Chinese 110 pit bike with rear disc brake and is locked need help to adjust them. Please There is no adjustment. Either the piston is hung up or one of the fluid pathways in the caliper is clogged.
I'd start by pulling the caliper off cleaning and partially compressing the piston and try it again. Additional to the first answer - could be one, or both, of your brake pads is seized. Undo the bolts holding the caliper on & try to pull it off the disc. Twisting it helps. If you can't make it release then undo the brake pipe to release the fluid pressure and try again. A FEW THINGS COULD HAPPEN. DID YOU PUT NON -BRAKE FLUID IN THE SYSTEM? IF YOU DID THEN THE SYSTEM IS ALL MESSED UP. PETROLEUM OIL WILL SWELL UP ALL OF THE RUBBER IN THE SYSTEM AND MAKE THE HOSE SWELL UP INSIDE,SO WHAT HAPPENS THE OIL CAN BE FORCED IN BY THE FOOT LEVER BUT THE PRESSER CANT BE RELIVED TO GO BACK IN THE MASTER CYLINDER. WHICH KEEPS THE CALIPER LOCKED UP. IF YOU HAVE A CABLE OPERATED SYSTEM THEN ITS IN THE CALIPER . WHICH IAM NOT TO SURE ABOUT .THAT ITS WORKS BY A THREADED SYSTEM LIKE A NUT AND BOLT | 