i have a strange rattling loos metal noise also
but not sure where its coming from.
i am hoping its a damaged muffler as i hit it on the curb side as i rode off the foot path. ended up breaking one of the muffler ring clips that secure the muffler to the bike.
gona check the muffler tonight see if there is anything loos inside it, take it off the bike and give it a shake, might borrow a mates xb12SS new 60db silent pipe to double check nothing wrong with engine... fingers crossed it the muffler and not something more serious...