wiring a cdi ignition box

I recently purchased a 1980 yamaha xs400 and trying to do some rewiring as i am new to the bike building . I dont know how to rewire the cdi ignition box to the bike. the ignition unit is a 3f9-10. just has a back and front light on it and a key switch and thats about it.
could somebody please help
Thank You

Lets start by saying welcome to the board.
Next lets get something clear. The XS400 never used a CDI, it uses a TCI.
Now on to your question. Your TCI box has a A plug that hooks to the pickups, you need that. Hook up to the coils, you need that.
This leaves some other wires. One black, goes to ground. One red/white That's power in.
If you look up at te top of te page you will find a XS400 TECH button. This leads you to a list of threads about many things. One is about wiring diagrams, one on rewiring an XS400. Read up on these things It will help a lot.
Leo

the problem i think is the owner before me has modified this bike and all of the wiring is spliced. There are no plugs in any of the wiring. My ignition unit has 7 wires coming out that i have no idea where they go to or any way of finding out. So i thought the 3f9-10 ignition unit would have some kind of diagram of where all of the wires connect to. hopefully that explains a little more and thanks for the quick response and i will also go to the tech button and see if anything helps me in there

print the diagram at the top of page 2 and disregard the stuff you don't have. The wiring on these bikes is pretty simple once you have the "roadmap"
http://www.xs400.com/forum/showthread.php?t=4466&page=2

As frwinks said, find a wiring diagram for your bike. It shows the TCI unit and how it hooks to the pick ups and coil. I looked at that diagram, it shows two red/white wires. You may have a problem with figuring out which one does what. One R/W wire is power in from the engine stop switch, the other is shown going to the pick ups.
Other than that it shows where the other wires go.
Leo