Getting a bike to South America from North America seems a pricey proposition, from what I read and hear, passedoutwookie!
You can't, in practical terms, RIDE into Colombia from Panama; for one thing, the Darien jungle interferes.
For the past two weeks, I've been helping outfit a man from South Africa who plans to ride to Tierra del Fuego, the tip of South America. He flew to Washington, DC from Johannesburg, South Africa; bought a Generation 2 KLR650 and contracted its build-up (10-gallon fuel tank, trick front and rear suspension, etc., etc.) over the Internet. He's vying for passage for him and his bike aboard the good ship, Stahlratte
, from Panama to Colombia, when he gets that far along.
An alternative: Air freight the bike between hemispheres.
Depends upon your motivation, objectives, goals; time and resources, passedoutwookie! And . . . what will you do with the bike, AFTER you make it to South America? The same problem, in reverse, arises in getting the bike back into the northern hemisphere.
All that said, it's been DONE. With determination, money, and time, you can likely do it, too.