Topic: Home-brew muffler..

[Fabricator]

Howdy all,

 I thought I would share the results of some recent tinkering on recent "bargain bike".  I am doing a full cafe/overhaul on my original '76 750K, but picked up a low miles '75 model 750 recently to ride until then.  It had stock pipes, but I gave them to a friend (the mufflers were trash, and he needed the head pipes for ground clearance), and put the "Mac-style" (Mfr. unknown) 4-1 from my other project on this one.  Since the 4-1 had no muffler, and I did not want to go without some sort of sound dampening, I decided to make one from some medical-grade tubing scraps laying around the shop.  The collector outlet was 2.5".  The actual muffler housing is 3", and the length of the "can" is about a foot.  I made a "core" from 18ga perforated 304ss sheet.  The ends of the core were welded to some 2" (o.o65" wall 316l tube).  I machined a quick 45 degree cone from some 3" 4140 bar, and used it to flare the ends of the core tube extensions in our big press.  The end inside the muffler was expanded so that it would need to be pressed into the 3" outer housing, and would hopefully prevent it from rattling.  After making a 2"id/3"od washer from some more 18ga. scraps for the end-cap, I pressed out another "trumpet" for the outlet.  All this was wrapped in fiberglass matting from the local auto parts store (Mfr. says it begins to melt at at 1100F...) before being safety wired and forced into the housing.  I made a few "Tig" welds to close it all up, and took it to the local muffler shop to have them use their expander to make the inlet slip over the header.  I still have a nice t-bolt clamp coming from Mc-Master Carr that will keep it snug, but it actually did not leak (not that I could tell).  A quickie hanger bracket was plug-welded to the can, and borrows some space from the p-peg bolt to keep it all "happy".  The pics below were taken at night in the shop, so they are a bit "washed out" by the flash, but you will get the idea. 

http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack1.jpg
http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack2.jpg
http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack3.jpg
http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack4.jpg
http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack5.jpg

Unfortunately, it is the shiniest thing on the 'ol ride...  It sounds good (to me anyway), and has enough growl to be a bit on the loud side when you are on it, but idles and cruises with only a moderate "burble".   Anyone else out there make their own muffler?

Cheers

Fabricator

[c91x]

yeah.... i wanted a shorty muffler and the stock was rusted out  so i used the stock chrome shock cover cut it down to diam used the inner core off the old muffler and cut down and rewelded the stock clamp... i'll have to take pic later 

[mystic_1]

Hey Fab, here's a tip for posting pics:


use your mouse to highlight the URL of the picture, and hten click the "Insert Image" button in the button bar above the smileys.  That'll add IMG tags around your URL, and your pics will appear inline with your text, like so:

Code: [Select]

[img]http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack1.jpg[/img]
[img]http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack2.jpg[/img]
[img]http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack3.jpg[/img]
[img]http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack4.jpg[/img]
[img]http://img.photobucket.com/albums/v619/FabricatorCEO/Glasspack5.jpg[/img]







Nice work btw

cheers
mystic_1

[Fabricator]

Thanks for the picture tip Mystic.   Sorry for the crummy shots on the bike... By the time the muffler was done, and the bike was running it was late.  I did not even bother to wipe the thing off before taking pics...  It was done more for grins than show.

Fabricator

[Industrial Cafe]

that looks really good, I like the bell end, I want to make the same thing but shorter and a rolled out end.

[Jerry Rxman Griffin aka MuthaF'er]

Nice work Fabricator.

Well boys, it looks like we have another SUPPLIER on board. Hope you might decide to make these/others available.

[Fabricator]

Fellas,

   I never thought about selling them...  If anyone needs some flared ends, let me know.  I machined the forming cones for 1 1/2",2", 2 1/2", and 3" tube.  I have 1"-6" (0.065" wall ) 304 and 316L tube in stock, and could send the parts to interested folks.  In the meantime, I will look into getting some better pics, and put a dollar figure on the concept.  The 2" flared cones are nearly perfect for velocity stacks too .

Fabricator



On edit:  I have decided to go ahead and make 5-6 of these shorty glasspack silencers.   I will "bump" this thread then.  I will be able to sell them for about $120.00 each,  and  shipping would be whatever it is to you.   If there is enough interest to make many more, the cost will obviously drop.  One of the tubes is over $10/ foot, and that makes for a fair investment for me when my "pile-o-scraps" is depleted     I did not include the cost to expand/swage the part that fits over the header outlet. You really need to take your header with you and have that done fit at your local muffler shop.  If done properly, on a true piece of tube, it will prevent you from needing a pair of notches and a clamp (like mine... My collector was beat up).  I will deal with determining what it will cost to swage them and make the 2 notches, and add a clamp shortly, as I need to machine the expansion die.  If I get too busy, I will have my local muffler shop expand them for me    I have changed the design slightly to streamline the transition from the 2 1/2" inlet to the 3" housing.  I will post pics of the completed design as soon as I get a few made.