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  1. #1

    787 Engine Condition...!??

    Here's the story...
    My friend has a 97XP with a fresh rebuilt ~30hr 787 motor... He went to the lake the other day and has always everything was going great until the overheat buzzer kicked in and the engine didn't want to start anymore! Got towed and inspected the ski, cleaned the cooling hoses and putted it back in the water... Engine started and worked fine but there was a leak in the back so putted it back on the trailer!

    It's getting cold up here so we decided to start stripping the ski to clean it up and replace what was needed... I also noted that the gray fuel lines where still there and it was planned to replace them!

    We did a compression test on the engine and the result was 180 mag and 165 pto...

    Since we got those we result, it was planned to replace the high compression West Coast head he had for a stock one...

    During that procedure we inspected the engine and those were the results of the cylinders;

    Click image for larger version. 

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    What do you think of those cylinders!? I know the picture aren't perfect quality but we plan on opening the engine up more and take some better ones!

    Does that engine need a new top end again!?


    Thanks


  2. #2
    looks like one set of rings seated and the other didnt, is there water in the lower crank case or water drops on the spark plugs and did you give the ski a break in period?

  3. #3
    The ski was bought after the rebuilt and the break in was supposed to be done... There is no sign of water anywhere inside this engine! We will get more details when the cylinders are removed...

  4. #4
    RumRunnerRon's Avatar
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    Quote Originally Posted by falconflyer04 View Post
    The ski was bought after the rebuilt and the break in was supposed to be done... There is no sign of water anywhere inside this engine! We will get more details when the cylinders are removed...



    Well if you found the grey lines it sounds like all the PO did was stuff an engine in it. Im sure you realize now that you should have pulled the carbs to clean/overhaul them and replace the lines before riding it. Could be why you lost compression. Some better pics would be great too. Pics of the tops of the pistons and a good shot of what the cylinders look like.

  5. #5
    "Tearing it up on the water" seadoobutch787's Avatar
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    Make sure that your tray seal is new on that 97xp. I had one and all that thing ever did was take on water either jumping waves or if someone falls off all the water goes into the engine compartment and if you don't turn it over the right way it will go right into your engine! INVEST IN A BILGE PUMP!

  6. #6
    Well thanks all for your answers.... just to be sure this is not my ski and I am not taking responsibility in maintaining this ski...
    I pulled the carbs and checked the fuel filters and they are perfectly clean so the shop that did the engine rebuilt did overhaul the carbs!
    So I am really puzzled as to why there is such a huge difference in compression between cylinders! I will take better pics tomorrow but both pistons looks very clean!

    What could be causing that difference in compression? What do the marks on the cylinder walls in the picture above means? Does my friend needs to rebuild the top end even if the engine runs ok!?

    Thanks

  7. #7
    steach's Avatar
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    Post better pics. The lack of wash on the left picture tells me it was a LEAN seizure.
    Run a finger nail arround the cylinders to feel for nicks/grooves.

  8. #8
    RumRunnerRon's Avatar
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    Quote Originally Posted by steach View Post
    Post better pics. The lack of wash on the left picture tells me it was a LEAN seizure.
    Run a finger nail arround the cylinders to feel for nicks/grooves.



    +1

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