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  1. #1

    1996 Polaris SL780. Just bought and stumped

    Recently purchased a SL 780 and an SLX 780 and I have rebuilt the carburetors, changed fuel lines, bypassed oil injectors, rebuilt fuel pumps, added extra fuel filters, changed spark plugs as far as maintenance.

    The SL 780 is very hard to start once started on hose and in the water once it runs like its like it has a misfire under a load. It will clear up at a higher throttle or rpms -like it disappears

    It will only idle after its warmed up or it will stall. I have checked resistance in the stator and ignition coil and wires and the resistance values are to spec while
    In a no start spark is present all the time in all 3 cylinders ... Also wet with fuel and oil

    ...And have checked compression 145 on all 3-

    I changed to a brand new set of spark plugs BPR8ES so what else can I do to resolve this problem?

    Swapped CDI's from each SLX ski and SL Ski, it made zero difference and SL CDI started up fine in SLX ski.

    How do u test if the magnets in fly wheel are any good?

    What do I do I'm stumped -all power and grounds and relays -- even tested kill switch - it was good Need help please.

    Everything here was tested with accurate multi meter and highly dependable so it's not that either.

    Lost please any ideas or comments are very welcome at this point.


  2. #2
    What about timing?!

  3. #3
    1996 models

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk.

    Does one machine run properly?

    If my understanding is correct and the SL 780 does not run properly with either CDI, while both CDI work fine in the SLX, then my initial guess would be to check the SL 780's flywheel timing. If the flywheel has sheared the woodruff key then the engine will have spark but will not run properly.

  5. #5
    SLX is running fine so yes.
    That was my next question -Can you verify timing thru the inspection hole of the stator cover??

  6. #6
    Thanks by the way. I'm just frustrated bought them and had no idea what I was walking into and want to make them dependable and sea worthy bc we have 2 small kids. Being dead in the water would be bad.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by HkLind View Post
    Thanks by the way. I'm just frustrated bought them and had no idea what I was walking into and want to make them dependable and sea worthy bc we have 2 small kids.

    Being dead in the water would be bad.
    Reliable and dependable is possible, but it will take significant time and effort to ensure a pair of sixteen year old watercraft meet that requirement.

    Essentially you would need to check everything and upgrade or possibly replace/rebuild a number of items.

    Without that up front effort, all you can do is hope that age and wear have not degraded anything to near the point of failure.

    My own view is that the two seater machines are best for a single rider. Carrying passengers works better with the three seat models, which are also more stable.

    Another issue is what happens if one machine fails. With the larger passenger capacity models at least both children can ride back on the running ski while one adult stays behind with the stranded unit.

    Polaris did make a four person Genesis model which is very stable and capable of carrying everyone if needed. My own practice is to always go out with two machines so that we always have a ride back regardless of how badly one machine fails or even sinks.

    A pair of 3 or 4 person watercraft would seem safer than a pair of SL size machines.

  8. #8
    Understandable. The question I have though is can you check timing through the hole in the cover? Is it possible?

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by HkLind View Post
    ... can you check timing through the hole in the cover? Is it possible?
    Fuji engines are not my thing, but I think the answer is yes.
    Edit: I defer to xlint on such matters

    You may need to mark the flywheel TDC and the desired degree advance mark using a dial indicator on the piston.
    Last edited by K447; 06-24-2012 at 08:51 AM.

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    You'll never see through the hole when running.

    You'll want to make a mark on the pto engine coupler and temp install a pointer indicator. That's how you check timing.

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