I have a BSA M21 that was sitting for awhile. When I started it, I had oil seeping out the top of the time cover and lots of white smoke. I recently changed the oil. Due you this is just from a wet sump. I did change the oil grade.
The White smoke part sounds like steam , as the bike sat (for awhile) , its quite possible for more than a little moisture to have condensed inside the crankcase , (Along with storage-wet-sumping) As the engine heated up the water evaporated as steam ( lol) Louisiana , Does it ever get humid where the bike lives ?
White smoke is water, you see this on cars all the time in cold weather. It is made a lot worst with the 10% alcohol gas that they now sell as "normal" gas. Oil is blue and you can smell the difference. Black is running too rich. If the bike has sat for a while or the gas has, then it has absorbed moisture from the air. Jeff