Cam Chain Tensioner  
Latest O/E Yamaha  Cam Chain tensioner that will stop the camchain from rattling if it develops a rattle. 2001 - 2010 model FJR's can all be affected as the cam chain tensioner can fail at any time.
Ignoring a rattling cam chain will eventually result in the chain jumping the camshaft sprocket teeth and the valves will then hit the pistons with disastrous results. It is imperative that it is fitted correctly as serious damage can be done to the engine if it is fitted incorrectly.
(The cam cover must be removed to check timing marks are correct when fitting.)