Brazil can be tricky because a lot of local shops don't have much of an online presence and communication can be hit or miss. Best way to avoid showing up and finding nothing available is to book through an aggregator that vets the vendors. You can compare options and secure a legit motorcycle rental in Brazil ahead of time through a platform like this
https://getrentacar.com/en-US/motorcycle-rental/brazil . Takes the stress out of landing and hunting around.