Honda CRF300LR 2021 Owner's Manual page 86

Coolant Adding Coolant
u
Adding Coolant
If the coolant level is below the LOWER level
mark, add the recommended coolant
( P. 68) until the level reaches the UPPER
2
level mark.
Add fluid only from the reserve tank cap and
do not remove the radiator cap.
Remove the reserve tank cap and add
1.
fluid while monitoring the coolant level.
Do not overfill above the UPPER level
u
mark.
Make sure no foreign objects enter the
u
reserve tank opening.
Securely reinstall the reserve tank cap.
2.
82
WARNING
3
Removing the radiator cap while the
engine is hot can cause the coolant to
spray out, potentially scalding you.
Always let the engine and radiator cool
down before removing the radiator cap.