There are good articles via Google on storing a bike for long term, tips such as, pull battery, drain gas from tank completely, spray some oil in cylinders put plugs back in, one guys say to spray down with wd40, another says to get the bike tuned well, like carbs synch, timing set, right before storage, cover with blankets, keep it fully jacked up off ground or expect the tire(s) supporting the weight and losing air, those may have to get replaced.
You're also prob thinking about after storage and long term can mean any rubber stuff may dry out, seals may go bad, be prepared to perform a full tune up and go through as tho you just something in a barn.
I know mine were stored for a long time and under what kind of circumstances I have no idea.
But, they're still running.