Only at first, and only on the surface, it was ironic to walk out of this afternoon’s moving screening into the Republican National Convention city of New York, securitied from above, on and below the pavement, sirens, barracades, guns, aircraft, sniffing dogs, plainclothesmen, my own particular corner a blue-thronged staging area.

But only, for The Motorcycle Diaries is not strictly about the era’s most iconic leftist revolutionary qua revolutionary -- Fidel prohibits public posting of images of himself. Nor, title notwithstanding, is it Robert Pirsig Self-Esteem Zen nor yet the facile drug-financed search for continental roots of an Easy Rider. True, the latter did vitalize the road movie of picaresquely-strung episodes, of which the new Walter Salles film is an example, but this current effort has more in common with Nicholson’s following-year Five Easy Pieces and its cultured middle-class young man who comes to identify with the have-nothings.

The no-frills film is based on two books, Ernesto Guevara de la Serna’s The Motorcycle Diaries and Traveling with Che Guevara by Alberto Granado. Co-executive produced by Robert Redford and prèmiered to a standing ovation at Sundance not long ago, on one level this is a tale of adventure, a modern Grand Tour as two young men from money set off to explore the Continent that is not Europe, on a proud, let’s-pretend shoestring.

A semester short of his medical degree with specialization in leprosy, but with dad’s wistfully jealous blessing, Ernesto (Gael García Bernal) bids goodbye to parents, four siblings and wealthy girlfriend Chichina (Mía Maestro). It is January 4, 1952, the year he would later participate in anti-Perón riots and a Bolivian miners’ strike, but here the seriously asthmatic twenty-three-year-old is off on youth’s romantic jaunt, joining a friend’s biochemist brother Alberto (Rodrigo de la Serna) on the latter’s “La Poderosa” (“The Mighty One”), a beat-up Norton 500 motorcycle more than half Che’s age. Their plan is to travel across vast Patagonia, the Pampas, the Andes, and Chile’s driest desert on earth at Atacama, visit Peru’s Inca sites and work in a leper colony in that country, and, some nine thousand miles later, make it to Venezuela before Alberto turns thirty.

The two are complementary, as they curse (more common in Spanish than English), love and push one another through eight arduous months. Initially called “(El) Fuser,” Ernesto is much the shier, seemingly more introspective and sensitive. Rhythm-, voice- and dance-challenged on a musical continent, he keeps a journal, reads (imagination suggests sociopolitical works), and is faithful to Chichina and the fifteen greenbacks she gave him for her bathing suit should they reach the U.S.

A carefree, unattached partyer with maybe a job awaiting in Caracas, his “chubby” companion’s goal is “to get laid in every country of the continent” and to browbeat and baby Fuser and his beloved mechanical Rocinante through the odyssey. As they travel up the Pacific Coast and along the cordillera after the cycle gives up the ghost, their sympathetic characters, Alberto’s tales and outright lies, and Ernesto’s slim attractiveness and fierce honesty (though he, too, chips in with a helpful exaggerated story for Tamuco’s small newspaper) secure them shelter, food and sometimes women, though at times things backfire.

Che’s own son Camilo observed that the journal “is about Ernesto Guevara before he becomes ‘El Che.’” Puerto Rican-born José Rivera’s screenplay avoids the insulting absurdity of Egyptian Omar Sharif as Che!, while his non-“induced documentary” boys-to-men story subtly deepens as the travelers discover the open veins of Latin America in the rape of the land’s indigenous peoples, which will change their lives: “something happened in the long time we were together, something I have to think about long.”

With earthy colors and the humor of camaraderie and of the people, and backed by indigenous-tinted music, director Salles does not stoop to travelogue insistence in his four-country Super 16 mm (with some 35 for night shots) location filming. Atacama, Machu Pichu, Cusco, the Amazon, faces and costume and custom are not overplayed like, perhaps, the too obvious three-week stay at San Pablo leper colony. Argentina’s de la Serna makes his international film début here, and, with Mexican García Bernal as the exception, otherwise local, often mestizo, Argentine, Chilean and Peruvian actors are natural and unaffected, balanced against sparing b&w stills.

At the airport, a small motivating white lie is confessed to, but both men knew it, anyway. They embrace, then Ernesto-on-the-way-to-Che boards a plane and flies back home as well as into a future of death and fame. Thirty-year-old Alberto waves. Same view of an ascending flight, but the observer is now a skin-damaged “young man of 82”: the Alberto Granado settled in Cuba since his unhappily administrative Minister of Industry friend Che invited him there after the Revolution.

(Released by Focus Features and rated "R" for language.)