The fact the lights work, doesn't mean the battery is ok - when you thumb the starter, the starter relay closes, the starter motor takes a huge drain from the battery, which drops the voltage which can no longer hold the starter relay closed so it opens - the battery voltage returns, the relay closes again and repeat. The noise you're hearing, is the relay closing and opening.
That's what I reckon your problem is - and Mosser's tests will prove me right or wrong.
There's another potential reason for the relay to be cycling like this, and that's a dodgy connection, and for that, it's Fazerider's connection block testing / cleaning.