A Head Hunters gang member attacked and knocked out an innocent motorist who had a "minor crash" with another gang member during the memorial ride for motorcyclist Johnny Danger.

Police are appealing for witnesses to the "unprovoked, malicious assault" which took place during the memorial ride for Danger, who died in a fatal crash on April 25.

Detective Senior Sergeant Marcia Murray, of Waitemata Police, said the assault took place at approximately 9.40pm, on April 27, when about 12 Head Hunter gang members on motorcycles were driving along Coronation Rd in Hillcrest.

"One of the gang members had a minor crash on Coronation Rd with a Nissan ute which was not part of the memorial ride.

"The driver and his passenger got out of their ute to check on the motorcycle rider who was not injured."

The pair were then approached by another Head Hunters' member who punched the driver in the head, rendering him unconscious, and causing him to fall to the ground.

"He has then punched the passenger twice before the group left on their motorcycles," Murray said.

"The driver of the ute was left badly injured and the pair are shaken from their ordeal, and are still recovering."

The motorcycle involved in the incident was then moved to a superette carpark on the intersection of Stanaway St and Coronation Rd.

Police are reviewing CCTV footage and would like to speak to anyone who saw the incident or events that occurred afterwards; in particular, a male riding a moped/scooter with a red and silver helmet; a male and female who were walking their white terrier dog who stopped to look at the damage to the motorbike at 9:53pm.

"This was an unprovoked, malicious assault and police are looking to identify and hold the person responsible to account," Murray said.