That sounds like a loose chain (or unevenly worn one), not a tight one. Now that it was replaced, it should have been solved with correct adjustment. Did you buy the bike new? How many miles on that chain/sprocket set?
Too bad you don't have the bike, it's really easy to check for that. When decelerating, pull the clutch in and see if the noise changes. When the chain is loose, removing the engine resistance makes it go away (unless it's really, really, loose, then it will continue to slap the swingarm).