Tachometer Ratio

Discussion in 'Airheads' started by Boxer Metal, Apr 20, 2014.

  1. Boxer Metal

    Boxer Metal Mad Scientist

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    Anyone have the answer?
    #1
  2. jellycow

    jellycow out there without a clue, now on a '99 640 AVD

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    42.............Unless you actually provide us with an question :rofl
    #2
  3. Boxer Metal

    Boxer Metal Mad Scientist

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    Tachometer Ratio
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  4. Boxer Metal

    Boxer Metal Mad Scientist

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    I agree that 42 is the answer for everything in life but not for my current question:)

    Sent from my SCH-I535 using Tapatalk
    #4
  5. JGT

    JGT Been here awhile

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    If you are looking for input rpm at the cable vs. readout on the tach, I know it is 1:2 for the /5 bikes. That is, if the cable is turning at 3000 rpm the tach should read 6000. Not sure what it is for other models, though.
    #5
  6. Wirespokes

    Wirespokes Beemerholics Anonymous

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    JGT nailed it. The tach reads twice as fast as the input.
    #6
  7. Voltaire

    Voltaire Triumphant.

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    What do you need to know for electronic ones? My race bike tacho did not like 8000 rpm and the needle fell off....:huh
    Thinking aftermarket of oilhead one...? probably need one that reads to 10k for the next engine.
    #7
  8. Boxer Metal

    Boxer Metal Mad Scientist

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    On the race bikes we have always used the oilhead tachs.
    I'm looking for something small for my shop truck(/2 conversion).
    #8
  9. knary

    knary Long timer

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    Do most mechanical tachs use the same kind of connection?
    #9
  10. Boxer Metal

    Boxer Metal Mad Scientist

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    I would think the cable ends would be bike specific.
    #10
  11. knary

    knary Long timer

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    That's what I always assumed. Or that they'd certainly be in the case of a certain German manufacturer.
    #11
  12. pommie john

    pommie john Long timer

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    I use one of these on my little Honda, they're available in various ratios, I'm
    not sure about a 2:1 version though.

    http://www.dimecitycycles.com/vinta...ni-chrome-white-face-tachometer-15-0033w.html


    EDIT: Here you go, neat little 2.5" tacho in 2:1 ( It's described as a Harley fitment so that may put you off :) )

    http://www.ebay.com.au/itm/like/261...e&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107
    #12