The linked braking system on the ST1300 is a lot easier to understand with the help of a colorized version of this diagram from the service manual:
The red lines represent the part of the system pressurized by the front master cylinder. The brake line goes from the master cylinder to a splitter which connects to the two outer pistons on each of the front wheels.
As the front brakes engage, the left brake compresses the secondary master cylinder, which is shown in yellow. Pressure is applied to the rear outer pistons via a proportioning valve.
The rear master cylinder, in green, provides pressure directly to the rear center piston and to the front center pistons through a delay valve. The delay prevents the front end from diving.
This process is identical for non-ABS bikes.
The red lines represent the part of the system pressurized by the front master cylinder. The brake line goes from the master cylinder to a splitter which connects to the two outer pistons on each of the front wheels.
As the front brakes engage, the left brake compresses the secondary master cylinder, which is shown in yellow. Pressure is applied to the rear outer pistons via a proportioning valve.
The rear master cylinder, in green, provides pressure directly to the rear center piston and to the front center pistons through a delay valve. The delay prevents the front end from diving.
This process is identical for non-ABS bikes.
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