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  1. #1

    tach not giving me right number

    i bought this tach from ebay.. and i even how i change the settings, it won't give me right numbers... =( so i cannot use this one?



  2. #2
    Your ski is odd in the way that it sparks 3 times per revolution, so its going to show you a reliable, yet incorrect number. It shouldn't make a difference for tuning, and there is some magic number you can divide by to get the real RPM, im just not sure what it is.

  3. #3
    ryandi2's Avatar
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    how many times do you have the wire wrapped around your first plug wire?

  4. #4
    4 to five times.. i wrapped it on the pto plug, manual says settings are 1,2,3,4,5 1-is spark plug fires twice per revolution, 2- once per revolution, 3-every other revolution, 4-hour only, will not display RPM , i think i don't have these settings for my skii???

  5. #5
    Canadian Beaver Inspector jkindt's Avatar
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    If you swap out to a Pro 785 CDI unit, it will only spark the plugs once per revolution and allow you to run that tach.

  6. #6
    hmmm.... its that thru? pro cdi is giving 1 spark per 1 compression stroke of the piston? thats good... who's selling pro cdi =)

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by andy95'slx780 View Post
    hmmm.... its that thru? pro cdi is giving 1 spark per 1 compression stroke of the piston? thats good... who's selling pro cdi =)
    Quote Originally Posted by andy95'slx780 View Post
    ...manual says settings are 1,2,3,4,5 1-is spark plug fires twice per revolution, 2- once per revolution, 3-every other revolution...
    Pro 785 CDI is wired to the coils differently, and Pro 785 CDI has a different spark timing curve. Otherwise it can be made to work.

    It may be cheaper to buy a stock Polaris MFD than a Pro 785 CDI.

    Your Tachometer will work with your current CDI. Your stock Fuji engine fires three times per revolution. Set Tach to mode 2 and the display will be three times the actual RPM.

    Set Tach to mode 1 and Tach display will be 50% higher than actual RPM (if my arithmetic is correct).

  8. #8
    ryandi2's Avatar
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    i think you are supose start with one wrap and work your way till you get a signal and no more then necessary.

  9. #9
    If the tach is well and properly designed, the number of wraps isnt very important. The issue is the 3 spark / revolution... Thats not very standard.

  10. #10
    yep.... thats true, the problem is spark fires 3times per revolution, i understand.. better set to mode 2 , and divide the rpm by 3, =) its ok ... my mfd is also coming =)

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