are you sure its the chain?, does it rattle only when you first start it up , a few engines tend to be a little noisy for a few seconds until it gets enough oil up there. (not the chain obviously but moving parts inside the head)
has the chain be changed lately maybe the tensioner spring has had it, it may pay to replace it, its a cheap option and if its not the problem only a few dollars have been wasted.
Bookmarks