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  1. #1

    Join Date
    Jul 2013
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    Louisville, KY
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    787 Cylinders / Piston Inspection - First Ski

    I recently got the PWC itch and started searching craigslist for what looked like (to me at least a good deal). I ended up buying a 1995 Kawasaki zxi 900 and a 1996 seadoo GSX with the 787 rotax on a double trailer for $1300. The zxi runs fine from what I can tell after a 30 minute outing. However the GSX was advertised as needing a top end rebuild. The seller offered to start the engine for me, but I declined thinking it would prevent any further damage.

    The VTS still works fine and overall I think the ski is in good shape. I decided to pull the engine out without doing a compression test or anything else because I figured at least one cylinder was shot or the guy wouldn't have advertised the ski as such or sold them for so cheap. Well after the engine was out and pistons/cylinders exposed I was pretty surprised.

    At this point they look fine to me, but I wanted to get some others opinions because I'm still a novice at this. They look fine, are OEM seadoo, and move freely. If they look good to everyone else, my next step is going to be put the engine back in the ski and fire it up and see what is going on from there.

    Many thanks in advance.
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  2. #2

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    Jul 2013
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    Louisville, KY
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    More pictures. These are the PTO side.
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  3. #3

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    Oct 2009
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    Maasin, Southern Leyte, Philippines/CA
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    try to take the cylinders off to see the condition of the pistons and piston rings.

  4. #4
    steach's Avatar
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    that looks like its had some seizures from lack of fuel.
    a dime sized piston wash on the front piston and none on pto confirms no fuel.
    a hone and a new set of rings might work just fine. good catch.

    The fuel system is gummed up...see sticky

  5. #5

    Join Date
    May 2013
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    fargo nd
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    time to get a squish measurement and get the head modified, do some air filters and call it a day after your new rings.

    i can see scoring on the cylinder wall slightly, so get it machined, a good machinist will know what to do.

    nice skis btw

    don't forget to replace all your fuel lines, and get a genuine mikuni rebuild kit for your carbs, and likely replace the needle/seats

  6. #6

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    Oct 2009
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    Maasin, Southern Leyte, Philippines/CA
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    will those require an oversize pistons and reboring the cylinders?it doesnt have crosscuts anymore.

  7. #7
    njk4o5's Avatar
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    Jan 2009
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    Boston, MA
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    wow looks like you got a good deal!! your cylinders dont look bad at all. id get them honed, its real cheap (guy around me does them for $10 a hole) and it will prevent the motor from slowly deteriorating after some use. a hone job and some new rings and run it. Youll be into that ski for $50 and some wrenching time

  8. #8

    Join Date
    May 2013
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    fargo nd
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    Quote Originally Posted by njk4o5 View Post
    wow looks like you got a good deal!! your cylinders dont look bad at all. id get them honed, its real cheap (guy around me does them for $10 a hole) and it will prevent the motor from slowly deteriorating after some use. a hone job and some new rings and run it. Youll be into that ski for $50 and some wrenching time
    what, no modding it to death?
    He's probably right, keeping it that cheap will make it just that much more fun.
    The crosshatch that you don't see will be put back in from the hone, no big deal.

  9. #9

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    Jul 2013
    Location
    Louisville, KY
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    Well they don't look as good from the sides as they do the top. The rings look fine, but there are some groves in the pistons and cylinders that i can feel with my finger, dont even have to use my fingernail.

    Here are some pics to hopefully show, not sure how good they are.

    Here are the forward (non pto) side of piston shots and pictures of the bottoms of the cylinders.
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  10. #10

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    Jul 2013
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    Louisville, KY
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    Here are the PTO pictures.

    Thanks again so much for all your help.
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