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A lot ppl must have noticed the sticker"EXUP" on YAMAHA's, specially R1's .What is an EXUP? It stands for "Exhaust Ultimate Powervalve" .
What it really is a sort of valve that sits just after the exhaust header's . As you ppl must be knowing the exhaust needs to be tuned for a particular engine, down side was that the exhaust could only be tuned so that the engine makes good low end power,good midrange,or good top end power, it was very difficult to have all three in package,there are other ways like Honda's VTEC valve arrangement which it uses in the VFR800's but its too complicated and adds too much weight to the motor which is why they dnt use em on their sports bikes.Yamaha's soluion , the EXUP system varies the exup valve opening according to RPM and some other variables and "fool's" the engine into thinking it has an exhaust tuned for that particular RPM.Once again this is not to be confused with the valves in the engine.
check out this picture for a better under standing.
Yamaha had a patent on this technology for quite a few years which is why other bike makers could not use it I think the patent rights only ran out a couple of years back and Honda and suzuki are the two factories which are using the same technology in their blades and gixxer's though they have different names for it.
What it really is a sort of valve that sits just after the exhaust header's . As you ppl must be knowing the exhaust needs to be tuned for a particular engine, down side was that the exhaust could only be tuned so that the engine makes good low end power,good midrange,or good top end power, it was very difficult to have all three in package,there are other ways like Honda's VTEC valve arrangement which it uses in the VFR800's but its too complicated and adds too much weight to the motor which is why they dnt use em on their sports bikes.Yamaha's soluion , the EXUP system varies the exup valve opening according to RPM and some other variables and "fool's" the engine into thinking it has an exhaust tuned for that particular RPM.Once again this is not to be confused with the valves in the engine.
check out this picture for a better under standing.
Yamaha had a patent on this technology for quite a few years which is why other bike makers could not use it I think the patent rights only ran out a couple of years back and Honda and suzuki are the two factories which are using the same technology in their blades and gixxer's though they have different names for it.
keep more comin 
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