Primary connections are black to yellow or black to blue. The stock coils measure about 5 ohms. There are replacement coils available in 5 ohm and 3 ohm primaries. This will give you a higher voltage/hotter spark. But, they also draw more current and decrease the life of the contact points.
The secondary of the SOHC coils are from ignition lead to ignition lead as two plugs fire at the same time. I don't remember what the resitance of the 15000 turns of wire is there. But, there should certainly be continuity between them. Note that the spark plug boots/caps are supposed to have resistors in them. These can go bad (open). So, for checking the coils, unscrew the caps from the wires.
Sparking at the points is somewhat normal and not normally a concern by itself. However, the sparking can cause the points to pit and or carbon up. So, the points are considered expendable and replaced during a normal tuneup of the bike. Experience tells when they need to be replaced. But, if you look at new set for comparison, you ought to be able to make a reasonable judgement. If the old points have very high peaks and valleys burned into them, then replace the condensers as well.
As for question # 4... If I was too lazy to clean all the wiring system connectors to keep these voltage losses down, then, I suppose, direct wiring the coils with a relay could be an effective alternative. I'll have to go look for that FAQ, though, to establish a context.
Perhaps you'd be interested in a little post I made some time ago..
The Honda SOHC4 ignition coil is just a simple transformer.
If that doesn’t mean anything to you, then understand that this one is a
device that changes low voltage from the battery to high voltage for the
spark plugs.
The coil has “gazinta” connections and “gozouta” connections. 12v is
applied to the small “gazinta” wires. And, the spark plugs connect to
the bigger “gozouta” wires.
With a multimeter set to measure continuity, the two “gazinta” wires
should have continuity between the center conductor of the wires.
With a multimeter set to measure continuity, the two “gozouta” wires
should have continuity between the center conductor of the wires.
With a multimeter set to measure continuity, any “gazinta” wire should
NOT have continuity to any “gozouta” wire.
With a multimeter set to measure OHMs, the two “gazinta” wires should
have about 5 ohms resistance between them, give or take an OHM.
Ideally, the “gozouta” wires should have the plug caps unscrewed and
removed from the ends for the above tests.
Functional test.
If your spark plug boots are still installed, insert a spark plug in
each one and arrange them so that the threads of each plug are touching
the other. Each time you apply and disconnect 12v to the “gazinta”
wires, both spark plugs should display a visible arc between the center
electrode and the plug body electrode.
If your spark plug boots are removed, arrange the “gozouta” wires so
that their ends are about 1/8 inch apart. Each time you apply and
disconnect 12v to the “gazinta” wires, there should be a visible arc
between the “gozouta” wires.
It is best to keep personal anatomy inventory well away from the
“gozouta” vicinity during the functional test.
The coils believe you are a conductor, regardless of whether or not you
have lead an orchestra, or handled tickets on a train, and will deliver
a strong message to you if you provide the opportunity.
The 12v source should have a current capability of at least one amp.
