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+1 on the servo buddy. Ordered mine. Installed it. Now I have a nice little nook for the PCV and the SpeedoHealer.

Which means, I actually have more room in the tail for things like wallet/phone/firstaid kit/ or some energy bars or what not.
 

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quick question, i read somewhere that the servo valve is shut at lower rpm for some added backpressure that boosts torque.. and opens up at higher rpm... i know adding an aftermarket exhaust is really good but will it lose that "added backpressure that boosts torque" if we took off the servo cable or motor that controlled the valve?
 

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From what I understand (at least on the 07) the butterfly valve was added as a noice emissions feature in the US. It would start to close at around 10k rpm to reduce noise pollution.
 

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The Indifference Engine
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From what I understand (at least on the 07) the butterfly valve was added as a noice emissions feature in the US. It would start to close at around 10k rpm to reduce noise pollution.
14k, and it still cycles at lower rpm and throttle closings.
 

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No, its not about back pressure its about noise, I know people that have put aftermarket exhaust on theirs and it increased the powerband all the way through the rpm range. Just do it! You will not regret it.
 

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i wanna keep my stock can since it looks awesome, but i wanna loose the valve(s), i wanna have a punch through system any advice or links guys?
 

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Alot of people don't realize exactly why the manufacturers use these exhaust servos, but the true reasons are:

1.) Extra midrange power and torque
2.) Noise emissions

When you place a butterfly valve in a pipe (as you will find in the exhaust, or secondary throttle bodies of many sportbikes) when it is fully open almost no restriction to flow is present. However when the valve begins to close (at lower rpms), the cross-sectional area of the pipe is effectively reduced which increases the velocity of the fluid traveling through this pipe (via Bernoulli's principle). So basically it works like this, at low rpms there is hardly any flow going on, so to speed up the exhaust flow the valve is actuated (it partially closes). At high rpms there is a lot of flow going on, so to the valve opens fully so that top end horsepower and maximum flow is not affected. When you remove this valve, it hurts performance. This is why you see many bikes in Moto GP and WSBK that utilize this technology. The only problem is that the butterfly valve is attached to the HEAVY stock oem system, and most chucklehead club racers don't really know enough about engines to realize its true function.
 

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^^ i dont know about you, but im either on the brakes or that throttle is wide the fuck open, in which case that butterfly valve is open.
 

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^^ i dont know about you, but im either on the brakes or that throttle is wide the fuck open, in which case that butterfly valve is open.
The butterfly valve in the exhaust servo system and in the secondary throttle bodies actuate as a function of two things: engine speed (rpm) and throttle position. Lets say that you are coming out of a corner: if you are at a low rpm and the throttle is open 100% the valve will only be partially open because the motor doesn't flow much air at that point (it will only open fully when throttle is 100% and RPM is near peak). So this will help you get a better drive coming out of a corner. It should also be mentioned that these butterfly valves can also be re-mapped in the factory race ecu to also control engine braking (when throttle is 0% and rpm is high). Alot of people think that bigger is better when it comes to exhausts, cylinder head porting, valves, cams, etc. but this is simply not the case. Bigger is only better when you are flowing enough air to require that amount of flow at peak top end horsepower, but at the lower rpms your torque and power production will be suffering hugely because of the slower intake air velocity and exhaust scavenging, that is why devices like this have been invented, to help high rpm motors become more efficient at lower rpms.
 

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i'm aware of how secondary's & exhaust valves work, but thats easily taken care of by getting on the gas sooner & braking later ;) the tiny bit of power that is created by the back pressure from the valves isn't worth their weight. as far as low RPM is concerned, the only time i think my bike is even below 6K is in the pits.. And no, larger primaries aren't always the answer, hence why leo vince tells you NOT to buy their $2100 system unless your doing a supersport build.
 

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I've seen butterfly exhaust valves on race bikes.

I can't remember where I saw that posted I believe it was a magazine.

I'll look around and see if I can find the article.

;)
 

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thanks guys, this is my first ss and and trying do do things to make it lighter i like how the stock exhaust is relatively quite, wanted to make it a bit louder thats why i was considering taking the servo/valve out but i like the look of the can, honestly i havent seen any after market cans that look as good on this bike,

any suggestions i dont plan on taking this one to the track any time soon, however that was the goal behind its purchase i wanna familiarize myself to the bike before i convert it to full track ina few years
 

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Butterfly valve default position

You definitely will not get the FI light if you just remove the wee little cables from the servo and let it freely do it's thing. So don't worry about leaving it plugged in while you wait for your servobuddy to get in... or like me, just leave it like that forever ;)
So, if we simply remove the cables, what would be the position of the valves? Will they stay fully closed or fully open or something else? Either way, is that harmful in the longer run?
 
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