I’m on an electronic Boyer…
Could it be faulty grounds along the line?
No; most likely is the battery is flat or failing, another possibility is a wiring fault, just not in the "grounds".
Ignition coils only give an HT spark at the plugs when the LT power is switched off - one of the troubleshooting tests for an electronic ignition is simply turn the ignition switch on and off a few times, each time the ignition switch is turned off, the plugs should spark.
First check the battery with a Voltmeter or multimeter set to Volts. You need a 'good' - not cheap - meter for this because the decimal readings are important, cheap meters are not usually calibrated well so it is hard to use the decimal readings for problem diagnosis.
Assuming 'good' meter, fully charged lead-acid type battery (so including AGM and gel), one lead connected to each battery terminal:-
1. All switches off, meter should display 12.6V. Higher is not a 'better' battery, it is a poorly calibrated meter ... lower could also be a poorly calibrated meter, but it is more likely a failing/failed battery - 12.3V is a half discharged battery. This is why a well calibrated meter is important for correct fault diagnosis.
2. All switches off, meter displaying 12.6V, turn on just the ignition (not lights). At most, meter should display 0.1V less and stabilise there, it should not display any less and, when the Boyer turns off the coils, the meter should return to displaying the same or very similar reading as at 1.
3. 2. happening, turn off the ignition switch and then back on (to reset the Boyer). Meter again displaying at most 0.1V less, turn on the flashers. If you see HT sparks when the flashers ... flash, I suspect you will also see the meter display drop below 12V at the same time. If so, that is the reason for the HT sparks, battery cannot supply sufficient power to the Boyer when supplying the flashers.
4. To decide between battery or wiring fault, turn off the flashers and turn on the lights including the headlight:-
. if the meter display drops at most only another 0.1V, most likely a wiring or flasher or relay fault;
. if the meter display drops more than 0.1V, most likely battery's dying (assuming the bike does not have a 100W headlight and a couple of spot lamps? ...); if you do not have a load or conductance tester, haul it to an auto electrician (or battery seller?) for that test.
Post what you find?
