Thanks guys, Mikaw and SWest, for your keen and accurate observations. It's really helpful to know what I'm dealing with for this bike.
I was thinking about that 70 mph S-curve sweeper south of town where my lean and speed is about as risky as I get, and unless my wheels are good and well assembled, I might not enjoy that ride so much.
So, I dug into that front wheel.
The first thing I noticed was those rotor bolts were not very tight, and tightened unevenly. Definitely someone has been in there. All the bolt threads are good.
Those are flange head bolts so the lock plates would never really bend up nicely onto the bolt head flats. As you've pointed out, those lock plates were likely never part of the design.
And when I cleaned up those bolts, there's that gold paint on the heads.
Interestingly, the mounting surface between the rotor and wheel was showing the presence of of gold paint and black paint. Weird! Paint is far from an accurate machined surface, and those rotors need to be fixed to an accurate surface so they don't wobble and push the brake pads back into the calipers. So I'll give those mating surfaces a careful cleaning and test the rotors for truth.
There was some black paint over-spray on the inside surface of both rotors where the pads don't rub. I think the black paint job to cover the gold front wheel was not carefully done.
Both front discs have a 3A stamped one them. I have no idea how that translates into a date code.
Thanks again guys, your help is exactly why I signed up.
Still going hard at making the best of the wheels on this old KZ1000.
Including the rear wheel, which doesn't seem to have any of the gold paint and has a rotor with code 1K, whatever that date format translates to?
Most of the effort has been cleaning the surfaces where the rotors mate to the wheels, as I'd like these rotors to spin as true as possible.
South wind brought it up to 10ºC here today, so I fired up the pressure washer. It's not a very powerful washer, but it did shift a lot of the loose black paint on the front wheel revealing much more gold paint. I'll get after it with some more preparation and flat black paint.
A little rigging with some gaskets and big washers was effective in keeping the pressure washer water out of the bearings.
Both wheels have the Enkei name cast in, probably the Made in Japan manufacturer.
Gotta decide on tires. Advice? I live in the land of straightaways !!
If the black paint is chipping off I'd use some paint stripper to remove the rest of it. Chances are if the gold is factory it won't come off without a fight. It would make a good primer base. I used semi gloss on mine. Turned out great.
The front tubless didn't hold air very well so I installed a tube.
Torqued the rotor bolts to 33 ft-lbs. And the rotors spun truly. A precision made old beast!!
It was interesting to note that when working with the bare cast wheel it was very light, and when the tire, tube, rotors, axle, and speedo drive were added, it morphed into a rather heavy lump. When you add in the fork sliders and brake calipers, there's a lot of unsprung weight.