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Thread: power valves

  1. #1

    power valves

    I'm putting the ypvs back together. yamaha 1200xlt I didn't look at it when I took it apart, but now going together it looks as if all the valves open at the same time. As far as I can tell the assembly can only go together one way, and I have the manual.
    Are the valves opening/closing all at the same time, or is the offset so minimal that I can't tell?


  2. #2

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    Welcome to the forum.

    They open at the same time. They are set up to slowly open and give a smooth transition from a small exhaust port to a larger one. They open at at a fixed RPM range.

    The gas valves are independent of each other, but if they are tuned correctly, they will virtually come and "pop" open at the same time. They are much more aggressive and open based on gas pressure. They are either full open or full closed. There is not much of a transition.

    I personally like the feel of the gas valves.

  3. #3
    Thanks Salty, I feel better. I haven't tackled the carbs yet. Gonna at least clean them up. Time to move on, but waitin on parts.

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