Hey all, got an electrical issue that I don't understand. No electrician myself so hoping someone here might be able to explain what is happening/what I am doing wrong.
Bike info:
Bike is a 1975. Running stock alternator with a Boyer electronic ignition. Kick start only with a lithium ion battery. Built the wiring harness myself so it is far from perfect but has worked for two years now. Recently redid all the wiring connections due to this issue (hoping that would fix it and I wanted to replace the cheapo connectors I had used with better bullet connectors). Unfortunately that didn't turn out to be the solution
Issue:
When I turn the ignition switch on and then toggle the stock kill switch, I get a 4-6 volt drop for a second. Same thing happens when I sound the horn. I have a volt gauge connected to the brown output wire from the ignition switch and this is where I am seeing the drop occur. So for example, with ignition on, I toggle kill switch, gauge back light flashes 2-3 times, voltage drops from 12 to 6-8 volts for a second and then bounces back up to 12 volts. Same thing happens with the horn.
Troubleshooting I have done:
Disconnected my ignition wire from my 6 blade fuse box, issue goes away when horn is used.
Disconnect all outputs from 6 blade fuse box except ignition feed, issue remains.
Is it possible I have an issue with my Boyer ignition box? Seems like the obvious culprit but not an easy/cheap thing to swap out. Haven't tried to start the bike because I don't want to button everything back up and have it still not work due to this gremlin.
Shoot me any questions you might have as I am sure I missed some important details.
Here is my current wiring schematic (not shown is a line from "lights on/off" to running tail light):
Bike info:
Bike is a 1975. Running stock alternator with a Boyer electronic ignition. Kick start only with a lithium ion battery. Built the wiring harness myself so it is far from perfect but has worked for two years now. Recently redid all the wiring connections due to this issue (hoping that would fix it and I wanted to replace the cheapo connectors I had used with better bullet connectors). Unfortunately that didn't turn out to be the solution

Issue:
When I turn the ignition switch on and then toggle the stock kill switch, I get a 4-6 volt drop for a second. Same thing happens when I sound the horn. I have a volt gauge connected to the brown output wire from the ignition switch and this is where I am seeing the drop occur. So for example, with ignition on, I toggle kill switch, gauge back light flashes 2-3 times, voltage drops from 12 to 6-8 volts for a second and then bounces back up to 12 volts. Same thing happens with the horn.
Troubleshooting I have done:
Disconnected my ignition wire from my 6 blade fuse box, issue goes away when horn is used.
Disconnect all outputs from 6 blade fuse box except ignition feed, issue remains.
Is it possible I have an issue with my Boyer ignition box? Seems like the obvious culprit but not an easy/cheap thing to swap out. Haven't tried to start the bike because I don't want to button everything back up and have it still not work due to this gremlin.
Shoot me any questions you might have as I am sure I missed some important details.
Here is my current wiring schematic (not shown is a line from "lights on/off" to running tail light):