Yes, a dirt bike can start without a functioning kill switch. The kill switch is primarily used as a safety feature to quickly shut off the engine in case of an emergency or to prevent the bike from running when not in use. If the kill switch is faulty or not present, you can still start the dirt bike using the ignition key or kick-start mechanism, depending on the specific model of the bike. However, it is important to get the kill switch repaired or replaced as soon as possible to ensure safe operation of the dirt bike.