Replace the gasket if it is damaged.
If they are clogged, remove the tank and drain it, and then blow the breather free with compressed air.

NOTICE
Do not apply compressed air to the air vent holes [D] in the tank cap. This could cause damage and clogging of the labyrinth in the cap.
Fuel Tank Installation
Fuel Tank CleaningExhaust Butterfly Valve Actuator Sensor Resistance Inspection
Turn the ignition switch to OFF.
Disconnect the exhaust butterfly valve actuator sensor
connector (3 pins connector) [A] (see Exhaust Butterfly
Valve Actuator Sensor Input Voltage Inspection).
Connect a digital meter [B] to the exhaust butterfly valve
actuator sensor connector.
Measur ...
Coupling Bearing Installation
Replace the bearing with a new one.
Press in the bearing [A] until it is bottomed.
Special Tool - Bearing Driver Set [B]: 57001-1129
Pack the bearing with high-temperature grease.
Replace the circlip with a new one.
Special Tool - Inside Circlip Pliers: 57001-143
Replace the grease se ...
Specifications
Connecting Rod Big End Bearing Insert Selection
Crankshaft Main Bearing Insert Selection
*: The bearing inserts for Nos. 2 and 4 journals have an oil groove,
respectively. ...