Your on track. I'd add that if your rear sprocket is fairly worn noise could come from the chain slapping the teethe. With the ajuster loose does the chain slide front and year on the sprocket or is it held tight. Check the swing arm bearings and the lash of the front sprocket, both chain to the sprocket like in the rear and the sprocket to shaft. I've had everyone of those make noise over the years dumping the clutch, usually only in first do to there being more torque.