When you adjust the cam tensioner, make sure to a) NOT spin it around and around, and b) to lock that nut to the cylinder case and not the end of the thread on the screw. In other words, it works by creating friction between the cylinder, the nut and the screw, but if you have a washer that's too thin, you'll just lock it down to the shoulder at the end of the threads. You'll go nuts trying to lock it down so it doesn't spin, and in the process risk breaking the slot out of the end of the screw and destroying your tensioner. If it's an issue, just throw another washer under it, and watch the problem magically go away.
This happened to my (former) bike- the PO didn't know what they were doing and wrecked the tensioner. I had to go and do a top-end rebuild to fix that. Then I almost made the same mistake- figured out what was going on, added a washer, and the issue went away and the bike got much quieter.