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Aftermarket Muffler Repacking

2K views 2 replies 3 participants last post by  hillscbr 
#1 ·
Most manufacturers of aftermarket mufflers recommends repacking their slip-on mufflers every 15-18K kilometers; though can be extended depending on style of driving and climate. Most companies will sell specific repacking kits; though for less than half the price, any decent packing material will achieve the same effect.

It's quite a simple process, go-to-whoa in under an hour.
This process was done on a Yoshimura R-77 Carbon, though the process is basically the same for all others.
Note, this does not apply to the factory fitted muffler, as it uses a series of baffles for sound deadening.

Parts required:
muffler packing material.
I went with both a mat style and loose pack fibreglass. (Total cost $50 delivered)
High temp gasket goo

Tools required:
Whatever it takes to remove the muffler from the bike.
A pin punch and hammer
A drill and 5mm drill bit
Rivets and a riveting tool
Wire brush
A long poky thing

Method:
1) Pin punch out the centre of the existing rivets
2) Drill out the rivets
3) Remove ends of muffler
4) remove old packing material and discard
5) wire brush clean the exterior of the perforated inner tube
6.) When reinstalling end caps and muffler onto exhuast pipe, run a bead of gasket goo to ensure a good seal.
6a) For mat material, wrap mat around tube and re-insert into muffler
6b) For loose material, insert end containing the perforated tube, and stuff material into cavity using a rod to push it down and compress.
7) Replace end cap.
8) Reinstall muffler.

First end cap off


The old muffler material
For the Yoshi, it has a 0.5cm wide chainmail tube containing steel mesh that wraps around the perforated tube. Then there is loose matting encased in netting that goes around that.

The original material wasn't too far gone, coloration still good though towards the engine end of the tube it was at the stage of crumbling in the hands. The tube of steel mesh was quite solidly caked with carbon soot.

Packing in the new stuff

I put a layer of loose material on the inside of the mat material then rolled that around the perforated tube. Installed it in the bike and then pressed some more loose material into the thing to fill any gaps.

I was going to post up a before and after video of the results from the repack... but it was so negligible not worth the effort of video editing, here was me testing though.


Results:
Before - Idle 73-75db | 5000rpm 84-86db
After - Idle 72-74db | 5000rpm 82-85db

Not as much of a difference as I thought there would be; though they do say it will get quieter after a few hundred kilometers to bed the new material in.
As for the sound, the note of audio... I can't tell any difference.

Conclusion:
It was cheap, easy to do and not much time, but negligible benefit. Judging by the perishing of the original material, although it was probably due from a manufacturers standpoint, one could easily go at least another 10,000km (say 30-35K kms) before thinking of requiring this sort of maintenance.

What happens if it isn't done... not much, the packing disintegrates and gets blown out the exhaust. Eventually it will just become louder and you may loose fractions of a horsepower.
 
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#2 ·
Most manufacturers of aftermarket mufflers recommends repacking their slip-on mufflers every 15-18K kilometers; though can be extended depending on style of driving and climate. Most companies will sell specific repacking kits; though for less than half the price, any decent packing material will achieve the same effect.

It's quite a simple process, go-to-whoa in under an hour.
This process was done on a Yoshimura R-77 Carbon, though the process is basically the same for all others.
Note, this does not apply to the factory fitted muffler, as it uses a series of baffles for sound deadening.

Great tutorial, and very helpful to me especially, given that I also have a Yoshi.
 
#3 ·
Great write up TTZ! If I had the spare cash, that's my exhaust of choice, but with 4 kids I'm lucky to even have a bike!

I'm off to Bunnings to ask for a long poky thing.
 
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