Norfolk Police are looking for a biker clocked at 170mph by a speed trap on the A47 near Kings Lynn.
The fastest-ever recorded biker was riding flat out on the dual-carriageway near Terrington St John on Saturday aftertoon. However, he was travelling so fast that the officers on scene were unable to read the number plate.
Details are sketchy but officers report he was wearing a blue jacket and his bike had “bright yellow features”.
Inspector Julian Moulton said: “This person was riding beyond the capabilities of conditions - both road and sensibility. They were not only putting themselves in real danger but unsuspecting road users too.”
The Police want to speak to witnesses who might have seen the biker on the road.