have you replaced the bulbs at any stage? you may have the wrong amperage type bulb in your ped. do you have any accessories on the bike, led lights, extra lights, modifications, that sort of thing? there is something drawing power away from your lights. if it's no to all the above then you may have an open circuit somewhere, give the wires & connector blocks to the lights a good wiggle, you might just have a bad connection. is the battery in good condition? having done all that & still the same i would check for a faulty rectifier or alternator.
steo
June 2009