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  1. #1

    Join Date
    Oct 2013
    West Central Florida

    No power valves in a power valve

    Hey Guys, I have an outside the box crazy question. Has anyone ever ran a power valve motor without the power valves installed? If so, how does it run. I know the power valves work to spread the power band over a wider range. So without them installed, wouldn't it just run like a non-power valve setup?

  2. #2
    Sit tight as the experts should the meantime I believe by leaving them in, the exhaust port is effectively lowered, and by doing so you only benefit from low-end exhaust port timing. If that's correct, then you would suffer on the top-end because the valve does not open and raise the port for quicker removal of exhaust gasses at higher RPM... . And in theory the opposite if they're left out.

  3. #3
    TuningForkMarine's Avatar
    Join Date
    May 2013
    Palm coast FL / Shakopee MN
    u know i bought a motor before for one of the skis i was working on, and realized it had powervalves missing.... always wondered about this... forgot about it till you mentioned it....

  4. #4
    Happily Self-Employed WFO's Avatar
    Join Date
    Nov 2005
    Houston, Texas
    You have to have the valves installed, because there is a big hole in the exhaust port without them. You can lock them in the up position, but will have little or no bottom end power.

  5. #5
    ...and I'd be willing to guess that a non-power valve cylinder for say a 1200 v. pv1200, has a completely different exhaust port shape/height and... . FWIW, Group k has a big bore setup that locks the powervalves in-place, but that's for the gp800r.

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