Susan Linda Chiverton, from Lymm, died at 7.30pm last night, in Walton Hospital, Liverpool,where she had been transferred from Warrington Hospital because of her condition.
She had suffered head and chest injuries in the collision in Brick Street, Warrington just before 5pm on Wednesday last week.
Another woman, aged 18, also from Lymm, was injured in the same incident and is still in Warrington Hospital with head and spinal injuries. Her condition is said not to be life-threatening.
The collision involved a green Kawasaki 600cc motor cycle driven by a 23-year-old local man. He was uninjured and was subsequently arrested on suspicion of dangerous driving and other driving offences. He was released on bail after being questioned.
Police are appealing for any witnesses to the collision to contact Warrington Traffic Unit on 0845 458 0000.