How do you remove the piston from a front master cylinder on a Kawasaki KZ1000 B3 1979 LTD

First you must remove the lever from the master cylinder, then you will see a rubber seal this must be removed, it is not always possible to remove this seal without damage so i would suggest u find a replacment, the outer of the seal can corrode to the master cylinder, once you have removed this you will find a circlip which holds in the piston, remove this keeping a slight pressure on the piston as it is spring loaded, remove carefully so u can ensure correct reassembly of parts, in some occasions the circlip is located on top of the rubber seal.