For the rotors , there will be a minimum thickness spec'd in the book which Im pretty sure is 3.5mm ( standard is 4.4 to 4.6mm ) but if they aint pulsing as you say and don't look rooted ( all gouged up ) and are over the 3.5mm they should be ok
Cam belts ..... well it would seem that me and the rest of the world have differing views here , where I think an inspection for wear ( working side of the belt looks all shiney )and fraying is the go , refitting a passable belt and correctly tensioning it I would think that 12000m is not excessive . Other ( quite knowlegable and experienced people ) think that a belt should be changed at anything from 3000m (5000km ), or every year or if the bike has not been used for some time ( apparently they develop a memory but if that is so check the factory packaging
and ask yourself . I think that some people get a bit hysterical about the life of a belt but I gotta admit that if one does break it will pretty much fuck the whole motor , so its up to you to balance the cost of replacement against failure due to wear/age/ memory . I personally have no problem leaving a belt for 30000km BUT I do check them ( as in take them right off for a good look see )when I check the valve clearances and change the oil every 5000km's . Another thing that adds to the problem is that factory spec'd change intervals seem to get longer as time goes by so it may depend wether you read a 1986 p750 service manual or a 1000ds manual . Having said all that if you have a 907 with the original (17000m ) belts I would definatly change them.
