Lincolnshire Police have issued an appeal for witnesses following a collision on the B1202 between Lissington and Linwood at 4pm on Saturday (April 7).
A black Kawasaki and a white Vauxhall Adam collided at a location known locally as White House Corner.
The rider and passenger from the motorbike were taken to Hull Royal Infirmary with what police have described as serious injuries.
The driver of the Vauxhall Adam was not seriously hurt in the collision.
The road was closed for about six hours after the collision.
A Lincolnshire Police spokesman said: “We are appealing for anyone who saw either a black Kawasaki or a white Vauxhall Adam prior to the collision or the actual collision to contact us.
“We have spoken to a number of witnesses already.
“If you have information that could help our investigation and have not contacted us, please call 101 or email email@example.com