View Full Version : 1982 Yamaha XJ650 - MINI-MUFFLER!!

08-22-2009, 12:44 AM
I have a Supertrapp 4-1 system but it is getting a little loud. I emailed Supertrapp to see if the muffler is repackable. Unfortunately it is not - because the core is welded in. It is also missing the discs that should be on the end to tune the tone. It also looks like someone tried to hollow it out at some point in its life.



The header outlet is 2.5" O.D. I just happened to have some 2.5" pieces of exhaust pipe laying around so I decided to build a mini-muffler. I started by cutting a piece of 2.5" pipe about 6" long. I rolled one end and took it to a muffler shop to have them expand the other end to fit over the header.



08-22-2009, 12:44 AM
I got a scrap piece of 1.75" pipe from the muffler shop and flared one end the opposite direction. This will act as my core.




08-22-2009, 12:45 AM
I slid the core into the header (flared end first) until it contacted the inner pipe (see pics). I slid the outer pipe onto the header and marked where to cut. I left it about 1/4" long to allow for the flare.



I cut the pipe to length and flared that end. Now it is flared on both ends. I drilled 40-50 holes in the core. I had some #0000 steel wool laying on the shelf and decided to use this as my packing. The steel wool I had actually unrolled into a sheet. I wrapped the core as tightly as I could. The steel wool kind of acts like velcro - it holds to itself.



08-22-2009, 12:46 AM

I slid the core into the body, carefully stuffing all the packing in with it. (I will clean the burrs from all those holes before final assembly.)



Here's a test fit. I started the bike, but the muffler kept blowing/rattling off. I still need to get a clamp and cut a few grooves in the clamping surface of the muffler so it will tighten up. I like the look. I will get it cleaned up and paint it with some high temp paint. I'm gonna try to get a few videos comparing the Supertrapp to the mini this weekend. I still don't have the thing tuned right. I've got brand new intake boots ordered because mine are all cracked - causing it to run super lean.


08-24-2009, 9:04 AM
Cool, good solution! I bet you could get stainless exhaust and do it too, that way you could polish it up.