gday all, my bf2 xr6t has developed a brief rattle on start up.. now b4 we start saying idler pulleys, oil change etc, I replaced pulleys with the nuline kit. when that didnt work I decided on somr fresh nulon 10w 40 full synthetic hi tech oil and a filter.. no joy.. the noise still persists.. sounds to me like the cam chain.. no noise at idle after initial startup, however , if I hold the revs just over 2K I can hear it.. do the engines have cam chain tensioner issues.. if so im told it can be changed with the rocker cover removed.. is this correct.. any other ideas what it could be?