Seems we get this question regular on the older evo's & shovelheads . Guy starts the bike and it pukes a blob of oil out the breather on the floor , most all will do this after sitting a while .

Cause is the oil gets past the check ball in the oil pump . Can happen because of weak spring or the seat in the pump itself has gotten out of round a bit .

Easy fix find an Evo push rod the ball on the end is the exact same size as the check ball . Use a little fine lapping compound and gently lap in a new seat , go easy doesn't take much . It can be done on the bike by an experienced mechanic but off the bike is best for cleaning the compound out .

The brass bushing I use as a guide is a standard size ( 3/8"ID x 1/2"OD ) that can be had at any decent hardware like Ace .