How do I make exhaust noise as quiet as possible

[tirebiter]

I'm not a performance oriented rider. I am interested in getting good fuel economy. I also want to have a very quiet motorcycle. "Stealth mode" if you will. Anybody have suggestions as to how to make the exhaust noise all but silent ?

My 1980 GS850L shaft drive has a 4 into 1 megaphone exhaust which is relatively quiet already except above 6500 RPM where it begins to snarl. I am prepared to suffer some decrease in horsepower and fuel economy if I can get this thing to be nearly silent.

 

[tom203]

"I'm not a performance oriented rider. "

Me neither, so keep it below 6000 rpms ! My 650 is reasonably quiet till about this point. What brand of exhaust do you have?

 

[sinkankan]

Exhaust "experts" will tell you that wrapping the baffle between the outside of the baffle and the muffler wall will reduce noise, problem is it also increases back pressure to the cylinders, you MAY have to retune your bike if you take this avenue. Wrappings in the past have included fibreglass hi-density blanket which is relatively heat proof, and I've even seen steel wool packed down a muffler, this is not suitable for high temperature mufflers.
My Yoshi exhuast has a optional extra baffle at the end of the pipe, ask your Suzuki dealer if they have anything suitable because these fit in under 10 minutes and really help reduce the noise.

 

[Jethro]

Do whatever it takes to find a nice, stock 4-2 header and pipes. It's best for fuel economy, it sounds better than anything, it's quiet and increases the value of your bike. Downsides are they can be expensive in good shape and they are heavy. Just my opinion but nothing is better than stock pipes.

 

[BigD_83]

Now this is a refreshing thread...I can't remember the last time I read someone asking about reducing exhaust noise. Whisper quiet like an ST, or a Goldwing would be great for living in the city.


I don't have any immediate solutions for you, but Jethro's suggestion is very good.

Mine was replacing the entire, rotted out pipes with a BUB 4 into 1 system, but it is a beast when it gets into the upper rpm range, far louder than I think you have in mind.

 

[Steve]

Exhaust "experts" will tell you that wrapping the baffle between the outside of the baffle and the muffler wall will reduce noise, problem is it also increases back pressure to the cylinders, ...

That depends on the type of baffle that is installed. If you have one of the "competition" baffles, the bore is open for the entire length of the baffle. The fiberglass that is wrapped around the core only deadens the sound in the outer chamber, which eliminates much of the echo. Because the exhaust basically flows down the middle of the open core, back pressure is unaffected.

I have seen two different types of "street" baffles. One is similar to the OEM mufflers, where a small pipe goes most of the way back, through a couple of blocking plates. The exhaust then has to reverse direction, go through another pipe back toward the front, then finally go through a third pipe to get to the exit.

A second type is what I have, it is similar to the competition baffle, but has a plug in the middle, which forces the exhaust to go through the perforated tube (and the packing material) a couple times before it gets out.

... and I've even seen steel wool packed down a muffler, this is not suitable for high temperature mufflers.

Actually, if you use STAINLESS steel wool, it works quite well. It helps to use the coarsest grade possible. I have a header and muffler of unknown origin. The baffle has a plug in the middle of the core, which forces all the exhaust to go through the front half of the perforated tube, into the outer chamber (which is packed with stainless steel wool), then back through the back half of the perforated tube to exit the muffler. It is wonderfully quiet at most road speeds, and does get a little bit louder past about 6000 RPM, but that's just fine with me. :encouragement:

.

 

[posplayr]

Works great and is designed for exhaust. be careful it will slit your fingers faster than a razor. Use gloves when handling. Even just rubber gloves.

http://www.ebay.com/itm/Stainless-S...467?pt=LH_DefaultDomain_0&hash=item4844d74b1b

[SIZE=+2]Lustersheen 1 lb. Stainless Steel Reel in AISI 434[/SIZE][SIZE=+2]Grade ~ Coarse
[/SIZE][SIZE=+1]COMPARES TO [/SIZE] # 3 Steel WoolAVERAGE FIBER WIDTH : 120 microns (0.12mm) / 0.005" (5 mils)(Picture shown is of Medium Grade)

• This stainless steel wool is made from Alloy type AISI 434 stainless steel, a corrosion resistant steel.
• The 1 lb. reels are a woven web of stainless steel wool approximately 1/4" thick in a relaxed state and 4" wide. The web is wound onto a fiber core and weighs 1 pound. There is about 18 feet of web per 1-pound reel. Length of the web varies, usually in excess of 18 feet.
• 434 stainless steel wool withstands temperatures in excess of 700?C, exhaust acids and high vibration.
• Furnace tests show that stainless steel wool will withstand sustained temperatures of 700?C and peak temperatures of 800? C for up to 10 minutes without damage or degradation.
• CHEMISTRY : C (Carbon) 0.12% max. ; Si (Silicon) 1.0% max. ; Mn (Manganese) 1.0% max. ; S (Sulfur) 0.03% max. ;P (Phosphorous) 0.04% max. ; Cr (Chromium) 16.0 - 18.0% max. ; Mo (Molybdenum) 1.25% max.; Fe (Iron) remainder
• The simplest form of stainless steel wool is a continuous woven web of wool, 4 inches wide on reels. This product meets all of the physical demands for exhaust applications.
• The continuous web format is ideal for the making of custom exhaust or for the repacking of exhaust as would be done by car and motorcycle enthusiast.
• This is a Complete Made in the USA product.

 

[tirebiter]

Tom203,

I have been a long tiem replying but it's time I have to do some work on the exhaust. A header pipe has started to leak at the head. #2 or #3, not sure which but it's loud and aggravating. Needs to be taken care of.

"Little Suzy" came with no-name megaphone pipe from a no-name 4 into 1 header. The megaphone has a reverse flow silencer in it. Zero baffling of any kind at this point. I've welded and rewelded the reverse-flow silencer and put small machine screws at the exit. two of them, double nutted to hold it in place. It's amazing how the vibration keeps loosening things up.

 

[scratch]

I'm ready to jam the Kerker so full of steel wool that I can see it coming out the back of the carbs.