Master cylinder questions

For manual disc brakes, the diameter of the piston in the master cylinder directly affects the amount of pedal pressure required to stop. A master cylinder with a smaller piston, generally around 15/16", will take less effort than one with a larger piston, which could measure 1-1/32".
It's possible there is a stamping or cast number on your MC that will tell you the bore/piston size. However it is possible that to determine what you have could require removing and/or dis-assembling your master cylinder.