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 CleaningRocker Arm Removal
Squeeze the brake lever slowly and hold it with a band.
Remove the front footpeg bracket bolts.
Raise the rear wheel off the ground with the jack (see
Rear Shock Absorber Removal).
Special Tools - Jack: 57001-1238
Jack Attachment: 57001-1608
Remove:
Lower Rear Shock Absorber B ...
Fuels Containing Oxygenates
Gasoline frequently contains oxygenates
(alcohols and ethers) especially
in areas of the U.S. and Canada
which are required to sell such reformulated
fuels as part of a strategy to
reduce exhaust emissions.
The types and volume of fuel oxygenates
approved for use in unleaded
gasoline by th ...
Compression Damping Force Adjuster and Rebound
Damping Force Adjuster Adjustment
The compression damping force adjuster
and the rebound damping force
adjuster are located on top of each front
fork leg.
Turn the adjuster clockwise with a
screwdriver to increase damping
force.
Turn the adjuster counterclockwise
to decrease damping force.
NOTICE
Do not force to t ...