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[shark]

Apologies if this has been posted before - I am a new boy 

Does any one have any idea of the real purpose of the butterfly valve in the exhaust system - I have my suspicions, but hey what the f**k do I know...

I have a carbon Acrapovic fitted to my 08 10R with the valve fitted (came as one of George Whites deals) I have since removed the cables as the valve is spring loaded open and Servo continues to tell the ECU it is making a difference. I have noticed no change in mid range power - although the pipe is a little louder...

[Andy J]

there are a few threads on this, try the search option pal 

[ZX10R-RACER]

its just to make the power delivery smooth.

[shark]

there are a few threads on this, try the search option pal 

Cheers Andy, will do in future.

[jpaterson69]

Shark,
official Kawasaki speak is that it is there to increase the exhaust back pressure by limiting exhaust gas flow at lower than 6k revs. But concensus of option is that it is there mostly for noise regulations.
The exhaust valve and secondary injectors on 08 model are not really active till after 6k.
If you received an Akra end can from the dealer as extra, then the valve will have been removed. The valve is part of the end can assembly on the 08. on 04/05 the valve is not on end can or link pipe but at the start of pipe to headers.
I am surprised dealer did not remove the cables from the motor assembly under the seat and remove and keep with whole end can assembly to give you, or remove cables from can end valve. It's not neat just leaving them dangling there.
Anyway, I never noticed any difference either on removing valve, except louder noise.

John

[shark]

Cheers John,

The Akra end can fitted to mine has the valve grafted in (maybe road legal version of the can) so cables were connected as expected on delivery. I removed the cables completely after 250 miles, but am considering refitting them now I've done a few more miles and got to know the bike (just to prove my earlier theory for myself).
I keep hearing mentions of 6-7000rpm for valve opening - looking at the V.I.N plate on the 08 10R, the exhaust noise is quoted at 94dB @ 6250rpm - coincidental or am I just a cynic at heart..

At the end of the day the 10 has more than enough power for me and I love it with or without the insects.

N.B removal of the cables on the 08 10 are a piece of piss (Kwaka design) unlike the performance my brother in law has got to go through on his blade since he's looked at doing it.

[Ali-B]

I had an Akra fitted to mine when I bought it back in May, which has no exhaust valve, and although it has the removable baffles, is marked up as "Not For Road Use". (Anyone know how to get rid of that? It looks as if it is laser etched into the metal). I saw one of the cans with the valve fitted a couple of weeks ago in our local dealers, and apparently, these are the road legal versions, (as well as being significantly more expensive). From that, I guess that at least part of the valves purpose IS to reduce the noise levels.

Al

[GRNINJA]

most people think is just a way to make the exhaust quiter in these times of bike hating....

kawasaki as john says say its for exhaust back pressure.... but not a great deal of difference is seen by keeping them open...

[jpaterson69]

Shark,
Ah I see what you are talking about now mate, they are Akra specials made for Kawasaki and yeah will be road legal. As you will be aware, standard aftermarket end cans would not have the valve installed in the can, well I have never seen any, that is what was throwing me with your comments about disconnecting cables on an aftermarket can.
Glad you are enjoying it mate, it's a hell of a kick once you are in the green zone with the valve open and secondary injectors kicking in.

JP

[shark]

Oh Yeah!!!!

[drewk8]

does the valve not stay closed if cables removed? isnt it in closed poss when bike not running then the cables open the valve? perhaps you should re connect or remove the blade, then you might see  a diff..

i took the baffle out my growler and couldnt believe the diff ! i had to tell my other half i broke the baffle so as to keep it out ! lol...

wow.... cant hold on now.....

[HammyUK]

Valve is sprung to stay open in the event of a cable/servo failure, etc so as not to produce too much pressure as poss blow your engine

[jpaterson69]

drew,
are you serious, you noticed a difference between baffle in and baffle out on the Growler.
I have fitted the baffle from day one, not had it out, that is why I am asking. If that is the case then its coming out tomorrow.

Rgds
John

[shark]

Indeed that is correct, the valve is spring loaded open. Only thing I noticed by removing cables and leaving the valve full open is a slight increase in noise.