More '08 Stock Muffler ?'s


40 replies to this topic
  • swaldrop

Posted May 19, 2008 - 07:47 AM

#1

I'm in great need of a repack and had a few questions...

1. Is it easier to drill the forward/aft/both rivets to take the can apart?

2. I have a rivet puller somewhere, but not sure on the size rivets I need. What size and material do you suggest I replace them with?

3. Local Yamaha dealer doesn't have any 4-stroke silencer packing in stock, let alone the OEM replacement 'fiber' (awful, awful place. Barney's of Brandon, FL). However, I did find some MSR packing, part #9105 at a Honda shop. Will this work for this pipe?

4. Finally, once I have it apart, is there any hope of removing the inner cones to get back the low end?

Thanks in advance for the advice.
Steve

  • StPeters21

Posted May 19, 2008 - 07:49 AM

#2

I thought it was mechanical.....ie...no packing??????????????????

  • swaldrop

Posted May 19, 2008 - 08:00 AM

#3

I thought it was mechanical.....ie...no packing??????????????????


It has packing. With no moving parts, there is nothing 'mechanical' about the muffler really.

  • grayracer513

Posted May 19, 2008 - 09:52 AM

#4

Shown here with the packing removed:

http://www.motocross...F3E7ECC2A3CD20C

:thumbsup:

  • swaldrop

Posted May 19, 2008 - 10:02 AM

#5

Shown here with the packing removed:

http://www.motocross...F3E7ECC2A3CD20C

:thumbsup:


Thanks for the pics Gray, but that doesn't really help with my original questions. Any thoughts on those?

  • grayracer513

Posted May 19, 2008 - 10:28 AM

#6

Drill the forward rivets out, same as the older mufflers, and as shown it the second of the two pics that don't help. The rivets are probably 5mm (3/16").

Note that the muffler is "packed with a special heat-resistant glass wool". Be sure you use something specified as high temp four stroke packing.

  • swaldrop

Posted May 19, 2008 - 10:47 AM

#7

Drill the forward rivets out, same as the older mufflers, and as shown it the second of the two pics that don't help. The rivets are probably 5mm (3/16").

Note that the muffler is "packed with a special heat-resistant glass wool". Be sure you use something specified as high temp four stroke packing.


Ahh... The old 'a pictures worth a thousand words' post. Got it.

To be honest, I have seen that pic posted soooo many times on this board that I didn't even pay attention to it. My bad.

Any wisdom about removing the cones, or should I just leave well enough alone? I don't really want to buy a pipe as more power isn't really what I 'need' but rather just something that would be nice.

  • grayracer513

Posted May 19, 2008 - 11:15 AM

#8

The way it's described, the exhaust flows both through and around the yellow secondary cone to exit the muffler. Unfortunately, this detail isn't shown, so I'll guess that it does. If you remove both of them and convert it to a conventional "glass-pack", you'll definitely improve at least the low end performance, but it will almost certainly be very loud.

If you wanted to experiment, you could cut the first 50% off of the secondary cone to allow more gas through the center more freely, or possibly remove the first cone by drilling the spot welds holding it to the perf core.

Bear in mind, the results may not be totally desirable.

  • swaldrop

Posted May 19, 2008 - 11:49 AM

#9

Bear in mind, the results may not be totally desirable.


That's what I'm afraid of. I was hoping that someone else had done the experimenting for me :thumbsup:

  • MX926

Posted May 19, 2008 - 01:33 PM

#10

I removed secondary cone, and noticed a slight gain in throttle response, and a slight increase in sound. It was not a substantial gain in power and really didn't seem to be worth the effort.

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  • swaldrop

Posted May 19, 2008 - 02:04 PM

#11

I removed secondary cone, and noticed a slight gain in throttle response, and a slight increase in sound. It was not a substantial gain in power and really didn't seem to be worth the effort.


Thanks for the heads-up. I'm better off working on my corner entrance speed, rather than my exit any how.

  • Sprew

Posted May 19, 2008 - 09:44 PM

#12

The way it's described, the exhaust flows both through and around the yellow secondary cone to exit the muffler. Unfortunately, this detail isn't shown, so I'll guess that it does. If you remove both of them and convert it to a conventional "glass-pack", you'll definitely improve at least the low end performance, but it will almost certainly be very loud.

If you wanted to experiment, you could cut the first 50% off of the secondary cone to allow more gas through the center more freely, or possibly remove the first cone by drilling the spot welds holding it to the perf core.

Bear in mind, the results may not be totally desirable.


The primary cone influences the flow at the beginning and middle (critical reversion) of its travel through the muffler. Modifying either one will achieve minimal results. Take note that the end of the secondary cone (open) resides inside the primary cone (closed) such that minimal flow will occur upon the waves initial entry. Also note the reflective characteristics of the tertiary cone at the base of the secondary cone in which the perforated baffle is seated (not visible in photos reference above).:thumbsup: :rolleyes: :rolleyes:

  • grayracer513

Posted May 20, 2008 - 07:46 AM

#13

Take notice that the muffler on my 5 HP chipper engine is at least as sophisticated as this pile. There's no more acoustic engineering evident in the '08 muffler than there was in the cheap aftermarket custom street exhausts we used to use 40 years ago.

  • j-ripper

Posted July 03, 2008 - 12:46 PM

#14

well what if you simply drilled more holes in the yellow cone and removed the small cone, isn't that what the aftermarket ones are? if thats not somewhat agreeable how bout just takin out the little cone?

  • grayracer513

Posted July 03, 2008 - 01:38 PM

#15

If it was me, and I was determined to try to keep it, I'd remove both cones, making a conventional "glass pack" out of it. But I'd be surprised if it wasn't louder than I wanted it to be.

And in evaluating the amount of noise generated by an exhaust, remember that it sounds a whole lot different from off the bike than it does from in the saddle, so have someone ride it past you at full throttle before you say, "Heck, that ain't so loud."

  • j-ripper

Posted July 03, 2008 - 05:47 PM

#16

i see, but i'm lookin for more power all around, thought that it may increase it,, i wonder if they changed them for 09 since were all bitchin about them! they pretty much are all show,,no go. would you have any ideas for better jetting? i live in mid eastern pa and race district 6 so i really would appreciate some help, also heard lowering the radiators an inch makes the bike feel lighter, but i think that, that would hurt more then help cause of how close they would be to the header, thinking the engine may run hotter??? please help,,thanks

  • swaldrop

Posted July 03, 2008 - 10:09 PM

#17

I finally removed both cones and WOW!

http://www.thumperta...ad.php?t=665143

  • j-ripper

Posted July 04, 2008 - 09:55 AM

#18

thats not for an 08 pipe and muffler, thats an 06 setup.

  • swaldrop

Posted July 04, 2008 - 10:39 AM

#19

thats not for an 08 pipe and muffler, thats an 06 setup.


You're joking, right?

  • j-ripper

Posted July 07, 2008 - 05:40 PM

#20

sorry, if i would remove both cones on the 08 muffler, is the bike better all around?





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