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Old November 29th, 2015, 06:46 PM   #1
MauR
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TOO Loud DanMoto GP Carbon

Hello Everyone!!

Another question after the plugs one...

I have a DanMoto exhaust for my 250R but it is too loud for me. I like the tone but the volume is too high even with the baffle in the inlet side of the exhaust.

My questions are:

1. Why is the baffle installed on the inlet side?? All aftermarket exhaust use this on the outlet

2. Is there a way to reduce the noise level to some thing between OEM and DanMoto??

3. Could I modify the baffle to reduce even more the sound??

4. What is the double wall on the baffle for??

I'n trying to understand how this baffle but not sure what to do.

I know loudness is what most riders like from DanMoto but it is too much for me and my neighbours.

Thanks in advance!!!

I love this bike and really appreciate all the help in this forum.
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Old November 30th, 2015, 08:29 AM   #2
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Hola Mauricio,

from what I think your point no. 3 is the best idea, just modify the baffle like the Leovince DB-Eater 32BF in the attached picture.
Idk how the baffle from Dan Moto looks like, but guess it is fully open?
Good luck

Last futzed with by Somchai; January 23rd, 2016 at 11:38 PM.
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Old November 30th, 2015, 10:12 AM   #3
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There's a product called the DB Dawg. No experience with this:

http://www.dirtwerkz.com/mm5/merchan...egory_Code=260



Basically it's an insert you shove into the end of your pipe. It's held in with set screws, so you can take it out pretty easily. You'll need the one suitable for your pipe inner diameter.

I might have to buy one of these things... I picked up a track bike at the end of last season and it has an aftermarket exhaust. Not truly obnoxious, but the noise level might be marginal for one of the tracks I ride.
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Old December 1st, 2015, 09:39 AM   #4
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Following...

Planning on picking one of these slip ons up just because of the price point and the weight savings over the stock can.
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Old December 1st, 2015, 04:43 PM   #5
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I'm currently working on the baffle mod to see if this helps. As soon as I have a result I'll let you know.
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Old December 1st, 2015, 05:05 PM   #6
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best bet is to extend the baffle tube and wrap it with fiberglass.
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Old December 1st, 2015, 09:33 PM   #7
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This is what I have done so far...

Now the baffle could be inserted in the outlet side without causing any damage. I working on how to fix it there.

If this does not work the next options would be:

1. Remove the double wall (the one I have cutted)
2. Cover the tube with a copper one with smaller holes
3. Replace the inner tube with a larger one with smaller holes

cuong-nutz:
1. should the fiberglass be between the baffle and the perforated tube in the exhaust can??
2. How long should the tube be??
3. Any suggestion about the holes size?? I'm thinking on 1/4"

Thanks again to all
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Old December 18th, 2015, 08:02 PM   #8
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Today I was finally able to try the slip-on with the baffle in the outlet side...

It didn't work, still too loud.

Should smaller holes reduce the dB???

Measured with an iPhone app the stock exhaust generates 90dB @5000rpm meanwhile DanMoto does 120dB!!!!!

Any suggestions??
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Old December 18th, 2015, 08:43 PM   #9
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Exhaust systems are mostly tubes that contain sound waves. (The waves produced by the pulsing of the engine combustion.)

The exhaust "muffler" works to muffle the sound by forcing it to slow down and expand before it can exit. The stock system does this with physical interruptions to the path, forcing the gases to pass through restrictive porting (the small holes) and/or sound-absorbing fiberglass matting. (FWIW, the fiberglass is simply a non-combustible material...steel wool would do the same if equal density, but steel is prone to rust, so....)

If you want to restore the sound deadening to your muffler, I'd recommend a restrictor that turned the end of the muffler into a solid tube that extended into the muffler a ways, with NO HOLES, forcing the gasses around it to enter turbulent flow and interfere with the gases allowed to pass "straight through" at the narrower diameter.

A longer slip on would be quieter, as would one with less direct passage of gasses, as would more dense packing (to a degree....past a point, it's WORSE, acting like a straight pipe once it's all packed in and clogged.)

YMMV. Hope that helps. Think about what the gas is trying to do and hinder its' progress.
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Old December 20th, 2015, 08:11 PM   #10
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Quote:
Originally Posted by Somchai View Post
Hola Mauricio,

from what I think your point no. 3 is the best idea, just modify the baffle like the Leovince DB-Eater 32BF in the attached picture.
Idk how the baffle from Dan Moto looks like, but guess it is fully open?
Good luck
They making dildos for moto exhaust systems now
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Old December 28th, 2015, 08:24 AM   #11
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@MauR

you see this?
https://www.dan-moto.com/DM_INT/inde...oducts_id=1424
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Old December 30th, 2015, 01:22 PM   #12
MauR
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Yes Thanks, but it was too late for me... As I live in Mexico I have to order trough the international site where the parts are cheaper but the shiping is really expensive.

I paid 86 for the Carbon GP and another 86 for shipping, so order a new one is not an option.

I keep trying to modify the baffle with no results so far

I'll keep you informed
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Old December 30th, 2015, 02:51 PM   #13
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I can only imagine how loud my bike is gonna be. I got the same exhaust but it didnt come with a baffle. If its too much then ill order one but hope i dont have to.
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Old December 30th, 2015, 03:39 PM   #14
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Quote:
Originally Posted by MauR View Post
.........

I'n trying to understand how this baffle works but I'm not sure what to do.

