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  1. #1

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    94 Polaris SL 650 Spark issue

    Hi,
    I have been trying to figure out why this ski will start and idle great but will not rev up seems to be hitting a rev limiter, like I am in limp mode but if I am correct this model did not have limp mode. I have a New Battery, Plugs, Upgraded the fuel pump to a triple outlet, had the carbs rebuilt, New fuel filter and lines, The compression is 115 on all 3 cylinders.This is a 94' Polaris SL 650. Please Help Me.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    Will it rev up out of the water on the trailer?

    Is it actually operating on all three cylinders? Do all three spark plugs get equally warm when you run it?

  3. #3

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    HELP,
    No it does not rev up on the trailer either. Well it does but only bout half way. I have checked the spark with it is running using a spark tester and all cylinders have good spark. Then when you rev it up all cylinders are dropping in and out. Sounds just like my drag car hitting the rev limiter. And from what I see from the spark tester it looks that way as well. Could it be a bad CDI box. How can I check the CDI to determine this is the problem. All cylinder are getting warm when I run it.

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Do you have a tachometer?

    It may very well BE hitting the rev limiter.

  5. #5

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    No,
    it does not have a tach. and if it is hitting the rev. limiter than something is wrong cause it set way way too low. So how do I fix this issue?

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    Click avatar for tech links/info, donation request K447's Avatar
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    Arrow General Info regarding Polaris RPM limiters

    Quote Originally Posted by james5 View Post
    No,
    it does not have a tach. and if it is hitting the rev. limiter than something is wrong cause it set way way too low. So how do I fix this issue?
    On many Polaris PWC engines there are TWO rev limiters. The hard limiter (red line) is somewhere in the 6000+ RPM range. The exact RPM level varies depending on model and year.

    There is a second, lower RPM limiter which is used to limit engine power when a trouble condition occurs. Engine overheat is the main reason, but on some models the limiter is also triggered by Low Oil or Low Fuel signals.

    RPM limit when the lower limiter is active is about 3500 to 4500 RPM, again it depends on the engine and model year.

    Most of the time when folks here talk about the RPM limit they are talking about this lower 'overheat' limit. But when talking about modified engines and changing impellers for peak performance, they are talking about the higher 'red line' RPM limiter.

    The Tan color wires handle the temp sensor signal. When the temp sensor gets too hot it grounds the Tan wire. Inside the electrical box the Tan wires carry the grounded temp signal to the CDI's Tan wire, which then limits the engine RPM to the lower level.

    On models with MFD digital display the Tan wire also carries the HOT signal to the display, and the display triggers RPM limiting when Low Oil or Low Fuel warnings appear.

  7. #7

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    Thank for the reply.
    My Ski does not have the MFD Display. I have checked the tan Temp. Sensor wire it is not grounded at this time. Also have checked the fuel sending unit this is O.K. as well.

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by james5 View Post
    No,
    it does not have a tach. and if it is hitting the rev. limiter than something is wrong cause it set way way too low. So how do I fix this issue?
    Looking at the 1994 SL650 wiring diagram, your model does not have a lower RPM limit in the CDI. There is no Tan wire running into the CDI.

    The Tan wire connects the warning buzzer to the temp sensor, and to the low oil and low fuel signals. Any of these will sound the buzzer.

    I suggest you do the usual things to improve spark. If none of them solve the problem you may need a replacement CDI.

    Unscrew the spark plug boots and trim the plug wires back about 1/4 inch to eliminate any fraying of the wire core. Then rescrew the plug boots onto the wire ends.

    Disconnect and ohm check each ignition coil. Specs can be found through my signature links.

    Note that these Fuji engines use the wasted spark method, where all three spark plugs fire together every time any cylinder needs spark. At 6000 RPM the system is firing the spark plugs 18000 times per minute.

    It is critical that the CDI and electrical box have a solid ground connection back to the engine. Verify zero ohms from electrical box Black wires to engine cylinder heads.

  9. #9

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    Thanks for the INFO.
    I have located a 94 SL 750 CDI box to replace my 94 SL 650 CDI box. Will this work for me?

  10. #10
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by james5 View Post
    Thanks for the INFO.
    I have located a 94 SL 750 CDI box to replace my 94 SL 650 CDI box. Will this work for me?
    Check with Xlint89 on that question.

    There are some 650 vs 750 differences...

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