Quinten and Stuart are telling me I can't measure voltage at the coil in my negative "ground" (I've learned to always put it in quotes) installation
or I've done something wrong.
Uh-uh; to clarify:-
you cannot measure Volts in any circuit containing a B-B e.i. or one of the clones, because ...
I made a jumper from the black wire coil to "ground"
. on your bike, "negative ground" means metal bits of the bike are connected to battery -ve;
. "black wire coil" means the (B-B) Transistor Box Black wire is connected to coil -ve;
. "I made a jumper from the black wire coil to "ground"" means you connected battery -ve to coil -ve; i.e. you bypassed the Transistor Box, it was not in the circuit that you were measuring Volts, your Volts readings were (should've been) accurate.
measured at the red wire coil. It measured battery voltage less any loss from the switch, etc.
However, afaict this is incorrect ...
. First you measure between battery -ve and battery +ve, to get a reference = none of the bike's electrical components involved;
. then you can measure between:-
.. coil -ve ("black wire coil") and battery +ve;
.. battery -ve and coil +ve ("red wire coil");
.. note the opposition of the two terminals in each phrase, because the coil/s is/are the resistance in the ignition circuit;
.. if there isn't any additional resistance in any other component in the ignition circuit (e.g. across fuse, ignition switch, kill switch, etc), the Volts readings above between each coil terminal and battery terminal should be the same as the first reading just between the battery terminals;
. so there should not be "any loss from the switch, etc."; if there is, the component/s where this "loss" occurs is/are faulty.
Even without the jumper I still measure battery voltage at the coil.
This measurement only while the B-B Transistor Box is conducting
; when it switches off, any Volts readings anywhere in the ignition circuit are
same as they would be if the ignition or kill switches were off, any fuse was out or blown, etc.
you shouldn't be able to read voltage at the coils wirh negitive ground
'Fraid I have no idea what this means ...
As I posted earlier, and you can see in the B-B wiring diagrams, any e.i. is connected exactly
the same, totally and utterly irrelevant of "ground". In the case of B-B or Pazon/Wassell clones, the Box White wire is connected to battery -ve, the box Red wire is connected to battery +ve, the Box Black wire is connected to coil -ve (only one coil -ve in the case of multiple coils), (one) coil +ve is connected to battery +ve. That's the ignition circuit. The position of any switches within the circuit might be different but they are (should be) simply connections within the circuit.
Because any e.i. is connected exactly the same, irrelevant of "ground", if the e.i. Box is powered down, the ignition circuit is not complete, any Volts 'readings' aren't meaningful. Bugger-all to do with "ground", "negative" or 'positive'.