Muffler repacking

**bungbung** · 18th March 2004, 11:39

My vtr has carbon arrow cans which are well loud. The bike had these cans on when I bought it.

I'm wondering if they were this loud when they were new. They sound nice but could do with being toned down a bit.

Is it likely that the packing in these could move around at all?

To repack, can I just drill out the end cap rivets and pull out the center to get access to the packing?

Is this a maintenance thing, i.e needs doing from time to time. I hear twins give the packing a harder time than fours.

**White trash** · 18th March 2004, 11:47

Yup. You should be able to get a repacking kit to suit the Arrow's specifically. Bike should be a little quieter afterwards but also run better. Be carefull dismantling carbo cans as if they're not riveted tight enough they flog out the rivet holes.

**dss3** · 18th March 2004, 15:57

I'm also looking to do a similar thing on my two brother pipes. They have been backfiring a lot. After advice from this forum I looked for, and found not only large leaks around the rivits, but also that the internal pipe in the exhaust had broken off and was sitting on the bottom of the exhaust. Meaning air flowed right over it and straight out the exhaust. I'm now missing around 2/3rd of the packing, and am rebuilding them.

**Coldkiwi** · 19th March 2004, 11:28

you should be able to buy proper exhaust packing. failing that, try insulation suppliers like CSR and see if they've got any high temp MINERAL wool (aka.rockwool..not be be confused with fibreglass) off cuts/scraps you can use (a good approach if you're a tight westie!)

**speedpro** · 19th March 2004, 11:37

Originally Posted by Coldkiwi

you should be able to buy proper exhaust packing. failing that, try insulation suppliers like CSR and see if they've got any high temp MINERAL wool (aka.rockwool..not be be confused with fibreglass) off cuts/scraps you can use (a good approach if you're a tight westie!)

Being a tight Westie myself I've used with some success the following combination. First I place stretched out "platinum" pot scourers onto the baffle tube and secure it with loops of lockwire. The platinum scourers are fairly course and don't easily blow out. Then onto that I pack large non-soapy Steelo pads and secure with lockwire again. This works real well on 2-strokes anyway but I'm not sure how long the Steelo pads would last in a 4-stroke. It definitely takes the bark out of the noise.

**pete376403** · 19th March 2004, 13:09

Cycleworks in Taita have repacking kits, not expensive. Ive repacked the "muffler" on my IT400 several times and haven't used up the first kit yet.
(observation - its a noisy old crate - most of the noise seems to be the sides of the expansion chamber resonating. Blocking the pipe off doesn't make that much difference to the noise until it finally stalls. then its blissfully quiet )

**bungbung** · 19th March 2004, 13:34

Cheers pete#

I rang Cycleworks. They recommend "Silentsport" material for big twins.

TSS sell this in a big bag for $51. I have no idea how much I need.

**bungbung** · 19th March 2004, 13:49

Handy!

http://www.yft.org/tex_vfr/tech/repack.htm

**speedpro** · 19th March 2004, 14:08

I've got high temp stuff like that from Forman Insulation before. comes in a roll and you just cut off what you need. They used to call it "Rockwool", nice white colour and completely heat proof. Not sure how long it would last in a muffler. You can also buy a sort of woven ribbon sort of stuff from them as well, generally it's used for wrapping things like really hot pipes, or expansion chambers.

**bungbung** · 22nd March 2004, 11:21

Well, I repacked both mufflers on Saturday with this silentsport fill, kinda looks like 8" pieces of knitting wool.

Ever so slightly quieter at idle, more so at revs. The bike seems to be running a bit smoother too.

I expected a bigger drop in volume, but given the straight through design of the cans there is a limit to the effect changing the packing will achieve.

ps wear gloves. glassfibre sucks