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Here is another idea for guys who like to have more sound at higher RPM's.

At high RPM's the exhaust valve is closed by the ECU to reduce the sound emissions.

The butterfly valve is held by 2 screws onto a rotating rod that is attached to the spring mechanism and control wire.

You will need to drill out the screws since they are welded tight onto the valve. A little tedious job, but can be done without damaging the thread and/or valve.

Good luck!

(ps, you can also buy the DUC.EE Servo Eliminator; MotoCreations -- Duc.EE Servo Eliminator. But you can save yourself $155)
 

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So A320 driver,
Hows it run? hows it sound?

By the way, that looks like Malaysian mud on your collector box. Been playing in the Palm oil plantations? woohoo! :D
 

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At high RPM's the exhaust valve is closed by the ECU to reduce the sound emissions.
where did this info come from? we had a long discussion about how the valve works a while ago. the valve is only closed when you're sitting in traffic to keep the sound down. once you're moving it opens and stays open.
 

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Discussion Starter #4
TimOz;
The sound is better in my opinion. And yes! that is Malaysian mud. well spotted :) Have done a few jungle/palm oil plantation trips and that was really a lot of fun.

Martys;
You could be right. I basically got my info from the local dealer and also from running a stationary test while revving the engine. I noticed that the valve, when stationary, is normally in an open spring-loaded position and while revving the engine you can see it open and closes. I just wanted it to be open all the time.

Just had a ride around town and felt it was a bit louder. Of course you can get the full termi system, but I feel that might get annoyingly loud when doing long touring. Anyone experience with that?
 

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So A320 driver,
Hows it run? hows it sound?

By the way, that looks like Malaysian mud on your collector box. Been playing in the Palm oil plantations? woohoo! :D
Had my flapper valve out for about 3 months, little bit more Ducati sound at idle, can't say it makes much difference. No real performance gain.

I'm just about to fit up my modified standard muffler - I have removed the internal muffler cat and modified the internal baffles, should have some feedback in about a week. Cost about $250 all up, with professional re-welding so might be a good mod that the noise police don't notice and pick on
 

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Had my flapper valve out for about 3 months, little bit more Ducati sound at idle, can't say it makes much difference. No real performance gain.

I'm just about to fit up my modified standard muffler - I have removed the internal muffler cat and modified the internal baffles, should have some feedback in about a week. Cost about $250 all up, with professional re-welding so might be a good mod that the noise police don't notice and pick on
Let me know how it sounds.I have been thinking about doing this.My uncle has a welding shop,so free labor but wandering how long it takes to do this.
 

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Here is another idea for guys who like to have more sound at higher RPM's.

At high RPM's the exhaust valve is closed by the ECU to reduce the sound emissions.

The butterfly valve is held by 2 screws onto a rotating rod that is attached to the spring mechanism and control wire.

You will need to drill out the screws since they are welded tight onto the valve. A little tedious job, but can be done without damaging the thread and/or valve.

Good luck!

(ps, you can also buy the DUC.EE Servo Eliminator; MotoCreations -- Duc.EE Servo Eliminator. But you can save yourself $155)

This is a very good video showing the exhaust valve at work. Looks to be only closed at idle.
 

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That was my understanding aswell.. The exhaustflapper is only closed on idle and maybe also at part throttle when in neutral for emissions/noise testing (EG: neutral 5-6% throttle @ 3000RPM = 98dB(a) )

I can check with a buddy of mine if he can see the flapper closing when he dynos the bike.
 

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Guys I think you got all of the wrong, as far as I was told the buffer closes the pipe at 3000 rpm to cut down the noise level at high RPMs.
when the engine is turn off valve stays open, when you stating engine ECU cycling the valve to check if it is operational and valve stays open at idle.
the easy verification of that fact is to remove the exhaust tip.
 

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guys i think you got all of the wrong, as far as i was told the buffer closes the pipe at 3000 rpm to cut down the noise level at high rpms.
When the engine is turn off valve stays open, when you stating engine ecu cycling the valve to check if it is operational and valve stays open at idle.
The easy verification of that fact is to remove the exhaust tip.
The clip joeducati posted up seems to show the opposite??? I have a hard time understanding closing the flap at high rpms.
 

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The clip joeducati posted up seems to show the opposite??? I have a hard time understanding closing the flap at high rpms.
Wow, seems to be mass confusion on this topic. The video I posted clearly shows the valve moving when the rpm's go up. The question is, when the bike is off, is the valve open or closed? I assumed it was closed, maybe it's the opposite, but doesn't make sense to me! The cat that started this thread will have to answer that, then we will all know. I never pulled my stock cans to find out.
 

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Wow, seems to be mass confusion on this topic. The video I posted clearly shows the valve moving when the rpm's go up. The question is, when the bike is off, is the valve open or closed? I assumed it was closed, maybe it's the opposite, but doesn't make sense to me! The cat that started this thread will have to answer that, then we will all know. I never pulled my stock cans to find out.
look just take muffler tip off and it will be clear, I think the valve is open at the idle and the only function of the valve is to cut down the noise at high RPM.
I don't know if you guys hear that engine with the short termi and MIVV cat eliminator no DB killer, but let me tell you at 6k RPM it makes D16RR sounds like moped :)
 

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I've had the stock cans off a couple times to mount new tires. Never thought to look at the valve.
 

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there is no back pressure function to that valve only noise reduction.
Wonder how it does that without creating any backpressure? Just looking at the flapper, it looks like it closes off the exhaust pretty solidly.
 

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The valve is open when the bike is not running (a spring keeps it open when there is no pull from the servo).

When you power on the bike, the ECU tests the valve and attempts to close it and allow it to reopen.

The valve remains open until around 3,500 RPM - at the precise RPM the EURO noise and emissions drive-by tests are done - when it is closed by the servo pulling on the cable. Soon after that (around 4,200?) the servo allows the value to reopen and it continues to be open right up to the red line.

The purpose of the valve is purely to limit the sound at the specific rev range used for European noise testing. Even in Europe, most countries don't have a noise test for motorcycles after they leave the factory.
 

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The valve is open when the bike is not running (a spring keeps it open when there is no pull from the servo).

When you power on the bike, the ECU tests the valve and attempts to close it and allow it to reopen.

The valve remains open until around 3,500 RPM - at the precise RPM the EURO noise and emissions drive-by tests are done - when it is closed by the servo pulling on the cable. Soon after that (around 4,200?) the servo allows the value to reopen and it continues to be open right up to the red line.

The purpose of the valve is purely to limit the sound at the specific rev range used for European noise testing. Even in Europe, most countries don't have a noise test for motorcycles after they leave the factory.
thank you !! :D
 
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