Decades-old pin, barrel and spade connectors will always benefit from application of a protectant. We apply No-Oxid to every location where a conductor is broken by a connector including chassis grounds. Spray cleaner can help in some cases, but won't remove carbonized deposits. Physical cleaning using scraping and / or abrasive, is sometimes required to arrive at truly clean contact surfaces.
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It's not always easy to clean switch contacts. A compelling reason for the relay mod, on Z1's / Z2's specifically, is due to Mama Kaw's crude design of the Z1 / Z2 electrical system, wherein the same high current that passes through the single 20A fuse (that runs hot anyway) on the WHITE circuit is also directed through a single(!), small ignition switch contact, also in the WHITE circuit, that isn't really capable of switching high current repeatably and reliably.
We were forced to troubleshoot the innards of a '72 Z1 ignition switch a few years ago on a resto to maintain OEM key #'s across all locks. Don't remember the exact numbers, but the affected ignition switch also exhibited elevated resistance across the WHITE circuit contacts while in the ON position, that inevitably reduces voltage at the coil primaries. This in addition the the intermittent OPENS when ON that forced our hand (see link below).
We built a prototype coil relay harness that isolates the coil primary circuits from the ignition switch. The prototype was just for length sizing and proof of concept. We copy that prototype for every Z1 we do. It doesn't require any butchering of any OEM harness of a Z1 or Z2. A good crimper, plus one male and one female 4.9mm (AKA 5mm) std. barrel connectors, results in a plug n' play relay harness mod that is easily undone roadside if ever necessary just by swapping barrel connectors to their original factory positions. It's a clean mod that doesn't result in clutter, conductor butchery, or mysterious butt connectors, and is easily understood by anyone else who might see it.
If one chooses to do a relay mod, don't cheap out on the relay! Make sure the barrel connector crimps are sound (if used), and it will likely work for a lifetime.
Installing a modern 20A blade fuse holder to replace the problematic old glass tube fuse and it's holders, plus the relay mod, will make the Z1 or Z2 as modern and reliable as possible, short of extensive main harness mods that would be necessary to split critical circuits each onto their own fuses, as Mama Kaw did on later bikes.
Our ignition switch troubleshooting post:
www.kzrider.com/forum/4-electrical/60681...-and-troubleshooting
Good Ridin'
slmjim & Z1BEBE
