Name that failure - Seizure
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  1. #1
    PWCToday Newbie
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    Name that failure - Seizure

    I'm trying to determine what caused this seizure. Same on frt and rear cylinder pistons on the intake/injector side and the seizure pretty much matches the port window. My initial thoughts are the fuel washed the intake side of the piston and caused the damage. Ski is a 2004 RFI and seemed to be running rich.
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    Last edited by mphudak; 05-24-2019 at 06:49 PM.

  2. #2
    PWCToday.com Is My Home Away From Home Grumpy Old Guy's Avatar
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    Re: Name that failure - Seizure

    Just rebuilt ??? Whats the story ??

  3. #3
    PWCToday Newbie
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    Re: Name that failure - Seizure

    Bought ski as a basket case last year that had overheated and I rebuilt it. Complete fresh motor, rebuilt crank, top end and was pressure tested good. Has new OEM injectors, all new cooling lines. TPS was checked, reset to factory spec (have my own mpem programmer) and confirmed it has the proper Bosch computer for the black/ribbed cylinders. Seemed to be running fine then fouled a plug and ran great for the next hour or so. I've built a number of SeaDoo's and this one has me stumped.

    Just took a better pic of the mag cylinder. Odd markings on top of the piston is the reflection from the camera flash.
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    Last edited by mphudak; 05-24-2019 at 07:51 PM.

  4. #4
    PWCToday.com Is My Home Away From Home Chester's Avatar
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    Re: Name that failure - Seizure

    Why don't you pull the cylinders off and post some pictures of the pistons?

    Chester
    Speed is very expensive. How fast do you want to spend?

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  5. #5
    PWCToday.com Is My Home Away From Home Myself's Avatar
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    Re: Name that failure - Seizure

    My first guess is water intrusion. The carbon is getting steam cleaned off the piston tops. That will also short out a spark plug.
    http://www.facebook.com/twinlakesjetskirepair

    '89 Kawi 650SX 42.4 GPS
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    '99 Yama GP1200 65U 61.8 GPS
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  6. #6
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: Name that failure - Seizure

    The cylinders look like they were only honed, and then installed aftermarket pistons?

    What brand were they, and what clearance did they have. They look like the
    cylinders were only lightly honed.


    Bill M.
    Horsepower == Speed, RPM != Speed



  7. #7
    PWCToday Newbie
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    Re: Name that failure - Seizure

    Fresh bore/hone at the machine shop with .007 clearance since they are wiseco's. Both cylinders look the same in the same spot, which is what has me wondering what happened.

    The ski is a buddy's that we built late last year. Only thing I got out of him that he did while I wasn't around was tried to start relentlessly before we went to the lake, not realizing the spark plug wires werent on the plugs.

    I havent had time to pull it apart with the holiday weekend. Hopefully I can next weekend.
    Last edited by mphudak; 05-27-2019 at 08:33 PM.

  8. #8
    PWCToday.com Is My Home Away From Home Myself's Avatar
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    Re: Name that failure - Seizure

    Are the head domes also unusually clean?
    http://www.facebook.com/twinlakesjetskirepair

    '89 Kawi 650SX 42.4 GPS
    +3" stock pipe, ported ex. manifold, drilled waterbox, blueprinted pump, Ocean Pro ride plate

    '99 Yama GP1200 65U 61.8 GPS
    ported cylinders, matched cases, milled head, blueprinted pump, long ride plate

    '96 Seadoo HX 717 53.13 GPS
    light porting, massaged cases, lightened flywheel, port matched manifolds, Rossier pipe, stubby pump cone

  9. #9
    PWCToday Newbie
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    Re: Name that failure - Seizure

    Head had what a little more carbon film on it from being rich but was an even pattern. I've already cleaned the head else I'd post a pic of it.

  10. #10
    Resident Guru JC-SuperJet's Avatar
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    Re: Name that failure - Seizure

    Intake Side Seizure is almost always caused by loss of lubrication (oil). No oil supply or water intrusion washing away the oil.

    There is a small possibility that the Rings were not gapped properly. Me thinks that too small of a ring gap will cause the ring to expand at the hot Exhaust end and then elongate towards the Intake side pushing the Ring hard against the Intake Cylinder Wall.

    The Piston Rings have more room to expand on the Exhaust Side due to the large Exhaust Port size which allows the Rings to extend inside the Exh Port and also has the Exh Port Chamfers which prevent the Rings from snagging. When the Chamfers "squeeze" the Rings back into the Bore, the elongated Rings are pushed against the Intake Cylinder side. But there is no room on the Intake side. Rings then breach/scrape the oil film on the Intake side, then Metal to Metal contact = Seizure.

    Also, aren't Seadoo Cylinders taper-bored? I believe that Seadoo Cylinders don't have the same diameter all the way thru, from Top to Bottom. Can someone confirm?
    Last edited by JC-SuperJet; 05-28-2019 at 10:00 AM.

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