Glass pack packing

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muddybike

New Member
Jul 31, 2010
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Calgary
Well for some time, I have kinda wanted to make my bike a bit quieter.
I have a SBP expansion chamber and I bought the silencer with it , but even with the silencer on it, I still felt its a little bit too loud.
(wouldnt feel comfortable leaving for a late night ride while the neighbors are sleeping).
So I took the plunge , and tore apart the SLP expansion chamber , took out the old fiberglass insulation , it was quite oil soaked so maybe that why the bike seemed louder. And found some pipe that I could extend the muffler , to twice the normal length .
Now I want to experiment with different mediums to pack the glass pack with, and compare what has the most sound dreading qualities.

Want to try steel wool , course , med and fine, insulation of different kinds and textures, and try all of the above loosely , or packed in.

Any ideas what might be a good thing to try ?
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
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Conveniently enough, 2" aluminum conduit is perfect for a SBP silencer extension (2" OD, 1/16" wall thickness) & I just used a chunk of (metal obv) window screen to extend the internal baffle & a chunk of everyday fiberglass wall insulation (seems the most common material): http://motorbicycling.com/f3/whats-difference-20708.html#post197273

...and yea, glasspacks do load up after a while on even four strokes, w/a two stroke it's obv gonna happen faster - but it's such an easy thing to repack once a season it's not much of an inconvenience.

For maximum sound deadening ya might wanna try some header wrap: http://motorbicycling.com/f3/wrapped-my-exhaust-24846.html as the expansion chamber itself sorta "rings" with the detonation & the walls are kinda thin.

Other than that, you could experiment with a more advanced baffle - most glasspacks just have a tube w/regular holes drilled in it w/the 'glass wrapped around it... but if you could figure out how to make lil "scoops" into the tube, directing the exhaust flow pulse into the 'glass mat (cut V shapes & bend in or w/e) that may provide a lil more silencing effect w/o much increase in backpressure... I unno tho, I've not tried heh

I did take a chunk of hi-temp auto heater hose and stuck it over the protruding tailpipe, making about a 5" extension to redirect the exhaust past my rear mount kickstand (it was gettin' nasty lol) and that actually quieted it down some too... dunno if that's somethin' that'd work w/your build's "look" tho *shrug*
 
2door

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Let's not overlook intake noise. A lot of the popping you hear when riding isn't coming from the end of the exhaust pipe but from the inlet of the carburetor.

I've experimented with a few ideas to quiet the sounds produced by the intake but the effective ones proved too restrictive. If my memory serves me, Barely Awake had some luck with a remote air box. My best to date is a rattle can top stuffed with a heavy grade felt with the stock air cleaner tubes extending out from it.
Tom
 
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muddybike

New Member
Jul 31, 2010
124
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Calgary
Yeah I have the header, wrapped with header wrap, but as of now not the expansion chamber.
I extended the glasspack part to heh 10 inches long, and for the internal baffle tube thingie , I used copper tubing with 1/4" holes drilled along its length and stuffed the chamber with course steel wool.
I had no luck finding the 2" alum conduit, but used a chunk of pipe that works for now , until I can find the proper tube.
The bike is much quieter now, mostly when idleing when you get on it as BarelyAWake puts it it really wakes up.
All said and done so far for extending the glasspack by almost 3 times the bike is not that much quieter like 2 door said the intake is really quite a bit of the noise of the engine.
It sucks because on my bike I have almost no room to add a remote airbox , a low profile air filter just fits (some dremel work needed).
 
Ernst

Ernst

New Member
May 28, 2011
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Turlock Ca
Very interesting. I am a wandering soul. I like going new places and or taking the path least travelled.

I like the road and the radio so anything that helps me hear my ear buds better is worth the effort.
Also I have the expansion kit on order. Great links and great threads.
 
Ballin on a Budget

Ballin on a Budget

New Member
May 26, 2011
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Vernon, British Columbia
Just thought id mention that if your looking for a packing medium, any motorcycle shop sells the actuall proper packing by the bag and its really cheap. Plus I think one bag would be enough to pack that lil muffler once a month for a year! Maybe somethin to enquire about...
-Dan
 
rustycase

rustycase

Gutter Rider
May 26, 2011
2,746
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Left coast
Better we can do without losing too much horsepower, the better off we all shall be!

I really appreciate the thread.
rc
 
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