23000 miles i just baught a bike from england so i dont know enything about it. Some they that it could be CCT cam chain tensioner problem, or its valve problem, maybe both maibe someone had the same sound and solved the problem?
cam chain or valves. Sounds like ind of a constant buzzing sound to me. In any case take the head cover off and follow the procedures for checking valve clearances. My guess is the cam chain tensioner.
I had a slight ticking noise like that after i had rebuilt my engine, which included adjusting the valve clearance. turned out what it was is that i had over tightened the exhaust header mounting rings at the head which caused them to bow making one of the exhaust gaskets not seal properly. I have silenced it with exhaust putty until i get the header mounting rings (can't think of the correct terminology for them right now) repaired.