The Silencer

[Mike B]

In an effort to make the happy time a bit more quiet, I came up with this.

An Arnold 1/2" B&S muffler with the threaded end cut down and 1/2" copper pipe brazed in. And some elbows and street elbows.

It works! The sound is lower and the low end torque is higher. I can now run slower w/o the annoying "jerkyness". Rolling off the throttle coming to a stop is much smoother. I'm going to add another elbow and a reducer tomorrow and see how that works.

Then I'll paint it all with the high temp grill paint and life will be good.

 

[Mike B]

Added some more fittings

Another elbow and a reducer with a little copper pipe brazed in the end. I dunno about that reducer size, it wasn't 3/8" as advertised. I cut some 1/2" copper pipe and removed a section so I could squeeze it into the reducer.

Now on to the painting and it goes back on the bike.

 

[Mike B]

Done

Looks and works great!

I know the exhaust noise is a lot less because the gear noise is now much louder than it used to be -

The extra elbows seem to take a little more noise out and the great low speed performance is still there. Rolling off the throttle is so cool, the bike gets even quieter with no popping or surging, just a smooth decel. Idle is unaffected and smooth. Not to mention I can now roll at idle speed w/o stall. It's a little jerky that slow, but before that was impossible.

It's worth a try guys, less noise and smoother running.

I Like it -

 

[lowracer]

MikeB,
Looks good.
I too am on a mission to reduce noise on one of my 3 MB's.
I have used the sausage mufflers (large & small) & need to try something else for more reduction. I'm using a pocket bike engine & expansion chamber so noise is much more to begin with. I was thinking of wrapping the pipe in header tape? Think that would do anything?
-Lowracer-

 

[Mike B]

Dunno. I wouldn't think so.

In order to reduce the noise you need to reduce the pressure pulses coming out of the exhaust. Increase volume, add baffles, add restriction.

 

[BarelyAWake]

Header wrap will help reduce exhaust noise somewhat, particularly with the resonant "ping" of a typical expansion chamber's relatively thin walls - think of a V8 with headers vs cast manifolds & the under hood noise.

Not all silencers are dependent on baffle plates, nor is restriction the only way to silence, although it's the easiest way to reduce noise. In fact "loud = power" is a commonplace association that isn't inherently true & I suspect stems mostly from the placebo effect and/or misplaced four stroke exhaust theory. While it is far easier to silence by reducing power through restriction - this does not inherently mean a louder bike is more powerful or that you can't have power and a quiet exhaust.

An example of a quiet, preformance exhaust on a two stroke is a combination of smooth, gentle bends, a matched expansion chamber and header, a glasspack silencer and most importantly - a full length system. Here's the system I've built for my Rollfast, which is both far quieter and more powerful than stock or straight (silencer modified by increasing length/amount of packing);

 

[MEASURE TWICE]

Re: Done

Looks and works great!

I know the exhaust noise is a lot less because the gear noise is now much louder than it used to be -

The extra elbows seem to take a little more noise out and the great low speed performance is still there. Rolling off the throttle is so cool, the bike gets even quieter with no popping or surging, just a smooth decel. Idle is unaffected and smooth. Not to mention I can now roll at idle speed w/o stall. It's a little jerky that slow, but before that was impossible.

It's worth a try guys, less noise and smoother running.

I Like it -

Nice looking with the paint now!

Measure Twice

 

[lowracer]

BarelyAwake,
Nice pics (going previous in your album).
I may try a different chamber since I have a fairly quiet one on one of my MB's ($40 on eBay). The one I am trying to silence is just that much louder than any other.
Thanks...
-Lowracer-

 

[Mike B]

This thing works good.

Like I said, the gear noise was much louder so I removed the cover and greased the gears.

Then I went for a ride and heard this new "ticking" noise on decel. I smiled when I realized it was intake noise I was hearing, the little suck when the intake port opens and the charge is drawn into the crankcase.

I can tell you that this was the first time I heard that noise when the motor was running.

So yeah, I can say that this thing works so good that you will hear intake noise.

Someday I'll cut the thing and replace that bottom 90 degree elbow with a couple of 45's so it won't be so low to the ground.

 

[Tacotruck]

So what actually lowers the sound

 

[locutus_1]

im sorry but that thing looks horrible.. go to a metal shop get yourself 2 inch outter diamiter tube 24 inches long then take the bafles out of the stock muffler drill more holes in the tube insert into new pipe then get fiberglass insulateion stuff it.. then get exhaust flex tube from napa.. and run it from the bike to the back of your tire it will be 1/2 as loud

 

[MysterySandwich]

Aesthetics aren't always everything, if he's saving money and it really works (I mean he can hear his intake noise...) then it's just fine.

Also just wondering, is there a way to do this without welding/brazing, like screwing in copper fittings that are threaded with some silicone sealant in between the threads?

 

[Trey]

Mike B- Good tinkering man! Nobody else has the 'Mike B switchback exhaust quieting system'!


MysterySandwich_ Brazing and soldering don't appear too daunting, having never done them before myself. I suggest you spend $20 and give it a shot! That's what I intend to do. It's not a gas tank that may require quite a bit more finesse, so why not?

Aesthetics aren't always everything, if he's saving money and it really works (I mean he can hear his intake noise...) then it's just fine.

Need It Make It Got It

 

[Goat Herder]

So what actually lowers the sound

I know this is a old unanswered question. I want to add a comment that will help some folks understand. Every time sound has to travel through a 90 degree bend it becomes less loud. The steep angle of the turn it has to make traps and deadens audible noise.

 

[Master-shake]

I found a better web page for some of that rubber exhaust hose. I might go this route if the autozone doesn't have any. I don't want to go stainless. and the flex tubes price per foot at the diameter I wanted was insane.

http://www.westmarine.com/webapp/wc...&subdeptNum=50650&classNum=50651#.UWJD4qLvt8E

 

[JaxInsany]

In an effort to make the happy time a bit more quiet, I came up with this.

An Arnold 1/2" B&S muffler with the threaded end cut down and 1/2" copper pipe brazed in. And some elbows and street elbows.

It works! The sound is lower and the low end torque is higher. I can now run slower w/o the annoying "jerkyness". Rolling off the throttle coming to a stop is much smoother. I'm going to add another elbow and a reducer tomorrow and see how that works.

Then I'll paint it all with the high temp grill paint and life will be good.

Hi there Mike! I apologize for bothering you so long after you made the original post, but I LOVE what you did here! I was curious where you purchased the small sausage muffler at the end of your copper piping? I am working on an exhaust rig using the same basic design (90 degree turns with more copper piping and routing exhaust behind me). I would love to get my hands on one of those compact sausage mufflers as an addon to my exhaust system to make it much quieter

 

[Mike B]

No problem, glad to help another guy wanting a quieter bike -

The little muffler is an Arnold 1/2" pipe thread Briggs and Stratton muffler that you can get at the hardware store in the lawnmower parts area. I cut off the threaded section and just brazed the copper pipe after inserting into the steel pipe.

 

[JaxInsany]

Thanks so much!! I really appreciate the specific info and I am now even more excited to get going on the exhaust! Thanks again Mike!

 

[jrol22]

So, this might already been answered, it IS possible to just use that copper piping to have the muffler go straight to the back of the bike and then just add the B&S sausage muffler at the end??

 

[Skidmark63]

Thats a db snorkel design