My bike makes more sound than it did in the beginning. It sounds like some metal balls at low rpm. First I thought about the big end, but there is no metal in the oil nor in the oilfilter. Adjusted the valves and the cam looks normal. Now I am thinking of the timing chain. What is the life span of it, can it make a knocking sound at low rpm, I always thought it was more of a rattle sound.

BTW it has 60.000km on it.