Exhaust butterfly valve disconnected ZX10 2008?

[Mumbles]

Quick question folks, just been taking the bike apart to have a look at stuff (first time I've been able to take a look since I purchased it) anyhow I noticed under the seat there was this thing that looked like there should be cables coming out of somewhere and going into it :(, himmm me thinks I better look this up in my manual, turns out this is actually the Exhaust Butterfly Valve Actuator :shit:.
So its not got any of the cables hooked up or even present, but still has the standard exhaust on it (so me thinks the last owner has put this back on to sell the bike standard ish)

What I want to know is will the Exhaust Butterfly Valve Actuator being disconnected do damage to the bike? :doh:

[pete376403]

Shouldn't do any damage but the motor won't run as well as it should. The butterfly provides a bi t of back pressure at (I think) low revs to improve low end torque
Put it back to standard - chances are Kawasaki know more about the engine and its design that the previous owner.

[imdying]

Or is it so the bike can pass the noise emission tests. Kawasaki might not have wanted it there in the first place.

[Sensei]

Disconnected mine on my old GSXR1000 & it went the best it had ever gone .

[pete376403]

Hmmm ok. At a guess I would say it serves the same purpose as the EXUP valve in certain Yamahas, purpose of which is explained here:
http://en.wikipedia.org/wiki/Exhaust_ultimate_power_valve

At full throttle it would be wide open, so difficult to see how disconnecting it would alter power. Maybe it made a difference to the sound, which could have altered perception of performance, but, without dyno charts, difficult to say.

[Sensei]

Bottom end & mid range improvement , top end was pretty much GSXR1000

[imdying]

Hmmm ok. At a guess I would say it serves the same purpose as the EXUP valve in certain Yamahas, purpose of which is explained here:
http://en.wikipedia.org/wiki/Exhaust_ultimate_power_valveNice idea, but they fucked up as many Yamahas as they helped.

[pete376403]

Yeah? I read (never ridden one) the EXUP was a bit of a goer (for its day) and more powerful than the non Exup FZR1000.

[Mumbles]

Shouldn't do any damage but the motor won't run as well as it should. The butterfly provides a bi t of back pressure at (I think) low revs to improve low end torque
Put it back to standard - chances are Kawasaki know more about the engine and its design that the previous owner.
I wish I could put it back on but I can't if I dont have it. Thanks for the help

[Pussy]

Maybe it made a difference to the sound, which could have altered perception of performance, but, without dyno charts, difficult to say.

Excellent point! What may be "perceived" as increased power means jack shit without dyno evidence

[F5 Dave]

Search for ZX forums I guess. On Exups you have to leave the servo in place even if not attchd as if the ign doesn't 'see' the servo electrically it will revert to low power mode, though you can buy or make emulators. Might not be a drama on a ZX, but wot a winker to be too lazy to put it back together properly.

[Gremlin]

When I had a 2004 zx10, I disabled the exhaust butterfly... was supposed to improve low down performance, also sounded deeper. I believe its mostly for emissions control, but then, I'm certainly no engineer...