The man was riding the bike when it was in collision with a car in Hall Road, Hull, at around 6.40pm on Friday. He tragically died from his injuries at the scene.
The motorcycle the man was riding was removed from the crash scene before police attended.
Officers are appealing for its return so collision investigators can examine it.
Humberside Police Roads Policing Sergeant Matt Hemingway said: "I am not interested in why or how this bike was removed from the scene, I just want it to be handed in so that we can fully investigate the collision. A young man has lost his life tonight I want to make sure a full investigation takes place so that his family can have the full facts.
"If you have any knowledge of where this bike is please call us now on 101 quoting log 487 29 November 2019."