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  1. #1

    Question SL900 / 1200 Conversion Top RPM Issue

    Hi all-

    I have a 96 SL900 that is converted to a true 1200 (MSX cylinders). It has the ignition update kit for the 900 as well along with the orange wire mod for starting.

    When going WOT will only pull 5800-6000rpm, then all of a sudden it will pick up to 6600-6700rpm. It will continue to rip at this higher RPM until I shut the machine off for a while or drive at slower speeds for a bit. It almost feels like its dropping a cylinder or pulling timing out, and picking it up intermittently...the ski RIPS when its working right, but feels like a turd when its not working right.

    I am getting no warning messages or lights on my MFD.

    I cleaned and inspected the re-jetted 900 carbs, and recently completely swapped the carbs out for 1200 carbs with 1200 jetting. Wash looks good on all 3.

    I've replaced the plugs, and clipped the plug wires.

    I found a thread from redfro that had an identical problem on a SL900 that got the ignition update kit.

    Here is a thread with more details on my boat:

    Thanks for any help!

  2. #2
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Is MFD 100% good? Sometimes a bad MFD can interfere with the ignition system.

    Try holding down the Bilge button if the 1996 had the button. Otherwise undo the Orange wire mod and connect CDI directly to Red/Purple power source.

    Carefully check and ohm-meter all grounds, especially the stator Black wire. Did you remove the thin black wire between the battery and electrical box?

    Resistor spark plugs?

  3. #3
    Yep MFD works awesome...bright numbers and all the functions are good. No bilge button on mine at all, but I can definitely try undo-ing the orange wire mod.

    I did still have the thin black wire connected to the battery...should I get rid of it?

    Currently running BR8ES plugs.

    I will check into ground wires tomorrow...I assume I can find the info I need in the PWC database you have?

    Thanks for the help,

  4. #4
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    near Toronto, Canada
    Well, the update kit install includes a delete of that thin black battery wire.

    Disconnect battery positive, isolate that thin black wire, and then ohm check the stator ground connection between engine block and electrical box. Must be a solid zero ohm connection.

    Remove and clean both ends of both battery cables, just in case.

  5. #5
    I checked the stator ground wire (black) and had a solid 0.0 ohm to the engine block. Un-did the orange wire mod and it did not effect anything. Also removed thin black ground wire from battery terminal with no effect on the issue.

    I am also having the issue that when the engine is cool, I am seeing RPM limiting to ~4000rpm with no warning light on the MFD...if I shut down the engine and restart a few times it goes away. I am starting to think that this issue (cold rpm limiting) and high-speed power surging are related. I read somewhere that the '96 900s had a timing retard for hot or low-oil condition? I am not hot (per my hand-check) and I am full on oil...I'm wondering if the LR module is causing the timing to retard at high RPM intermittently. Do I dis-connect the gray wire from the LR module to bypass the rpm limiting / timing retarding?

    It is exactly what it feels like...I am driving the ski and it feels like a complete dog (slower than it was as a 900 for sure), then all of a sudden I jam the gas and it tears out 6600-6700rpm!! Intermittent power, and I'd like it to be constant. It "feels" like all 3 cylinders are firing, but with alot less power than what I was used to (makes me think that timing is getting pulled away).

    Regardless, my plan of attack it as follows:
    1. Bypass or replace hot/low oil LR module
    2. Replace stator
    3. Replace the other LR module

    P.S. I believe I found another guy with the same issue:

  6. #6
    I'm addicted to Polaris PWC ghostinstallations's Avatar
    Join Date
    Aug 2011
    Rochester, New York
    Disconnect the CDI gray wire with spade connector from the terminal board. NOT the CDI gray wire with bullet connector that goes to the stator harness.

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