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the only one is a R1
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Discussion Starter · #1 · (Edited)
ex up/smog block off

i have a 2002 R1. what is the deal with the ex up. 95% of the time i am on the track.my question is what does it do.should i take it off? i plan on getting a full system after my suspension upgrade so for now would i get any gains on taking it off.do i need to do anything after like a re map?? all info would be great
 

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Action figure sold separately
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The EXUP is a valve in the exhaust collector that opens and closes in response to cable tension actuated by the servomotor, which is controlled by the ECU based on RPM (and possibly throttle opening position). At lower RPM, the valve closes to increase back pressure and alter the resonant frequency of the exhaust pipe. This alters the timing and frequency of the arrival of positive and negative pressure pulses at the exhaust valve in such a way so as to increase the presensce of negative pressure waves coincident with exhaust valve opening and valve overlap. This inmproves exhaust scavaging and aids cylinder refilling with fresh fuel/air charge within the lower RPM ranges. This boosts torque output at lower RPMs. The effect of disabling the EXUP is to decrease the low RPM torque and tractability of the engine. When you install a full exhaust. the EXUP is defeated, as no aftermarket full system has provisions to retain the EXUP. The effect is an incrrease in midrange and peak torque/HP, at the expense of low RPM torque/HP, a very good trade off for a track bike, but not so desirable for a street bike.
 

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the only one is a R1
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631 Posts
Discussion Starter · #3 ·
that was some great info. now can you explain to me about "smog block off plates" and if this would be beneficial to me. graves sells them for like 20 bucks is this something i should consider doing and is it easy to do or worth it??
thanks
 

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Action figure sold separately
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12,213 Posts

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Action figure sold separately
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12,213 Posts

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Akrapovic xplane
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Eyespy said:
The EXUP is a valve in the exhaust collector that opens and closes in response to cable tension actuated by the servomotor, which is controlled by the ECU based on RPM (and possibly throttle opening position). At lower RPM, the valve closes to increase back pressure and alter the resonant frequency of the exhaust pipe. This alters the timing and frequency of the arrival of positive and negative pressure pulses at the exhaust valve in such a way so as to increase the presensce of negative pressure waves coincident with exhaust valve opening and valve overlap. This inmproves exhaust scavaging and aids cylinder refilling with fresh fuel/air charge within the lower RPM ranges. This boosts torque output at lower RPMs. The effect of disabling the EXUP is to decrease the low RPM torque and tractability of the engine. When you install a full exhaust. the EXUP is defeated, as no aftermarket full system has provisions to retain the EXUP. The effect is an incrrease in midrange and peak torque/HP, at the expense of low RPM torque/HP, a very good trade off for a track bike, but not so desirable for a street bike.
Had a similar question, thanks for clarifying.
 

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see you at the races and ride
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the exup and collector on the 02-03 bikes is a great design, I would keep it as there is no power to be gained by removing it or fixing it open. It is wide open at high engine speeds already.
 
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