Honda CRF300LR 2021 Owner's Manual page 51

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.95)
47