Charging enough? 1976 KZ400

1976 KZ400D that I just got running.

Took it out for a spin, running great, then get's absolutely poured on while I'm playing volleyball. Starts up fine and runs good for about 10min on the way home, then dies. Starter turns over a couple times then stops, won't kickstart. Fuses are fine. Lights are very dim.

Took the battery out and charged for a few days and cleaned the ground connections. Put the battery in today and started checking voltages.

With bike off I get 12.66 consistent on the battery. At idle I get 12.1 and at 4000rpm I get the same 12.1 volts.

Do you think it was just the rain that caused the failure and I am OK to take the bike to work tomorrow? Or am I not getting enough charge from the charging system to keep the battery up?

The rain was torrential, like Noah's flood type stuff with 60mph gusts and sideways hail...

Not enough juice there, you need to be like at least upper 12v at Idle and 14v when revved. You should check your manual for the correct figures but thats close. Look closely at the connections coming from the stator to the Regulator/ Rectifier. Also you should check the ACv coming from the stator. Does it have 2 or three yellow wires coming up from the stator? 2 would be single phase, and you should see like 75 volts AC from the two yellow wires, disconnected and the engine running at 4K RPM. If three yellow wires, Three phase, then each pair of three should be 56 ACv.

Thanks. I couldn't find specs on the charge numbers. Tonight I will bust out the manual and go through the tests.

Thanks again.

I thought I posted another reply yesterday, but it must not have worked...oh well I have updated info anyway.

So I tested the regulator per the shop manual and I got slightly higher resistance than spec.

When I'm supposed to get 0ohm resistance I get .3ohm
When I'm supposed to get 9ohms, I get ~11ohms
When I'm supposed to get ~100ohms, I get ~112ohms

So is that enough to say my regulator is bad?

I tried cleaning the points with electrical connector cleaner and a piece of paper, but it didn't really change anything. I also adjusted the points gap and the adjusting arm, but it yielded no change to the charge at the battery. Still only 12.1v at idle and 4000rpm.

Today I tested the rectifier and I actually think that's OK. On the diode setting on the multimeter I get ~475 for each wire in one direction and then no reading (infinity?) in the other direction.

Next up I guess is to test the dynamo and field coil, but should I order a new regulator?!

Thanks!