I have a Honda Z50 that I picked up at a bargain and it wasn't firing if you hold the plug on the head, I noticed if I hold the spark plug about an inch or so away from the head spark will jump from the plug to the head or what ever else you hold it next to or if you just hold it in your hand it will shock you, so I assumed it was a bad coil, I had a little four wheeler here that I robbed the coil off and put it on there, and it worked perfect... I sold the four wheeler the other day so I had to take the coil off the bike and put it back on the atv, I picked up a new coil today and put it on there and it is doing the same thing the old one was doing... what is the deal?

I would suspect the plug.