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Hello,
I am stripping an 08 R1 to put engine and associated bits into a car.
Got a question about the ex-up valve.
What is its true purpose? Back pressure mapping? Sound deadening? Emissions?
Any help would be great.
Ideally would probably delete but need to know all the facts.
Thanks.
 

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R1.. The fast kind
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902 Posts
According to Yamaha its purpose is to improve low and midrange torque.

I guess there's people out there that can vauge for that.

Others think it's a kind of sound dampening device to pass noise regulations.

When i got my ECU flashed with YEC/YMS software i removed the entire EXUP butterfly assembly since the servomotor isn't supported anyway, i also fitted linkpipe (decat) and slipons.

Thanks to the unrestricted software the low and midrange improved even though the EXUP was gone..

Many years ago i made a simple investigation of the -07 EXUP and found it was only responding to rpm and it opened 100% before 4000rpm

To be honest i can't say how important the EXUP is since i havn't tested it on a dyno...

 
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