Take a voltage reading with the key off (in the high 12 vt. range), then with it on (should drop slightly) and then a reading when you hit the start key.
If the voltage drops to a really low reading, then you don't have much capacity (this is a poor man's load test).
Oh, you checked the batt. water level, right?
Were it my bike, I'd be poking around the starter relay or key switch start postion.....
