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Discussion Starter #1
I know it's against the grain -- I put an OEM exhaust back onto the '09 I bought after having too many conversations with officer friendly concerning the M4.:rant

I don't mind it being slightly quieter. I get to run the bike harder, as a result of NOT announcing what I am doing to who, where.:devious

The OEM system has the valve in the muffler section, and had the cables attached. I routed them back up to the servo under the seat, and installed the cable ends into the servo drive wheel. Buttoned it all back up, and have ridden it around 500 miles, since.

What RPM does the servo flip the valve at? I presume it goes from partially blocked to WFO around 8K? Can anyone check this for me?
 

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Discussion Starter #3
It closes partially at low rpm and wide open throttle.
Not sure of exactly what rpm.
It is strictly a noise emissions package
Thanks for answering. I knew it should be restricting the pipe at low RPM and may choke it up high..... I believe it also defaults to open if you put the jumper in to defeat it, right?
 

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I've been told by a racer/track day enthusiast that on the 2009-2012 ZX6R the valve is actually a power valve and it gives you greater low end power. It may be different for you guys in america but I believe the powervalves are fully open at WOT
 

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Discussion Starter #8
I've been told by a racer/track day enthusiast that on the 2009-2012 ZX6R the valve is actually a power valve and it gives you greater low end power. It may be different for you guys in america but I believe the powervalves are fully open at WOT
This would be my expectation; having said that now that I have gone back to OEM from the M4, I seem to be getting lower MPG. This is either due to my romping on the gas harder (because it's quieter, and I can), or the pipe is more restrictive.

It would be nice to know what RPM the cables move the valve at. If it's a two stage setup, I would expect it to be closed at low RPM, then WFO up to near where the motor is loudest, then in a nod to the emissions police corks it back up to limit the sound.

I had a Yamaha FZ6 before this, no valve in the exhaust.... the ZX6 is stronger just about everywhere in the RPM range, which I think is in part due to the higher compression, and probably also due to the variable back pressure from the valve.
 

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VA doesnt have laws against noise do they... ive lived in VA for 28 years until 4 months ago when I moved
 

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Is that m4 for sale?
 

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Discussion Starter #11
Is that m4 for sale?
The M4 is sold. After I got pulled over the second time, getting a ticket out of it that time, I looked into the law in VA. There is a law on the books which states after market cannot be louder than OEM. Not terribly enforceable, but it's there. You have to have an obnoxious exhaust to get a ticket, I think.
 

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Discussion Starter #12
Does anyone know if the bike does a self check on the valve when you start it up? Does it sweep through the positions like some bikes do with the speedo needle?
 

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The M4 is sold. After I got pulled over the second time, getting a ticket out of it that time, I looked into the law in VA. There is a law on the books which states after market cannot be louder than OEM. Not terribly enforceable, but it's there. You have to have an obnoxious exhaust to get a ticket, I think.
I have not got a ticket it with my m4 slip on thankfully. I get followed by cops all the time. Eventually they just continue on.
 

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Discussion Starter #14
I have not got a ticket it with my m4 slip on thankfully. I get followed by cops all the time. Eventually they just continue on.
The ticket itself was $30, with 60+ in court fees. I could have just paid it and hope to not have been tagged again..... the locals had my number and would have tagged me again. They could do it every day, until I fixed it to their satisfaction.

The county seat is about 6 miles from my house, and the state trooper's office as well as the county sheriff's office are both there. My route to work takes me right through their favorite speed trap, and they didn't like the noise of me hopping on the throttle to get up to speed on the 301 bypass. Apparently one of county officers lives right around there and didn't appreciate the sound blasting through his bedroom.

VA doesn't seem to have 'fix it' tickets, I did ask the LEO that tagged me, and he explained that if I 'repaired' the exhaust in a reasonable time, the charges could be dropped at court.

I showed up, pled guilty, showed them the receipts for the replacement exhaust, had photos of it installed on the bike, and the judge dropped the charges.

I had to burn a vacation day to do this, so the cost to me was significant, not to mention the $ for the OEM setup.

It would have cost less to eat the ticket, but it would have been a bigger PITA in the long run, if they decided to persecute me about it. I do believe they would have.
 

