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  1. #1

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    97 GTX 787 motor maybe hydro locking on its self?

    Have a friends 97 GTX 787 trying to figure it out. It seems to be hydro locking on its self. It will turn over and start on one cylinder no problem. With both plugs in it will not really turn over. Replaced started, new battery, ground is good. I have gotten it started on each cylinder. Compression is about 150psi in each hole. The motor does not really seem like it have any extra oil in it. The ski is super clean and only has 45hrs on it.

    Any ideas what it could be? Help!


  2. #2
    RXPIndy's Avatar
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    Do the rave valves move freely? And you do have spark from both plugs? Check your carb filters. They can get clogged like you couldn't imagine. I bought a gtx for $300 cause the guy thought the motor was blown. Turned out it was just clogged filters in the carbs. I've Run the snot out of it for years since then. Oh has he ever taken the timing wheel off? Could need timing checked. Pretty easy to do.

  3. #3

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    Yes both rave valves move freely? I had replace all fuel lines before I tried to start it. Yes spark in both holes. Will start and run with only one plug in either cylinder.

  4. #4
    RXPIndy's Avatar
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    If you try to start in the dark, you can see if the spark plug wires are arcing. Another common problem with the old skis. Or touch them as you're starting, but you'll light up like a Christmas tree

  5. #5
    RXPIndy's Avatar
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    And for the oil pump, you can check that by taking it off and using a drill. You should get a certain amount flow rate at idle. I'll have to check that amount when I get home. I have a complete dealer maintainence book for that ski. If you take the air cleaner off, you can look down the carbs when you turn it over and see if it's flowing to much as well.

  6. #6

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    Quote Originally Posted by RXPIndy View Post
    If you try to start in the dark, you can see if the spark plug wires are arcing. Another common problem with the old skis. Or touch them as you're starting, but you'll light up like a Christmas tree
    I don't understand what this would have anything to do with the motor not turning over? I do have spark and it will run.

  7. #7
    RXPIndy's Avatar
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    If you want to call me so I can understand whats going on with it. The things I mentioned are the most common problems with the older skis.
    443-366-1014

  8. #8
    RXPIndy's Avatar
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    If it's water , t's your head gasket or little o ring between halves of head. Oil it's your oil pump or lower motor leak. If it's fuel, it's your carbs. If it won't turn and your starter and battery are good check your starter relay.

  9. #9

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    No water involved not hooked up to hose.
    Motor turns over very strong with both plugs out and both have great spark.
    1 spark plug in (either cylinder) and the other plug out ski will start and run fine on one plug.
    both spark plugs in ski will not turn over. It's like it is locked up.
    I have tried warming ski up on 1 cylinder at a time and then putting both plugs in and still will not turn over.

  10. #10
    RXPIndy's Avatar
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    That's weird. New battery so it has a charge, starter is new so that ain't it, battery connections even in the back box with the starter solenoid good? Seems like when under full compression it doesn't have power to turn it over. Which all those things are related to.

    Worse case scenario, you might have a spun crankshaft and the pistons are fighting each other. Which is why one of the mods to older skis was to weld the cranks. Take the head off and make sure one pistons is all the way up and the other is all the way down. Careful of the head bolts if they haven't been off in awhile cause they can break.

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