Honda SH125 2023 Owner's Manual page 104

Coolant Adding Coolant
u
Securely reinstall the reserve tank cap.
3.
Install the parts in the reverse order of
4.
removal.
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.
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