Here's a wiring diagram for a Targa.. see attachment.
At least this one has wire color codes and, although the scan makes them hard to read, you can figure them out with some care. It shows many things the other diagram doesn't show, like a connection between the magneto and voltage regulator.
Study it a while and see if it helps.. take your time and determine what the electrical components on that bike actually are.. the "indicator relay" (turn signal flasher) and "electronic box" (coil/spark plug wire), etc.. Label the components with masking tape if that helps keep things in order...
The bottom line is that all wires should be connected to the proper places and not accidentally grounded.
i got it from a manual for the Targa posted here:
Here's the page with wiring diagrams:
As far as testing a coil, its just coils of wire.
I dont know the proper ohms but if the coils show continuity in or below the kilo-ohm range, the coil is probably just fine.. a bad coil is the last thing i would suspect..
First thing i would suspect is you have some wire connection problem.