Either 77 or 81. both are identical. That is the same as the tan(?) wire on your picture. It is part of the loom not the solenoid. In the picture, behind the wires you see the connector to the start switch on the handlebars. The lower nut on the solenoid is the connection for the starter cable.
The red(tan) wire I have feeding to the main fuse. I am still figuring out how to wire my bike up. Is that where yours leads to?