You need to examine exactly where your choke cable puts the choke blade at various positions.
For carburetors available with automatic choke, there is a "vacuum break adjustment" given in the service literature, which is the precise amount the choke is held open by the diaphragm by engine vacuum when the engine starts dead cold. The choke will retract as it heats up, but that setting is fairly critical: too far closed and you get black smoke, too far open and it will stall repeatedly.
IIRC the setting for a "B" is 5/32" from completely closed.
