Author Topic: Homemade custom muffler build (with pictures) - Second Attempt  (Read 49716 times)

Offline quiktaco

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Just wanted to start the thread for my custom muffler build.  I'm making my own muffler.  From scratch.  No slip ons.  No pre-made stuff.  The reason...I hate the look of a muffler.  I'd like to just chop it off, but things like back pressure and noise level have kept me from that.  So my solution will be a short and small homemade muffler.  it's about 11 inches long and it will be 2.5 inches in diameter.  I want it to almost look like I just chopped it off.  It's going to go straight back with no bends, and almost look like a straight pipe.  Very clean and simple, to make the bike as minimalistic as possible.

As I go, I'll post pictures of the actual build, the conceptual drawings, and video so that you can hear the sound of the muffler when it's complete.

I'm estimating the cost will be significantly less than $50 to complete, with much of the cost going to fiberglass packing (hopefully I can find it cheap).  So far I've spent about $15 on the actual pieces of the muffler.  It will all be welded together with a Hobart Handler 140, except for the baffle, which will be removable to make adjustments and to repack if it ever needs it.

I welcome all your comments and suggestions, good or bad.  In the end, I'd like it to be as quiet as possible and maintain about the same back pressure as the stock muffler.  I know it's not going to be possible in a significantly shorter and smaller space, but those are my hopes for this project.  I'll be rejetting afterward to get the air/fuel mixture back to how I have it now.

Hopefully you'll enjoy this, and be inspired to do some project on your own bikes.
« Last Edit: July 16, 2008, 01:11:44 PM by quiktaco »
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline darb85

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Re: Homemade custom muffler build (with pictures)
« Reply #1 on: March 26, 2008, 02:56:20 PM »
would love some pics when you are done!
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Offline bucks1605

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Re: Homemade custom muffler build (with pictures)
« Reply #2 on: March 26, 2008, 03:12:45 PM »
I'm very interested to see how this turns out. Keep us updated.  :thumb:
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Offline dgyver

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Re: Homemade custom muffler build (with pictures)
« Reply #3 on: March 26, 2008, 04:00:36 PM »
....
I'm estimating the cost will be significantly less than $50 to complete, with much of the cost going to fiberglass packing (hopefully I can find it cheap).  So far I've spent about $15 on the actual pieces of the muffler. 
....

Is this cheap enough? I have the same stuff to repack several exhausts.

http://cgi.ebay.com/ebaymotors/10-x-38-MOTORCYCLE-EXHAUST-MUFFLER-FIBERGLASS-PACKING_W0QQcmdZViewItemQQcategoryZ34284QQihZ004QQitemZ140218227745QQrdZ1QQsspagenameZWDVW

http://cgi.ebay.com/ebaymotors/20-x-38-MOTORCYCLE-EXHAUST-MUFFLER-PACKING-WRAP_W0QQcmdZViewItemQQcategoryZ35573QQihZ003QQitemZ130208723582QQrdZ1QQsspagenameZWDVW
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Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #4 on: March 26, 2008, 04:03:39 PM »
HOLY CRAP! That's perfect.  Cheapest I found was 25 bucks, but I hadn't really looked yet.  Thanks for that link.

Update to estimated cost... $25
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #5 on: March 26, 2008, 04:52:57 PM »
Just bought the cloth.  Thanks so much for that link dgyver.  That one piece will probably work for 2-3 of these mufflers.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline ben2go

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Re: Homemade custom muffler build (with pictures)
« Reply #6 on: March 26, 2008, 04:57:21 PM »
May I ask, what materials you will be using to make the shell and baffle?
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Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #7 on: March 26, 2008, 05:07:16 PM »
It's 1/16 inch exhaust tubing.  Steel/zinc coated for corrosion.  (The baffle however is a piece of galvanized emt) Shhh don't tell.  I figure since there's only about 2 inches of weld that will be on it it's not a big deal for the fumes.  Just grind of the galvanizing and I'll be good to go.  I'm making the baffle myself too.  It's a 1" piece, but actually measuring 7/8" outside diameter and 3/4" inside diameter.  It matches up to the size of the existing outlet of the stock exhaust pretty well.  I also got a plate of 1/16" steel to cut out some miscellaneous other pieces I'll need.  And also an adapter to bring it down to the 1.75" of the stock exhaust tubing.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline darb85

