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General Category >> Technical Documents/Reference >> Change EMGO (or any) muffler to work well
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Message started by Gyrobob on 11/07/12 at 07:48:30

Title: Change EMGO (or any) muffler to work well
Post by Gyrobob on 11/07/12 at 07:48:30

The EMGO muffler sent with the RYCA kit is a commonly used aftermarket muffler that costs maybe $70 if you buy it separately. It doesn't muffle any after it is used for 20 miles or so. The excuse for packing EMGO puts in there disappears soon,... then all that you have is a perforated pipe inside a chrome megaphone-shaped case,... loudy loud loud!!

I tried fooling around with better packing as shown in pic #2. It got just a little quieter, but the back pressure went up because ALL the exhaust has to flow through the perforated baffle in the middle of the pipe.

The final solution is to take out the packing, and add three baffles so the exhaust flows out through a couple compartments inside the case on its way out. The final baffle is a sink strainer bought Home Depot or Walmart. Use the one with the thickest metal.

Some welding is involved, but it is really simple stuff you can do with a cheapo wire feed welder bought at some discounter like Harbor Freight for less than the cost of two of these mufflers. Something like this one maybe: http://www.harborfreight.com/wire-welder-90-amp-flux-68887.html

Of course, a better MIG or TIG or gas welder will work fine. A stick welder, with my limited skill, would be too crude for the thin metal of the perforated core.

This mod can be used on all sorts of mufflers that have a perforated core inside a larger case. The idea is just to get the exhaust (and the associated noise) to have to flow through a couple or three compartments on its way to the street. I even made one once out of a 24" piece of exhaust tubing (1 1/2") and a propane canister.

Here's the EMGO muffler taken apart showing what THEY believe is good engineering.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/RYCAEmgomufflerpack3Large-1.jpg

Here's a close up of the perforated core and the toilet-paper-grade packing.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/RYCAEmgomufflerpack2Large-1.jpg

Here's my first attempt at better packing, using some stainless steel scouring pads and the original packing scrunched up into a denser mass. It didn't last long, and it was still pretty loud even though it added backpressure.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/RYCAmufflerrepack8Large.jpg

Here's what it looked like with the blown-away fiberglass replaced by more stainless steel.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/Sinkstrnrmod3a_zps4a7afdaa.jpg

Sink strainer with some additional holes,.. brazed on to the outlet side of the core. The brazing didn't hold very long. it probably would have if I would have brazed it all around the strainer. The tone of the muffler was less offensive, but it still felt like it was choking off the exhaust flow.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/Sinkstrnrmod10a_zps8802dbe1.jpg

So here is the solution that works. All the packing is removed. A concave baffle (shown being held outside the core for the pic) is to be welded inside the perforated core. A large baffle is to be welded to the outside of the core. Not shown is the sink strainer. The stock perforated baffle is still inside the core.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/EMGOMod04.jpg

This is what the exhaust flow looks like.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/EMGOmoddrawing01.jpg

The baffles welded to the perforated core. From left to right:
-- sink strainer
-- original baffle still welded inside the core
-- the large baffle welded on the outside of the core
-- the concave washer baffle welded inside the core

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/EMGOMod05.jpg

Looking at the input side of the baffle with the concave washer welded in.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/EMGOMod03.jpg

The assembly with the sink strainer baffle welded on,,, inserted into the case.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/EMGOMod02.jpg

All assembled.

http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/EMGOMod01.jpg\

This setup has been working for a hundred miles or so now. The aggressive thumper noise is still there, but nowhere near as obnoxious. I can now ride around in traffic, or drive through a neighborhood late in the evening without feeling like I am making people hate motorcyclists. It feels like there is less backpressure, too, because it doesn't act like it is running as rich as it did before.

Title: Re: Change EMGO muffler to work well
Post by 360k+ on 11/08/12 at 08:09:25

LOL, at first I thot your handle was Gynobob 8-)

Good job documenting the muffler work you did. Man you've thrown everything in there but the kitchen sink... oh, wait a minute!