Jack Ehret's Vincent Black Lightning has been recommissioned exactly as it was when Ehret raced it in the 1950s. Picture: Bonhams

Las Vegas, Nevada - What you are looking at here is a million-dollar motorcycle, or very nearly.

This 1951 Vincent Black Lightning was sold at last weekend’s Las Vegas Motorcycle Auction for a jaw-dropping $929 000 (R11.05 million), thought to be the highest price yet paid for a motorcycle at auction in the United States.

But then, even for a Vincent, this is a very special motorcycle. The Black Lightning was a non-street legal racing version of the Vincent Black Shadow, itself a sports model derived from the Rapide, and renowned as the world’s first superbike.

The 1948 Black Shadow had a 998cc pushrod V-twin engine rated at 41kW, weighed 208kg dry and, with a top speed of more than 200km/h, could easily outrun a Jaguar XK120, much to the embarrassment of the gentlemen from Browns Lane.

The Vincent Black Lightning was derived from a one-off called Gunga Din, modified by factory test rider George Brown with its compression ratio raised from the standard 7.3:1 to an explosive 12.5:1 (what Brown ran it on, in those days of octane-challenged Pool petrol, is not recorded) stronger con-rods, larger inlet ports, polished rocker gear, steel idler gears, Amal GP racing carburettors, and a manual-advance magneto ignition system.

It was good for a genuine 52kW and Philip Vincent was persuaded to offer replicas to order, shorn of lights, hooter, silencers and instrumentation, and fitted with magnesium alloy engine covers, rear-set footpegs and controls, aluminium mudguards and special racing tyres on alloy rims.

Ehret Black Lightning is a rolling time warp. Picture: Bonhams

The Black Lightning weighed 170kg ready to rock ‘n roll, and was geared for a top speed of 240km/h at a time when very few production bikes were capable of more than 150. Just 31 were handbuilt in the competition department at Vincent-HRD in Stevenage, Hertfordshire (now better known as the hometown of Lewis Hamilton!) between 1948 and 1952, of which 19 are known to be still in existence.

Ironically, a number of Black Shadows have been modified to Lightning specification over the years in a bid to increase their value but, with the ever-increasing cult status of original Vincent motorcycles, they would be worth more today if they’d been left unmolested.

The Black Lightning became an instant legend in September 1948 when American stunt rider Rollie Free rode one to a US motorcycle land speed record of 239.1km/h on the Bonneville salt flats, stretched out face down on top of the bike wearing bathing trunks, plimsolls and a pudding-bowl helmet.

If this picture taken by a Life Magazine photographer from a car speeding alongside didn't exist, nobody would believe that Rollie Free set a US motorcycle land speed record of 249.1km/h wearing bathing trunks, plimsolls and a pudding-bowl helmet.

South African motorcycle racer Vic Proctor tried unsuccessfully in 1952 to better that mark at Verneukpan in the Northern Cape, also on a Black Lightning, and later set a record for the flying mile, on a closed section of public road (the cops were more understanding of the need for speed in those days) that stands, officially anyway, to this day.

The million dollar Black Lightning was ordered in 1951 by Tony McAlpine, who took it to Australia and later sold it to Jack Ehret, who rode it to many race wins and in 1953 set an Australian land speed record of 226.4km/h with it. The hand-painted signage with which he celebrated that feat is still to be seen on the bike’s fuel tank.

Jack Ehret shows how it's done in this 1952 photograph. Picture: Bonhams

Ehret kept the Black Lightning it for nearly 50 years before selling it, and the current owner, only its fourth from new, has had the bike recommissioned in full running order - but without restoring it in any way - just as it was when Ehret retired it from the track almost 60 years ago.

And that, of course, is why this Vincent, the most famous one in the world after the Rollie Free ‘Bathing Suit Bike’, is so special; it’s a rolling time warp, and a monument to those magnificently crazy young men who rode flat out with no more protection than an unshakeable belief in their own immortality.

In case you were wondering, the only motorcycle we know of that fetched more at auction was the sole survivor of the two "Captain America" choppers built for the movie Easy Rider, which was sold in Britain during October 2014 for £836 337 (then R14.77 million).

You can see - and hear! - Ehret's bike running in the short video below.