The collision involved a Lambretta Li 150 Series 3 scooter and the rider, a man in his 70s from Truro, sustained serious head injuries.
He was taken to Treliske Hospital for treatment.
Police are appealing for witnesses to the incident and would also like to hear from any road users who may have any footage to assist with the investigation.
Please email [email protected] or telephone 101, quoting log 0815 of 26 April.
The road was closed for around two hours. Police would like to thank the public for their support and patience while officers closed the road to carry out investigative work.
