Sound Dampener "Before" and "After" Comparison

[Nashville Kat]

Sound Dampening A 2 cycle China Girl Bicycle Motor.wmv - YouTube

Final grade here for Damp-Pro China Girl dampeners- 7 out of 10

They cut down some Db's and make motor sound smoother- maybe 20-25 percent

you be the judge!


got chased by a dog yesterday- so easier to drop them with a motor!

 

[matthurd]

the less grindy sound alone kinda makes me want to pick some up.

 

[mainstreet]

EXCELLENT demo video! Very well done!

 

[Nashville Kat]

I made some dampeners of my own today and put in the 50cc build (which is temporairly down)

I used some poster mounting backing board from a Dollar store- sorta like extruded styrene- only just 1/8" thick- and I stuck some thin pie plate aluminum, from a store-bought pie over that- used a little gasket sealer on both sides of poster foam board-

Won't be testing it for a week or two-but it's actually a bit thicker than the Damp-Pro, and the 50cc is a little more quiet than the 66 to begin with- Didn't do any "before" video- the motor's apart and I just wanted to get it done-Had all the stuff, so it cost nothing.

Have taken several trips now on the 66 in the vid- and the Damp-Pro dampeners don't seem to be any problem otherwise. I'm pretty happy with the whole thing.

 

[decoherence]

thanx for posting that. now i can identify what the "gear" sound everybody complains about.
i guess i will go get me some sound dampening.

 

[Nashville Kat]

I think a longer pipe also cuts a good bit of noise- except maybe an expansion chamber-
I had to cut a poo-poo pipe to extend it below the bottom bracket
but here's a nice alternative that may be just a bit more quiet than a stock muffler- with another six inches of pipe and a little longer muffler-

and not priced too far above a standard replacement
http://www.gasbike.net/bike-motor-engine-fancy-crome-pipe.html
has anyone tried this pipe?

 

[vincent713]

I haven't tried this pipe but I like it alot. I wonder how much noise reduction I would get from this pipe and would I need any modification?

 

[Nashville Kat]

I haven't tried that pipe, but do have a longer one-

It's all like blowing through a horn- the longer the horn, the lower the tone will be-
It would take some of the high end off- with that pipe in the link above it looks like you'd only be adding about 8 inches or so of pipe, maybe ten- it would be minimal,

but if I was needing a REPLACEMENT muffler for the kit-for the price, I'd probably order one-

my 50 motor is already a little more naturally quiet than the 66-

Hey maybe I'll shoot just a short video of it with the kit muffler and homemade dampeners and compare it to the other.....

 

[CroMagnum]

BTW, the word is "damping" not "dampening." You're attenuating the sound level, not making it wet.

 

[Nashville Kat]

"Dampen"-1. to make or become damp. 2. make less forceful or vigorous, choke.- Oxford Dictionary

a similar more lengthy definition applies to "damp"

Both damping and dampening are correct

The Sound-Pro Product Description at Pirates uses both terms-
Hate to say it and discourage commerce, but I think the homemade dampeners I put in my 50 cc actually work better, with 1/8" styrene poster board backing from a dollar store under a thicker store bought pie plate- although it rubbed off some aterial near the center I wiped away upon inspection.

I think the styrofoam material absorbs more sound than their tar substance and my aluminum is thicker too.

Another note: BE SURE TO TIGHTEN THE COVER SCREWS WELL- I lost a couple, but had replacements-

I think eventually I may get some titanium bolts to replace them when I have more money

 

[vincent713]

Now that English 101 session is over........so where exactly did you put this dampening material at? I want to dampen the centrifugal clutch cover but it's a tight fit and I don't want anything rubbing on the clutch. Any input is much appreciated.

 

[diceman2004]

if you have an old seatpost kicking around that you don,t need ... try this .
Mind you , I did this on my 97cc 4 stroke .

1 : the post NEEDS to be one with rolled in rounded ends .
the inside of the seatpost is bigger in diameter( around 7/8 ) than the hole on the rounded end ( between 5/8 and 3/4 ).
( this is important ... so don,t go cutting up a seatpost , if ya don,t know what i,m sayin ... ya know what i,m sayin ? )
2 : you are going to use the bottom end - not the end that the seat attaches to .
3 : cut about a 4 inch piece off the bottom end
4 : hold this saw cut end over the outlet of your muffler . you want the rounded end to be the end of the muffler .

sounds cool EH !

 

[vincent713]

Do you mind showing us a pic of your mod?

 

[diceman2004]

i don,t have pics of that mod ( but it does sound good on the end of the large tube type screw in lawnmower muffler .

i do however have a few pics of a custom mufler i made in this thread .
http://motorbicycling.com/f36/over-winter-performance-mods-14474.html

 

[Nashville Kat]

Hey Vincent- look at the video again- in the middle when I open the deampener package-

there are three - one for the clutch cover, one for magneto and one for the sprocket cover-
I didn't add the sprocket cover when I put my opwn in the 50 because it is open there anyway and you have to mess with the cable a bit.anyway- It to it may block some sound, but I didn't bother- the lightweight 415 Trike chain DOES run quieter though- see thread in General discussion-
http://motorbicycling.com/f3/im-really-jazzed-over-new-chain-34585.html

I used 1/8 material from the dollar store- the school supplies- and it's poster mounting board I think- I cover it with pie plate because I didn't know how well it would stand the heat and to keep any chewed material out of the motor- You may get awy with no aluminum or pait or glue tin foil--
I didn't cut quite enough of a hole in the middle- see patterns in video- and it chewed a little bit of material around the edge of the hole- but no problem- the motor had it's way!
It's all thick then- about 3/16 I guess- I think the Sound Pro store bought are thinner

You can use cardboard I hear- but I tried to make something more permanant- although nbow I see that the covers aren't difficult to remove.

 

[F_Rod81]

Good job with your video. Not much to say, the stuff works. I have had the Damp. kit for over a year now. I recommend it for those that don't have it.