No, the bike would run until the battery was completely dead. The regulator/ rectifier is a voltage regulator that keeps the battery supplied with a steady 13.4 dc volts no matter what the stator is putting out, which is AC volts that varies with engine RPM. A bad regulator/ rectifier will result in a dead battery, and once the battery is competely dead you will not get a spark. But if the battery shows a charge, then the regulator/ rectifier is not the problem.