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  1. #1
    I wanna go FAAAAASTer!! CDW78's Avatar
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    Exclamation Gp1200 Major HELP!

    Well, as some of you know, I an extreme newbie at jet skis, so please go easy one me I've searched but cant find the exact of issues here.

    I was able to pick up the Gp1200 I bought a cpl. of weeks ago, and I was originally told it had low compression on one of the cylinders, but did run.
    The marina I got it from didnt inform me ( and I ask for old records,etc. ) how low it was or what they knew about it, it's problems, etc.
    It had set for about a yr. & 1/2

    Ok, I was expecting to have to resolve this issue with the compression. ( Should I be able to feel equal amounts of air pressure with my hand from each of the 3 holes, because the one in the rear doesn't feel as strong and dont have a gauge yet )

    I installed a NEW battery. It wouldn't even turn the crank. ( the pistons wouldn't move ) I put a little oil down in the sparkplug holes ( as directed by the marina I got it from ) and let it set for a little while. I hit the start button slowly and it finally started to move.

    It started after being primed with some starting fluid, but the whole motor shakes badly ( seems bouncey ) like something is warped.
    I hooked it up to the flush hose today, installed new plugs and put the nozzle back on the end. I started it, put the water to it and it runs, but bouncy......
    Now when shut it off, it is just stuck again, cant even crank with the starter. Also, some how one of the new plugs broke completely in two. The one on the rear cylinder, the only good thing I can tell from this is the bottom of the plug appears to be fine. When I look into the plug holes, the best I can, it looks dry, kinda rusty or something.

    Obviously, this is some kind of issue causing it to cease. So please, where shall I begin ?
    Thanks a bunch!


  2. #2
    Moderator OsideBill's Avatar
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    Pull the head off and take a look at the pistons and cylinders.

  3. #3
    quadzilla's Avatar
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    Quote Originally Posted by OsideBill View Post
    Pull the head off and take a look at the pistons and cylinders.
    +1..

    No matter what you will have to get into this engine..

    Continually turning it over isn't helping you in the slightest..
    All you will end up doing is causing more and more damage..

    Get the head off..
    It will only take you about 20 minutes..

    Post up some pictures of what you find..

  4. #4
    Mpeavler's Avatar
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    Sounds like you may end up buying a crank if your damaging plugs. It's going to be easier to go ahead and pull the engine out and start taking it apart. Pulling the head will only confirm what we know...."the engine will need to be completely rebuilt" it sounds.

    Rebuilding the engine is very basic when compared to a 4 stroke that's in your car etc. There is no cam, valves etc....just a crank/rod/pistons and basic parts bolted on. The hardest part....is ensuring everything is 100% air tight on a 2 stroke. If there is any air leak, the engine will destroy itself quickly.

    Show us some pics...but prepare for the worst... =0(

  5. #5
    I wanna go FAAAAASTer!! CDW78's Avatar
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    Thanks for the info so far.... much appreciated.
    I took these with my cell, but they are pretty good and can hopefully give you all enough info. to direct me from here. I guess the bouncing from the motor was was maybe from a lose rod ( ? )

    Here's the pics, as you can see, the piston is def. jacked up. This is the rear one.
    There appears to be some scaring / grooves in the sleeve and little chunks of the piston in the exhaust ( not sure if you all can see or not )
    Hope these help you help me !!!

    Thanks a bunch, again
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  6. #6
    1131 Adam E.'s Avatar
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    Unfortunately that definetely going to be a rebuild. If you see pieces of the piston chances are they may have gotten into the case and jacked up your crank. I would pull the motor out (it has to come out anyways) and see whats up with your crank cases and crank.

  7. #7
    Flying Scotsman's Avatar
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    Pull the motor split the cases an go from there.
    Hopefully theres no holes in the cases.Good luck with the crank.Cylinders will need repaired and new pistons installed.
    Make sure you find out why it grenaded or it will happen again.

  8. #8
    Moderator OsideBill's Avatar
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    The shape of the piston tells me it was hitting the head, this was a crank bearing failure. You are looking at a crank + seals, bore and hone cylinder, new pistons. The head may be salvaged with a cut on the surface and squish band. Were there any signs of oil leaking? maybe a lube line came lose? maybe water ingestion caused this. Time to pull it and continue with the tear down. I always bag my bolts when I tear down and mark them, exhaust, head, front cover, etc. saves a lot of headaches down the road.

  9. #9
    I wanna go FAAAAASTer!! CDW78's Avatar
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    The oil tank is still more than half full, but there is oil in the bottom of the hull.....I thought maybe this was from just sitting for the year or more it sat.

    The top half of the plug was what was broken, not sure how it happen, but if it were hitting the head, wouldn't the bottom of the plug be damaged?
    I noticed when installing a new plug into that back hole, it didnt want to get as tight as the others, or maybe I just babied it to much as I didnt want to strip the threads, but they dont appear to be damaged as of now or before.

    Im going to spend the next couple of day getting the engine out so I can start getting into it. Luckily ( since I'm new at this ) SBT has the engine removal steps I can print.

    Anyone got some GUESTIMATES on what this may run me ? ( Im kinda afraid to ask!! )

    Thanks a lot

  10. #10
    Flying Scotsman's Avatar
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    $600-$1100

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