Honda CRF150F Owner's Manual page 175

Free Play Adjustment:
Measure the throttle grip free play at the
throttle grip flange.
The standard free play should be
approximately:
2 – 6 mm (0.1 – 0.2 in)
To adjust, pull the rubber dust cover (2) back.
Loosen the lock nut (3) and turn the adjuster
(4).
Tighten the lock nut and return the dust cover
to its normal position.
After adjustment, check for smooth rotation
of the throttle grip from fully closed to fully
open in all steering positions.
If proper throttle free play cannot achieved,
contact your Honda dealer.
64
(1)
(2)
(1) Free play
(2) Dust cover
(4)
(3)
(3) Lock nut
(4) Adjuster