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Re: Homemade custom muffler build (with pictures)
« Reply #8 on: March 26, 2008, 07:43:38 PM »
by the way, where are these so called pics! :D  I want pics! ;) :laugh:
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Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #9 on: March 26, 2008, 07:45:38 PM »
lol, I was waiting for that.  I'm going to post them tonight.  I just started the thread while at work and I'm not home yet, so no pictures yet.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #10 on: March 26, 2008, 07:58:54 PM »
BTW, I purchased the 10" x 38" piece, not the 20" wide one.  The baffle that I'm making is either 8 or 9 inches long, don't remember.  There's also a diffuser and a small expansion area in my design that doesn't require the cloth.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline ben2go

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Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #12 on: March 26, 2008, 08:40:52 PM »
I had thought about that, but with only a baffle the noise level would be too high for me.  Also, the size of the baffles that I did find were too large of an inside diameter and would allow too much flow, causing a huge drop in back pressure.  From what I've seen, this bike needs the back pressure or the exhaust valves will die a horrible death.  Tell me if I'm wrong, but I figured I could make a descent muffler with a smaller diameter baffle, fiber packing, and a diffuser, and get the sound level down pretty low and keep the much needed back pressure.

Thanks for the comment though.  If this project turns out to be a huge disaster, then maybe I'll try that route before welding the stocker back on.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline makenzie71

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Re: Homemade custom muffler build (with pictures)
« Reply #13 on: March 26, 2008, 09:21:17 PM »
hmmmm...I don't see any pics.

Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #14 on: March 26, 2008, 09:40:23 PM »
Here's all the supplies that I've got so far.  Uncut and just some pencil markings on them.



Here's the basic design.  I've kinda layed it out in the picture.


Let me know if you have other questions about what's going on here.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline ben2go

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Re: Homemade custom muffler build (with pictures)
« Reply #15 on: March 26, 2008, 10:09:01 PM »
Have you tuned a lot of 2 strokes?4 stroke engines don't use expansion chambers.3/4 inch outlet?A flow thru slip on is 1 and 1/8 to 2 and 1/4.Find a dyno when you're dun.Maybe you're onto something.  :dunno_white:
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Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #16 on: March 26, 2008, 10:19:32 PM »
No, haven't tuned two stokes.  I've studied up on muffler design, and diffusing the gasses/soundwaves, then letting them expand slightly, then forcing them into a smaller opening again tames the noise level and increases backpressure.  An expansion chamber in a 2 stroke is a lot larger than what I have here, and are generally used to increase low end torque if I'm not mistaken.  Thanks for the input.  I was thinking about ditching the idea of diffusing it, but figured I might as well, cause I want it as quiet as possible.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline quiktaco

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Re: Homemade custom muffler build (with pictures)
« Reply #17 on: March 26, 2008, 10:21:17 PM »
Oh, and the 3/4 inch outlet is because I'm cutting away about 2 feet of pipe that the gasses would normally travel through, so I figure a smaller diameter outlet will increase backpressure some.
147.5 mains / 40 pilots / 2.5 turns / 3 #4 / 2x 3/32" holes in slides / lunchbox / 15 tooth / Chopped Exhaust . Seat . Subframe

Offline bombadillo

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Re: Homemade custom muffler build (with pictures)
« Reply #18 on: March 26, 2008, 10:52:28 PM »
More pics, I demand more pics of a finished project!!!  :icon_lol: 

keep us posted!
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Offline Kurlon

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Re: Homemade custom muffler build (with pictures)
« Reply #19 on: March 26, 2008, 10:53:07 PM »
A lack of backpressure is only a problem if you don't rejet.  If you jet up to match the increased flow, your exhaust valves won't cook.
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