A motorbike enthusiast has spent more than $60,000 to prove he was not driving at 90km/h over the speed limit in the Royal National Park.

John Busuttil, 29, was charged with riding his Suzuki 1000cc motorbike at 149km/h in a 60km/h zone on Lady Wakehurst Drive in May last year.

The view from the police camera ... the road, the reading and the ticket that led to $60,000-worth of legal action to see speeding charge thrown out.

He faced a fine of $1744 and a six-month suspension of his driver's licence.

In the Sydney District Court today, Judge Greg Woods quashed the conviction and returned Mr Busuttil's licence, finding the highway patrol officer's use of a radar gun was "radically wrong".