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Re-packing muffler cans
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brian



Joined: 22 Aug 2011
Posts: 3243
Location: Australia

PostPosted: Mon May 06, 2019 8:59 am    Post subject: Re-packing muffler cans Reply with quote

I know that there’s nothing too technical about re-packing an exhaust can, but I’m just after advice regarding how packing a muffler differently will alter the sound level and note of an exhaust system.

I finally got around to fitting a race exhaust system that I bought a while ago for my SB6. My intention was to simply get some more noise out of it rather than chasing performance as the stock SB6 system is very quiet. When I bought the system from a member on here, the seller told me that it was too loud for him..... well I can confirm, it is very loud and sounds tinny. It has no packing in it at all and I think the sound is echoing in the empty aluminium cans.

I want it loud but not too loud and not tinny. I’m just wondering if there is a method of packing the mufflers or partly packing the mufflers that will achieve this?

Any ideas?
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brian



Joined: 22 Aug 2011
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Location: Australia

PostPosted: Mon May 06, 2019 9:18 am    Post subject: Reply with quote








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brian



Joined: 22 Aug 2011
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PostPosted: Mon May 06, 2019 9:22 am    Post subject: Reply with quote

It looks like a stock system to me but it bolts together rather than being rivitted together and it has a Plate on it saying ‘for race use only’
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Current motorcycles - '99 Bimota DB4 #104, '96 Bimota SB6 #1165, ‘94 Bimota DB2 J #652, '99 Bimota DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, ‘94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, ‘61 BSA A10 650
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GeeKay



Joined: 29 May 2009
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Location: West Yorkshire

PostPosted: Mon May 06, 2019 10:02 am    Post subject: Reply with quote

for my 2-strokes I buy exhaust wadding off ebay, wrap it around the baffle tubes and secure with stainless wire (the stuff used for lock-wiring race bikes). How much you wrap it determines the noise level (to some extent).
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2bims



Joined: 03 Apr 2010
Posts: 6570

PostPosted: Mon May 06, 2019 11:36 am    Post subject: Reply with quote

As per Geekay.....When I bought my New FMF Gnarly end can for my KDX...it was immediately noisier...but not too noisey….as it was a straight thru end can....instructions said re-apck after every 20 hrs of use....meaning....after 20 Hrs it will get noisier....as the material gets soaked with exhaust products and its sound deadening performance diminishes.....My interpretation was …."use for 20 hrs and the true sound will come through and just get better and better after that if you dont repack....and I can confirm that to be the case......Thus yes...it will stop the tinny ring sound.....and as it gets coked up the straight thru principle will increase as gases are like water...they take the path of least resistance in their efforts to escape......thus when new they will go into the material but this will get less and less
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Bud977



Joined: 03 Mar 2013
Posts: 436
Location: Sydney

PostPosted: Mon May 06, 2019 9:57 pm    Post subject: Reply with quote

The packing deteriorates quicker in a two stroke like the KDX because it get soaked in two stroke oil splooge, making it effectively solid.

So it lasts much longer than 20 hours in a 4 stroke.

So Brian, I'd pack some of that exhaust wadding in there and it will do the job.

Quite an unusual looking pipe for a race pipe. 4-2-1 pipes are usually a mid range pipe, the junctions and pipe sizes??
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2bims



Joined: 03 Apr 2010
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PostPosted: Mon May 06, 2019 10:13 pm    Post subject: Reply with quote

Bud977 wrote:
The packing deteriorates quicker in a two stroke like the KDX because it get soaked in two stroke oil splooge, making it effectively solid.

So it lasts much longer than 20 hours in a 4 stroke.

So Brian, I'd pack some of that exhaust wadding in there and it will do the job.

Quite an unusual looking pipe for a race pipe. 4-2-1 pipes are usually a mid range pipe, the junctions and pipe sizes??



I do like "splooge"....Or Gook or splurge its often referred to...but yeh...I concur....I just didn't have any knowledge of packing 4-stroke exhaust cans to offer.... Embarassed
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brian



Joined: 22 Aug 2011
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Location: Australia

PostPosted: Mon May 06, 2019 10:42 pm    Post subject: Reply with quote

Thanks for the replies fellas. I’ll buy some wadding and do some experimenting. It’s not too much trouble to pull apart so I might try a couple different ideas
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brian



Joined: 22 Aug 2011
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Location: Australia

PostPosted: Tue May 07, 2019 9:00 am    Post subject: Re: Re-packing muffler cans Reply with quote

brian wrote:
..... well I can confirm, it is very loud and sounds tinny. It has no packing in it at all and I think the sound is echoing in the empty aluminium cans.




