http://www.cartalk.com/content/features/premium/questions.html (there are lots of other sites that agree, this was the first I found. plus I like these guys.)
I’m coming from a car background here, and I’m not sure if all bikes are required to run premium. If your engine isn’t designed to run premium gas don’t use premium. Premium gas is harder to burn than regular gas. Running premium will lead to more incomplete combustion causing more pollution and less power. Read the owner’s manual it tells you what type of gas to use.