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  1. #1
    Kiwi spanner handler
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    Dec 2007
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    Christchurch NewZealand
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    gp1200 hotrods crank failure

    I rebuilt a 1200 (power valve) motor recently and put in a new hotrods crank the top end was mint so didnt replace pistons just little end bearings (old motor the rear seals came out and rattled around the pto) but no engine damage just rod were pitted and through the hardening so replaced it.

    Then engine did sound a little rattly after but not much different than a good engine and after around an hour the front big end bearing completely dissapeared and the piston hit the head and broke.
    When I pulled it down the cylinder was still oily so signs of over heating and the oil lines etc all full and i spun the pump with a drill and oil flowed oit all 3 nozzles.
    The engine ran fine before and after the only change made was a converter removed and plete fitted.
    Has anyone struck this? is this just a bad crank that failed or can you think of anything missed?
    Front crank seal perfect and rod still in tacks the thrust washers look hot and beaten up and no needle rollers to be found (nice xmas present!)
    Cheers

    Jason..........


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  3. #3
    race jase's Avatar
    Join Date
    Feb 2007
    Location
    auckland nz
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    Is this mainly a yamaha problem as i have used plenty on seadoos with no issues.
    I also built a gp1200 with no problems.

  4. #4
    Kiwi spanner handler
    Join Date
    Dec 2007
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    Christchurch NewZealand
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    I had an sxr crank spread on the front and started to rub on the cases after 1 hour! only spotted it when doing some other mods otherwise it would have busted the front out of the cases.
    I didnt want to use a hot rods but his old crank was fairly buggered and the reconditioner was flat out given the time of year and he had the crank in stock so told him he is paying to fix it and he came around and went over everything and cant fault anything I have done or the owner just looks like a bad crank.

  5. #5
    TX21's Avatar
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    May 2007
    Location
    North Texas
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    Is this still true? I heard they are better then they used to be.

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