Break in?

[cb400four_imp]

I did the first oil change last weekend. No difference. Try blipping the throttle slowly at idle and see if that doesn't sound like the same sort of click.

Edit : Obliviontoad - You can hear the sound best if you give it a lot a gas coming onto second. Any faster and it's covered by wind noise. It's kind of a rythmic ticking sound.

I hear the very same knocking or chatter sound when giving it a lot of throttle in second as well; the knocking sound in these situations are always accompanied by a wide grin under my full-face though.