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  1. #1
    kemper1976's Avatar
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    Seadoo RXX not running good with fresh motor. I've tried almost everything!! Help!!

    Hello everyone. I rebuilt my RXX a couple of months ago and installed a re manufactured BRP crank I bought from PPG, forged 1.5mm over Wiseco's and Cometic gaskets.

    Carbs are fresh but I didn't change the needle & seats. All fuel lines are new along with internal & external filters.

    I bought this ski with a weak motor and never rode it prior to rebuilding it. I don't know if this was a preexisting problem or something I caused on accident.

    The rest of the motor is basically as it came from the factory. It's only turning 7,000 rpm's and should be turning 7500 like my other RXX. It barely squeaks out 54 on GPS. Yes, the rpm and gps speed are correct in this case.


    The motor has 175psi of compression in each cylinder. Stock head milled .002"
    for truing
    BRP Crank spins free and smooth. It starts and idles great, just runs terrible.

    Here's what I've changed/swapped so far. Luckily I have a spare working
    RXX I can take parts to test

    Jet Pump - I have a spare skat pump from my other
    RXX that I swapped into this one - no change
    Reeds - Swapped the Rinaldi's from my other ski and even tried some stock reeds - no change
    Turned the high speeds out 1/4 turn - no difference from closed
    Swapped the MPEM- no change
    Rave valve solenoid- tried a spare one- no change- unplugged solenoids lost 500 rpm's so I know that each of the two I tried are good.
    New Sparkplugs - no change

    My next steps are to switch the rave valves and if that doesn't change I'm planning to swap carbs. This is basically all I have left to try.


    Anyone have any ideas? It has to be something simple. I've tried just about everything I know. I've built a bunch of 951's but never ran into this issue before.


    Thanks in advance for the help.


    Last edited by kemper1976; 07-10-2011 at 06:12 PM.


  2. #2
    speedskixp's Avatar
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    Quote Originally Posted by kemper1976 View Post
    Hello everyone. I rebuilt my RXX a couple of months ago and installed a re manufactured BRP crank I bought from PPG, forged 1.5mm over Wiseco's and Cometic gaskets.

    Carbs are fresh but I didn't change the needle & seats. All fuel lines are new along with internal & external filters.

    I bought this ski with a weak motor and never rode it prior to rebuilding it. I don't know if this was a preexisting problem or something I caused on accident.

    The rest of the motor is basically as it came from the factory. It's only turning 7,000 rpm's and should be turning 7500 like my other RXX. It barely squeaks out 53 on GPS (way off) , launches like a turd and I cannot figure it out. Yes, the rpm and gps speed are correct in this case.


    The motor has 175psi of compression in each cylinder. Stock head milled .002"
    for truing
    BRP Crank spins free and smooth. It starts and idles great, just runs terrible.

    Here's what I've changed/swapped so far. Luckily I have a spare working
    RXX I can take parts to test

    Jet Pump - I have a spare skat pump from my other
    RXX that I swapped into this one - no change
    Reeds - Swapped the Rinaldi's from my other ski and even tried some stock reeds - no change
    Turned the high speeds out 1/4 turn - no difference from closed
    Swapped the MPEM- no change
    Rave valve solenoid- tried a spare one- no change- unplugged solenoids lost 500 rpm's so I know that each of the two I tried are good.
    New Sparkplugs - no change

    My next steps are to switch the rave valves and if that doesn't change I'm planning to swap carbs. This is basically all I have left to try.


    Anyone have any ideas? It has to be something simple. I've tried just about everything I know. I've built a bunch of 951's but never ran into this issue before.


    Thanks in advance for the help.


    TPS in throttle cable. There is a test for it but I cant remember exactly, Basicly the tps is like a switch that sends the mpem a signal to advance the timing at anything over say 75% throttle.

  3. #3
    If i knew,...I wouldn't ask sea-one's Avatar
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    Read the plugs and eliminate fuel flow,sound like you covered most everything really.

  4. #4
    kemper1976's Avatar
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    I had to swap the throttle cable because I broke then end off my cable. I put a cable from an RX on it. This may have just fixed my problem. This has to be it. I'll pull the throttle cable from my other RXX and give it a shot. I'll post the result. Thanks!!

  5. #5
    kemper1976's Avatar
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    Plugs have a nice bronze color. They look normal.

  6. #6
    speedskixp's Avatar
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    Quote Originally Posted by kemper1976 View Post
    I had to swap the throttle cable because I broke then end off my cable. I put a cable from an RX on it. This may have just fixed my problem. This has to be it. I'll pull the throttle cable from my other RXX and give it a shot. I'll post the result. Thanks!!
    No problem, Could just need adjusted also. If I rememder correctly the way to test it is to put a volt meter on the black/white wire on the tps and ground. When powered up you should see 5 volts from 0%-75% throttle. Anything more than 75% throttle should read 0 volts. Use this to adjust the cable until it's right if the tps is good.

  7. #7
    kemper1976's Avatar
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    I'll try the test. If the test fails or is inconclusive, I'll switch the cable with my normal functioning cable from the other RXX.

  8. #8
    If i knew,...I wouldn't ask sea-one's Avatar
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    Speed, this is a carbed race ski RXX,there is no TPS, plugs ideally should be chocolate brown with wet around the edge and on the threads.
    ps. i wish i could find and RXX

  9. #9
    speedskixp's Avatar
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    Quote Originally Posted by sea-one View Post
    Speed, this is a carbed race ski RXX,there is no TPS, plugs ideally should be chocolate brown with wet around the edge and on the threads.
    I know exactly what it is. TPS is in the throttle cable. Not your typical tps. Post 2 explains how it works. It's basicly a switch.

  10. #10
    If i knew,...I wouldn't ask sea-one's Avatar
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    my bad

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