Thanks to this forum I got my friend's FXD '04 Dyna mobile.
I will let you know the problem, solution and pathway taken (on the journey).

PROBLEM.
The bike was sitting for a year. Had run perfectly when layed up, but then when he tried to start it recently=NO SPARK.

SOLUTION.

The Dyna has two earth studs just below and behind the electrical box.
The earth lead from the ignition module had a bad connection. We removed both the ignition module and the starter motor leads, fitted a star washer then the two leads, standard star washer and tightened the nut. Hit the starter button and away she roared.

PATHWAY.
On finding no spark, my friend borrowed and changed over plug leads, ignition coil, crankcase position sensor, ignition module, battery and of course fuses.

The bike turned over briskly on a well charged new battery, but no spark. In desperation he asked me for a hand. I turned the the HD FORUM, found a wiring diagram and diagnostic code information.

Ran through the speedo diagnosis and came up with the fault code P0364, for which there was no information. I suspect that this code is connected to injector problems as all similar codes (ie P0373 etc) are connected to injectors. This bike is a carb model, so the codes were of no use. Will check that code again and come back to you.

Sat down with the (fantastic) wiring diagram supplied by FXD2003Rider and traced and checked through. Within 10 minutes I was pretty sure that it was an earth problem. Squeezed my fingers in, wriggled the earth, hit the starter button and away she went.

As mentioned, there are two earth studs. The lower stud is the connection for the starter motor earth and the ignition module earth. The starter motor earth connects at about 10 o'clock when looking at the stud. As the seat is pushed down, the main loom is also pushed down. This action will push on the starter motor earth. It will turn counter-clockwise, therefore loosening the connection. My guess is that causes a rachet action and bouncing down on the seat progressively loosens the connection. A star washer between the electrical connector and the stud as well as positioning the starter motor earth wire in the 1 o'clock position should solve the problem permanently.
Elecrtical box needs to be moved (2 star allen keys on top and one normal allen key in center of box) to access the earth studs properly.

I suggest that when dealing with the infamous no spark problem that this earth connection be considered.

Thanks to FDX2003Rider for the diagram and WS6 Formula for the codes.
Couldn't have done it without you.
All the best
gary