If you start worrying too much about replacement parts in Central/South America the only true option you gonna have is a Honda CG 125.
If I had to choose a bike for this kind of trip my preferred options would be a KLR 650, XT660 or DR650, but in Brazil find replacement parts for the KLR and DR could be very difficult because none of those bike have been available for sale in the Brazilian market.
Suzuki GN125 2005
- Uberlândia / MG - Brazil
You don't need to have a big bike to have a great adventure.