As Jeff (c7xf) has stated, I'd check the battery first. This was exactly the same issue I was having at Nelsons when I was taking my race school a couple years ago. It got so bad that I did not run the last 2 session because it was getting dangerous for me and others. To test it I simply charged the battery for 24 hours, pulled it off that and check the voltage 14.4v and looked great. Then I started the bike and check it again at idle and again at RPM to check that it was charging. Every single time the charge fell way low when the bike was running and the charging system just couldn't keep up with the bike needs and charging the battery. Swapped out the battery for a new one, problem solved and it's been a champ ever since.