Make sure the fine threaded end of valve cut off in lower left of pic is all there. There is a valve inside it.
Look at the oil supply port that comes up to the primary shaft SEAL, the upper case has something pressed into it that is either a poppet valve of some type or a restriction that needs to be there.
That washer obviously goes with the BB and part of some kind of valve to something, the engines have them in several places and not all are separate parts supplied without buying the bigger part. There should be a spring to go with the other parts somewhere. Smaller than what you have picced there.