Motorcycle Repair: 1982 honda v45 magna, honda v45 magna, 1982 honda v45 magna

Question
My husband just bought an 82 honda magna, it obviously needs a little tlc since it has been in a garage for the last 5 years.  The battery filler caps keep popping off and normally we find them quickly and put it back on. this last time we lost a filler cap.  What would cause the filler caps to keep popping off?  We do live in the desert so could heat be a factor?  It came with a new battery when we bought the bike - Battery says May 2009 on it.
Thanks
Bobbee

Answer
Sounds like the battery came with a breather tube cover that was not removed.  On the side of the battery will be a little tube, normally has a red or pinkish rubber cover over it when new.  Remove this cover (carefully, may be pressure behind it) and connect a clear breather tube.

Good luck,  Jan