If the master cylinder has a larger bore, it will move more fluid, but you won't be able to develop the same brake system pressure. That was one of the problems people were having with throwing GMT800 master cylinders onto the GMT400 brake system. The pedal felt nice, but in an emergency stop they couldn't even get near getting their brakes to lock up because the force multiplication wasn't there.
The master cylinder size has to be in correct proportion to the size of the front calipers and the rear cylinders/calipers. If the master cylinder is too small, you'll get a higher force, but only if it can move enough fluid to get the pads in contact with the rotors. If the master cylinder is too large, you get a lower force, but you can move the pads further.
Calipers typically use more fluid than wheel cylinders, so that's why the GMT800 has a larger bore.
Fun related fact - the average person can only press hard enough on the pedal to use about 1/4 of the braking power of a Formula One car.
The master cylinder size has to be in correct proportion to the size of the front calipers and the rear cylinders/calipers. If the master cylinder is too small, you'll get a higher force, but only if it can move enough fluid to get the pads in contact with the rotors. If the master cylinder is too large, you get a lower force, but you can move the pads further.
Calipers typically use more fluid than wheel cylinders, so that's why the GMT800 has a larger bore.
Fun related fact - the average person can only press hard enough on the pedal to use about 1/4 of the braking power of a Formula One car.