Rear brake caliper -- KZ650 C2

The rear brake caliper on my 78 KZ650C2 is sticking. I've Taken it apart, replaced the seals, but it still sticks. Probably time to replace the piston.

Kawasaki used 2 different rear calipers and pads for these bikes, my bike uses the earlier design utilizing a 38mm piston and a round pad.

Can anyone confirm for me that this is the same piston as used for the front twin disc setup(38x40mm)? Z1-enterprises acknowledges that 2 different pistons were used -- but only says that if you are rebuilding the caliper for an early bike, you should substitute a 38mm seal -- because the rebuild kit is set up for a 40 mm piston and a "square" set of pads.

Before I take this thing apart again, can someone confirm the specs on the early bike's rear pistons? I suspect they are 38mmx40mm -- like the front brakes, but need to confirm.

TIA.

Check your brake pedal and make sure that the (adjusting bolt) is set right , if it is out too far the pedal will not return enough to allow the brake fluid return to the reservoir and pressure builds up in the system holding the pads tight to the disk.

I'll try that. Thanks!

bluej58 wrote: Check your brake pedal and make sure that the (adjusting bolt) is set right , if it is out too far the pedal will not return enough to allow the brake fluid return to the reservoir and pressure builds up in the system holding the pads tight to the disk.
You were right. The pedal return wasn't allowing the pedal to come all the way back. It wasn't because of pedal stop, though. The bolt head for the footpeg was keeping the pedal from returning. I shimmed out the pedal mount (with a large flat washer) and it works fine.

It should not have interfered, but the pedal itself may be bent inward a bit -- as it has a bit of road rash.

Thanks again for your help.

Cool! back in the 80's I paid a shop mechanic a lot of money to rebuild my rear caliper and master cylinder before his boss and I discovered the real problem in about 10 seconds working back from the brake pedal.
It went "brake pedal " check, "brake pedal adjuster" :pinch: :S :whistle:

That was the last time my bike was ever in a shop