses.  Bigger chambers would probably be better - but it does a good job and is louder than the DYNA muffler conversion but not as loud as a SuperTrapp.

If you are running a straight pipe it will be tough to cut the noise down much - the best you could do is install a perforated baffle that restricts the flow some and uses the header pipe to even out the pules a bit.

I don't like the looks of aftermarket pipes - prefer the stock look - someone put a lot of time and effort designing them to fit the lines of the bike - so is there something that can be done to improve the stock pipes - which sound like crap to me?

Here's a thought, since you like the straight, fat, drag-pipe look:



Make the thing as long as you want.  If you want it sticking out past the end of the motorcycle, you can do that easy.  Three or four feet long, maybe.  Two feet long would be pretty noisy.

It'll be cheap.  All you'll need is a length of 2 1/8" pipe, a length of 1 1/2" pipe, a 3/16" drill, some scrap, a hacksaw, and access to a welder.  Shoot,.. you could buy ALL the parts AND a wire-feed welder on sale at Harbor Freight for what a four-foot-long fat-looking drag-pipe would cost!

You'll also need a couple clamps and some bracketry of some sort to fasten the aft end to the bike.

After you make one or two of these, you could probably crank one out in a couple hours (not counting the time to drill and bend the zillion holes).  Make a few, sell 'em, and get all your money back.

If you want it chromed, that'll set you back a few bucks.  You could wrap it in a header-sweater or paint the thing with high-heat paint.  Some of those paints work really well,... most don't.

savagebob wrote on 07/09/13 at 14:18:40:


Neither one of those alleged mufflers will make any difference sound wise unless you choke them off so much the back pressure will make the bike feel like a 350.

It's just plain physics.  You have to have some volume somewhere to attenuate the sound pulses.  Those little chromed bits have no volume.

Those chrome shorties will work like a megaphone with the large outlet.  The BCB pipe has round plates with @5/16" holes welded in about 4" from the head pipe, in such a way that the holes in the plates are offset.  The extra length and smallish diameter help with velocity/evacuation of gasses.

I have the bcb muffler and the plates have four holes. Here's a pic, don't know if you'll be able to see it as muffler is on bike so had to take pic from other end.

Can anyone tell me what kind of impact removing one of the plates would have on noise and backpressure?

I've emailed bcb and asked those questions as I needed some info from them anyway, ill post here when they reply.