Altering stock mufflers

[RacingOrangeRoadster]

I am wanting to make my Ultra a little louder and I was at a swap meet in November and bought some 06 CVO mufflers for $20. I figured for $20 if I screwed them up I wouldn't be out enough to worry about. Well I got them home and installed them and my bike would hardly run. Turns out they had Catalytic converters in them, so I ground off the welds holding the sleeve in the muffler and removed the Catalytic Converters. Re-installed the sleeve and put the mufflers back on and the bike ran fine but it wasn't any louder than stock. Pulled the mufflers back off and removed the fiber glass from each one and then tried them and they are still only slightly louder than stock during normal riding but if you get into the throttle you can tell they aren't stock.

I'm not looking for the sound of gutted mufflers but a little rumble would be good. The way the exhaust pipe comes into the muffler it comes in about 10 inches and then is diverted into the large chamber. Has anyone altered the inside piping of the mufflers to redirect the flow and if you did, how much did you change it?

[arthureld]

I've never done it but I have heard of people taking a long 9/16 drill and drilling a hole thru a plate inside the exit side of the exhaust. The hole is supposed to be in the center.
That sounds ok. Probably just as good as most aftermarket slip ons.

It's worth a try since you have extra mufflers anyway.

I'm sure Heretic will give you much better advice because he's always tearing up exhaust and creating new ones.

[RacingOrangeRoadster]

Yeah I figure he'll chime in here sometime unless the Lion's mate ate him.

[Heretic]

no...I have not become cougar bait yet..

anyway, mufflers really have little to do with performance, IF the exhaust is tuned properly....but of course, we know that most systems are not.......so here is the big point to remember. Most of the noise you hear is NOT combustion. that is actually insulated within the engine. most of what you hear can best be described as rapid firing mini sonic booms. When an exhaust valve opens gasses escape even before the piston starts up on the exhaust stroke. This is called a primary pulse. In layman's terms, this is just an escape of the pressure in the cylinder head. This primary pulse leaves the head at 1300 to 1700 feet per second. That creates the mini sonic booms I mentioned......in a well tuned exhaust the primary pulse maintains so much pressure and momentum it shoots down the pipe, leaving a low pressure area behind it. Then as the piston starts up, forcing out the remainder of the spent gasses, it encounters less resistance, because the low pressure in the exhause it "vacuuming" out the remaining gasses. This secondary pulse only exits the head at 300 to 600 FPS, so menas nothing to exhaust sound......this whole effect is called a scavenging effect.......
if an exhaust scavenges well, no muffler is necessary for performance. In fact mufflers are really only necessary if the exhause pipe diameter is too large, or the pipe is too short.......But as this applies to the muffler, is that all that is necessary to lower the noise level is for the exhaust gasses to lose velocity....anything that slows the gasses down will quite the noise./...that is whybpacking a pipe with steel woll will baffle the exhaust note......it will not hurt anything to remove the internals of the muffler, and start cutting it down, in any way you are comfortable with

[IamVince]

http://www.xlforum.net/vbportal/foru...ad.php?t=16948

I have done this to a few bikes

[junior]

however....

i noticed in your thread it says you have a '10 ultra. you can punch the mufflers....but it does affect the a/f ratio dramatically. i have already done this to a later model 96 inch bike and found that the added flow caused the narrow band o2 sensors to read lean and the end result was that the ecm fattened the bike up so much it blubbered around town. the guys mileage went from 52 to 38 and the bike did not perform well at all ( this was cured by pounding an automotive freeze plug down the cute and plugging the hole we made back up).

so, imho, punch them if you want for sound (it did sound good for a while), but be prepared you might have to address the a/f issue through a flash or ecm upgrade.

j

[arthureld]

Good point junior. I ran slipons with my stock 08 RK for a while. I never noticed a difference in performance but I always had it in the back of my mind that I could burn something up.
I ended up putting on a tuner.

Drilling a hole thru the baffles and tuning it properly would probably add about 10 hp.
But, I was never comfortable with adjusting my own tuner either so dyno cost should also be concidered.

[RacingOrangeRoadster]

I have put about a thousand miles on since I removed the fiberglass and catalytics and the fuel mileage has not changed if any. It still only gets between 35 and 40 mpg.

[blkfalc4]

The '10' touring models have a cat in the headpipe. Thus the reasoning for the o2's further down the pipe.
Fulsac makes a nice non-cat replacement for the '10's.

Attempting to get 'sound' cheaply, while definately doable, will take a hit on performance.
There are some decent slip-on's that will give more sound without a big hit on performance. A complete system, more money , Anything done, some sort of tuner should be looked at being added to the mix.

The exhaust should be looked at as a complete tuned component from head to tip, along with intake thru cylinder, for best results.

[Heretic]

the V&H fuel pack controller allows you to manually adjust your a/f ratio......my buddy just swapped to slip ons, a screaming eagle air cleaner, and the V&H fuel pack on a brand new 96 incher...he loves it