Honda PCX 150 Owner's Manual page 213

Starting the Engine
If you cannot start the engine:
Place the scooter on its centre stand and
a
squeeze the rear brake lever.
With the throttle slightly open (about 3 mm
b
(0.1 in), without freeplay), press the start
button.
About 3 mm (0.1 in), without freeplay
56
(Continued)
If the engine does not start:
Open the throttle fully and press the start
a
button for 5 seconds.
Repeat the normal starting procedure.
b
If the engine starts, open the throttle slightly
c
if idling is unstable.
If the engine does not start, wait 10 seconds
d
before trying steps a & b again.
#
If Engine Will Not Start
(P.108)