Exhaust -  Holey Muffler! (4451 views) Notify me whenever anyone posts in this discussion.Subscribe
From: maxriderdon5/27/10 12:39 PM 
To: Bike30  (14 of 28) 
 16833.14 in reply to 16833.13 
What do you mean by "second" hole? You only drilled one right? I know I just misinterpreting, but I'm confused.

From: jb99255/27/10 1:15 PM 
To: Bike30  (15 of 28) 
 16833.15 in reply to 16833.1 

have u posted any pics on this mod yet?  I want to do this to mine, but pics always help simple guys like me.


Jim Bennett

Cibolo, TX



From: Bike305/27/10 2:00 PM 
To: jb9925  (16 of 28) 
 16833.16 in reply to 16833.15 

Hello Jim. No pics and I apologize for not doing so. I can try this weekend. As far as a second hole, what I'm referring to is drilling a second hole through the interior bulkhead adjacent to the Factory's readily unseen single outlet through the rear bulkhead.

If you look up the outlet of the stock muffler you'll first see a curved 1 3/4" tube welded to the very outlet. It curves to the right and looks forward at a bulkhead. That stainless steel bulkhead separates the cat convertor from the rear muffler chamber. The bulkhead has a "X" formed in it (for structural strength I assume.) You can see the bulkhead and X through the tube with a flashlight.

With a 1 1/2" hole saw snaked in through that curved tube on a 24" drill extension (2x12" coupled) I drilled a hole through the X. I then enlarged it to 1 3/4" with an abrasive flapper wheel as described earlier.

As mentioned the first hole through that baffle is unseen, but it's a straight 1 3/4" tube welded to the bulkhead and parallels the curved tube on the left muffler side stopping just short of the outlet. Put a small mirror up the curved tube and you'll see it. It carries the exhaust gas to the rear of the muffler from the cat chamber. The flowing exhaust gas then makes a 180 deg turn forward to the curved tube's inlet, followed by a 180 deg turn out the curved tube to the rear of the assembly. Adding a second hole simply straightens and increases the flow to the outlet tube, which remains at 1 3/4" due to the muffler's design. It's louder, lower in sound, but not obnoxious. And the mod retains the cat for emission purposes.

Gary in Alaska


From: 19star615/27/10 2:16 PM 
To: Bike30  (17 of 28) 
 16833.17 in reply to 16833.16 
Sounds like my kinda mod, no pun intended. Can you feel any difference in performance. I sure would like to see some pictures too.

From: dcoul15/27/10 2:19 PM 
To: Bike30  (18 of 28) 
 16833.18 in reply to 16833.16 
Hey Gary, I think you should come down and do a tour of the lower 48 so we can all hear it!

From: Bike305/27/10 3:37 PM 
To: 19star61  (19 of 28) 
 16833.19 in reply to 16833.17 

The performance is great, but then so was it before. I had to add the CO fuel mod to reduce the increased popping so I know it changed flow. How much more power is anyone's guess.

Time for a new bike anyway.



From: Bike305/27/10 3:48 PM 
To: dcoul1  (20 of 28) 
 16833.20 in reply to 16833.18 

A tour would be great, and I need to do just that soon before I forget how. It's been 23 yrs since I've left Alaska on vacation in the Summer and I need to do it. The wife does it yearly if not more often. I like it here in except for a few dark cold mid-winter months.

The sound increase change is like operating the bike with or without the exhaust valve functioning. Disconnect the two cables at the valve, tie the EXUP valve open, and ride. It's louder than stock. At idle the valve is always open anyway, but closes some and quiets down when moving out on the road. It opens again at WFO. So now it's louder at idle and WFO, and slightly more so when the valve is closed in cruise for torque.

Is it a D&D with all the knocking?...No. Is it a loud boom like the Roadhouse units I've owned...No. It's just all the noise I'd care to tolerate in a long cruise.

Gary, as forrest fires consume Alaska


From: dcoul15/27/10 4:23 PM 
To: Bike30  (21 of 28) 
 16833.21 in reply to 16833.20 
I sold my D and D because the sound annoyed me on long rides. 30 minutes was all I could stand. I wouldn't mind a little more ruble than stock, if it's lower pitched.

From: Bike305/27/10 5:13 PM 
To: dcoul1  (22 of 28) 
 16833.22 in reply to 16833.21 

It's lower no doubt, is good and deep WFO, but not a harsh bark like an open exhaust or te Speedstar pipes I had earlier. The cat tones down the high notes some and there's no whistle-ass sounds like we can get when drilling a bunch of small holes in a muffler outlet.

The outlet size is unchanged of course, but one fellow here did remove the curved tube by cutting the tube lose and pushing it aside inside the muffler. The tube could be removed from the rear but Yamaha chose to put a flared end on the tube's forward intake. It won't easily pull out from the rear without some creative cutting.

A good hole saw turned slowly with a drill goes through the baffle with lube quickly. I greased mine to stick to and remove the cut plug with the saw. Don't want that rattlin' around in there.



From: dcoul15/27/10 5:45 PM 
To: Bike30  (23 of 28) 
 16833.23 in reply to 16833.22 
This sounds great. I sure hate to ruin a perfectly fine muffler though if I don't like it.

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