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1968 Commando

Discussion in 'Norton Commando Motorcycles (Classic)' started by jms, Mar 12, 2020.

  1. jms

    jms

    Joined:
    Jul 26, 2005
    I have an early 1968 Commando that has been rewired to negative earth by a previous Owner. The bike has been converted to look like a Production Racer and had the typical Ammeter / light switch/ choke lever holder. I recently purchased an ammeter to go into the holder as it was missing. Question is what would be the proper way to wire in the ammeter? Plus side of the battery directly to the ammeter and then the other side of the ammeter to where? I probably would prefer to use a Voltmeter but it seems impossible to find one that is 1-3//4" in diameter
     
  2. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    They were all negative earth!
     
  3. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Battery positive to ammeter negative and ammeter positive to the ignition switch.

    Note that the positive (in this instance) charge output wire should also be connected to the ignition switch side of the ammeter or it will show a continual discharge.

    No! :eek:
     
    jbruney and dynodave like this.
  4. jms

    jms

    Joined:
    Jul 26, 2005
    Thanks all
     
  5. jms

    jms

    Joined:
    Jul 26, 2005
    So when I turn the ignition on brfore kicking it over the ammeter needle should register all they way over to the left?
     
  6. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    Left, yes, but not that far. The ammeters I've seen are +/- 12 amps and (points) ignition takes about 3 amps max.
     
  7. jms

    jms

    Joined:
    Jul 26, 2005
    L.A.B.
    -when you say that the charge output wire needs to be attached to the ignition switch side of the ammeter. Which wire is that? From the Tympanium unit ?
     
  8. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    A Podtronics diagram but the Tympanium connections will be the same, so for negative earth/ground, the Tympanium positive (red?) wire connects to the ignition switch side of the ammeter.

    [​IMG]

    For positive earth/ground it would be the negative (black?) wire.

    [​IMG]
     
    maylar likes this.
  9. jms

    jms

    Joined:
    Jul 26, 2005
    Thanks L.A.B. ! For some odd reason my Tympanium only has three wires so my assumption is the forth missing wire is a ground achieved via one of the mounting bolts. That said I have a capacitor so how would that wire into the negative ground diagram above?
     
  10. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Assuming it's negative earth/ground.

    Connect capacitor(+) between the fuse and the ammeter and (-) to 'ground'.
     
  11. jms

    jms

    Joined:
    Jul 26, 2005
    This may be a stupid question but I'll ask anyway. Looking above at the Podtronics neg earth diagram, the right side of the ammeter represents it's plus side correct?
     
  12. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    No, the left side (from the regulator) is meter positive. You want the meter to point positive when the battery is charging.
     
  13. jms

    jms

    Joined:
    Jul 26, 2005
    Well I've tried just about everything and can't seem to be able to get the meter too register anything. The way this bike is wired is as follows. Neg earth. Two wires joined together from battery plus. One goes to a fuse the other goes directly to a three terminal ignition switch. The fuse then goes to the plus side of the capaciter. Hot lead from Typanium to plus side of capaciter as well. negative side of capacitor to ground. At the switch when turned on the other two terminals become hot. the 2nd terminal goes to the light and the third I assume goes to the ingnition which is an electronic Boyer. I've added a jumper from the third terminal to the neg side of the ammeter and then from the plus side of the ammeter connected via another jumper to the lights. There is a continuity between the plus and neg side of the ammeter. Without the engine running when you turn on the key and turn on the lights, the ammeter doesn't move?
     
  14. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    The wire that goes to the ignition switch (which should also be fused) should be going to ammeter(-) then, from ammeter (+) to the ignition switch (see previous Neg. Earth diagram).

    The hot (+) Tympanium wire should be connected to the ignition switch side of the ammeter (see Neg. diagram).

    Edit: CORRECTION. According to the factory diagram, the brown/white battery feed (from the ammeter), brown/white charge wire and white/brown lighting wire connect to the two common terminals and the (double?) white wire connects to the single terminal so the lights work independently of the ignition switch. You could, however, leave it as it is.

    Was that with the lights wire connected to the ignition switch? If so, then that probably explains why the ammeter wouldn't work. Even if the lights wire is disconnected the ammeter still won't work correctly as it is.
     
    Last edited: Apr 1, 2020 at 7:24 PM

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