1998 FLHT wont fire up

Are there any codes. Does it backfire?

To start you need spark at the plugs, fuel in the induction module or tubes and compression in the combustion chamber. Have you checked any or all of these???

As a starting point install NEW plugs and also:

Ignition Coil Primary Circuit Test
Remove the coil. THEN set your ohmmeter scale to RX1 and place ohmmeter leads on the primary coil windings A (front of coil) to B (middle of coil), B to C (front of coil) and check for primary coil winding resistance which normal resistance range is 0.5-0.7 ohms. If primary resistance is not within this range check out test results below.

Ignition Coil Secondary Circuit Test
With the ignition coil removed from the motorcycle and the ohmmeter set to the RX1K scale place the ohmmeter leads on the secondary coil windings B (middle terminal) to
R (rear secondary terminal/socket), B to F (front secondary terminal/socket) and check for secondary coil winding resistance which normal resistance range will be 5.5-7.5K ohms. If secondary resistance is not within this range check out test results below.

Test Results
A low resistance value indicates a short in the coil winding which requires coil replacement.

A high resistance value might indicate that there is some corrosion/oxidation of the coil terminals requiring the coil terminals to be cleaned and the resistance test then repeated and if after the test is repeated the resistance is still high after the terminals were cleaned the coil must be replaced.
If there is an infinite ohms or no continuity) resistance value the coil is open and must be replaced.