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  1. #1

    SLX Piston install and general questions

    Hello All,

    I have been lurking for a couple of days and feel like this is an awesome group of people. Hopefully I will be able to contribute in the future.

    I recently purchased two 96 SLX jet ski's. One was running the other has no spark. After some tinkering, I have learned that the non running jet ski has been submerged, (water in the crankcase). The running jet ski has 30 psi compression on the piston closest to the gas tank. The middle piston has 145 and the rear has 135 psi. I have attached a picture of the one piston. Not for sure what caused the piston to melt, guessing blocked oil line, will investigate more. Currently the plan is to utlize the submerged ski to fix the running one.

    I have three questions:
    One of the 4 exhaust bolts is directly under the fiberglass section and to remove it I guess I will have to slide the motor over or remove the motor. (Picture of problem bolt is attached) Any suggestions.

    The second question is which cc motor is this? I'm guessing 750cc and the SLX Pro is 780. Is that correct.

    The last question is where should I go for parts?

    Thanks for the help,

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  2. #2
    dr.ipper's Avatar
    Join Date
    Mar 2008
    Tallahassee , FL.
    hey there Zazoos2, welcome to the Hulk

    im guessing you have a 96' slx ? and yes it is a 780cc fuji motor. The slx pro are 785's and a whole nother level !

    The header bolt should sneak by the lip there , but if not loosen one side of the engine mount and it should come right out.

    as for parts there are all kinds of stores on the web, but if you want to talk to someone you can try John Zigler ( he helped me a lot with some new and used parts or

  3. #3
    rlharrison60's Avatar
    Join Date
    Aug 2007
    Orange, Texas
    The experts will chime in soon, and give you all the information you will need. Welcome to the HULK.

  4. #4
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Welcome to the Hulk!

    Click here for Polaris Service manuals and other useful info, including a spreadsheet of all Polaris PWC models.

    You can confirm the model year by looking at the last two digits on the metal HIN number plate on the rear deck.

    Engine size can usually be checked by looking at the white sticker on top of the water manifold, on the top of the engine. Look for 650, 750, 780 in the engine code.

    There is a huge difference between a Fuji 780cc engine and a Fuji 785cc Pro engine. The first year for the SLX Pro 785 was 1997.

    Posting some medium or high resolution pictures of the outsides and the engine area will help us see what you have. Often, the guys here can notice lots of useful things from a few good photos.

    The piston photo you posted is a little hard to make out, but it looks like there is damage to the piston top from metal debris. What does the inside of the matching cylinder head look like?

    Tip: If you set your camera to close-up mode (often a Flower icon setting), then close detail pictures should be sharper. And the more uploaded resolution (within reason), the better.

    As for removing the bolt, I seem to recall that a few people have filed the hull lip back a little, and then with a little effort, have been able to get that bolt to loosen just enough to allow the exhaust to be shifted. I think a few have even shortened that bolt by a few threads to make it easier the next time.

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
    Join Date
    Oct 2006
    Cleveland OH
    Welcome to the Hulk Zazoos2.

    First we need to know what engine you have exactly. The SLX is a 780, but people have been known to do odd things. Get a pic of the serial number at the back of the engine on the exhaust side.

    I can see that piston has been changed before. The .50 stamped on the dome means it's .5mm oversized.

    I don't believe the oil system had anything to do with that piston damage. More than likely, ran lean on fuel, detonation, or engine overheating.

    Before you do anything, try this:

    Remove all sparkplugs

    Turn the engine over by hand until the damaged piston is at Top Dead Center (a dial indicator helps to find "true" TDC)

    Then stick a new pencil into the spark plug hole of the other cylinders. Using a razor blade sitting flat on the cylinder head, make a mark.

    Measure the 2 marks. They should be exactly the same distance. (or REAL dam close)

    If the marks are off, the crank is out of phase and will need servicing. (A trued crank is exactly 120* apart for 3 cylinders)

    For the tough bolt, undo all the others first and that one last. Hopefully there should be enough play in the exhaust pipe to clear the lip. Everyone asks about that bolt, but they all seem to find a way of getting it out.

    Many places to get parts from. It just depends on what parts you're looking for.

    Obviously you need a piston and gaskets.

    For the piston, I'd get a WSM single piston kit from Ebay. Runs around $72, but you'll need the gaskets still. For those, I go to for Cometic gaskets.

    Or you can rebuild the entire top end with a WSM piston kit and gaskets for around $270 off Ebay again.

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