Anatomy of a Harley muffler

Soon you all shall see the innards of them thar Harley mufflers. I'm modifying and replacing the baffles in mine.

Looking forward to it. It will be nice, for a change to have you baffle us for a good reason.

JPSmit said:

Looking forward to it. It will be nice, for a change to have you baffle us for a good reason.

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:lol:

Will post pics later. Got it back together, as quiet or maybe slightly louder than a stock muffler but still straight through.


Honestly, I don't know if I like it this quiet.

Center baffle tube removed with hole saw on outlet end (on right). Note removed center plug and weld bead on main tube where previously installed. Note uneven number of holes before and after plug.




Close up of center plug. Note weld marks.




Center of main tube with plug removed.






Modified main tube awaiting installation. Results are much quiter operation, close to stock levels. I've never heard a straight through muffler sound this quiet. It's almost too quiet.

Cool.

Morris, you running one?

I don't have any idea on what was going on to start with in that muffler... Did the exhaust go in one end, hit the plug, go out of the holes into the outer chamber then around the plug and back in through the holes to exit?

If so, was it louder that way, than straight through?

Were the cuts to allow more ventilation to the outer chamber?

JOeyKnapp said:

Did the exhaust go in one end, hit the plug, go out of the holes into the outer chamber then around the plug and back in through the holes to exit?

?

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Dead on!

I didn't ever install it with the plug in as its too restricitve that way. I installed it with the just plug knocked out. It was fine, but had a "tweet" sound like a VW. I didn't notice it at first but friends did. I could hear it evey so often after they mentioned it and it drove me nuts.

The "tweet" is from air sucking back through the holes. I cut the slots to allow the air to travel through w/o making the tweet sound. It definatly helps and also makes it quieter.

Thanks for the info.. Do you have a picture of one of those assembled? Which specific muffler is it? Is this a performance upgrade to the stock muffler?

Billy, I am not running one now. But I probably will be some day.

Joey, The best one to use is bullet shaped, tapered at the tip. A couple of adapters will get you to the right sized pipe and a big U bolt goes around that muffler and can attach to a hanging strap connected to the traditional mounting point. Mine came for free from local Harley store out of their scrap pile. These get replaced frequently as often damaged when someone drops their bike or when someone wants louder pipes. I tried a couple of the other variations, big tip, non tapered and they made Bugsy sound like a rice-rocket or a big fart can. The tapered one gives a quite pleasing sound when attached to a 4 cylinder engine. No pics here, I can post one later from home. Search Harley Muffler on this site for further discussion and pics as lots of folks are using these mufflers.

Softail or Dyna uses the bullet shape. Make sure whatever you get hasn't had the whole baffle core removed and isn't the catalyst type.

I don't like adapting to the stock Harley sized pipe. That kills too much velocity IMO. You don't have to use adapters if you have a stock sized pipe (1500) and a welding machine. You cut the mounting end off of the Harley muffler and shove the stock pipe inside. It has a nice pressed fit. (It really doesn't need to be welded but may have slight leakage if not. You can run it that way for a while, I did.)

What I did was cut the outlet pipe off of my stock MG muffler, then shove it in the Harley muffler (after I cut the mounting end off) and weld that in. I then used a coupler to mount it to my pipe. That way, I could remove it later if I had to. The sytem is now the same ID size all the way through and velocity is almost as high as a straight factory sized pipe. It has as little restriction as a straight pipe but still silences the noise.

IMO the center plug must be knocked out. Look at the number of holes on the outlet side of the baffle plug. This is designed for ONE cylinder of HALF the volume of the 4 cylinder it will now go behind. It was designed to handle ONE exhaust event, not four. Let's not forget they have a balance tube between the mufflers on a Harley, thereby connecting BOTH mufflers to handle ONE exhaust event every 360 degrees in stock form.

If you are so equipted (welder and grinder) you can increase flow with the plug in by the above mods. Having run both unplugged and unplugged/modified, it's my opinion just knocking the plug out is the best method for both noise control and power. (although does have some VW "tweet" with the plug removed and no baffle mod)

There is an extra layer of soundproofing in the outter shell that does a good job of silencing things.

It's a lot quieter than you would think and produces more low end power than the baffle core in modified form or removed completely. It may very well be the best performance muffler avalible for the stock sized pipe....as long as the center plug is removed. I'll try to get some pics of what I have.


I wish I had a dyno as I'd put it up against anything that's out there. It's that good....if you can live with the tweet (plug out, no baffle mod).


With the plug out and baffle mod, I have more wind noise than exhaust at highway speeds. It's almost too quite. I may go back to unmodified baffle and no plug. Bare in mind, this is with a 7.5-to-1 1500. Higher compression will result in more noise.

kellysguy said:

I wish I had a dyno as I'd put it up against anything that's out there. It's that good.)

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Please bare in mind I'm talking aboutt he muffler itself, not nessisarily anything I've done to it.


I forgot to mention, all you need to do is hole saw the outlet end to remove the baffle. Once it's cut it'll slide right out with a bit of wiggling. Use the smallest hole saw possible (I'll measure mine) as you want lots of meat b/w the weld area and the chrome around the tip. Don't try to pull it all the way out as it won't come unless you trim the hole biggeer. The idea is get it far enough out to modify the holes without removing too much material from the muffler housing.


I used wet toilet paper as a heat sink to keep the chrome from discoloring. I had the machine set pretty cold too. "Booger" welds are fine, it doesn't take much to hold the baffle in and you can grind them back down. The main concern is don't get things too hot and discolor the chrome. Staying as close as possible to the center of the baffle is the best way so don't get crazy when cutting. A heat sink goes a long way too.

Dumb question: I've got a couple of H-D mufflers (case of beer to the shop that gave them to me for free; an owner had upgraded to more noise...)but they're pretty bulky. I tried lying under the BE a year or so back, and couldn't figure out how to install them, as they were too long to go behind the axle and too bulky to install under the axle.
I'll try to get some pictures this week, and also try to figure out how to attach the photos!
Thanks,
Doug

This is the one you want to look for.

One More time

Installed

From he back

That looks nice!

Jim, it's kind of funny.. You see so many car pictures on the net with the license plate blurred.. Your plate is your avatar!