Unusual Condition Found On 650 Crankshaft
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  1. #1
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    Unusual Condition Found On 650 Crankshaft

    I just disassembled a used 650 engine and discovered an unusual condition that I have not seen before. The center carrier of the crankshaft has raised bumps of aluminum on it. The crankcase halves has corresponding indentations. I am thinking that this is from some kind of galvanic action or electrolysis, but I am just guessing. The locating pin and hole are in good condition. The bearings are all good. I am thinking I can use the crankshaft and case halves as is, but I wanted to bounce it off the members of this forum first.

    Also, does anyone have any concerns about using crankcase halves from two different engines to make one good crankcase?

    IMG_20190505_174520242.jpg IMG_20190505_174437930_HDR.jpgIMG_20190505_174506630.jpgIMG_20190505_174450108_HDR.jpg

  2. #2
    PWCToday.com Is My Home Away From Home BLRider's Avatar
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    Re: Unusual Condition Found On 650 Crankshaft

    All of that started from the crank moving for and aft and eventually started vibrating in that position and having the outcome you found.
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  3. #3
    PWCToday.com Is My Home Away From Home JHR's Avatar
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    Re: Unusual Condition Found On 650 Crankshaft

    Normal on the earlyer model .
    Futur model got a improvement , they add a ring to fix the problem and also mod the case

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  4. #4
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: Unusual Condition Found On 650 Crankshaft

    Echoing what BL and JHR said, it looks like fretting from the surfaces moving relative to each other. The material transfer is the give away with this. This happens when you have relative motion of surfaces from vibration loads or that sort of thing. Galvonic corrosion looks a bit different, with aluminum and steel its primarily a white powdery substance that's produced. Also the oil in the engine will help keep that at bay if not entirely prevent it. Outside the engine and elsewhere on the ski though, totally different story.
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  5. #5
    PWCToday.com Is My Home Away From Home john zigler's Avatar
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    Re: Unusual Condition Found On 650 Crankshaft

    Yup. Normal K650 crank chatter.

    DO NOT mix/match case halves. They are machined and matched as a set.
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  6. #6
    PWCToday.com Is My Home Away From Home JHR's Avatar
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    Re: Unusual Condition Found On 650 Crankshaft

    Quote Originally Posted by john zigler View Post
    Yup. Normal K650 crank chatter.

    DO NOT mix/match case halves. They are machined and matched as a set.
    agree 100% , case are matched ,

  7. #7
    PWCToday.com Is My Home Away From Home Myself's Avatar
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    Re: Unusual Condition Found On 650 Crankshaft

    You can use them as is. Use your case sealant and smear it on both case halves at those locations. It will keep any further movement from happening.
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