Front brake not working and the handle feels spongy

Hows the brake pads?
Is the brake handle soft or spongy?

I have read and re-read your problem and I keep going back to the "spongy" feel, which strongly suggests air in the lines.
Make sure you have no brake fluid leaking anywhere, especially in the "tee" where your brake line splits to feed both calipers.
Even the smallest leak will allow air to be introduced.
If you are absolutely certain that you have no air in the lines, the most likely problem is one or both caliper pistons are worn and allowing fluid to leak by under pressure.
I recommend replacing the calipers- If you rebuild them, the slightest mistake honing the cylinders will result in your needing to replace anyway.
HD parts can be very expensive, so I suggest you check out Tedds in Newburgh, NY: They have a huge selection and prices are reasonable. You will need to google it because this site keeps dropping me when I try and post the link- world wide web dot vtwinmfg dot com
If you have ever watched American Chopper (love 'em or hate 'em), this is where the Tuthills get allot of their parts. They will send you a HUGE catalog for free.
Good Luck! FYI my first street HD was a 1980 Sportster.

I would bleed the rears too especially if the brake fluid reservoir drained empty. Also you may need to drive the vehicle to seat the brake pads. Check and see how the pedal feels initially before you road test to make sure you don't need to pump the brakes in order to stop. if you do then re bleed all four wheels.If you don't have to pump the pedal and it just feels spongy then try going around the block a few times and see if the pedal stiffens up after the pads have seated.

loosen of the hand-brake adjustment and press the brake pedal a few times to self adjust the rear brakes.
Re-tighten the handbrake adj last.
Front brake sounds like a seized caliper,If possible remove caliper and clean and lubricate the piston.
This may work but replacement caliper may be the only other solution.Make sure the caliper slides are also clean and lubricated and the brake pads are in good order.(TRY THIS FIRST)
Also new brake shoes can make the pedal feel spongy for a couple of hundred miles until they have been run in.

you can renew the master cylinder seals, the calipar seals can also cause the lever to feel spongy, they grip the pistons and pull them too far back into the bores instead of letting them return just enough to realease the brake, in this condition when you apply the brake most of the lever travel is just pushing the calipar pistons out to reach the pads and the little travel that is left is pushing the pads on to the disc, hense the spongy feel

I would make sure all the air has been bled out of the abs unit and all other components. Any air in the brake system will cause a spongy pedal and is not acceptable.

yes new fluid and proper bleeding will make the brake feel normal, the sponge feeling is air in the brake system compressing

yes i would bleed brakes , and check and make sure that no grease or oil got on brake pad's. let us know how it works out . Thank you fore using fix ya.

Check the brake hoses. The rubber hoses that come from the hard line, (Metal), to the caliper.
If these are the original ones that came with the vehicle, they are overdue to be changed out.

Do they have any weather cracking on the outside? No? That's okay as they break down on the inside, and sometimes this isn't apparent from the outside.

The rubber brake line is a composite. A sheath on the inside, then a steel braided hose, then another sheath on the outside.
The sheath on the inside breaks down, and a piece of the rubber compound blocks the hose opening, when you step on the brake pedal.

The brake line can also swell up a little, as you step on the brakes, causing that spongy feel.

have you check? the master cylinder. sometine when you get the rotors cut they dont come out right because they may be warped or to thin. if you did the job yourself you might have put the calipers in on the wrong side. this happens alot . if your rotors front and rear are fine then switch the calipers to the other side.