Motorcycle Repair: starter and battery, starter solenoid, solenoid

Question
I recently purchased a 1981 low rider.  When I first got it, it ran and started great.  I left for a couple of months for work, when I returned and tried to start the bike the starter solenoid burned up.  I bought a new solenoid and installed it.  I then charged the battery.  When I was hooking battery back up, I get sparks from positive when I touch the wrench to tighten wires to post, and starter just runs and runs until battery is dead, solenoid burns up or I disconnect wires.  Is this a bad battery or do I have wiring issues?  Or neither and it is something else.  Any insight will be greatly appreciated.

Answer
I would first have the battery tested to make sure its good. If it is, check the ground wire at both ends to make sure you have good contact. Also, when you replaced the solenoid did you replace the spring as well? It might be weak
Good luck and happy riding
Mike