An ultra-rare 1954 AJS E95 “Porcupine” is set to smash records and become the world’s most expensive motorcycle at Bonhams‘ automotive auction at Quail Lodge in Carmel, CA on August 18.

One of just four E95s ever built, the Porcupine (so nicknamed because of the spiked cooling fins on its cylinder head) was created as a works racer by British manufacturer AJS.

An ultra-rare 1954 AJS E95 ‘Porcupine’ expected to fetch up to $750,000

One of the most legendary motorcycles in history owing to its brief but astonishing racing success and extreme rarity, the example on offer at the Bonhams sale is expected to fetch up to $750,000.

That will shatter the current world record of $520,000 for a 1915 Cyclone Board Track Racer set in 2008.

“As far as motorcycles go, the Porcupine is at the very top,” notes Bonhams CEO Malcolm Barber.

“It is arguably the most beautiful, graceful and innovative racing motorcycle ever built, the perfect blend of technology and art.”

We won’t argue with that.

UPDATE: Forbes‘ luxury guru Hannah Elliott notes that the Porcupine has been on loan for the past 20 years to the National Motorcycle Museum in England.