We had a New Jersey chopper guy wrenching at Hollywood Honda for a while and he claimed that his ear was "trained" to set the 350 tappets by sound. Oddly enough he was overall a good technician but his tools were a scandal, screwdrivers, pliers and open ends were all reclaimed from the tool kits of Japanese bikes. Joe Minton used to say "Harvey buys his tools by the pound." I never saw him within 25 yards of the Snap-On truck.