Sunday's Scarborough Spring Cup meeting was abandoned after a serious incident involving promising Manx rider Billy Redmayne.
The 25-year-old came off in the feature race, which had been restarted after Northern Ireland's Lee Johnston was involved in a spill.
Johnston was taken to hospital but was later pictured giving the thumbs-up from his hospital bed.
Redmayne, who won last year's Junior Manx Grand Prix and had been set to make his full Isle of Man TT debut this year, was more seriously injured and was airlifted to hospital in Middlesbrough.
A statement issued by the organising Auto 66 Club said: “Billy Redmayne, the rider involved in the incident during the Bob Smith Spring Cup Race at Oliver's Mount, has been taken by airmed to Middlesbrough Hospital, where he is undergoing treatment for his injuries.
“He is now breathing on his own and his condition is improving. Further information will be released when available.”
The organisers took the decision due to a lack of medical cover in the aftermath of the incidents.
The Spring Cup race has been rescheduled for later in the season at the Cock 'o the North meeting at Scarborough in June.