Bike runs but coil 2ndary resistance is infinite

Is this even possible? I went to measure the ignition coil resistances on my 1980 kz650 - I had recently noticed that both ignition coil bodies had cracks. Primary is right where it should be for both coils, 4ohm, but the secondary for one read 2 MEGA ohms, and the other wasn't even reading a connection. I measured between the spark plug caps on each coil, and then removed the caps and checked right at the spark plug wire. I cut back a bit of the spark plug wire to reveal fresh copper, so I was definitely reading where I should be.

Again, the odd thing to me is that the bike does run, though it has a HELL of a time starting up, and I'm bump starting most times I need to get it going cold. It runs seemingly fine though when it warms up, though it gets terrible mileage, like 20-25mpg. Is this possible? Is this the nature of ignition coils, that they can make a spark even when the secondary coil is burned out somewhere?

If not already done, would remove plugs and look for fat blue sparks on each and every plug..

Good Fortune!

They can fail in different ways. I'd replace them.
Steve

My guess is that you indeed have an open in your secondary. The coil however produces a spark that jumps a gap to get to ground. Well it can jump two in series. One in the secondary wiring and the other at the plug. With time however the gap in the secondary wiring will grow to a point that it won't work. Replace the coil.

Not totally uncommon, but the cracks are letting you know those coils are done.

I hadn't thought that the spark could jump inside the coil as well. that makes sense, must be what's happening. replacing it asap.