On a 2010 450 EXC with 57 hrs I am getting a loud rattling noise when bike is at idle. I have been searching online, and I'm reading this may be a normal noise??? The noise sound like the cam chain is slapping around. The noise is only at idle,as soon as you give a little throttle the noise goes away. Before I carry to a shop and have to pay the shop labor rate, I would rather fix myself if not to complex. I appreciate any advise available.