67 Daytona T100r No Spark Help!!

Discussion in 'Vintage Classics' started by chazdo2, Jun 3, 2020.

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  1. chazdo2

    chazdo2 New Member

    Apr 16, 2020
    10
    3
    auburn new youk
    #1 chazdo2, Jun 3, 2020
    Last edited: Jun 3, 2020
    I posted this again because my latest response never posted! I have two new coils ( Boss Emgo manufacturer says will work with 6 or 12 volt system). The spark plug cap is a non resistance cap and from the cap to the negative post on the coil is around 10k ohms for both. The primary resistance on both coils is 5 ohms 10 in series. New spark plugs, new wires good 12 volt battery. Wired exactly as the positive ground schematic says to do. I have the red lead from the Micro IV ignition unit to the positive side of the second coil then to positive side of the battery. Black lead to the first coil in the series to the negative primary post and the positive post of the first coil wired over to the negative post on the second coil. White wire to the battery negative. I ran a separate wire from the case of the coils to the positive side of the battery also. When I touch the stator wires together no spark when I touch them release them nothing!! I am going crazy here please HELP

    I just noticed I have no voltage at all on the black wire going to the first coil in series. Shouldnt I have something?

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  2. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,355
    800
    Nr Biggar
    Have you got a multimeter? I would be double checking all your wiring and doing continuity checks on both +ve and -ve sides of the low tension circuits. I would be more reassured if they could spell ‘capacitor’ in their ‘destructions’.
     
  3. SprinterII

    SprinterII Noble Member

    Mar 27, 2020
    642
    443
    Scotland
  4. SprinterII

    SprinterII Noble Member

    Mar 27, 2020
    642
    443
    Scotland
    https://www.triumphrat.net/threads/electrical-cunundrum.972095/#post-2004085542

    StuartMac
    Moderator


    Hi,

    chazdo said
    Micro IV
    When I touch the stator wires together no spark when I touch them release them nothing
    To be clear, the wires that should be touched together for this test are the Black/Yellow and Black/White out of the "Transistor Box" ... the Stator is electrically inert when it's disconnected from the Transistor Box.

    no voltage at all on the black wire going to the first coil in series. Shouldnt I have something?
    Depends. Ernie (Bransden) incorporates a jolly little jape in his Transistor Boxes for twins (and singles) ... Once the Box is powered up from connection to the battery (turning on the ignition switch usually), if it doesn't 'detect engine movement' (i.e. Volts and Amps changes caused by the Rotor being moved past the Stator magnets) within a few seconds, the Box powers itself down ... it powers up again either when 'engine movement is detected' or if it's disconnected and reconnected to the battery. Ernie's always reckoned this 'feature' is to stop the coils draining the battery ... in a few seconds? upload_2020-6-3_21-3-25.gif One might wonder why B-B Boxes for triples don't have this 'feature' ...

    To beat the 'feature', when the Box White wire is connected to battery -ve, all the EI and HT connections must be made already, at least one plug out of the engine and visible and the Box Black/Yellow and Black/White wire ends should be held together already ... Only then if a stream of sparks at the plug is still not seen is it likely there's another problem ...

    Chazdo
    two new coils
    primary resistance on both coils is 5 ohms 10 in series.
    Boss Emgo manufacturer says will work with 6 or 12 volt system
    No, they won't ...

    Ignition coils on these old heaps were triggered by points before '79. The primary criterion of any DC coil triggered by points is the coil draws between 3 Amps and 4 Amps when its rated Volts are applied across it; this applies whether a given coil's rated for 12V, 6V, 4V or 3V.

    The Volts and Amps are linked together by a coil's primary resistance (Ohms), specifically Ohm's Law - Volts = Amps x Ohms.

    So, if any coil's going to draw between 3 Amps and 4 Amps, the primary resistance cannot be the same for both 6V and 12V - specifically a '6V' coil must have a primary resistance between 2 Ohms and 1.5 Ohms respectively, whereas specifically a '12V' coil must have a primary resistance between 4 Ohms and 3 Ohms respectively.

    Most EI for these old heaps is 'points replacement'; i.e. it just replaces the points (and auto-advance); risking labouring the point, they use the same coils as points ... Note neither of the ranges above include "5 ohms", because that cuts the current draw to 1.2 Amps if 6V is applied across it and 2.4 Amps if 12V is applied across it.

    Cutting the Amps draw of any ignition coil with high primary Ohms is a crap idea - slows the HT charge time and, if that's limited mechanically - points auto-advance or EI trigger unit - as rpm rises and dwell time falls, eventually the coil won't charge fully between sparks, meaning you'll get a crap or no spark ... As you've noted, individual component resistances connected in series are cumulative, so 10 Ohms will allow just 1.2 Amps to be drawn ... to charge two coils ... mmm ...

    Aside, Ernie Bransden (Boyer-Bransden) does continue to maintain twins can use '12V' coils in series and triples can use '6V' coils in series. However, from personal first-hand experience, if you 'phone B-B tech. help ("'phone" should give you an idea of how long ago this was ...) seeking help with a malfunctioning EI, one of the first questions certainly used to be, "Does the bike have 6V or 12V coils?"; if the answer was, "12V", the immediate advice was to fit 6V ... Wisely ime, most other EI makers advise just '6V' coils (on a twin) ...

    Some contributors might post they're using '12V' coils with EI on their twins without problems; however again, I'm pretty certain none will post they're using two 5-Ohm coils in series ...
     
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