Peter Fonda's "Captain America" chopper from cult classic Easy Rider achieved $1.3m at Profiles in History in Los Angeles on October 18, an increase of 8.3% on a $1.2m estimate.
This makes it the most valuable motorcycle ever sold.
The film stars Dennis Hopper and Henry Fonda as two hippies travelling between LA and New Orleans at the tail end of the 1960s.
The pair also wrote and directed the film, managing to pull together a compelling narrative despite a famously fraught atmosphere on set, caused primarily by Hopper's heavy drug and alcohol use.
The lot displays the iconic stars and stripes fuel tank and is the only survivor of the four motorcycles built for filming - including two machines ridden by Dennis Hopper.
It was accompanied by a letter of provenance from Fonda that reads in part: "This bike was built and ridden in order to switch back and forth due to the rigors of film production.
"This bike was also used in the crash sequence at the end of the movie. When filming was done, I gave the motorcycle to Dan Haggerty as a momento of his work on the film 'Easy Rider.' Dan later reassembled and restored the bike at his Woodland Hills, California home."
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