Having a second look that may be the coil wire which is supposed to go to the points. There should be 3 wires going to the points if the condenser is in the ignition. 1 from the coil for power, 1 from the points to the condenser and 1 from the points up to the top coil. It looks like your ignition has had the lighting coil removed so there should also be a ground or earth wire going up top as well. Usually green.