Yamaha YP250A 1999 Supplementary Service Manual page 19

At the time of urgent braking (When ABS works)
1) Decompressed state
When the wheel is almost locked, the solenoid valve's port D
from the electronic control unit. At this time, the spool 9 of flow control valve compresses the return
valve to close the port B
Brake fluid which has entered through port A 8 is restricted by the orifice
Accordingly, the brake fluid from the brake caliper is sent in the line of Port C
buffer chamber 6 .
The brake caliper fluid pressure is now reduced.
Brake fluid which has been stored in the buffer chamber is pumped by the fluid pressure pump inter-
locked with motor and returned to the master cylinder.
.
10
ABS OUTLINE
opens by the "decompression" signal
12
Brake master
1
cylinder
Brake switch
2
Silencer chamber
3
Motor
4
Pump
5
Buffer chamber
6
Flow control valve
7
Port A
8
Spool
9
Port B
10
11
GEN
INFO
11 .
, Port D then to the
14 12
Orifice
11
Port D
12
Solenoid valve
13
Port C
14
Brake caliper
15
Electronic control
16
unit
ABS warning light
17
Brake fluid pressure
18
Time
19
Repressurizing
20