Motorcycle Questions? Ask a Mechanic.
Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially and if have not been tried; inspect the battery & ground lines and/or check/clean the battery cables + terminals, fusible link(s), connectors and wiring as a preliminary consideration. Have the battery externally charged and then LOAD TESTed (even if new and just for the purpose of eliminating it as a suspect).
Still, proposed further checks (again if have not been done) on the possibility of over/under-voltage, regulator/rectifier and/or stator issue. With a volt/multi-meter, determine the battery voltage when: