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  1. #1
    Gin nhaase79's Avatar
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    1994 SLT won't go faster than 30 mph

    I have fixed the exhaust leak and change all fuel line, filters, and plugs. I also rebuilt the fuel pump. Its starts good and with one person on it it will go 30 mph if you put another person on it it might do 20 - 25 mph. Does anyone have any ideas what might cause this? It is a SLT750.


  2. #2
    ripcuda's Avatar
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    I have the same ski. Completely stock. Mine tops out at around 41mph... MFD indicated (stock digital display)... solo 200# rider... @ 6300 rpms.

    I have my ski tuned a little on the rich side... which I can see on the piston wash... and that is likely why I lose a few mph's on the top end. Others report slightly higher mid-40's on theirs.

    So that's what you should be able to do. Now as to why you can't?

    > Is this ski new to you?
    > What do you know of it's history?
    > Has it ever run "correctly" in the past?
    > What is the max RPM's you are seeing?
    > Have you done a compression test on the cylinders?
    > Are you running the stock single outlet fuel pump?
    > Are you running the stock autocock? (installed/attached to the fuel pump)
    > Did you drain/clean/inspect the fuel tank/lines/separator? (ensure no water in there)
    > Which spark plugs are you running?
    > Did you trim the spark plug wires?
    > Are you getting a solid blue spark (or weaker yellow)?
    > Are you oil injecting (stock) or premixing?
    > Did you clean/rebuild/adjust the carbs at all?



    These answers will give the good folks here something to work with to help you.


  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by ripcuda View Post
    I have the same ski. Completely stock. Mine tops out at around 41mph... MFD indicated (stock digital display)... solo 200# rider... @ 6300 rpms.

    I have my ski tuned a little on the rich side... which I can see on the piston wash... and that is likely why I lose a few mph's on the top end. Others report slightly higher mid-40's on theirs.

    So that's what you should be able to do. Now as to why you can't?

    > Is this ski new to you?
    > What do you know of it's history?
    > Has it ever run "correctly" in the past?
    > What is the max RPM's you are seeing?
    > Have you done a compression test on the cylinders?
    > Are you running the stock single outlet fuel pump?
    > Are you running the stock autocock? (installed/attached to the fuel pump)
    > Did you drain/clean/inspect the fuel tank/lines/separator? (ensure no water in there)
    > Which spark plugs are you running?
    > Did you trim the spark plug wires?
    > Are you getting a solid blue spark (or weaker yellow)?
    > Are you oil injecting (stock) or premixing?
    > Did you clean/rebuild/adjust the carbs at all?



    These answers will give the good folks here something to work with to help you.

    Xlint response ^^^^^^^^^


    Welcome to the Hulk nhaase

  4. #4
    Gin nhaase79's Avatar
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    > Is this ski new to you? Bought last summer
    > What do you know of it's history? He said he rebuilt carbs
    > Has it ever run "correctly" in the past? Yes ran perfect last summer and fall
    > What is the max RPM's you are seeing? 4300 in water 6700 on trailer
    > Have you done a compression test on the cylinders? No
    > Are you running the stock single outlet fuel pump? Yes
    > Are you running the stock autocock? (installed/attached to the fuel pump) Yes
    > Did you drain/clean/inspect the fuel tank/lines/separator? (ensure no water in there) Everything except return line
    > Which spark plugs are you running? MGK I forget the number I will have to look when I get home. It is what it calls for.
    > Did you trim the spark plug wires? I have not is this something that needs done? I have never heard of doing this.
    > Are you getting a solid blue spark (or weaker yellow)? Solid Blue
    > Are you oil injecting (stock) or premixing? Stock Injecting
    > Did you clean/rebuild/adjust the carbs at all? I have not done anything to the carbs.

    What octane do you suggest I have hear 91.

  5. #5
    seaobin's Avatar
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    > Have you done a compression test on the cylinders? No--_Get a gauge and test compression

    > Are you running the stock single outlet fuel pump? Yes
    > Are you running the stock autocock? (installed/attached to the fuel pump) Yes--Get a new triple outlet Mikuni fuel pump and replace booth of these items and replumb the fuel system

    You might or might not have blown a piston due to lack of fuel. These skis will run on 2 cylinders adn will lose power as you have seen. Best way to check is compression

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    4300 RPM in water?

    Is the MFD light flashing or displaying anything?

  7. #7
    Gin nhaase79's Avatar
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    Quote Originally Posted by xlint89 View Post
    4300 RPM in water?

    Is the MFD light flashing or displaying anything?

    Yes it was. I unhooked the battery. Is that all I need to do to reset it?

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by nhaase79 View Post
    Yes it was. I unhooked the battery. Is that all I need to do to reset it?
    We found your problem.....


    What was it displaying? Low fuel, low oil, or hot?

    Disconnecting the battery won't reset it. You have something triggering your limp mode. One of the 3 conditions I listed above.

    Lets fix the probem and get you on your way.

    But first do a simple test for me. Open up the elec box and disconnect the grey wire coming from the CDI box. Did that solve your issue?

    If so, that's just a temporary band aid to get you running. You still need to address the issue causing it to go into limp mode.

    Most of the time it's a faulty float in the fuel sender. A replacement can be had from John Zigleer or Sharp's Marine for around $30.

  9. #9
    Gin nhaase79's Avatar
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    Quote Originally Posted by xlint89 View Post
    We found your problem.....


    What was it displaying? Low fuel, low oil, or hot?

    Disconnecting the battery won't reset it. You have something triggering your limp mode. One of the 3 conditions I listed above.

    Lets fix the probem and get you on your way.

    But first do a simple test for me. Open up the elec box and disconnect the grey wire coming from the CDI box. Did that solve your issue?

    If so, that's just a temporary band aid to get you running. You still need to address the issue causing it to go into limp mode.

    Most of the time it's a faulty float in the fuel sender. A replacement can be had from John Zigleer or Sharp's Marine for around $30.

    I will try it this weekend and let you know. Thank you. I don't think it has the fuel sender in the fuel tank at all so that is my problem. I will get one.

  10. #10
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    What don't you have?





    EDIT: I just reread the post and found you have the 750, not the 780, so you don't have the grey wire, and your ski doesn't have "limp mode". Sorry.


    Back to the drawing board.......






    First do a compression test

    Second, throw the autocock as far away as you can and cap any hoses/fittings that it required air tight.

    Might want to consider getting a new fuel pump. The old one is 16 yrs old and pretty tired. (john Zigler sells the triple outlets for around $26)

    Even though the previous owner said the carbs were rebuilt, you'll want to go through them to verify the condition, and inspect the internal filters.

    But do the compression test first before all else.

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