.......
Mauricio,

You paid for a straight passage to exhaust gases with some attempt for attenuation of noise by absorption.

The excessive noise comes from the disturbance of the atmosphere that the sudden successive expansions of those gases going from high pressure (several atmospheres) to zero atm and subsequent speed produce.

Those are high pressure/speed pulses in the gas (high energy) that reach ears via the atmosphere.

The manufacturers use several methods of noise (energy) attenuation:

1) Using baffles and internal passages and tubes, they divert the flow back and forth and then make the pulses of one interfere with the pulses of the other (a + peak overlaps a - peak, resulting in close to zero pressure.
Your DanMoto does not do that: it is a simple straight shoot.

Installing internal baffles and tubes and experimenting with the location of those could help you.
The main problem would be anchoring those things to the carbon-fiber shell.

2) The OEM mufflers also try cooling the exhaust gases between inlet and outlet, achieving less volume to be discharged, which equals reduced disturbance.
They do that using big shinning surfaces exposed to the air stream and keeping the gases moving back and forth within those surfaces.
Your exhaust gases reach the atmosphere hotter and occupying more volume.

3) They sometimes try creating noise absorbing internal walls with soft materials protected by some mesh or perforated sheets.

That works for the gases hitting those walls at relatively low speed, but does nothing for the gases that move faster by the center of the pipe.
That material tends to get burned and blown away, and needs periodic re-packing.

I believe that is the purpose of the double wall on the baffle of your DanMoto, which is doing some attenuation (if in good condition), but not enough for you.

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Old December 30th, 2015, 04:56 PM   #15
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Thanks Motofool!!

Attached is the photo of the DanMoto baffle without the double wall and the cap...

If I understand correctly using a longer tube with smaller holes in two sections might help.

Now that I removed the double wall I think it was there to protect the carbon fibre from the heat...
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Old December 30th, 2015, 08:00 PM   #16
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Quote:
Originally Posted by Dsheumaker View Post
I think I may have finally found a slip on exhaust I may get
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Old December 30th, 2015, 08:40 PM   #17
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Quote:
Originally Posted by MauR View Post
Thanks Motofool!!

Attached is the photo of the DanMoto baffle without the double wall and the cap...

If I understand correctly using a longer tube with smaller holes in two sections might help.

Now that I removed the double wall I think it was there to protect the carbon fibre from the heat...
You are welcome

It may help, as long as is not aligned with the exhaust pipe.
Try thinking like you were the exhaust gases traveling the easiest path between high and low pressure.
Would you go through those holes on the wall or through the center of the main tube?

The attached schematic belongs to real Yamaha engines.
Notice how the flow is forced to follow a path with successive expansions.

Yes, heat and epoxy resin don't get alone.

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Old December 31st, 2015, 05:02 AM   #18
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Looks like ill just be getting used to riding with hearing protection on haha.
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Old December 31st, 2015, 03:23 PM   #19
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Finally the modification to the DanMoto baffle is done.

Using Motofool advice and some images from internet I made a baffle.

It all started with a 1", thin wall copper tube. Some cuts, a hammer and a drill helped me to finish a baffle which I hope can reduce the dB my DanMoto creates.

attached are some images of the process. Maybe tomorrow I'll try it.

Thanks to all and have a happy new year!!!!
Attached Images
File Type: jpg IMG_0629.jpg (115.8 KB, 12 views)
File Type: jpg IMG_0631.jpg (94.1 KB, 7 views)
File Type: jpg IMG_0632.jpg (57.3 KB, 6 views)
File Type: jpg IMG_0633.jpg (117.2 KB, 6 views)
File Type: jpg IMG_0636.jpg (90.1 KB, 5 views)
File Type: jpg IMG_0638.jpg (105.1 KB, 7 views)
File Type: jpg IMG_0639.jpg (71.0 KB, 5 views)
File Type: jpg IMG_0640.jpg (67.8 KB, 7 views)
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Old January 1st, 2016, 06:12 PM   #20
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It DID work!!!!

Sound level is lower but the tone is great!!!. Maybe I'll try with some Steel Wool or exhaust packing to see what happens, but is already a lot better.


Thanks to all!!!
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Old January 3rd, 2016, 09:46 PM   #21
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Quote:
Originally Posted by MauR View Post
It DID work!!!!

Sound level is lower but the tone is great!!!. Maybe I'll try with some Steel Wool or exhaust packing to see what happens, but is already a lot better.


Thanks to all!!!
She is a beauty !!!

Copper may break soon, ....maybe not.
That material tends to develop cracks when stressed by temperature changes and vibrations.

Now exhaust sounds and noises are not a mystery anymore.

You are welcome
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Old January 4th, 2016, 09:04 AM   #22
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But now with this baffle in there would you need to rejet?
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Old January 4th, 2016, 08:38 PM   #23
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Quote:
Originally Posted by Dsheumaker View Post
But now with this baffle in there would you need to rejet?
i think so...

Dan Moto site says there is no need to rejet, but I'll see... Maybe 2 washers on each needle will help...
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Old July 11th, 2018, 02:55 PM   #24
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steel wool will definitely help. maybe put it in the mid pipe to prevent it from blowing out.
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Old July 13th, 2018, 06:48 AM   #25
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steel wool will definitely help. maybe put it in the mid pipe to prevent it from blowing out.
if you have steel wool in there and have a back fire or poof of flame come out the pipe expect a good fire show
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