I took my 71 for a ride today and both times I stoped and let bike sit for a few minuites there was a spot about the size of a half dollar of oil and water (muck) that came from the vent tube.bike has been sitting for about three weeks and is running fine ,I think this is just condensation inside the case but Iam not sure any one had this happen

 

When the bike sits for a while some oil will leak past the check valve in the oil pump, and come out the vent tube. Often it can be a lot of oil. Not likely in this case.

What you are seeing is what i have seen on my 1978. I usually get that much. No concern here.

 

As long as the oil in the motor doesn't look like mud I wouldn't be concerned about it.