I always thought that noise was just an inherent timing chain noise because of the twin cams.
Hall of engines link all the way back to knuckleheads
http://www.harley-davidson.com/EX/KNO/H101/en/hallofengines.asp?locale=en_US&bmLocale=en_US&WebLogicSession=A9Wg2ZXAKyv3xIy2tiErXvzoLZZQtT6l46sIjhOJ6C452wN7qe23!-1636602063!181237813!7005!8005
Nope, you're hearing several chains in an 88B, and it creates kind of a harmony. It's a different sound than your typical primary chain running through the bath.