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Unread 07-27-2006, 09:46 PM
Barbikes Barbikes is offline
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Question Newbie with Derbi Senda SM

Hello!
I'm new to this site but not to two strokes. I really like two stroke singles. I recently bought a 2003 Derbi Senda SM with the full Malossi 80cc kit. The first thing I noticed was the low gearing so I installed a Sprocket Specialists 47 tooth rear sprocket. Huge improvement! My son jumped on the back and with 370 pounds of rider/passenger sitting straight up it still did 63 mph (GPS) on the straight and level.
Anyway, my current problem is that I feel it's too loud for around town street usage. The loudness doesn't come out of the end of the pipe. It comes thru the side walls of the expansion chamber.
I realize this is heresy, but I am to the point that I would like to try a stock expansion chamber. Both because of the current setups loudness and for a broader torque range.
Anybody got a stock pipe for sale?

Thanks,

Barbikes
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  #2  
Unread 07-28-2006, 06:24 AM
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Pierce Pierce is offline
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I have a stock pipe I could sell you but you will be very disappointed in the actual performance of the bike at that point. The power band does start a little earlier around 5000 but pretty much tops out at 9500. So you will loose most of your top end speed for sure.

I guess if you want to try something that will reduce the tinging noise you could wrap the exansion chamber in exhaust tape but again that will disrumpt the sound wave principle of a two stroke pipe.

Do you know what pipe you are running curently? Could you take a pic? Also where are you located?

Oh and Welcome to BATS!
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  #3  
Unread 07-28-2006, 07:01 AM
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dankerson dankerson is offline
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just use a fiberglass wrap thats used for an exhaust system and no air filter will make it loud too.

DON'T FALL FOR THE BANNANA IN THE TAIL PIPE!!!!!!!
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  #4  
Unread 07-28-2006, 07:27 AM
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Four_Ari Four_Ari is offline
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Quote:
Originally Posted by Barbikes
Hello!
I'm new to this site but not to two strokes. I really like two stroke singles. I recently bought a 2003 Derbi Senda SM with the full Malossi 80cc kit. The first thing I noticed was the low gearing so I installed a Sprocket Specialists 47 tooth rear sprocket. Huge improvement! My son jumped on the back and with 370 pounds of rider/passenger sitting straight up it still did 63 mph (GPS) on the straight and level.
Anyway, my current problem is that I feel it's too loud for around town street usage. The loudness doesn't come out of the end of the pipe. It comes thru the side walls of the expansion chamber.
I realize this is heresy, but I am to the point that I would like to try a stock expansion chamber. Both because of the current setups loudness and for a broader torque range.
Anybody got a stock pipe for sale?

Thanks,

Barbikes
Are you running a Airbox?
I find that most of my sound is from the carb intake.
Also the MK thrower has to be the loudest exhaust i have heard
-Hollywood
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  #5  
Unread 07-28-2006, 03:09 PM
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eddiemcrider eddiemcrider is offline
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First of all welcome to the site! And congrats on the new bike.

You do not want to go back to stock. We're talking 50mph top speed derestricted of course.

Have you tried ear plugs? If your neighbor says your bike is too loud then rev the piss out of it and say can't hear ya with my ear plugs on. Talk to you later.

Seriously not sure what you mean by loud. Harley with straight pipes are louder than our bikes with aftermarket exhausts. With the 80 kit you should be able to cruise around the block at 1/2 throttle and still move around quickly.

What kind of carb are you running? The Delorto 21mm seem to work well with the OEM airbox. I believe the 24mm Mikuni may not and I know the 24mm OKO/Keihn will not work with the OEM airbox.

POST PIX of your ride. Good to know there are more of us that have 'em in the states.
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  #6  
Unread 07-28-2006, 07:15 PM
Barbikes Barbikes is offline
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Default Advice creates more questions than answers?

You guys have certainly given me some things to think about. I've attached a pic of the bike. I believe the exhaust is Malossi because the guy I bought it from said that the previous owner had the complete (cyl, 26mm carb, air cleaner, and pipe) 80cc kit installed when he bought it new. When I bought it there was an FMF shorty muffler on it. It was VERY loud. I installed a modified (no spark arrestor, smaller full length core) Answer SA Pro silencer. I know from previous experience that this muffler is quiet! I can lug the bike down low and it is quiet but as soon as it gets to about 5000 rpm it starts sounding like the worlds loudest popcorn machine and people a block away look up from their yardwork, mothers hide their children, and old women dial 911. As you can see in the photo it has no airbox but I've always experienced airbox noise as kind of a rasping or honking movement of air noise that sounds a bit like the sound a cow makes when it steps on its udder.
I have thought about trying to wrap the pipe with exhaust tape but I doubt if fiberglass tape is very stretchy and I wonder how it would work on the cone portions? Has anybody done this?
How much do you figure that stock pipe is worth Pierce?
Thanks again for the advice everybody!
Barbikes
Attached Images
File Type: jpg Derbi Senda SM.jpg (178.7 KB, 38 views)
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  #7  
Unread 07-28-2006, 07:48 PM
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Pierce Pierce is offline
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I'll sell it to ya for 25 bucks. Plus shipping. Where you located?
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  #8  
Unread 07-28-2006, 09:08 PM
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eddiemcrider eddiemcrider is offline
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That pipe is art work.
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  #9  
Unread 07-30-2006, 01:11 AM
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Karma Karma is offline
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Man, Dan taking my Chamber Wrap idea Copywrite time, lmao.

I got same setup as you "mechanical-wise" except that Huge Silencer?
& that 26mm Carb will make So much Noise on a 2 stroke without a Box.

So i know your Situation/Problem almost all to well...

Other Carbs with Open Filters do also but an 80 added "LOUD" i`ve
thought of wrapping pipe & shouldn`t be a problem "should benefit".
If no good there i`ve been planning a secret airbox design also

If you Run a Stock Pipe it will be like a Torque`d/Cruiser, Top End gone,
But it`ll be quieter?

Welcome-2-BATS: Fellow Malossi Pipe Owner
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  #10  
Unread 07-30-2006, 09:32 PM
Barbikes Barbikes is offline
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Default Dankerson, Hollywood, and Karma - Geniuses!

Hey!
You three guys hit the nail on the head!
I took the Derbi for a ride and really tried to pinpoint the source of the noise.
I now believe that most of the noise is from the intake.
So that leads to the next question. Does anybody have an airbox that will work with the malossi kit and it's 26mm Dellorto?
I don't have the stock airbox but if I did - Can it be modified to work with my setup?
I'm going to try the stock pipe that Pierce has mainly out of curiosity.
I've always liked 2 stroke enduro (KTM EXC, IT, WR) engines better than MX (CR, YZ, RM, KX) power.
Barbikes
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