Brake rebuild kits, hard to find!!

I want to rebuild the Rear Master Cylinder AND Caliper Cylinder on my 77 650 C1.

The local shop that I frequent does not even have my bike model in the books for the brake rebuild kits, they only have the B not the C model (which of course is a drum, I need disk.)

The Dealer assures me that I have the double piston brake cylinder, and they would need to order and blah blah blah...

I checked Z1 Enterprises and had no luck, I did find
"Front Master Cylinder Repair Kit - DUAL DISK 5/8" MASTER CYL..."
which does not help me.

Americanclassics.com had
"Complete front caliper repair kit for the 900 Z1, formerly sold by Kawasaki as set number 43073-004..."
which also does not help me.

I took my brake cylinder apart and soaked the rubber pieces in gasoline to loosen the crusty residue that was stuck to it. The pieces grew considerably but have now returned to normal size.
Are they still usable?

I do want to rebuild the master cylinder because it has rust underneath due to lack of a dust cover.

Does anyone know a dependable site to order brake parts? Rebuild kits specifically.

And if it is a matter that there are not kits for my specific bike, which kits may I use that are compatible?

As always, sincere appreciation.

Q

The diagrams at Kawasaki.com show that your rear brake has 2 pistons & they're listed as Active, so the dealer may have them; if so, Z1Enterprises.com should be able to get them. Try contacting Z1 - they're usually very helpful.

Also, you could try cross-referencing the parts at the Kaw site, and maybe try searching the part numbers on ebbaayy.

One note of caution when it comes to dealing with the rear brakes on a 650 C-1, Kawasaki used 2 different calipers in 1977. The first 10,000 or so units produced used a pad that is sort of oval shaped with 2 flat sides, the later production units used square pads so when ordering parts you have to be sure which type caliper you have.

I only see one piston in the diagram below for the C1&2.
The lower caliper is a C3> caliper.
My C2s are the same as C1 models.
I've also not been able to find MC repair parts.
The pads will be the round ones, as the square pads started on the '79 C3 models and '78 D1 models.
I often see caliper repair kits available for the front brakes, but only for the B model 650s and not C. The parts diagrams does list some differences between the B&C pistons IIRC.
The rear caliper is very similar to the fronts.
I was able to buy the caliper seals etc through a local Kawi dealer.
Didn't try the MC parts as I was not in desperate need of them as I now have an '04 GSXR rear MC.