If you owe money on your bike, then the lienholder is going to require you to carry full coverage. if you own it outright, then it's like Wayne R says; how much are you willing to lose if its totaled out. More importantly, how much discretionary money can you afford to part with if the bike isn't totaled out and you have to pay to repair it.
Even though you feel you are a careful rider, and any accident you might be involved in may not be your fault, there is always a good chance you could be at fault. All it takes is a momentary lapse in focus, a deer or dog running across the road in front of you, or a patch of fresh oil on the roadway to send you sliding down the roadway.
As for me, I carry not only full coverage, but higher liability limits than the statutory minimum. These days, minimum limits just aren't sufficient if you're determined to be responsible and the other person has more than just a sore neck or back.