Mike's commando muffler

pa23driver

pa23driver

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so apparently i failed to measure my stock exhaust headers correctly and i thought that the XS performance commando style megaphone muffler would fit without an adapter. Imagine my surprise when the mufflers designed to fit a 1.5 inch pipe wouldn't fit over my 1.57 inch headers.

so my question is what would be better.....

1) buying the reducer sleeve set from Mike's

or

2) grind out the weld holding the inner and outer walls together (the weld is in great shape) and put this exhaust adapter in between the two header pipes and clamp the muffler on the big end.

X8Bmphk4BwO-LWUyHY-XMH89_FBdUX_B2wq0PaDQ7wcoBP2ZnjprYxc5N3rZrYtKbziYISfBIJ6CIA4RcNiGK9HMA5tXEUBFftWUIV83R8MGZiFDU7rlsM93qZ8oaOHw9isVIK9osIK0N7TrWU2Z0TFj3BDDPkw8gvZbSQGETaO7mqaMp_hLQ5SUPTCg6OVLXxTkvzLLNYi8Ag81tyOxSAkuwNOgXBQ=s90

the adapter is 1.5" ID x 1.37" OD
 
pa23driver,

Are your stock headers double walled? If so, then you have to use an adapter to connect to the inner pipe as the outer pipe has holes in it.
 
yep, they're double walled.

the walls are welded together at the end where the muffler hooks up, and the weld is in great shape - i doubt exhaust would leak out of the inner header tube to the outer.
 
well i was looking at it again, not sure if its welded or if the inner pipe is just expanded at the end... either way i'd have to either cut or grind that expanded/welded portion out to fit the adapter. just looking for some opinions before i potentially trash my head pipes.
 
What i might try is expanding the muffler a bit. Get a piece of pipe that will fit inside the opening in the muffler, A foot or two of 1 inch water pipe will work. Slip about two inches into the muffler. As you hold the muffler roll the water pipe around the inside of the muffler while putting pressure outward on the pipe, this should open the end of the muffler enough to get it started on the head pipe.
Now mount your head pipe on the bike. Start the muffler onto the head pipe and move the end of the muffler in circles as you push the muffler onto the head pipe.
This may take awhile and make you sweat. Once you get it on the head pipe about an inch the clamp should seal the muffler onto the pipe.
When your doing this be sure you keep the muffler mounts in the right place so they can bolt to the frame.
On your headpipe whether its welded or expanded it will seal ok. It did with the stock mufflers.
 
On the older standard exhaust the mufflers were not welded onto the head pipes. The inner and outer head pipes were welded our the inner expanded to seal the pipes together. I think the out was tapered down just a bit to help the muffler slip on.
On the front of the muffler was a large nut that was threaded on the the muffler. There was a seal/gasket that fit between the nut and muffler. Once the muffler was on the head pipe and bolted to it's mounts the muffler nut was tightened to compress the seal/gasket and expand it to seal the muffler to the head pipe.
On the later Specials they welded the head pipe and muffler together as a single unit. Then to replace the muffler you need to cut the old one off at the weld. This is when you need the adapter to seal the inner head pipe to the muffler.
 
Thanks for the explanation on the various exhausts, helped me figure out where pamcopete was coming from. i'll try expanding the muffler with the head pipe, there is a slight taper on the end of head pipe that lets me get things started - i'm only able to get about 1/2 inch with a mallet and block of wood on the end of the muffler before things stop
 
Yes, wiggling the muffler around helps expand the muffler opening more than just whacking it.
 
Put anti-seize on the end of the headpipe to "lube" the install process. It will also help seal the joint and make removal in the future easier. We put a set of these on my buddy's bike last spring. One slid on perfectly, the other took some work. Obviously, they're not made to exacting standards. Better tight than loose, though.
 
Here is a procedure to install 1 1/2" mufflers to the inner pipe of the stock double wall headers.

Here are the materials you will need. All together cost about $10.

Materials.jpg


That object on the left is a brass, chrome plated, 1 1/2" sink drain pipe. I have already cut a section out of it and split it to be used to cover one of the adapters.

Here is a picture of the adapters connected:

Adapters.jpg


Here is what they will look like with the piece of chrome drain pipe:

ChromeCover1.jpg


Here are the adapters and the chrome cover installed in the muffler:

ChromeCover.jpg


And here is the finished installation. Notice how the chrome drain pipe cover hides the adapter:

OntheBike.jpg


Start by fitting the first adapter onto the inner pipe of the header. You will have to file the inside of the small end of the adapter and, as much as possible, the outside of the inner pipe.

I did this procedure to install Mikes #07-0065 "Commando" mufflers on my '81/H to work with Mikes 32mm Keihin Flatslide PWK Carb Set . This is a great combination, along with the "Ultimate" PAMCO ignition.....awesome power!!
 
Thanks all for the suggestions. I'm gonna rent a tail pipe expander from autozone today to see if i can stretch the muffler the extra .07'' i need for it to clear. if that don't work i'll try wiggling the muffler on again or see if a muffler shop can stretch it, if all else fails i'll do some grinding and do what pamcopete suggested
 
pa23driver,

Well, if you stretch the muffler you will not be able to use my suggested method and you will ruin the muffler for future attachment to Mikes replacement headpipes Part #07-0757 for which they were intended to be used. Basically, if you can't use my method because the original headers have been ruined, then order up a set of Mikes pipes.
 
the original headers aren't ruined, they're just off of a 77 standard which had detachable mufflers - the inner pipe isn't floating within the outer pipe - the inner pipe was expanded just prior to the muffler (from the factory) effectively sealing the inner pipe from the outer pipe at the muffler. XSLeo explained it pretty good in post #7.

with specials the mufflers are welded to the headers at the factory which requires you to saw em off to change em out - which leaves the inner pipe floating in the outer pipe allowing your adapter (which is a great idea) to work.

i may just order up a set of new headers, the stock head pipes are kind of rough looking, good candidates for exhaust wrap (which i'm not sure i'm ready for)
 
Well this sucks. Why do we have to jury rig everything? Just bought a set of these off eBay but I haven't tried them on my XS650B yet.
 
Mark, Why the suck?

74-79 Standard headers are different to the special Exhausts in that the 74-79Standards do not require Pamcopetes method for aftermarket exhausts, as explained in the post #14, the Special Exhausts are one piece and when the muffler gets cut off the header inner tube is not sealed from the outer header, Hence Pamcopetes solution.

74-79 Standards, (as per yours), have their mufflers as a separate part that has a screwed fitting to connect the Muffler to the header, so when they are separated you can see the header inner pipe is sealed to the header outer so Pamcopetes solution is not required
 
Pics or/and a detailed explanation of the parts bought and of you headers will help me to be able to help you. Afraid my esp is off line
 

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