EVO ignition problems

[TimberwolfFXDL]

Need some help troubleshooting... trying to restore my dad's old bike. One of the fist problems is this spark issue. When shutting off the key, I get an errant spark to the rear cylinder. See video here: http://youtu.be/P3XLRVQNQAg

Bike has a pair of dyna coils. I see nothing dead shorted. Ignition switch is new, and the only connections are B+, Ign, and Lights. The spark occurs when switch from the first "on" position to "off."

Thoughts on where to start looking?

[Sky]

I bet if you move the crank so the ignition isn't wanting to throw that rear spark you'll have no problem.
You probably just happened to land on the rear 30ish degrees BTDC.

[Sky]

If that's not the case, then look to the ignition pickup.
What ignition are we talking here anyway? Dyna S single fire, maybe??

[TimberwolfFXDL]

If that's not the case, then look to the ignition pickup.
What ignition are we talking here anyway? Dyna S single fire, maybe??

I believe so. Backstory is this was my dad's bike. It's been sitting unfired since 2010. I really don't know a ton about it, other than it's high compression, got S&S super stock heads, decent cam, S&S carb, etc.

I brought it home to my place a month ago and am trying to bring it back to life. It fights the starter pretty hard with both plugs in place. Like a low battery, even when on a full charged high cap battery AND a boost from a charger/starter. If I pull the rear plug, it will spin and fire just fine (on one cylinder of course). I have noticed that when it's making the starter stutter, it also flashes that rear plug like a strobe light. Every click of the starter is a spark at the plug. After I get it started for a minute or so, it gets a little easier after that.

But anytime I shut off the key, I get a pop either through the carb or exhaust (depending on which valve is open) as that little spark fires any fuel left in the cylinder.

[Sky]

Does the ignition switch keep current to the ignition when the starter is engaged? Could be shutting down the iggy and causing the rear spark signal
Some single fire ignitions can be wired as dual fire "wasted spark".
The coils defiantly can. That'd be my next move.

[TimberwolfFXDL]

took a few pictures to see if it would help... I'm starting from scratch here myself.

[BrokenSprocketGarage]

The great Skyfather has spoken, all great advice.
I would add a few other things.
Def. dyna s single fire ignition.
Coils look to be wired correctly, but could be cleaned retightened. I would actually cut off all terminals and recrimp, solder and shrink tube them. Also run a new heavier gauge ground wire to frame! The coils should have battery voltage to them at all times, even while cranking. There are ignition relay kits available that allow full battery voltage and current while cranking. See crane, Daytona twin Tec, etc for them. Maybe you have one already?
Other than hard starting and this errant spark problem, is the bike running ok?
I would not recommend using a starter/charger set to hi amp setting as this could damage electrical parts of the bike.
So here is my theory as to why this errant spark occurs. When you turn the key on, the coils power up, and build up a charge inside the windings. When you turn the key off you collapse the coil winding fields and this causes a spark. That is basically how a coil works. Sudden loss of built up voltage causes hi voltage spark to jump the plug electrode. Does this also happen on the front cylinder? Switch the coil power wires and see if it still happens .
Install a new high output starter and new battery cables too.looks to be a high compression built up motor. Is it stroked too?
I have observed this before with other ignitions and it didn't seem to be a problem.