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  1. #1
    JohnCiccarelli's Avatar
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    Help 1995 SeaDoo 650 GTX Won't Start

    This is the first time I have had a problem like this with a Sea Doo. It has good spark and gas. It does try to start, but does not fire more then a few times. It sounds like a car that has a timing problem. The motor was built with part from 2 different 657 X motors. I did not originally take the stator off, so It may not be exactly where it originally was. I tried to put it back where it previously was.

    I do have a service manual, but it only talks about setting the timing with a running motor.

    Does anyone have any ideas of the most likely cause of it not starting? If it is a timing problem, Where do I start. I hope to be able to solve this without pulling the motor.

    Any Ideas, John


  2. #2
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    sounds to me like you have a rotary valve problem..either the gear is stripped at the crank (very bad)or the rv timing is so far off you lose most of the fuel charge before the pistons reach tdc. ( correctable with a little pain)



    Quote Originally Posted by JohnCiccarelli View Post
    This is the first time I have had a problem like this with a Sea Doo. It has good spark and gas. It does try to start, but does not fire more then a few times. It sounds like a car that has a timing problem. The motor was built with part from 2 different 657 X motors. I did not originally take the stator off, so It may not be exactly where it originally was. I tried to put it back where it previously was.

    I do have a service manual, but it only talks about setting the timing with a running motor.

    Does anyone have any ideas of the most likely cause of it not starting? If it is a timing problem, Where do I start. I hope to be able to solve this without pulling the motor.

    Any Ideas, John

  3. #3
    JohnCiccarelli's Avatar
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    I tried everything I can think of.

    I checked the Rotary Valve timing and it was right on.

    I checked the stator location and it was a little off of the mark. I adjusted it

    I tore down and cleaned the carbs

    No help. I do not know where to go next. I am at a loss. It tries to start, but will not run. It fires a few times and then stops.

  4. #4
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    cdi problem

    try punching the start/stop button while trying to start it, I've seen a couple of cases where the cdi was acting oddly going into stop mode when it's not expected. Might want to disconnect alternator from the mix, a bad rectifier could be spilling ac into the system.

  5. #5
    JohnCiccarelli's Avatar
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    One more thing. I bought a crank to fix this motor and it was already installed in a case, so I used this one. There is one difference from the original. The pulse line is on the mag side. The original case had the pulse line on the PTO side. This makes the pulse line to the carb a little longer. Could this cause a problem?

  6. #6
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    Quote Originally Posted by JohnCiccarelli View Post
    One more thing. I bought a crank to fix this motor and it was already installed in a case, so I used this one. There is one difference from the original. The pulse line is on the mag side. The original case had the pulse line on the PTO side. This makes the pulse line to the carb a little longer. Could this cause a problem?
    no problem at all there...try the start/stop trick..you may want to check the electrical box if you had it apart.

  7. #7
    JohnCiccarelli's Avatar
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    Quote Originally Posted by nmpeter View Post
    try punching the start/stop button while trying to start it, I've seen a couple of cases where the cdi was acting oddly going into stop mode when it's not expected. Might want to disconnect alternator from the mix, a bad rectifier could be spilling ac into the system.
    I'm not sure what you mean by this. Can you explain?

  8. #8
    canuck's Avatar
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    I would be looking at the magneto coil location vs flywheel magnets vs crankshaft key to see if these different parts don't line up like the original ones as this will throw the ignition timing off.

    I worked on a 720 a few years ago that would run great then would not run at all and gave indications of timing problems. Turned out the center section of the flywheel was loose and occasionally on shutdown it would rotate about 1/2" and then the timing was out far enough that it would not start. Once that was welded up no more problems.

  9. #9
    JohnCiccarelli's Avatar
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    I guess I'm going to need to put this on the back burner for a while. I have several others that come first.

    Thanks for all of the ideas, John

  10. #10
    JohnCiccarelli's Avatar
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    It now RUNS!!!

    Well I will say it myself. I am a moron and should have known better.

    It was the rotary valve timing. I had the 147.5 degree mark at the wrong end of the rotary valve. This means the other end was nowhere near 65 degrees.

    I have set this timing many times before and know better.

    Thanks for all of the ideas. I should have noticed it when I checked it.

    John

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