The most valuable motorcycle ever sold at auction will soon return home to Australia where it set a national land speed record 65 years ago.

The British-manufactured 1951 Vincent Black Lightning became part of Australian motoring history after Mascot-born speedster Jack Ehret rode it into the record books in 1953.

Forty years later his son, former sidecar racer John Ehret, was the last person to ride the motorcycle in competition.

"It was an incredible experience to ride it," he said.

"When you open the throttle on that, it just pulls out of the corners, it's quite effortless and it just flies down the straight."

The 1,000cc motorcycle was bought at auction last week by an undisclosed Australian businessman for $US929,000 ($1.16 million) in Las Vegas.

"I think it's a very important moment given its historical significance," Mr Ehret said of the bike's purchase and imminent return Down Under.

"I'm very happy it's returning to Australia."

Jack Ehret with his Vincent Black Lightning at the Castlereagh airstrip speed trails in 1952. ( Supplied: John Ehret )

Riding into land speed history

In 1952 Jack Ehret began his quest to break the Australian land speed record held by rival rider Les Warton.

After a year of preparations, technical challenges and a battle to obtain permission from local authorities to stage the event, on January 19, 1953, he succeeded.

Ehret averaged a speed of 141.5 miles per hour (227.7kph) over two runs on a quarter-mile stretch of road at Gunnedah in north-eastern New South Wales.

Ehret's motorcycle encountered technical difficulties during the record attempt. ( Supplied: John Ehret )

Ehret had worked during and after WWII as a fitter and turner at the Garden Island naval base in Sydney, making around £7 a week in wages.

However it was his off-duty activities that earned him the funds to afford the Vincent Black Lightning, which cost £500 — a significant amount of money in those days.

"He was also racing speedway at the Sydney Showgrounds on a Saturday night making £28 and then fronting up for road racing on a Sunday and making about another £35," his son said.

"He was making about 10 weeks' wages racing motorcycles."

Ehret averaged a speed of 141.5mph (227kph) over two runs on a quarter-mile stretch of road. ( Supplied: John Ehret )

After the record-breaking ride, Ehret continued to race the bike for many years and won several titles.

"One thing about him, for all his faults and things like that, he could ride a bike," John said.

In 1999, two years before his death, Ehret sold the motorcycle to an Australian buyer who occasionally toured it around the rally circuit.

After exchanging hands, the bike was sent to France in 2014 and mechanically restored but retained its original factory paintwork and years of patina.

"When it was in dad's hands he very much had the philosophy to not play with it too much because it was a great bike as is," John said.

Another Australian connection to the story is Melbourne mechanical engineer Phil Irving who played a major role in the design of the motorcycle.

Jack Ehret beat the previous land-speed record of 139.81mph (225kph) set by Les Warton. ( Supplied: John Ehret )

Breaking auction records

Ben Walker of Bonhams auction house said the motorcycle attracted such a high price due its rarity, with only 19 remaining in existence.

"Most of them are not going to be seen or come out onto the open market," Mr Walker told ABC Radio Sydney.

"But then it's the history of this bike and the fact that Ehret got the Australian land speed record and that it had this continuous ownership."

While it is unknown what the buyer will do with the bike, Mr Walker hesitated to say if it was legally rideable on Australian roads.

"It's not just a trailer queen, it's not so shiny that you've got to wear sunglasses to look at it," he said.

"Hopefully the mystery buyer will take it out, put it on display, show it off to the public again; I think that would be really fantastic."