EXUP (Exhaust Ultimate Power Valve)

The exhaust system also features Yamaha's EXUP System (Exhaust Ultimate Power Valve). The single butterfly valve prevents the "blow back" phenomenon caused by "valve overlap". The EXUP system eliminates "flat spots" in the power band and reduces emissions too. <----I found this ^
HERE--->http://www.totalmotorcycle.com/photos/2008models/2008models-Yamaha-WR250X.htm

My Q is Why do people take it off? The description of what the EXUP does sounds important.
I'm set on doing this mod. I just wanna know why 80% of the WRR/X riders have.
Cheers!

StreetGhost wrote:

The exhaust system also features Yamaha's EXUP System (Exhaust Ultimate Power Valve). The single butterfly valve prevents the "blow back" phenomenon caused by "valve overlap". The EXUP system eliminates "flat spots" in the power band and reduces emissions too. <----I found this ^
HERE--->http://www.totalmotorcycle.com/photos/2008models/2008models-Yamaha-WR250X.htm

My Q is Why do people take it off? The description of what the EXUP does sounds important.
I'm set on doing this mod. I just wanna know why 80% of the WRR/X riders have.
Cheers!

Been asked and answered many times here.

Read around.

Short answer - it doesn't do what Yamaha says it does...it's more for emissions and noise.

It's welded into stock exhaust system so if you want aftermarket exhaust you either ditch the EXUP, or become a custom fabricator.



Set on doing what mod?

Also: please watch video and tell me - how much do you really think the EXUP does?

click me

motokid wrote:

Also: please watch video and tell me - how much do you really think the EXUP does?

click me

I think I saw it move a little only once.

Set on doing what mod? [/quote]

^
Yeah, buying the Graves EXUP plug in. Not really a MOD.

StreetGhost wrote:

Yeah, buying the Graves EXUP plug in. Not really a MOD.

1) Do you have aftermarket exhaust?

2) a 5 cent resistor can do the same job as the $60 Graves part

3) The Graves plug in does nothing for performance. It simply prevents a CEL light on your dash from being on once you remove the EXUP servo

motokid wrote:

StreetGhost wrote:

Yeah, buying the Graves EXUP plug in. Not really a MOD.

1) Do you have aftermarket exhaust?

2) a 5 cent resistor can do the same job as the $60 Graves part

3) The Graves plug in does nothing for performance. It simply prevents a CEL light on your dash from being on once you remove the EXUP servo

No aftermarket exhaust yet. I'm doing little bit at a time. I'm thinking the FMF Q4. For now I've only pulled out the spark arrestor, added a K&N air filter. Next is the AIS mod along with the flapper mod. Before the Q4 purchase I want to re gear it.

StreetGhost wrote:

No aftermarket exhaust yet. I'm doing little bit at a time. I'm thinking the FMF Q4. For now I've only pulled out the spark arrestor, added a K&N air filter. Next is the AIS mod along with the flapper mod. Before the Q4 purchase I want to re gear it.

Then why are you asking about the Graves part and/or posting stuff about the EXUP?

Also: click me

motokid wrote:

StreetGhost wrote:

No aftermarket exhaust yet. I'm doing little bit at a time. I'm thinking the FMF Q4. For now I've only pulled out the spark arrestor, added a K&N air filter. Next is the AIS mod along with the flapper mod. Before the Q4 purchase I want to re gear it.

Then why are you asking about the Graves part and/or posting stuff about the EXUP?

Also: click me

Because I'm a planner and I'm putting together my plan.

Then consider NOT getting the Graves part.