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  1. #1

    seadoo 657x question?

    I have a 95 gtx that has a 657x engine in it, is this engine the same as the 657, 650 when you do parts search, or is the 657x a totaly different engine? Thanks for any help.

  2. #2
    redemn93's Avatar
    Join Date
    Aug 2006
    Jupiter Fl
    the 657x is different from a 657.

  3. #3


    Do you know what the difference is?

  4. #4
    redemn93's Avatar
    Join Date
    Aug 2006
    Jupiter Fl
    i am not to sure. i think they use the 720 electronics. as far as the motor itself i know they are different but not sure how. hopefully someone who knows can chime in.

  5. #5


    I got it with low compression in the rear cylinder and was looking for a rebuild kit and didn't know if there was a difference. Thanks for your help!

  6. #6
    Ignition and Port Timing is a little more aggressive in the X I believe.

    Rebuild parts, gaskets O-rings are the same.

    By the way, if you need NEW OEM 657 (or 657x) Top End parts for reassembly I'll sell you some NEW packaged shelf stock for 65% retail.

    e-mail me if interested

    [email protected]

  7. #7
    Yes, there is a difference, The ports are oval instead of round, I do know that. I found some pics on the net but didn't save them. I too bought a 95 GTX unknowing the front cylinder had low compression. After doing some research I did find a few things differences but didn't save the sites and I don't remember exactly what they were now. Come to find out on mine, the piston rings were broken on the front, the cylinder walls and pistons looked great, so after figuring out what size I needed and installing new ones on both pistons, it ran perfect, until it started bogging down at 1/2 throttle, then progressively got worse to where I was only floating. I knew it was probably somewhere in the gray fuel line, which I found it was a totally clogged fuel selector valve, so thats my new project. Good luck with your GTX, they are a lot of fun.

  8. #8
    cylinder height is 1mm higher on the x causing the transfer ports and exhaust ports to be higher = more power

  9. #9
    BTW cases r the same

  10. #10
    also higher cylinders changes stroke. in 1985 the xp 800 had a 782. something but it too was a x series 1 bad ass 800 they only made 500 of that ski and even less of the x's makes u wonder where they came up with the RXX, RXP-x huh? a lil more food 4 thought when yamaha made the 1100 sea-doo came out with there own 1100 it was a triple 800 cylinder power valve with 88mm pistons and they only made 50 of them.......let me get my hands on one of those rxp who? trust me its a rocket!

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