The crash involved a Royal Enfield Himalayan motorbike and a white Mercedes Sprinter van.
It happened at 7.35am on Saturday, July 16 at the junction of the A672 and slip road of the M62 Eastbound at Junction 22 in the Rishworth area of Calderdale.
The motorcyclist, a 36-year-old man, suffered serious injuries.
He died at the scene.
The driver of the van, a 31-year-old man, was arrested on suspicion of causing death by dangerous driving.
He remains in custody.
Road closures remain in place.
Motorists are advised to use alternative routes where possible.
West Yorkshire Police are appealing for witnesses to the crash.
Anyone with information is asked to contact them on 101, or by using the LiveChat facility on the West Yorkshire Police website.
The log reference is 413 of 16 July.