Ignition wiring for 78 shovelhead

I don't know about shovelhead? As far as automotive ignition coils I can talk to you in general terms. Is the there a distributor? Take coil wire loose from distributor, hold close to engine ground, have helper crank engine, do you see a spark jump? I have been shocked when doing this test, It hasn't killed me yet. I don't like getting shocked with secondary ignition voltage.
If you see spark jump nothing wrong with coil.
In the past, I have used digital multimeter on spark plug wire, the engine was running, you don't penetrate the spark plug wire and you don't take it loose, it's an inductive reading. Some of the readings were .6 or .7 volt, not a full volt. The I found reading that bouncing off zero, that's where I started testing and I found the problem.
I haven't tried that with just engine cranking, haven't had the need.

i doubt that one exists for a assembled bobber. but dude all you need are 3 wires on ignition switch 1 from the batt. 1 to the coil 1 to the lights if you want to rewire your bike (kick start only) very simple..1st post on the ignition switch (key switch), 1 wire, from the battery to the ignition. on the second post (key switch), 1 wire from the top post on the coil, (note on the bottom post of the coil another wire goes to your points), on the top post of the coil add 1 wire to one side of the brake light switch, then another wire from the other side of the brake light switch to the brake light, 3rd post (key switch), 2 more wires, 1 to the head light, 1 to the tail light (if you want high beam run a extra off the 3rd post to the hi lo switch then 1 from the hi lo switch to the head lights high beam wire)
last 1 wire from the regulator back to the battery.
you have just rewired your bike. if you have a electric starter then just add another from the 2cnd post (key switch) to the starter button, then 1 from the starter button back to the solenoid.

there has to be a wire from the coil to the distributor to the points inside the distributor
if it has points , check that they are not shorted out and that the moving point is insulated from the distributor plate
check for a condenser attached to the moving point and fixed to the distributor body
if it has an electronic system , it could be a problem igniter unit in the distributor

It doesn't matter which terminal the wires go onto. Seems to me the '84 FXR was a Shovelhead powered machine, at least the early year models were. If the coil is located behind the rear cylinder on the left side of the bike, the white wire is usually on the top of the coil. But, like I said, the coil is not a "polarized" coil and it makes no difference really. Just make sure that you get all the wires together like they are supposed to be. The white wire that supplies voltage to the coil usually supplies voltage to the ignition unit as well and they must be on the same terminal. Check your wiring diagram that you got with your ignition unit. If you don't have one, go to their website, visit their "tech" section and download the installation instructions.

Good Luck
Steve

Run a wire from the postive side of the battery to the top side of the coil. There should be two white wires on the top side of the coil and a black wire on the bottom. Once there, you can kick start the bike. If you want to use the electric starter, pop the rubber boot off starter solenoid and jump from the large top lug to the small lug in the middle to engage the starter.

Or, you can purchase an aftermarket switch and change out the switch. You need a 6-lug switch for you 78.

Is this a Harley question? They have you up for a backup tape data unit.
Spark Plugs for
Twin Cam Engines
Plug Gap .040"

Shovelhead
78-79
.040"