Yamaha YFM80WP Owner's Manual page 301

4. When the machine is not to be used for a
month or longer, remove the battery and
store it in a cool, dark place. Completely
recharge the battery before reusing.
5. If the battery is to be stored for a longer
period than the above, check the specific
gravity at least once a month and recharge
the battery when it is too low.
6. Always make sure the connections are cor-
rect when putting the battery back in the
machine. Make sure the breather hose is
properly connected and is not damaged or
obstructed.
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