OK I am a mechanical dummy. With that said, I have been riding my bike for the last few weeks with no issues. I parked it yesterday and tried to start it today, and it acts like the battery is dead. it tries to turn over then just clicks like a dead battery. The lights seem to be on when the key is on. I can jump start it with my battery booster and it will start. I measured the voltage on the battery and it is at 11.75 with the bike turned off. Any ideas?

 

Basic test to be able to tell would be to fully charge the battery with a tender or charger, remove it wait over night then check the voltage on the battery if it has dropped then replace the battery. Checking the R/r is more tricky since it does two things limits voltage and changes AC current to DC current if one system fails the battery will not be charged after using the bike, so the other test (which can leave you stranded) is to charge the battery drive the bike park it then check the volts at the battery if it lower then 12volts the R/r is suspect.