First, I admire you for embarking on a S.America motorcycle trip where, based on your chain questions, I'm assuming you are pretty new to riding.
Maybe you've just never had a bike with a chain on it...
Anyway, the chain spec (which is a measurement of length), and chain tightness or slack, which is adjusted by loosening the back axle and moving the back wheel either forward or backward using the hex adjusters at the back of the swingarm, are two completely different things.
There is plenty of info on this site for both. Now that you know the difference, do some more searches. I guarantee you will find a wealth of information.
--jason
Maybe you've just never had a bike with a chain on it...
Anyway, the chain spec (which is a measurement of length), and chain tightness or slack, which is adjusted by loosening the back axle and moving the back wheel either forward or backward using the hex adjusters at the back of the swingarm, are two completely different things.
There is plenty of info on this site for both. Now that you know the difference, do some more searches. I guarantee you will find a wealth of information.
--jason