78 KZ1000 Electrical Question

Greetings all - I was prepping my ‘78 KZ1000 A2 for my usual Sunday morning ride and when I turned the key in the ignition, I had no juice. I had the bike out last weekend for a 30 mile ride with no noticeable issues. So this morning I took the battery out, tested it (tested as questionable on my meter - the battery is about 1.5 years old - and will run it to the shop for a proper test before replacing). I start/run/ride at least monthly in the cold months here along with taking the bike out every weekend or every other weekend for a 20 to 50 mile run in the spring/summer/fall months. I ran the battery recovery mode on my trickle charger on the battery for a period of time and dropped it back in and it appears to be taking some charge because I was able to get the bike to turn over using the button starter (but will still get it tested properly) before it ran out again. All of that was a preamble to this item: when I dropped the battery back in with some charge and hooked it up, the dummy lights came on (Neutral and Oil) without the key being in the ignition switch and the key position being definitely set in the OFF position. That is something I have not seen before with this bike. Curious if anyone has thoughts on what might be causing that response. I’m wondering if it might be a starter relay/solenoid thing that drained the battery in the first place, if, in fact, the battery is not the issue. Appreciate any thoughts or guidance.

For there to be power on the "output" side of the ign switch in the "off" position either the switch is faulty or there is a short in the wiring to the switch (both of which would cause a drain)

After charging the battery and hooking it back up, I had one more instance of the meter lights coming on without the key in. But inserted the key and turned ON/OFF and that seemed to clear it up. And the bike started up and ran fine. Still could be a battery problem but the ignition switch is the prime suspect at this point. Will treat it more more gingerly and continue to monitor. Thanks for your help.

The solder joints in the switch are now 47 years old, and are getting more brittle by the day. A loose one could be the culprit. Whether a loose connection or a shorted wire, tending to it sooner rather than later could prevent damage to various electrical components, or even a fire.

KYKZ this what i "believe" Texas is referring to he mentions solder joints. Note there are basically 3 different connector block types on every Z1-KZ. 4-pin, 6-pin small non-latching and the bigger spade Z1R 6-pin style. You will have the small 6-pin because the KZ1000 had a 3-fuse set-up. Note the picture of all those solder connections on the back of your switch, they indeed can wander off their respective places over time. I've seen a lot of this "factory' soldering so weak that while wire had solder on them barely any solder on their respective collets of breadboards. Also, look for distorted wiring insulation on both harness and switch side around connector block connection. Although and hopefully not your problem, wiring inside that shiny sheath that comes from under tank to headlight bucket gets a workout over all those years of making turns. Inside that sheath they also had connections that can fatigue and fail. Kawasaki harnesses used a crimped sleeve with no solder, Honda used just solder but that's a whole different story. As Texas referenced, fire, anything can happen but highly unlikely. Unless you used tinfoil wrapped fuses or waay too big rated ones.