After overtaking de Reeper at 240m/h, Robinson had come to a corner that had a cautionary sign of 75km/h.
"Travelling at 240km/h Mr Robinson may not have even seen the sign," Justice Gerald Nation said.
While Robinson had applied his front brakes just before the crash, he careered off the road, through a fence and came to rest in a paddock.
Justice Nation said while de Reeper had originally told police he had not exceeded 100kph the whole day while out riding, footage taken from a camera on Robinson's bike had shown he had reached almost double that speed.
Witnesses to the crash also said the sound of the motorbikes sounded like Formula One cars racing.
Robinson had contributed significantly to his own death by travelling at a "grossly excessive" speed allowing for no margin of error, Justice Nation said.
However, the way de Reeper had ridden was also a significant contributor to Robinson riding his bike at the speed he did.
de Reeper had known Robinson had not had his Suzuki GSX bike, which could reach speeds of up to between 303kph and 312kph, very long.
Prior to buying the bike, Robinson had previously ridden a 100cc trail bike.
Justice Nation said victim impact statements showed the death of their son was particularly tough for Robinson's elderly parents, "who should never had to experience the death of their son while they are still alive".
While de Reeper had stopped at the scene and had entered a guilty plea, Justice Nation was not persuaded de Reeper had shown tangible remorse for his part in the crash.
He also disqualified de Reeper from driving for two years.