Motorcycle Repair: 1971 sporster light motor noise, rotation pin, train noise

Question
hi i just purchased a 1971 shovelhead and there is light tapping coming from the push rods i did adjust them but the noise is still there any suggestions on what it could be other than that it seems to run pretty good

Answer
Jason,

a few things can cause valve train noise.

-dirty or faulty lifters or lifter block wear(excessive clearance)
-push rods rubbing.
-the tappets front and back sides have flat areas on them.
The tappet anti-rotation pin  goes against one of these flats
to keep the tappet from turning in it's bore.
The problem comes in because on the factory tappets,
the flat area often doesn't extend down far enough.
As a result, the tappet body can run into the pin
at full lift.
This makes for a noisy valvetrain and can even
cause a failure of the pin.
Some aftermarket tappets have a modification done,
or the stock tappets could be modified for more
clearance.
Some lifter noise is fairly common on older engines,
I wouldn't worry too much about it.
Just make sure the push rods are adjusted okay
and you have oil circulating.

-You may want to remove and lubricate the
auto-advance unit behind the points,
if they get dry, the timing can stick
in full advance and break starter parts
when it kicks back while starting the bike.