kz650LTD dual front brake conversion

No eBay APP ID and/or Cert ID defined in Kunena configurationNo eBay APP ID and/or Cert ID defined in Kunena configurationI stumbled across an old comment from 2008 by steell about the conversion, and I'm planning on doing it, since my brake fluid is brown, and the whole system is assumed to be sketchy until I overhaul it.
So his comment was:

You want a front brake system that will out stop any Kawasaki up through at least 1985, and you want it cheap?? Read on


79-80 KZ1000 brake rotors, thinner than single disk rotors, drilled for even less weight, 12" diameter, and they bolt right on the stock wheel.

83-85 GPz750 brake calipers. These are normally on a 10" rotor on the GPz's, but they bolt right on the 750 twin forks.

95-96 GPz1100 front master cylinder. Buy it used and rebuild it, no shortcuts, rebuild it, or I will hunt you down and dope slap you into the middle of next year. I didn't rebuild mine, I got lucky and no one was seriously hurt, rebuild any used master cylinder you get.

Stainless steel braided brake lines and fittings from Dennis Kirk, the single most expensive item involved.

Z1 Enterprises has the rebuild kits and brake pads.

My Nephew's 85 GPz750 Turbo will easily out run my 750 twin, but it don't come anywhere near stopping as fast as my 750 twin does.

I've sourced:
rotors (the drilled ones for kz650 with 4 bolt holes and the cutouts)
a pair of gpz750 calipers, new pistons and rubbers, painted the brackets, new pads, tested them
95 GPz1100 front master cylinder, rebuilt, tested
new banjo bolts, copper washers, and lines. Ill be using a double banjo off the master.
A right hand bracket for the brake line ()
and this -

I've done my homework (I think) but I am relatively inexperienced. I'm pretty sure I have everything I need, but I'd hate to take things apart and get that "aw shit" moment. My father commented about the spacer looking thing on the left side of the wheel, and how there isn't one on the right, I'm pretty sure that is the speedometer (a cable runs to it) and everything will work, but if anyone has experience or tips, I'd love to hear it.

There are two sizes of the thinner dual disk rotors If you got the dual disk from a KZ650 they are a smaller diameter than the kz1000 dual disk that Steell was referring to. the KZ650C and KZ650D had different fork lowers so the brake caliper was mounted lower on the fork tube to run a smaller disk.

The KZ650B and KZ650E (LTD) models had front rotors with a swept area of 250mm and a thickness of 6.9-7.1mm. The KZ650C, D, and F models had front rotors with a swept area of 231mm and a thickness of 4.9-5.1mm. Ed

No eBay APP ID and/or Cert ID defined in Kunena configurationSo these won't work?

I don't see why not. Did you ask about the diameter. I have a pair off a later KZ1000 that work well. Slightly different but no problems.
Steve

I already bought them; I'd measure them for real, but they are in my parent's basement with the rest of my parts. I didn't know diameter was an issue when I bought them. They are approximately 285mm outer diameter according to that picture of them with the ruler and some MS paint skills.

They look to be the same size as mine.
Steve

Assuming the numbers on the blue tag show the rotor thickness it looks like they are from a dual disk setup (that’s a good thing). The single disk versions were thicker and heavier. Keep in mind that the diameters shown in my previous posting show swept area not outside dimensions. Ed

How would I calculate swept area?

Also I'm getting a bad feeling that I didn't get the right ones because the diameter of the rotor currently on there seems bigger. I cant do an exact measurement with it on the bike still, but it seems like half an inch bigger.

The outside diameter of the 1977 KZ650-C1 front rotors is 10 15/16" Ed

I bought a whole dual brake system from a KZ 1300 off of E-Bay and fitted it to my 750 twin. Worked great. I don't remember what I did for the right hand fork slider but it couldn't have been too difficult.
Bill

If they are the smaller disk size your caliper may not be situated over the disk properly reducing your pad contact area. This is true with the stock caliper, not sure with the gpz calipers. The kz650 dual disks look identical to the kz1000 dual disks but they are slightly smaller.