Starting wiring soon on my '75 KZ400.
I've got the stock regulator and rectifier that came with the bike, but I'd like to combine them into a single unit if possible.
Replacing because, well, they're old and I'd like a minty fresh charging system!
I guess my question is whether or not any old R/R for say a late model KZ440 would work on my bike. I know my bike has the field coil vs the permanent magnet, so I'm guessing that may come into play.
There are a couple options for aftermarket R/R's for the '75 for $120 or so, but that's a tough swallow..
I don't know much about the various charging systems, so I would check the alternator output voltage.
With multimeter set to AC & the motorcycle running at about 4,000 rpms, test the voltage at the yellow wires in pairs, 3 measurements total. On my 81 650 w 3-phase charging system, each reading should be about 50 VAC. @ 4000 rpm.
The one in Martin's link does not have enough wires.
You are correct, you need a regulator designed for a field coil. More specifically, the regulator needs to control the positive voltage feed to the field coil. (Some KZ's have the regulator control the negative side of the field coil.)
You also have a 3-phase stator, so you would need a 3-phase rectifier.
You should be able to get both in a single unit, but sometimes it's nice to have separate units for troubleshooting.
I'm sure Oregonmotorcycleparts.com has what you need.
For the combo unit, in Ed's link, scroll down to part# VRREM7-KZ.