luggage weight for air travel from lax to brasil?

It depends on the air carrier, but it's usually 70# per bag international flights. Many carriers have reduced that to 50# per bag. Go online to your air carrier and read their luggage restrictions.
If your luggage weighs more than the limit, they will charge you a LOT for overweight baggage.

check http://www.cheapflighttracker.com, probably you will find what your are looking for. good luck

You will be able to take a total of 70 lbs and 2 bags on the international flight. BE CAREFUL - if you are connecting to a domestic flight in Brazil you will be limited to 50 lbs - and they will charge you a crazy amount for extra weight.