Exhaust Flap Thing?

[Quivorir]

Hi guys, bought a 2012 CBR1000 the other week and the dealership was talking about some flap in the exhaust that opens at the higher RPM. He mentioned taking it out out but I just wanted to ride the thing and wasn't paying much attention. What does it do?

[Shamizzle]

Dunno how it works on the '12. But on the '06s it's a butterfly valve operated by cables from a little servo motor. Opens up around 5000rpm from memory and is a waste of space. I believe Honda say something about air speed, which would make sense if the pipe it's self shrunk and grew along the length of it, but putting a flap in there is just a retarded restriction, so it can only be for noise. That's my theory. My bike definitely worked better without it. But I changed to a yosh slip on, so not really a definitive test....

[2K12Blade]

I'm pretty positive it's for noise emission reasons. Mine opens up at 3900 RPM and there is a noticeable sound difference from the exhaust. Same thing with the intake flaps, just to keep the bike quieter.


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[Quivorir]

Yeah I thought it must be something to do with noise more than anything else, it sounds much better when its open (what I think is open anyway).

[MrDude_1]

Originally Posted by Quivorir

Yeah I thought it must be something to do with noise more than anything else, it sounds much better when its open (what I think is open anyway).

if you want you can disconnect the cable.
this makes the flapper stay open all the time.

to do this:
remove the seat.
take out the screws holding the flapper servo motor in.
lift it up.
MAKE A NOTE OF HOW THE WHEEL IS. put a mark on it with a sharpie if you have to.
turn it by hand so you get the cable off
with the cable off now off, TURN IT BACK SO IT IS WHERE IT WAS.
bolt it back on, and turn on the key..

if you get a FI light, you didnt put it back where it was.. it doesnt have to be perfect, but it should be close.
if theres no FI light, put the seat back on and you're done.

[fashionrider712]

theres also a youtube vid that'll show you how to do it.

[Quivorir]

Thanks guys. I'll try hunt down that video.

[fashionrider712]

I ended up jus drilling out the screws that held the flapper thing on. So does anyone know since we are disabling the flapper, has anyone removed the servo. Can it be removed with out throwing a fi light?


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[Visionary]

I believe they have that on all cbr models...my 07 model had it too there was a spring mechanism under the seat for it...but i replaced the exhaust so no more flapper those poor japs adding things to get the bike sold in the U.S lol

[capt.america]

This is a 5 min. mod on a '12. No need to remove seat or unbolt or drill anything. Small panel under tail has 3 plastic push screws you remove to gain access to servo. After removing panel rotate servo wheel (note where you start) clockwise to remove cable. Return servo wheel to original position. Close panel, done.