Z1OwnersClub GB

So i got my gpz tank back from bike paints (i was getting the liner removed) turns out there was three failed liners in the tank and no rust wtf
So i get a new black chrome pingle tap fill with fuel and go for a ride ,its a big old boat compared to my Gamma and lc but ill get used to it anyway i got 4 miles before grinding to a halt with the back brake seized on took me three attempts at getting home after it cooled down bummer

Caliper strip on the cards I think- could be corrosion in the sliding pins or corrosion on the piston / brake cylinder wall or corrosion in the seal groove under the rubber seal in the caliper ( use a dremel to clear it out or a little Allen key held in a pair of Mole grips - that gives a good sharp edge to clear out the groove).
Or if your'e still running the original rubber brake hose it might have collapsed internally - allowing fluid into the caliper when you brake but not allowing it to flow back and release brake pressure when you're off the brakes

Just had something similar on my front brake. It was the return hole in the master cylinder blocked. This can be confirmed by unscrewing the bleed nipple a fraction then tightening it without touching the brake lever/pedal. It releases the built up pressure.