Since the weighted is a standard part with a weight added, the added weight does nothing to change the electrical potential of the unit. The stators for carbureted YZF's are a tiny little 4 pole thing that was only designed to support ignition. They cannot run lights at all as they are. Rewinding them is possible, but in order to power lights, two of the 4 poles are stolen from the ignition, and the only way to get such small coils to produce an adequate amount of energy is to use a smaller than recommended wire gauge. This results in both the lighting coils AND the modified ignition coils being less than adequately reliable, as the finer wire is more subject to vibration damage and burning open due to overloading.
The only practical way to run lights on the bike is with a straight total loss battery setup.