Yes... way too much time holding the soldering iron! Something is very wrong when you melt back several inches of insulation. You are melting back so much wire insulation that I wonder if the enamel coating on your coil wire survived.

I hate to pile onto somebody who is honestly trying, but you really should practice your soldering on scrap parts and wires far away from the machine.

The soldering iron should be hot enough to melt the solder within seconds. Very hot and very quick. Insulation should not be melting back like that. You are taking too long with the soldering iron for some reason. You need to figure out why... maybe you need better solder, new flux, burned tip, too cold, etc. Like I suggested above, practice on some wire scraps so you can figure out what is going wrong.

•  Strip off ¼ to ½" of wire insulation and immediately twist the exposed stands together.
• "Tin" the end of the bare wire; simply flux and solder the exposed end.
• If the metal tab of the switch or coil is bare, flux and "tin" this too.
•  Once both sides are tinned with solder, then it's simply a matter of holding the tinned wire to the tinned tab and touching them with a hot iron until they melt together. A few seconds at the most! If not, stop and figure it out.

The tip of your soldering iron should never be black. Keep copper wool, a wet sponge, a wire brush, and or a file handy. Clean the tip down to bare metal, get it hot, then apply flux and solder to the tip. Keep the tip of your iron shiny and silver, by wiping off dirt on the sponge or copper wool. Once the tip stops looking like shiny melted solder, stop, clean, and re-tin. If solder is balling up and not sticking to the iron, your wires, etc, stop and re-clean; you've either burned off the flux and/or it wasn't clean enough to start.