Motorcycle Repair: 1970 sl175 Honda, can of worms, couple days

Question
I have a 1970 honda sl 175 and am obviously having some issues.  Ive been trying to restore this bike with the help of a friend in Colorado before I graduated from up there and we had it running decently, but then the head light started having problems coming on when I fliped the switch, then the nuetral light started having problems, then neither workerd, then the bike stoped starting at all (all this was within just a couple days of each other).  Complicating things though, my friend that was helping me fix it up managed to light the bike on fire at one point which didnt cause as much damage as you might think but he wound up having to redo a lot of the wireing.  What kinds of problems should I be looking for that would do this and how can I figure out what it is?

Answer
Travis,
 Im sorry to say that I think you have the proverbial "can of worms".  What I would do if I were in your shoes is to purchase a manual from the dealer that contained a good wiring diagram and rewire the bike completely, making darn sure that you did not have any powers or grounds accidentally switched...If I could buy a new harness from the dealer, I might even consider that...It may cost you some hard earned cash , but when compared to the time you will spend and the issues you are having , it might be worth the investment....

Deron