A 40-year-old man died while practicing his motorcycle skills on Randall’s Island, slamming into a wall Thursday night, cops said.

A witness said the rider appeared to be practicing in parking lot D on the island beneath the Robert F. Kennedy Bridge before he crashed into a column while going at a high rate of speed at 6:38 p.m., police said.

The rider, who was not wearing a helmet, died at the scene, and was seen lying shirtless on the pavement beside the wrecked bike.

Police are withholding the victim’s identification until his family is notified.