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  1. #1
    Clayton G's Avatar
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    8 Pin MFD Question

    How many pulse tachs are in the 8 pin MFD's?
    Thanks.


  2. #2

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    Not sure I understand your question. Please elaborate.

  3. #3
    Clayton G's Avatar
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    Engines generate electricity with a certain number of pulses per revolution. This can vary from manufacturer and even from different engines from the same manufacturer. Tachometers operate on these pulses and read frequency for rpm change. I have a Harrison T-11 Tach Tuner that I would like to use to test the MFD's on our jet skis to see how accurate they are. In order to do that I need to know how many pulse systems these skis operate on, otherwise I could damage the MFD. This tach tuner is adjustable to test tachs with 1-16 pulse systems. I've used it on most of our snowmobiles so I could accurately clutch them. My daughters 93 Storm has a 3 pulse system tach. Our XLT's and my 800 XCR operate on 6 pulse system tachs. Some Ski Doos have 12 pulse systems and GM HEI is a 4 pulse system. I also have extra snowmobile tachs that I would like to use for testing on my wifes 93 SL 750 (no tach). And lastly I will be working on a project ski this winter that I am going to use a Digatron on so I will need to know how many pulse system this ski has so I can program that into the Digatron (1996 SLX 780 ignition system). I ask about the 8 pin MFD's because it sounds like they are all interchangable between fuji and domestic engines from what I have read here on GH.

    Thank you for any input.
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  4. #4

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    all of the polaris mfd's mfi's and even the newer ones will work on any polaris ski even the 4 stroke gauge will work on a two stoke ski . Thats a ? for Randy at Watcon

  5. #5

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    check out the below thread for additional info.
    The pulses from the charging coil on the stator are used for battery charging and to display the engine rpm on the MFD. The pulses are multiplied by 10 (in the MFD) and then display the rpm.
    Example: 60 pulses X10 = 600 RPM The below thread goes into more detail.

    polaris sl750 round mfd unit

    An easy way to check the accuracy of the RPM function of the MFD is to disconnect the yellow wire comming from the MFD in the electrical box then touch the metal portion of the connector on that wire with your finger.
    This introduces a very low voltage (milivolt level) 60 hz signal to the MFD. This is enough to wake up the MFD. It should display 600 RPM. (60hz X 10 = 600).
    Hopes this helps you out.

  6. #6
    Clayton G's Avatar
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    Well, I thank you for the information, but it still doesn't answer my question. I still need to know how many pulse per revolution these Polaris's use. I understand that it's the change in frequencies that shows RPM. But I cannot test a tach without knowing the pulse per revolution. The pulse per revolution stays constant and does not change. To put in the wrong pulse to test the tach could damage it. Kind of like plugging your 110V toaster into a 220V outlet. It would heat up, but wouldn't last long. It might be a poor analogy but you get the picture. If I had to hazard a quess (which I'm trying to avoid) I would say they are 6 pulse systems. The snowmobile tachs I have have the pulse printed on the back of them.

    I think I'll do what Lugs suggested and call Randy at Watcon or Jay at Sharps Marine. I've talked to both of them in the past and they are very easy to talk to and I'm sure they can answer my question.
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