I am cleaning up some of the wiring on my bike and am curious what the brown wire that goes to the bulb marked "side light" is for.  It has a female bullet connector on it but no obvious place for it to plug in.  Keep in mind that I no longer have the stock headlight or gauges so I may not need this wire at all.   

It only runs the tail running light.
We don't have front running lights so the wire in the front goes nowhere.
On "F" models there is a running light in the headlight and it operates that. Some old style round headlamps have a running light (like ones from Europe) and it is used to operate that.
For a stock USA model "E", it is not doing anything.

That is what I assumed.  Thanks!