A burned out SL70 headlight is pretty common. If you do not have a working battery in the bike, or if the tail light does not work, the bulb will often blow when the bike gets revved. It is just the way they set it up, where the battery and tail light draw current to act as a buffer to voltage spikes. Honda trail bikes makes a replacement unit that has a changeable bulb. A lot better than trying to find an original sealed beam unit and watching it blow (a sad situation I unfortunately have experienced.) Good that you are getting the new battery.