When I crank a bike (any bike), if the throttle is closed, then the bike cranks "slowly" in part because it's pulling against the intake manifold vacuum. If I open the throttle wide, the bike will crank faster because now there is no intake vacuum.
Is it possible that you've got the choke lever positions backwards?
On my ambassador, the choke cable is UNDER TENSION when the choke is OFF, and the cable is LOOSE when the CHOKE is FULL ON. This is opposite to the way it works in other vehicles, and may be the source of some confusion.