I have a 77 ironhead I picked up as a bar hopper and have an issue. I can't figure out how to wire in the rectifier. I know the wires coming off of the generator (green and tan) go to it but don't know which screw mout to put them on. I also know that the red ignition wire goes on it as well but also have no idea. Any help would be greatly appreciated.

 

BTW, it is a regulator not a rectifier. An engine with an alternator, like late 1984-on Sportsters, needs a rectifier. Engines with a generator need a regulator

1977 came with a traditional mechanical regulator. 1978 was the first year for the modern, solid state, electronic regulator. Which do you have? If you are uncertain post a pic of it.

I am not familiar with the traditional regulator.

The 1978-on regulator should have 3 wires, green, orange [which may be red] and tan. If it has three black wires then it is probably a rectifier for late 1984-on and would be no good to you.

Orange connects to a red that runs to the battery +
Tan connects to the A terminal of the generator
Green connects to the F terminal of the generator

A second tan wire runs from the generator A terminal to the GEN indicator lamp.

If still not clear please ask again. This stuff can be messy, depending on what the PO has done. And different years have different configurations of these wires.