Hi Mark!
I am working on a Tora also. If you have only two wires coming out of your mag (black and yellow) yours must be the "base" Tora. Mine has three wires, green, yellow and black and is the "Deluxe" Tora. The deluxe Tora had street legal lights and a battery.
If you go to the download section of this website you can find a Tora shop manual, and on page 24 there are basically three wiring diagrams, and the top two would be yours. It shows the yellow wire going up to the light switch, and it also shows the yellow wire splitting off to a red wire, which might be for the tail light (this is not clear in the diagram, the base Tora had off road lights).
I can't link you to the shop manual, it is in a pdf file that must be downloaded, but you can find it under the heading of: Manuals/Articles that you see at the top of this page.
I hope this helps!
Tomo