Lou Wambsganss
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Well, the wife and kids are out of state, so I have time to do stuff for a few days. Something that I've been thinking about is modding my Danmoto Jisu muffler to make it smaller. The shape isn't a simple circular tube like some, but it is still the same basic design. The endcaps are just riveted on. I did my cutting on the forward (inlet) end, since that cutline is perpendicular to the long axis of the muffler body. The outlet endcap is at an angle. It could certainly still be cut there as well, but I wanted this to be as quick and simple as possible.
First, the rivets must be removed. They are 3/16" stainless steel originally, so they should be drilled out with (obviously) a 3/16" drill, or a #10 or #11 drill. Once the head is almost drilled off, they punch out easily. Once all rivet shanks are punched out of the holes, use a flat punch or chisel to gently tap the endcap off. The inner perforated tube is spot welded to both endcaps, but the welds broke off easily for me. I didn't even have to drill or cut them. This is what you will see as it comes apart. It's just a basic fiberglass batting. Nothing fancy.
Something I noticed once it was all open was that there is a metal screen "sock" over the inner perforated tube. I'm guessing this sock is to help prevent the fiberglass batting from slowly getting blown out the perforations, which would lead to more noise over time. My muffler is exactly one year old, and the sock had started to disintegrate at the inlet side. So I just removed it. Maybe I'll lose by fiberglass batting more quickly, but now that I've had the muffler open once, it will be easier to do again if I want to replace the batting.
As for the mod, I wanted to make the muffler shorter. I figure that they put this same muffler on bikes that move a LOT more air than ours, so reducing the volume wouldn't hurt. I used a 3" wide masking tape as a cutting guide. Here is what was removed from the shell and inner tube.
To reinstall, I just used 3/16" aluminum pop rivets. The original rivets were steel, but you basically can't pull those with hand tools. You need a pneumatic/hydraulic puller. I'll keep an eye on the aluminum rivets to make sure they don't work loose or crack, but I doubt it will be an issue, especially with the now lighter and shorter muffler. There is no noticeable change in noise at all after cutting the muffler down. EDIT: I did put the baffle back in. Still a little too much bark without it for nighttime neighborhood driving.
Before:
And After:
First, the rivets must be removed. They are 3/16" stainless steel originally, so they should be drilled out with (obviously) a 3/16" drill, or a #10 or #11 drill. Once the head is almost drilled off, they punch out easily. Once all rivet shanks are punched out of the holes, use a flat punch or chisel to gently tap the endcap off. The inner perforated tube is spot welded to both endcaps, but the welds broke off easily for me. I didn't even have to drill or cut them. This is what you will see as it comes apart. It's just a basic fiberglass batting. Nothing fancy.
Something I noticed once it was all open was that there is a metal screen "sock" over the inner perforated tube. I'm guessing this sock is to help prevent the fiberglass batting from slowly getting blown out the perforations, which would lead to more noise over time. My muffler is exactly one year old, and the sock had started to disintegrate at the inlet side. So I just removed it. Maybe I'll lose by fiberglass batting more quickly, but now that I've had the muffler open once, it will be easier to do again if I want to replace the batting.
As for the mod, I wanted to make the muffler shorter. I figure that they put this same muffler on bikes that move a LOT more air than ours, so reducing the volume wouldn't hurt. I used a 3" wide masking tape as a cutting guide. Here is what was removed from the shell and inner tube.
To reinstall, I just used 3/16" aluminum pop rivets. The original rivets were steel, but you basically can't pull those with hand tools. You need a pneumatic/hydraulic puller. I'll keep an eye on the aluminum rivets to make sure they don't work loose or crack, but I doubt it will be an issue, especially with the now lighter and shorter muffler. There is no noticeable change in noise at all after cutting the muffler down. EDIT: I did put the baffle back in. Still a little too much bark without it for nighttime neighborhood driving.
Before:
And After:
Last edited:
. However, I also have the center stand. You mentioned (5:12 into the video) you made a custom bracket for the center stand. Can you elaborate and perhaps post a pic? I'm not as mechanically seasoned and would like to make sure this is doable before I make the purchase. Thanks for the recipe.
