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  1. #1

    How should the powervalve function (open/RPM) on the trailer/hose?

    The powervalve in my GP1200R (01) only wants to start moving open at max RPM, and it doesn't seem to move that much, is this normal? It opens and closes pretty quick but obviously I don't want to hold it revved with no load so I'm only giving it a full throttle blip for a couple seconds. I thought it should start to open in at least the upper midrange? Is it normal for the powervalve to only start to open at max RPM/fully wound out? And how much visually should the pulley be moving the servo cables hook to? Or does the motor need to be under load in the water for the power valve to open up fully? Thanks...


  2. #2
    Moderator RX951's Avatar
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    Read This:
    http://rivaforums.com/eve/forums/a/t...4/m/8881046954

    Here is a test for the servo motor. you can also crank the motor shortly, shut it off and the servo motor should cycle a couple of seconds after the motor is shut down.


  3. #3
    Quote Originally Posted by RX951 View Post
    Read This:
    http://rivaforums.com/eve/forums/a/t...4/m/8881046954

    you can also crank the motor shortly, shut it off and the servo motor should cycle a couple of seconds after the motor is shut down.
    Yes, it does that every time I shut it off I can hear it cycle. I'll check out the link and relay the info to my backyard mechanic. I was wondering if anyone has paid attention to how it visually works and at what RPM/throttle opening when running their ski on the trailer.

  4. #4
    Moderator RX951's Avatar
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    Quote Originally Posted by Emig5m View Post
    Yes, it does that every time I shut it off I can hear it cycle. I'll check out the link and relay the info to my backyard mechanic. I was wondering if anyone has paid attention to how it visually works and at what RPM/throttle opening when running their ski on the trailer.
    Don't pay attention to it on the trailer. Only flush on a trailer. If it cycles, and the adjustment is set properly, it should be fine. Yamaha’s Power Valve System is used mainly on high-performance two-stroke engines. A two-stroke engine produces optimum low-end torque with short exhaust port timing (low exhaust port height) and maximum high rpm horsepower with a high exhaust port. YPVS eliminates this conflict by incorporating variable exhaust port heights that change as rpms increase.

    "visually how it works"? uhm...here is some information on what "powervalves do" definition http://en.wikipedia.org/wiki/Two-str...r_valve_system

    Video> on a motorcycle engine with a YPVS


    cycling of a YPVS (motorcycle)...but still same concept on a GPR





  5. #5
    GGG's Avatar
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    Ya Ive revved them up on land before. the valves dont seem to move much til you put a load on it at high rpms

  6. #6
    Quote Originally Posted by GGG View Post
    Ya Ive revved them up on land before. the valves dont seem to move much til you put a load on it at high rpms
    Ok, I think mine is functioning normal then. I understand the point of a powervalve on a 2-stroke motor (former MX biker) but was just wondering if mine was working normal on this waverunner on the trailer/hose since this is the first servo controlled one I've ever owned. Thanks for the info.

  7. #7
    Moderator RX951's Avatar
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    Quote Originally Posted by Emig5m View Post
    Ok, I think mine is functioning normal then. I understand the point of a powervalve on a 2-stroke motor (former MX biker) but was just wondering if mine was working normal on this waverunner on the trailer/hose since this is the first servo controlled one I've ever owned. Thanks for the info.
    cool

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