This something to do with the clutch, not the cam chain tensioner (I have a manual CCT). I suspect the bearing in the centre of the pressure plate but I won't know till I strip it. Thanks to the folk over at CBRXX.com for the friendly advice, and to Patuleia for winning the "what the hell is that horrible noise" game.
Basically this is revving/blipping the throttle from tickover to approx 2000rpm (tick over is just over 1000rpm on my bike) and there is a really rough metal grating sound. If I rev smoothly this doesn't happen. If I pull the clutch in this almost 99% gets rid of the sound.
I'm familiar with hearing a spinning sound from the clutch bearing that disappears when the clutch is pulled but this one is a new sound for me.
