Gut Your Goat Bladder (Catalytic Converter)

Text by Ny2AZ

Hoss' Drifter Bladder Alternative Here

Inside The Pre-Muffler (Goatbelly)

Photos Courtesy of Clutch, Bullard Texas, VROC 17881

Objective: A little more sound and less back pressure without the high cost of aftermarket pipes.

Gutting the "goat's bladder" (catalytic converter, AKA "goat belly") if done correctly along with removing the innards from the stock mufflers sounds awfully close to the V&H baggers l've been told...Ok, lets get started...

Removal Of Exhaust System:

Remove all shield assy's and remove both rear muffler assy's. by loosening the clamps at the goat's bladder for the left and right mufflers. Then remove the two bolts holding each muffler to the brackets, one assy at a time. After the two bolts at the rear of the muffler have been removed you now slowly twist the muffler assy so that the front pipe that goes into the goats bladder slides out and frees the muffler. Place each muffler in a safe place so they do not get damaged or scratched. When both mufflers have been removed, you now proceed to the front and rear header assy's. Again, loosen the clamps at the bladder for the front and rear header assy's and loosen the header nuts at the cylinder head... REMEMBER to buy new crush gaskets for the headers.

When it is time to reassemble the exhaust system, new gaskets for the goat's bladder are not necessary since you are not removing the seals to begin with and may be re-used after the bladder has been re-assembled. When all this is completed you now have the goat's bladder suspended by two bolts mounted to the under body frame. Remove both of these
bolts and the bladder will drop.

This is where the work begins. If you have a 10" miter saw or table saw you can buy a 10" grinding wheel and do the work yourself or just take it to a muffler shop like l did. I had my local Midas muffler shop do it and he did the work for me for $30.00 . It took all of about 20-25 minutes to complete the whole process.

Cut On Dotted Line (click for larger image)
With the bladder assembly sitting in a sideways position tell him to slice through it as close to the middle as possible cutting into the lower half of the bladder. 

Catalyzer Removal

After he has completed this he will now have two halves of the bladder assy. One half of the assy will have a steel plate that runs through it with a 3" round honeycomb openingwhere all the exhaust gases have to pass to exit the exhaust. This is where the exhaust builds up extreme backpressure and also mutes the sound level of the exhaust as well. You or he will cut out this section on the bladder out completely.

You are now ready to re-assemble the bladder. Have him clamp the assy and weld it back together. After this is done, spray with black high-temp and re-install the bladder on your scoot just reversing the dis-assembly procedure listed above. After all is back together start the bike and listen to the new sound she makes.


I degreased the bladder with a degreaser, let dry completely and lightly sanded it, wiped clean and sprayed like l said with a black high-temp spray paint. l have since put on 4K miles and it looks as good as the day l sprayed it. No peeling or flaking of the paint. Also cutting a small hole in the bottom of the bladder will not accomplish the same effect as this procedure does. Look at the attached photo (above) and see that just removing the 3" honeycomb catalyst still leaves behind the steel plate which runs across the bladder and creates the backpressure and muffles the sound.

BTW, the goat's bladder does not weigh in at like some have said 20-40 pounds. It does weigh about 8 pound which is maybe a pound or two more than the Dutch bypass.



Here's an alternative method from Hoss using the Drifter converter.

RED areas are one welded on 1 1/2 tube for left hand pipe (area is clearly marked on Drifter bladder). The other red area is a reducer to bring the 1 7/8 exit pipe down to 1 1/2 to fit your Nomad's.

BLUE areas are the perforated tubes that are chiseled out or I used a large screw driver to break them free, then remove them from the larger drifter opening in the third pipe hole.

Black and Gray are the bladder itself.

Hoss' Instructions:

The Drifters bladder has only three external pipes, as opposed to four like the Nomads due to it's left side exhaust pipe. Of the three exit (entrance pipes) that they each have, the two that are above each other on the bladders right hand sides (as sitting on the bike) have 9 1/2" perforated tubes inside them. These two tubes just need to be hammered and chiseled, or a large screw driver will do to free them around there mounting locations, along with a few little tabs that hold them in place (see Drawing for clarification). Once this is done, they can be removed from the third opening that leads out to the back exhaust pipe (on a Drifter bladder it's a larger opening).

That's it, the bladder is gutted! You're done; no cutting open or welding it back shut! Just bolt it back on, re-install the stock Drifter pipe.

One drawback. Because the Nomad uses two pipes out each side of the bike, the exhaust exit ports are identical on the Nomad whereas the exit for the Drifter is larger. All FOUR pipes on the Nomad are 1 1/2" across, but the Drifter has two 1 1/2" and one 1 7/8" for the exit of the Drifters single exhaust pipe. You may need a muffler shops assistance modifying the pipe sizes.

Have You Ever Seen A Dual Exhaust Drifter?

Pretty Cool Eh?????
This Drifter Belongs To Scott "RIDEON" Steen

Tag: exhaust

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