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  1. #1

    pro 785 exhaust valves don't open

    Got a new to me 1998 pro 785, did some tuning on the carbs today and got a top speed of 53. I noticed the exhaust valves weren't opening regardless of throttle position. I tried to rig them open all the time but the ski would just bog and not get on plane. Whats the common fix for this? How much top end am I losing with the valves shut all the time?


  2. #2
    Moderator beerdart's Avatar
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    Manual with troubleshooting guide.
    http://www.mattmans.com/polaris/upload

  3. #3
    www.springbreak-florida.com rgard32's Avatar
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    prolly another bad actuator.....theres a little potentiometer inside that little black box that goes bad ..

    and you will lose roughly 800-1000 rpm

  4. #4
    Tested the motor, when you apply 12 volts it opens about halfway, then revers polarity and it closes. tested the resistance like the troubleshooting guide said and only getting 3ooo ohms on the RIW and green wires with valves closed and 5000 ohms on LGN and green wires when valves are closed. is this the measuremnt of the position sensor in the actuator? When are the valves supposed to open when the ski is running?? Thanks guys!

  5. #5
    Moderator beerdart's Avatar
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    Have you removed and cleaned the valves? Off the top of my head the CDI opens the valves around 4800,5000 rpm.

  6. #6
    www.springbreak-florida.com rgard32's Avatar
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    Quote Originally Posted by wrenchdaddy View Post
    Tested the motor, when you apply 12 volts it opens about halfway, then revers polarity and it closes. tested the resistance like the troubleshooting guide said and only getting 3ooo ohms on the RIW and green wires with valves closed and 5000 ohms on LGN and green wires when valves are closed. is this the measuremnt of the position sensor in the actuator? When are the valves supposed to open when the ski is running?? Thanks guys!
    opens halfway? ..Even if the potentiometer was workin properly(which is not i think closed is 1200 open is 5k i THINK) either way the motor in there is junk...

  7. #7
    valves are clean, took the actuator box apart and it was full off rust, suprised it was even working. gonna try to clean it up and see if she works right, where can i get a new actuator at?

  8. #8
    www.springbreak-florida.com rgard32's Avatar
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    a Brand new actuator costs 300+ (ripoff) better off watchin Ebay or put up a want to buy ad in the classified section

  9. #9
    the potentiometer is bad, one side is way off than the other. even if i get the actuator working properly im not sure that the cdi is giving signal to it, is there any way to test it w/o putting it back in the water?

  10. #10
    www.springbreak-florida.com rgard32's Avatar
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    i wouldnt worry about a bad cdi..i would try to get another actuator first...u know u need one.....its RARE for a cdi to be bad only for the actuator..but it has happened.but RARE.

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