Police have named the biker who died after a crash at Bucknall as Thomas Fairholm from Horncastle.
Mr Fairholm, who was 46, suffered multiple fractures and internal injuries after the crash involving his Honda motorbike and a Renault Clio on an unclassified road, off the B1190 at about 8.30am on Tuesday.
He was flown by air ambulance to Hull Royal Infirmary and had been described by police as being in a stable condition, but died in hospital on Friday.
The driver of the Clio was uninjured.
Collision investigators have reissued an appeal for any witnesses who saw the red Renault Clio or the black and orange Honda CBR motorcycle prior to the collision.
Anyone with information is asked to call the Lincolnshire Police witness line on 01522 558855.