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  1. #1
    boudin's Avatar
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    2005 STX-12F Rod Markings

    Have patience with me. This is my first 4-stroke Kawasaki.

    I have a 2005 STX-12F that broke the #4 rod. I was looking at the markings on the bottom of the rods, and notice the dimples next to the numbers are different on #1 and #4. I see only one OEM part number. Anyone know?
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  2. #2
    Those are casting markings. Don't bother with those. Thats the mold used for manufactures reference.

    Your looking for an inked mark on the side of the rod. If you want a matching set them you need to find ones that all match. This marking also is important in selecting a bearing size.

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    Reference your 1200 or even 1500 service manual on page 8-22 & 8-23.

  3. #3
    boudin's Avatar
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    Thanks for the quick reply!

  4. #4
    Pain is fear leaving your body.... rlovebk's Avatar
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    How did the rod break? Hydo-locked or??

  5. #5
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    water ingestion

    Sean

  6. #6
    boudin's Avatar
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    Quote Originally Posted by rlovebk View Post
    How did the rod break? Hydo-locked or??
    Probably. I bought the ski for a very good price last December and am working to rebuild the motor. The original owner said he did not know what was wrong, but with water in the oil I suspected hydro-lock. However, the rod went through the water jacket in the block (among other things), so the water may have come from there. I am not sure.

    Funny thing is that in searching for a new case and talking to other people, I have run into five people who had the same thing occur, #4 rod breaks. Not sure if it's a coincidence. Why always #4?

    In this case too the piston slapped the intake valves and bent them, as well as gouging the cylinder.

    It's my understanding the cylinders are Nikasel coated and that I cannot just fix one cylinder, all need to be done.
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  7. #7
    Quote Originally Posted by boudin View Post
    Probably. I bought the ski for a very good price last December and am working to rebuild the motor. The original owner said he did not know what was wrong, but with water in the oil I suspected hydro-lock. However, the rod went through the water jacket in the block (among other things), so the water may have come from there. I am not sure.

    Funny thing is that in searching for a new case and talking to other people, I have run into five people who had the same thing occur, #4 rod breaks. Not sure if it's a coincidence. Why always #4?

    In this case too the piston slapped the intake valves and bent them, as well as gouging the cylinder.

    It's my understanding the cylinders are Nikasel coated and that I cannot just fix one cylinder, all need to be done.
    You can fix one cylinder or jug of the the cylinders. We use Millennium Technologies. Mostly 2 stroke and punch outs of 4 strokes. Trust me we have used them for many many years of racing the Kawasaki Jetski brand. Since 1997. This Nickle has been used on many of their engines, 2 stroke and 4 stroke.
    Throw your cases, oil pump and oil pump housing away. That puncture your seeing is in the oil passage that is pressurized to 64psi.

    You had a water leak somewhere that caused the rod failure, no water jacket in the cases. Water jackets only exist in the upper cylinder and head then out the exhaust.

    More then likely you have leaking from the head or someone flipped the craft ingesting water and ran it with milky oil causing the bearing failure thus causing the rod failure.

    This too could be an issue to look into.
    rlovebk
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    Careful with the 12f ecu's. If # is 32 or lower this is the one that has advanced timing and caused detonation and cracked piston on my 12f. With performance in mind this may be what you want?
    The one on it now has a 36. These are the last 2 digits on the ecu.
    I was told that the 32 # was a ecu trying to meet E.U smog standards and that is why it was so advanced.
    This is all I really know about these. I may be able to find out more and will let you know. I follow your project because it is interesting and you are very informative. The knowledge you share is great. I don't chime in much because mine is quite limited. So in escence reading your thread is like ski school for me. Thanks.
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    #4 for us usually happens on water intrusion as its closest to the throttle body and will suck in more water then air if water is pressent.

  8. #8
    boudin's Avatar
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    Quote Originally Posted by Skips313 View Post
    You can fix one cylinder or jug of the the cylinders. We use Millennium Technologies.
    I am not sure. Millennium is actually who told me they had to do all four jugs. I would have liked to do just one as the others are fine. I sent them a picture as well.

  9. #9
    Wow!

    Weve had stuff fixed by them for years now. We dont normally do the 4 stroke cylinders alone as it seems to be more cost effective to buy a new one.

    We seldom see a 4 stroke that has a failure like that not score the other jugs.

  10. #10
    boudin's Avatar
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    Quote Originally Posted by Skips313 View Post
    Weve had stuff fixed by them for years now. We dont normally do the 4 stroke cylinders alone as it seems to be more cost effective to buy a new one.
    Yes, I came to that conclusion too after seeing the price. I am not in a rush, so I'll be looking for parts over the next few months. I have a line on a complete motor too, which is a possibility... just need to weigh the options.

    I even need to buy a new starter. A piece of the rod buried itself about an inch inside it. Ugh.

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