Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

cbr600rr exhaust

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by HILLY, Dec 28, 2007.

  1. hey evry one i got my new 600 the othere week and was cleaning it this morning and noticed there is a exhaust valve of some sort on the pipe just after the bend as it heads up to under the seat and it has 2 wire cables coming from it and run to a black box under the seat.
    i was wondering what does this thing do?
    also i was wondering if there is and thing i can remove cut or play with to make it half a bike its pritty gutless?
    thanks heaps

  2. I'm guessing an o2 sensor?
  3. It's a noise reduction valve (commonly known by Yamaha's trade name which is EXUP valve, EXhaust powerUP).

    It partly blocks the exhaust at low rpm to improve power and reduce noise
    and opens at mid-to-high RPM to improve power and allow noise.

    It is operated by the engine computer which runs a servo-motor, this
    motor pulls on the cables to open and close the valve.

    If you unplug the servo-motor your engine computer will get upset
    and put you in go-slow mode.

    If you remove the valve or jam it open, you will almost certainly need
    to spend $300-800 tuning the bike to get back the same
    horsepower as you had before, you *might* gain 5% horsepower overall.


    If you think your new 600 is gutless, you're right, you haven't found
    the guts yet. The "guts" of a 600 are all above 10,000rpm.

    Go to redline RPM in 4th, 5th, or 6th (on a racetrack please) and
    you'll get DOUBLE the horsepower that you have at mid-RPM;
    if you still tell us it's slow you have an excuse to buy a 1000cc.

    Took me 3 months to get my Kwakka production racebike set
    up properly in suspension, brakes, etc , and before I got used to it.
    I thought it was OK, but the same speed as my older bike, not
    faster, so I was a bit disappointed.

    Then I was eventually able to ride the bike at RPMs which
    got into the power zone.
    It felt like a whole new bike, and had twice the horsepower at 11,000rpm
    than it did at 8,000rpm!

    You Bl***y Ripper!
  4. thanks man :grin: