I bled the master,i took calipers off and bled them with old rotor shoved in. I went threw a qt of fluid. Now today i disconnected one caliper and brakes are hard. . I used stock harley dual piston calipers. I went by the harley specs ( 4 pot dual caliper: 11/16 or 3/4 bore.) for master cylinder.. I will try bleading the shiet out of them again.