Low voltage at coils, I've tried everything

Ok, I've read the Mfolks guide to cleaning connectors in the wiring harness, I've cleaned and sprayed everything connector under the tank, connectors in the headlight bucket, turn signals, rebuilt and cleaned the kill switch, headlight, signal lights. New coils, points and condensers. Replaced old fuses with soldered in blade fuses. I still have 9V at the coils, new charged battery has well over 12V.

I don't want to do the coil mod, I want to do this right and figure out where I'm losing voltage. Weird thing is that if I disconnect the coils, the voltage is 10.8 - 11V at the Yellow/Red connector to the coil. As soon as I plug the coils in, the voltage drops to 9V. Very odd. I have yet to clean the starter button connections and the horn and turn signal on the left side. Hoping that helps but I'm not convinced.

My turn signals are kind of sporadic, they blink slooowly if at all, if the ignition is on and bike is not running, slow when idling and normal when at higher RPM. Is this maybe a sign of something?

Sorry I'm just not sure what I'm looking for.

Any advice or help would be appreciated.

If not already done, would inspect and assure integrity of the ground connection where the negative battery cable attaches to rear of the engine. The lug may be corroded and thereby failing to provide a proper ground.

Using the specific wiring diagram for the bike at hand, would measure voltage at each connection from battery positive post to the ignition coils -- to determine location of the drop in voltage.

Here's a generic example illustrating the various points to measure.





Good Fortune!

Have battery Vdc up to the ignition switch (off position)...?

On output of ignition switch, disconnect lights and such other than Stop/Starter/ignition switches & coils... Turn key ON, battery still drop to ~ 8-9Vdc...?

Possibly bad ignition switch...

Other thought is in the charging circuits...
Considering 3 phase Dynamo (alternator, Vac generator, due to recent naming convention post, whatever you want to call it :whistle: ) @ 1/3rd max Vdc output, thinking bad rectifier, possibly regulator...

Happened on my KZ900, lost a diode (open) thus 2/3rds output at 9Vdc...

The KZ manual has a decent write up on how to test... Forget what member has the 70's OEM manual, check the file base....

KZ900/1000 but still applies regarding rectification & regulation theory...

While I don't see a C model wiring diagram in File Base, there is others. I would think it should be the same.
Basically you need both ends of the 12v circuit, power and ground for it to work correctly. Like Patton said, check the ground, but also where the Black/yellow goes to the neg battery terminal. You can add a extra ground circuit at the Black/ yellow along one of the other harness points to see if it lifts the voltage.
It could be in the harness splices, the Ignition switch, Run/Stop switch. You must do as Patton wrote and start with the voltage at the battery, follow the white wire to the ignition switch, then onto the brown leading out of the switch, to the Run/ Stop switch, then to the red/ yellow for the coils. Make sure you keep the black meter lead at the battery neg during the tests. See where it drops, fix and move on. Some members have found that splice points in the harness have gone green with corrosion.

Thanks for the replies everyone. Brand new rectifier/regulator working well and charging strong so it's not that. I'll take the advice and trace it from the battery to the coil and see where the major drop is.

Thanks.

"rectifier/regulator working well and charging strong ".... Huh...? :blink:

Not sure how'd that's possible for after the ignition switch (would have to review schematic/wiring diagram) but power feeds back to the battery...

Translation, this is the same voltage dc to the coils... How can battery voltage be strong but coil voltage low... :S

Have a 30 amp switch...
Can bypass ignition switch to supply coils battery voltage...
Trouble shoot see if the ignition switch is your cause...

The factory splices can, and do corrode. I had to re-do the FI harness on my bike, as I wasn't getting the voltage to fire the injectors. After tracing where they were, I replaced them with heatshrinkable splices, There are two types; one you crimp & then shrink down, and the other has a solder band that must be melted, doing so may take a heat gun that most people don't have.