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  1. #1

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    sl780 4500 rpm idle

    Can I get some advice. Bought a used 1996 sl780 in really good shape, under 300 hrs. Bought it last year, had not been started in 2 years or so. I never tried to run it. Just rebuilt carbs with Mikuni kits. Set hi--5/8 turns from closed on all 3. Lo-- 3/4 x2 and 1 on PTO. Did not replace jets, everything really clean. Replaced fuel lines.

    Am on vacation, had to leave without even trying getting it started- my son is dying to get on this thing. Hooked up to hose. Started OK after getting fuel.
    Problem: Idles at 4500 rpm+, bogs on throttle. Linkage OK. Not mechanical that I can tell. Smoking heavily, but I put oil in the cylinders, also in gas, because I had disassembled and cleaned oil system. Did not want to fill all the oil hoses.

    I am very handy with 4 cycle engines and mechanics. Cannot figure why it would be idling like this with throttle linkage fully relaxed. Bogging sounds like rich mixture, but can't really work on it at 4500 rpm on a garden hose.

    Please help.

    Thanks,

    Gary


  2. #2
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    Strap it down good to the trailer and back it in the water. See what it does there.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Hope you mean your lows are 5/8 turn out and the highs are 3/4 turn on MAG and CEN with 1 turn on the PTO???


    Is the idle stop screw turned in too much>

    Are your carbs in sync?

    Throttle cable hanging up or misadjusted?

  4. #4
    BlueFishCrisis's Avatar
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    Theres a pretty big difference between the two motors for that model..... Might want to check the crankcase to see which one you have...

  5. #5

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    Thanks for getting back to me xlint.

    Yes, I had the hi and low settings reversed in my post. Actual settings are correct.
    Idle stop screw is not even touching. Throttle cable is fine.

    I synced carbs when together as assembly before reinstalling. My idea of sync is to just adjust throttle butterfly and choke plate linkage so that they all operate exactly simultaneously and don't restrict each others movement. Is this correct for these?

    I have not been able to touch it today due to my brother's brand new Chapparral boat delivered from dealer Saturday causing problems. Unbelievable!! I've been on the phone and under the hood most of the day.

    BlueFishCrisis mentions 2 different engines for the 780sl?? This one is blue Fuji, but the carbs are black. The only thing I can remember (my notes on the existing carb settings are home) is that the hi speed needles were at 3/4, 3/4 and 1 before I disassemble for rebuild.

    Could engine version be an issue here? How do I identify?

    Thanks again,

    gary

  6. #6

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    Thanks BlueFishCrisis.

    Please see my answer back to xlint. I think I have this right based upon settings when I bought it.

    How can I tell which engine I have. It has triple black painted Mikuni Super BN38's, if that helps.

    I appreciate your help. This vacation is rapidly going down the tubes.

    Gary

  7. #7

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    Thanks BrianP. Please see my recent posts. I intend to do what you suggest tomorrow.

    I appreciate your help.

    Gary

  8. #8
    BlueFishCrisis's Avatar
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    Quote Originally Posted by garyg25 View Post
    Thanks BlueFishCrisis.

    Please see my answer back to xlint. I think I have this right based upon settings when I bought it.

    How can I tell which engine I have. It has triple black painted Mikuni Super BN38's, if that helps.

    I appreciate your help. This vacation is rapidly going down the tubes.

    Gary
    the motor type is stamped on the side of the block just above where the starter mounts like this:

    Click image for larger version. 

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    The manual lists EC78PWE-02/05 and EC78PWE-03/04 as the two types.

  9. #9
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Is the throttle cable letting out enough slack for the carb throttle plates to close fully? (idle stop screw can be turned out so that it will not touch the throttle)

    Is your oil pump linkage installed correctly?

  10. #10
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    Quote Originally Posted by xlint89 View Post
    Is the throttle cable letting out enough slack for the carb throttle plates to close fully? (idle stop screw can be turned out so that it will not touch the throttle)

    Is your oil pump linkage installed correctly?

    Ask Drkvampire about that one................He brought a friend's ski to me to look at and thats what the problem was.

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