minimum battery voltage starting
I installed one of those switches that prevents the headlight from coming on when you first turn on the key before hitting the starter button. This eliminates voltage draw by the headlight and makes more power available for the starter which hopefully will be enough juice for it to engage. I had the same starting problems with a seemingly good battery and this has helped. After starting the bike though you have to remember to flick the red "pass" switch to turn on the headlight.