Motorcycle Repair: 74 Yamaha Dt250- Wiring issue, brown wires, beam headlight

Question
Hey there. I am having a problem with the electrical system on my bike.
Whenever I put a good, charged battery in only the headlight works. I have
figured out that the headlight is running of the dc circuit and not the ac like it
should. I figured that the headlight was using all of the voltage from the
battery, and so the other lights/horn won't work. I guess my question is how
would the person who owned this bike before me tapped the headlight into
the dc circuit. I have looked for wires that have been spliced/chaged, and
have found a couple. These wires though don't appear (at least according to
my wiring diagram) to be associated with the headlight. I'd really appreciate
some advice. Thanks for your help!

Answer
Matt,

have you checked the fuse and battery
ground and cables?

-make sure the bulbs are good in the other lights
or you may blow the headlight.

-even if the headlight is working off
the battery the other lights should
come on. It should have enough power
if it is fully charged.
Try to get the other lights working
before you start into the headlight
wiring. It may be wired incorrectly
but the other lights should still
work unless they have done
some major modifications.

Here are some notes that may help:

-the battery positive is usually red or brown
wires.

-the yellow magneto wire runs up to the light
switch and then on to the high/low
beam headlight wires.

-I believe high beam is also yellow and low beam may be light green?

-check the headlight wires and the light switch
for any modified wires.

If you write back, let me know what you
find and what color wires are involved.