Beijing is 6 hours ahead of Bucharest
Best overlap: 8:00 AM to 12:00 PM in Bucharest is 2:00 PM to 6:00 PM in Beijing.
For the smoothest call, aim inside 8:00 AM to 12:00 PM in Bucharest, i.e. 2:00 PM to 6:00 PM in Beijing. With 4 hours to play with, a mid-window meeting keeps things balanced for Bucharest and Beijing alike. For part of the year the maths changes: Bucharest observes daylight saving, Beijing does not, shifting the overlap by an hour.