Voltage Regulator

Have 78 kz750b3. Ordered new regulator from Z1 Enterprises. New regulator has 4 wires, 2 yellow, one red, one green. Old regulator had 5 wires, 2 yellow, one red/white, one green, one brown. 2 yellows and one green are in a plug so okay there. I'm sure the red and the red/white connect to the same place. Is the green a ground, and what is the brown for? I have the factory manual but it only shows 4 wires.

From what you have described on the difference between the new unit and the old unit, number and color of wires, it sounds like the old unit is for an excited field system and new one for a permanent magnet system. I think the 78 model year (750 twins) is when the change happened. If what I am thinking is correct, that your mchine has an excited field system, the new unit will not work with your machine.  One quick way to see if that is the case. Look on the alternator cover (on the left hand side as you sit on the bike), are there 3 bolt heads on it. If so then your machine has the earlier excited field system
Here are some pics, yes of engine covers for the 650s but note the pic for the B1 and the 3 bolt heads the other versions do not have. This is what you would be looking for on your machine.

seebold wrote:

Have 78 kz750b3. Ordered new regulator from Z1 Enterprises. New regulator has 4 wires, 2 yellow, one red, one green. Old regulator had 5 wires, 2 yellow, one red/white, one green, one brown. 2 yellows and one green are in a plug so okay there. I'm sure the red and the red/white connect to the same place. Is the green a ground, and what is the brown for? I have the factory manual but it only shows 4 wires.

I have looked at the diagrams for B2, B3 & B4 (none Have a five wire reg/rec) red goes to red/white (battery positive) does the green go to a black/yellow at the plug ? Brown is "ignition live" which  none of the "B" series diagrams show (RR's without a brown sense system voltage internally from the battery connector (red or red/white) given the fact that the bike is 47 years old the RR you are removing may not be the original !!
PS: Out of interest why are you changing it ?

Battery wouldn't charge and regulator showed a fair bit of corrosion. The connector was so old and brittle is was easy to break apart. The green wire was connected to a black ground wire someone had just shoved into the connector. Tomorrow I'm going to replace the connectors and see what I get.

And this old regulator does have 5 wires. The brown wire goes to connector up under the gas tank. 

seebold wrote:

And this old regulator does have 5 wires. The brown wire goes to connector up under the gas tank. 

I wasn't questioning that, simply stating none of the "B" series diagrams show it. Brow s always ignition live on Kawasaki's

Agreed, my factory service manual also just shows 4 wires. Is the brown wire needed?

seebold wrote:

Agreed, my factory service manual also just shows 4 wires. Is the brown wire needed?

No, RR's that don't have a brown sense system voltage internally from the battery wire (red or red/white)
Just out of interest is the part number still visible on the old unit ?

Looks like SH522-12. Found lots of corroded terminals, looks like the battery had cooked at some point. Not horrible corrosion but certainly enough to be an issue. Just ordered new stuff, I'll re-terminate and see where I'm at then. This bike hadn't been rode in years, have it running nicely now just need it to charge. Last thing then hopefully ready for a ride.

seebold wrote:

Looks like SH522-12. Found lots of corroded terminals, looks like the battery had cooked at some point. Not horrible corrosion but certainly enough to be an issue. Just ordered new stuff, I'll re-terminate and see where I'm at then. This bike hadn't been rode in years, have it running nicely now just need it to charge. Last thing then hopefully ready for a ride.

The SH522-12 (just a quick search) is for AR, KMX, KDX125, KR1S 250 and GPZ305 so I suspect at some point in the past it has been "McGyver'd"