Hi Ash, and welcome to the HUBB!
If you are financially able to get a carnet, we recommend you do so. It will save a fair amount of hassle at airports and border crossings. It is not, strictly speaking required, but if you don't have one, each country has its own procedures and paperwork for temporary importation of vehicles. Fees are usually involved.
It is important to note, however, that in Central America only, the carnet is NOT used. Instead, your passport will be stamped with the vehicle details so that you cannot leave the country without the vehicle.
So, my best advice is to get the carnet. With it, you will be able to leave the bike in South America while you fly back to the US and return. But you will NOT be able to easily leave the bike in Central America, so plan accordingly.
Explanation of the carnet can be found at the following link:
http://www.horizonsunlimited.com/tri...#CarnetExplain
Carnets for North Americans can be obtained from the CAA, who are very helpful.
http://www.caa.ca/e/travel/id/index.shtml
Good luck, and let us know how you go!
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Susan Johnson
"It matters not what goal you
seek
Its secret
here reposes:
You've got to dig from week to week
To get Results or Roses."
Edgar Guest
'One world, two wheels'
www.HorizonsUnlimited.com