Generator Producing too much voltage

[DJ S]

As the title says, the car is producing a much higher voltage than it should. Instead of charging 6v, it's charging upwards toward 10-11 volts. The problem was discovered when the car kept burning out stop light bulbs. It is charging 5-6 amps however. 6v gnerator, stock cut-out, 6v battery, recently cleaned ground connections, and we still can't determine the cause.