In Colombia you can
* Buy a motorcycle and get it registered with you as the owner
* Buy insurance "SOAT" that is mandatory
* Legally leave the country


But to change owner, the new owner has to go in person to an office to get registered as owner.So no idea to speculate to sell it outside Colombia.
(Maybe for parts, and do not transfer ownership

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I have a bike in Colombia. I had prepared in advance. I came there on a Tuesday. Monday six days later I was driving my own motorcycle. Registered and insured. Totally legal.
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In Colombia, bikes up to 200 cc are very common and cheap.
So such a bike you could just leave behind in emergency.
TVS, not so known in western world. But it is very large motorcycle manufacturer from India is common.

https://www.tvsmotor.com/en/co

There are also a lot of bajaj

https://colombia.globalbajaj.com/en/

Some chinese bikes with different names E.g ATK

https://www.aktmotos.com/ttds-rally-edition

And some Hondas. E.G XL150 and XL190

And ......

If you have one of these,it will just be one of all the others on the street and parking. And with Colombian plates.....Noone will pay any attention.
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Non paid items, Speed tickets, parking tickets, non paid insurance, .... follows the bike. So if you buy a used one, this has to be checked.
So if you do not know the procedure and talk good Spanish, buy from a dealer.
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One of two markets for used bikes is OLX
https://www.olx.com.co/motos_c379?sorting=asc-price

Royal Enfield has built an assembly facility in Colombia (And Argentina and....). Avoid taxes and creates work and a network of RE dealers.
So RE Himalayan starts to show up. And at good prices.
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One favorite bike for travelling is Honda XRE 300, But than we are no longer talking about cheap bikes.
https://motos.honda.com.co/motos-honda/todo-terreno


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If you have questions, send me a PM

Thanks for the advice, I wasn't having much luck using the search function. I'll try browsing the South America and Central America forums. I already have my plans for this summer (HU Newfoundland!) so this wouldn't be right away. Just like to know what's possible and start (dreaming) figuring out budget. Columbia sounds like a great starting point for many reasons. Shorter flight from Canada, geographically at the top makes it great for a loop around South America plus stunning scenery and great motorcycling roads. I'm just not at a position I can take that much time off to do a loop... yet.

I've read that Guatemala is the best place to buy a bike in Central America. Apparently it's easy to purchase, register and insure as a foreigner assuming nothing has changed in the last few years. Also it's easier to go between Guatemala, Belize, El Salvador & Honduras when your vehicle is plated in one of those countries. Not sure what it changes or how it's easier. Seems like Guatemala and Columbia are good fly and buy destinations.

I write you from Spain (excuse me if my english is not very good). Me dream is also ride by SA so I have been reading a lot about to by a bike in SA. In most of countries is possible to buy a bike as a foreigner, register it and ride it legally, but in many of then you can spent a lot of time waiting for the documents. Said that, the better countries to do it are Chile and Colombia...as I kown.