In my never ending battles with tinkering...

[yzernie]

...I pulled off the end cap of the right muffler to see is there is an easy way to give the bike a little bit more rumble. Under the end cap reveals a fully welded and sealed end of the muffler. No easy way to get that off to modify a baffle or two. I take a look down the muff from the back end and see a baffle (for lack of a better term) inside a ways. On the outlet side of this baffle are holes in the main exhaust leading to the outlet. So, the exhaust gasses must come through the cat at the front of the muffler and empty into some type of chamber and pushed around the baffle and into the holes for the outlet.

 

The baffle is 12" inside of the outlet pipe and what I don't know is what is on the other side of that. The guys at the shop believe if it like many other Yamaha Star bikes, it is an open-ish type area. My question to them was this...if I was to drill a 1" hole through that baffle would I damage anything on the other side? They weren't sure but didn't think so. The lead mechanic was going to try and find out how the muffler is constructed and that will tell me if I am safe to drill of not.

 

I'm reluctant to do it without knowing what is on the other side because if I damage something there are no aftermarket mufflers out yet, or heck, not even any OEM mufflers available to replace it with so I am going to hold off for right now. I'll be down at the shop tomorrow and hopefully he will have an answer for me.

 

End cap removed

 

 

Overall look down the outlet

 

 

Closer look

 

Edited January 13, 2018 by yzernie

[mabeline]

Is it easy to get the muffler off, to have look from the other end?

How are the mufflers supported at the back ( bracket )?

Maybe you can do like we've done on the RSVs, Harley mufflers or Monster Ovals etc.

[WildBill1]

That looks to me like the old Harley muffler design. That said from the inlet side take a 1/2 rod and punch the freeze plug out and let her breath easy with a better exhaust note.

[yzernie]

After talking to the lead mechanic at the shop he said the other Yamaha mufflers have a chamber system on the inlet side of the plug. He said I would be fine to drill a hole in that plug but to be careful to not go to deep after it punches through because the cat is somewhere behind that plug. He said there is usually a couple inches of space between the plug and the cat.

 

Is it easy to get the muffler off, to have look from the other end?

How are the mufflers supported at the back ( bracket )?

Maybe you can do like we've done on the RSVs, Harley mufflers or Monster Ovals etc.

The other end of the muff, the inlet end has the cat a few inches inside. No way to get through that to get to that plug. It is mounted at the rear with an "L" bracket that is welded to the muffler and then bolted to its mount. I have muffs from my HD so when I get some time I don't know what to do with I'll do some checking and see if there is a possibility of the change.

 

That looks to me like the old Harley muffler design. That said from the inlet side take a 1/2 rod and punch the freeze plug out and let her breath easy with a better exhaust note.

Going to drill holes in it first. Not knowing the exact construction of the muffler I would absolutely hate myself if I got to pounding away in there and damaged something when there are no aftermarket replacements yet. That said, I'm going to drill a hole in the plug starting with 1/4" and progressively go larger if I feel the need to. The guys at the shop are still trying to get info from Yamaha on exactly how they are constructed.

[Tealw1]

So did you drill the holes or knock out the "plug". If so, did it make a big difference in the exhaust note/loudness? Any change in torque that you could notice?