Good diagram. Before you take the bike out for a test I would like you to do one other thing. Looking at your diagram, the coil has four wires going to it. On the TOP there are a pair of WHITE wires.
Question.
1) Was this the point where you attached your test light to? One wire of light bulb circuit to the pair of white wires (stud) and other test light wire to frame ground?
Perform the following step.
2) On the other side of the coil there appears to be a PINK wire and a Blue (? not clear in diagram). I want you to remove the PINK wire during your rode test. The tach will not work, Just ignore that for now. Remove the pink wire and conduct the spark plug gap test if/when the bike fails.
A few other added notes to check & do just so they can be eliminated from the overall picture.
3) Look at the ignition module in the schematic that you uploaded. You will see a Black wire coming out of the regulator that goes to frame ground. Locate that wire on the bike and make sure that ground wire ring terminal is clean and tight. Loosen the stud or bolt the ring terminal is attached to, check it,,clean it,, and re-tighten it.
4) The secondary side of your ignition coil does not use a "center tap". Therefore both plugs are in series with each other. That means if 1 plug goes "open circuit" for some reason, BOTH plugs will fail to fire. On most ignitions, a bad wire will only affect that associated cylinder. This is Not the case with your bike. Therefore in your case it is Very important that you check both spark plug wires using an ohm meter. Remove each wire and check the resistance for anything that may be way out of line. As long as you get a resistance reading of below 5K on each wire, your OK.
Normally I would not even be concerned about the condition of the wires for a problem like yours but on your particular setup it is important because if 1 wire is bad, BOTH plugs will fail to fire. It was not until you uploaded the diagram did I realize this. This is the reason why I love schematics. They give you little clues that are no where in print.
5) Even though you passed the "mini red test light" test early on, I want you to keep that light hooked up until you have resolved your problem. When you go out for the ride with the spare spark plug in your pocket, I want that red test light still in place and working. I want you to monitor it just like before. If your bike dies and you swap out the spark plug, when you are cranking the engine looking for spark,, that mini test light should be lit also. This is a must if you want to prevent going in circles looking for the answer to this problem.
