Rear brake sticking

I'm not usually working on hydraulic brakes. All my bikes except my 81 kz have rear cable brakes. My rear brake is sticking on about 15%. Most master cyl i work on are handlebars so i can open the top and clean the bleeder for the return. No way i can see to do this work on the slave cyl for the rear wheel.

I took the entire assembly off tonight and cleaned everything other than the slave cyl. The area where the c-clip holds the rod in is rusted on and won't pop off (i got the clip off, the plate won't budge).

I sanded and greased everything and it's all moving like new.

I can push the brake lever and open the bleeder then close it and the wheel spins freely. Once i push the lever a few times the brake is back to staying at about 15% lock roughly and dragging the pads enough to make me grunt to turn the wheel. Also, the ram is fully extended, not pushed in at all.

It's a hydraulic pressure issue. It's letting go of the pressure MOSTLY, but not all the way. Any ideas on fixing it?

Did you install a rebuild kit on the piston or replace it?
According to Partzilla the piston is still available from the dealer (they're showing a photo of it).
Another thing that can stick is the brake pedal shaft, but it sounds like you may have cleaned it up & lubricated it.

Get the brake to stick, crack the line at the master cylinder, if pressure releases the MC is bad. If not, try the line at the caliper, if pressure releases it's the hose. Still no good then do the bleeder. But make sure the caliper pins are clean, lubed and free from sticking before replacing/rebuilding the caliper.

I strongly advise a full system tear down and gunk clean out. That means popping out the caliper pistons and taking apart the master cylinder. Inspect the master bore for pitting and replace as necessary, then reassemble with new a OEM Kawasaki brake master plunger and seal. For the caliper, inspect the piston and replace if it's pitted, and then install new OEM kawasaki seals. Also, replace the brake line since it's full of gunk.

BTW, the reason the system is applying pressure is mostly likely because the return port in the master is plugged with gunk.

Nessism wrote: I strongly advise a full system tear down and gunk clean out. That means popping out the caliper pistons and taking apart the master cylinder. Inspect the master bore for pitting and replace as necessary, then reassemble with new a OEM Kawasaki brake master plunger and seal. For the caliper, inspect the piston and replace if it's pitted, and then install new OEM kawasaki seals. Also, replace the brake line since it's full of gunk.

BTW, the reason the system is applying pressure is mostly likely because the return port in the master is plugged with gunk.

+1

I've serviced the rear brake mechanical side regularly so the footbrake moves like butter. Here is the piston. No complaints with it. Looks like new.

it is moving smooth as butter so I'll try the method outlined above for bleeding at each point.

Ok here's where i am. The video explains my issue. Fyi i can blow through both hoses.

Have you check the bores of the banjo bolt on the MC are not plugged?
What happen if you open the banjo bolt a half / full turn?

That was merely an illustration of the issue. I can blow through both hoses and fittings. Makes no sense. I took the front end of the hose completely off. Changed hoses, etc. same result

Nessism wrote: BTW, the reason the system is applying pressure is mostly likely because the return port in the master is plugged with gunk.

This.

Good Fortune!