wat is this?
 

there is a little black cylinder underneath my battery on my 1976 sportster which has about 5 wires on it. wat is this? there is a bad wire connected to it... how would this affect my motorcycle?

Took me a minute, of thinking about this, but its your starter relay.

I'm not sure what you mean by bad wire though. There should be three red wires, a green wire, and a black wire.