Yeah, I was thinking valve adjustments on cylinder 4. Really though, the camshaft gears are marked on the outside with either an IN (intake) or EX (exaust). The markings are facing the frame, so you may have to use a mirror to see them with a flashlight. In the manual it will tell you the position these markings (they are underlined on the gear itself) they have to be in relative to the top of the head when set to 1/4 on the timing gear. In other words, you set the timimg gear to 1/4, and place the camshafts in the head so that the underlined IN and EX underlines are parallel to the top of the head. This will ensure you never screw the timing and is a good sanity check after you are done adjusting valves etc.