somebody explain this to me

I was working on a Eton Viper that someone had installed a free rev cdi and pro design kill switch on.While I was working on it I happened to notice that the coil wires were on wrong.The wire on the green post was run to a chassis ground and the wire on the black post was wired into the cdi.Isn't this backwards??Every one that I have wired up the instructions said to run the wire from the black post to a ground and run the wire from the green post to the cdi.The quad runs fine,will they run ok either way?I didn't switch the wires to see if it ran ok the other way because it seems to be fine.I was just wondering about this??????

Humm... banshees are the same way, you would think the black would be the ground....

I installed a no limit cdi on my sons viper50. You have to do that because the new cdi is a normally closed circuit....or normally open, I dont remember.