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Does anyone know if the bike does a self check on the valve when you start it up? Does it sweep through the positions like some bikes do with the speedo needle?
Yes.. thats why some people have issues when they replace the OEM exhaust with an aftermarket exhaust that requires the removal of the valve/cables. Also, on mine (I have a leo vince SBK) there is a clicking noise when you turn the key on. That is the servo doing it's thing. When the snow buggers off I will take the seat off and have a better look to understand what happens.

One way of finding out when the valves open is to book a dyno and do a run with the seat off. Film the servo doing its things and then you'll know at what revs it opens/closes
 

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You don't have to run dyno ...just expose the servo and watch the rpm gauge while you open and close throttle and you can do that at home in garage or whatever.
 

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You don't have to run dyno ...just expose the servo and watch the rpm gauge while you open and close throttle and you can do that at home in garage or whatever.
I did think about that but then I realised the bike wouldn't be under load.. I thought that would have an impact? The bike would only be on about 5% throttle and be hitting the redline so you'd never see what it does WOT
 

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I've been told by a racer/track day enthusiast that on the 2009-2012 ZX6R the valve is actually a power valve and it gives you greater low end power. It may be different for you guys in america but I believe the powervalves are fully open at WOT
The "Exhaust Servo/ Butterfly Valve" system is not for back pressure,
It is strictly a government mandated noise emissions package.
Here is a copy and paste from the 2009-2011 ZX6R service manual...

TAMPERING WITH NOISE CONTROL SYSTEM PROHIBITED
Federal law prohibits the following acts or the causing thereof. (1) The removal or rendering
inoperative by any person other than for purposes of maintenance, repair, or replacement, of any
device or element of design incorporated into any new vehicle for the purpose of noise control
prior to its sale or delivery to the ultimate purchaser or while it is in use, or (2) the use of the
vehicle after such device or element of design has been removed or rendered inoperative by
any person.
Among those acts presumed to constitute tampering are the acts listed below.
•Replacement of the original exhaust system or muffler with a component not in compliance
with Federal regulations.
•Removal of the muffler(s) or any internal portion of the muffler(s).
•Removal of the air box or air box cover.
•Modifications to the muffler(s) or air inlet system by cutting, drilling, or other means if such
modifications result in increased noise levels.
 

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Discussion Starter #19
Yes.. thats why some people have issues when they replace the OEM exhaust with an aftermarket exhaust that requires the removal of the valve/cables. Also, on mine (I have a leo vince SBK) there is a clicking noise when you turn the key on. That is the servo doing it's thing. When the snow buggers off I will take the seat off and have a better look to understand what happens.

One way of finding out when the valves open is to book a dyno and do a run with the seat off. Film the servo doing its things and then you'll know at what revs it opens/closes
With the OEM can in place, I could grab the cables going to the valve between finger and thumb, when I turned the ignition to 'ON'.... the self check cycles the valve, as I could feel the cables tug back and forth.

I'll follow up on this the next time I get to ride, and check to see at what RPM the servo moves the valve.
 

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Discussion Starter #20
The "Exhaust Servo/ Butterfly Valve" system is not for back pressure,
It is strictly a government mandated noise emissions package.
Here is a copy and paste from the 2009-2011 ZX6R service manual...

TAMPERING WITH NOISE CONTROL SYSTEM PROHIBITED
Federal law prohibits the following acts or the causing thereof. (1) The removal or rendering
inoperative by any person other than for purposes of maintenance, repair, or replacement, of any
device or element of design incorporated into any new vehicle for the purpose of noise control
prior to its sale or delivery to the ultimate purchaser or while it is in use, or (2) the use of the
vehicle after such device or element of design has been removed or rendered inoperative by
any person.
Among those acts presumed to constitute tampering are the acts listed below.
•Replacement of the original exhaust system or muffler with a component not in compliance
with Federal regulations.
•Removal of the muffler(s) or any internal portion of the muffler(s).
•Removal of the air box or air box cover.
•Modifications to the muffler(s) or air inlet system by cutting, drilling, or other means if such
modifications result in increased noise levels.
Not trying to be a d*ck about it:O; there's nothing in this quote that implies the valve is purely for noise abatement. As the valve sits between the two stages of the OEM muffler, it could easily be argued that removal of same does not constitute modification of said muffler.

It would be far more effective to show a dyno plot before and after removal of the valve, and see if the HP profile changes. Any time someone dinks with the back pressure a motor faces, the HP curve is going to respond to that. Most frequently the change is a loss of HP, or at best a few percent improvement.

More noise does not mean more HP. Weight loss has far more impact.
 
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