Complete repair kits for stock style brake master cylinders include all internal parts needed for a complete rebuild. Can be used with DOT 3, DOT 4 or DOT 5 brake fluid but you should always stay with the same brake fluid type as the three types are chemically incompatible. Bore size is usually indicated on the underside of the master cylinder.

Note: The new DOT 4 (as used in the late models Harley-Davidson) can be mixed with the old DOT 4 without any problem, even with the older DOT 3. The new DOT 4 CAN NOT BE MIXED WITH DOT 5. DOT 5 is a Silicon based fluid that has its own formula. This also means that DOT 4 can not be used in a system that has been on DOT 5 (and vice versa) unless the whole system has been taken apart and cleaned. It also needs new seals and cups before the DOT 4 can be used. Cleaning the parts with cloth or paper is also no option, the parts have to be very well cleaned with brake cleaner! (ZPN748043 or similar).