On Harley Davidson Ironhead motor (1975 XLCH), how do I adjust the valves?
I seem to remember a mechanism in the bottom end but....I can't recall.
Your engine should be cold. You will need to remove the push rod covers. They are easily removed by pushing down on them and pulling them out. If you can't get a good enough grip, use a small screw driver wrapped with a cloth. Be careful that you don't scratch the metal!
Remove your plugs so you can position your engine rotation easily without the compression stroke making things more difficult to find TDC (top dead center).
For each tappet you adjust, you will need to make sure that it is at it's lowest position. Turn the engine. The valve will be fully opened when the tappet on the other cylinder is at it's highest point. Don't use a pencil to check the piston, you will be opening a can of worms if you drop it inside the cylinder!
Intake valves are those nearest to the carburetor, exhaust valves are furthest.
Loosen the bottom tappet adjusting screw locknut, and then loosen then tappet adjusting screw which is touching the pushrod. You should see noticeable vertical play in the pushrod. You can then begin to turn the adjusting screw towards the pushrod until there is no vertical play, the pushrod should turn horizontally with no binding.
Torque the tappet adjusting screw locknut 8-10ft-lbs against the tappet body. Verify that there is no up and down play in the push rod. When you reassemble the covers, make sure that both ends are seated against the cork washers.
Servicing of pushrod adjustment was done at the initial 500 and 1000 mile mark, and then every 2000 miles afterward.