It totally depends... and Los Angeles is most likely the highest rates in the country... If he insures his bike through another company than his other vehicles, then he will have to be primary driver on his bike... that's big, and if he's had his license for under 5 years (drivers license, not motorcycle), then that's another big jump... again, a big jump if he's under 25.... I'm 21, and have one speeding ticket. I live near los angeles, and insure my car through mercury; who is giving me an awesome rate because I'm under my parents policy to save money... mercury doesn't insure bikes, so, the k5 I just picked up is going to cost me about 3300 a year through State Farm because of the aforementioned circumstances.
I have a buddy who is 21, but has had his license for 5 years, who has his auto policy through state farm, and he pays 32 dollars a month for his gixxer 600 (no tickets).
Incidentally, everyone else I tried to get a quote through, didn't care about the fact that I had one ticket. when they ran it with the ticket or without (it's about to roll off my record) they all gave me the same rate. The only company that seemed to mind was State Farm, who is still by far the cheapest.
So, State Farm is indeed the only way for a bike...