In fact.... I think the fookin thing is LOUDER with the mufflers on than it is with just the headers pipes on and the mufflers off Shocked Rolling Eyes
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2bims



Joined: 03 Apr 2010
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PostPosted: Tue May 07, 2019 9:49 am    Post subject: Reply with quote

If the mufflers have no wadding then its the acoustics effect of it resonating around the baffles evidently....that'll lessen with wadding ...just make sure you buy the right stuff thats fire retardant....I wont ever buy Ram air foam filters since I've heard and seen the horror stories of allegedly "fake" versions being sold...that catch fire....
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rpo83



Joined: 28 Oct 2008
Posts: 387
Location: Melbourne, Australia

PostPosted: Tue May 07, 2019 9:51 am    Post subject: Reply with quote

When i pulled my mufflers apart to get them polished, i repacked them lightly with 2 stroke muffler packing, It is widely available from most bike shops.
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Evilchicken0



Joined: 12 May 2010
Posts: 2959
Location: London

PostPosted: Tue May 07, 2019 1:52 pm    Post subject: Reply with quote

There are 2 stages to repacking. First is stainless steel wire wool (normal wire wool will burn !!!) around the baffle tube - wear strong gloves it will cut your hands to shreds. Then you put the wadding around it. You can get wadding that comes compressed it has a coating over it that lets go with heat, if you don't use this you need stainless cable ties to hold the wadding while you feed the can over it.

https://www.ebay.co.uk/itm/Exhaust-End-Can-Packing-Sound-Silencing-Sheet-Motorcycle-Bike-Motocross-1M-x-400/291805870634?epid=1505445054&hash=item43f0fc3a2a:g:KMsAAOSwbYZXcxZl
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brian



Joined: 22 Aug 2011
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Location: Australia

PostPosted: Tue May 07, 2019 11:09 pm    Post subject: Reply with quote

Thanks again fellas for the comments.

I’m still not sure how to control the amount of ‘loudness’ that the mufflers produce using the packing. I’m assuming that the packing will need to be tightly packed between the baffle tube and the outer can otherwise it will come loose and disintegrate? I’m also assuming that if it’s tightly packed then it will be quite? Is it possible to pack it with strips of packing leaving gaps between the strips of packing along the length of the can? I’m guessing not as this will come loose as well. Will it be louder if it’s wrapped more loosely?
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Current motorcycles - '99 Bimota DB4 #104, '96 Bimota SB6 #1165, ‘94 Bimota DB2 J #652, '99 Bimota DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, ‘94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, ‘61 BSA A10 650
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brian



Joined: 22 Aug 2011
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Location: Australia

PostPosted: Tue May 07, 2019 11:12 pm    Post subject: Reply with quote

Do you think the stock mufflers would be the same inside as these ‘race’ mufflers? Meaning, will the stock mufflers have a straight through baffle or a different series of baffles to make them more quiet? If that’s the case then simply packing these ‘race’ cans tightly may give me the result that I want..... loud but not offensively loud and tinny.
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Current motorcycles - '99 Bimota DB4 #104, '96 Bimota SB6 #1165, ‘94 Bimota DB2 J #652, '99 Bimota DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, ‘94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, ‘61 BSA A10 650
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2bims



Joined: 03 Apr 2010
Posts: 6570

PostPosted: Tue May 07, 2019 11:32 pm    Post subject: Reply with quote

A lot of "modern" 4 stroke end cans come with removable baffles....which is basically a cone inserted into the end with a flat plate on it that takes impact of exhaust gases and slows its exit...or diverts it around something to again slow it down...and when removed its classed as "straight through"...i.e. you can poke a stick the full length down until it hits a bend in the pipes after the end can....other large end cans can have cats in them.....more blockages...or fixed diversion plates to again slow....like putting your hand over the bell end of a trumpet to quieten it....
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