What is needed to install a light on a 1997 xr80r honda?

... A.C. regulator I believe?
Thanks!

First you need the light you want to install. Then based on the power needs of that light you can go from there.

I'm not familiar with the bike so i don't even know if it has a usable power system for running a headlight. You may have to go with a headlight kit for the bike.