The Spring Cup at Oliver's Mount is in doubt after the circuit was not granted a course licence.
A statement by the Auto Cycle Union (ACU), released this afternoon, states: "Following a comprehensive Risk Assessment of the Olivers Mount circuit, members of the ACU Road Race Committee met with Directors of Auto 66 / PMH Promotions in January this year and agreed additional safety improvements for the Olivers Mount Circuit.
"A circuit inspection took place on 21st March 2018, as agreed, to find that the Organisers had not achieved all the improvements required by that deadline. The deadline was extended to Tuesday 27th March and then further extended to Friday 6th April.
"With regret, the ACU are unable to provide a Course Licence for Olivers Mount circuit which means no Permit / Insurance can be issued for the Spring Cup
"Event due to take place on 20/21st April 2018. The Organisers/Promoters in conjunction with the ACU and Scarborough Borough Council will work together to try and achieve events at the venue later in the year."
However, Peter Hillaby, from the Auto 66 club said that he was still hoping the race could go ahead.
He said: "The issue is part of the course is waterlogged and we've not been able to put up some secondary fencing.
"I have my fingers crossed that we can still get it in and get another inspection.
"I've not given up hope. We've complied with everything asked of us but there was nothing we could do in this particular case.
"If it is cancelled we will reschedule."
Mr Hillaby said that the outstanding work was not connected to improvements made after several spectators were injured separate incidents on the course last year.
Lisa Dixon, Scarborough Borough Council Director said: “It’s disappointing that Auto 66 has not been able to secure a ‘racing permit’ from the Auto-Cycle Union Ltd (ACU) for the Spring Cup event on 21 and 22 April.
“Motorbike racing’s love affair with Oliver’s Mount goes back more than 70 years and it’s a circuit that’s been graced by some of the best road racers to have ever sat on two wheels.
“We do not underestimate the enormous contribution that race meetings make to the local economy and we will work with Auto 66 and the ACU in an effort to resolve the current difficulties and ensure the viability of future events.
“While this is a blow for motorbike racing fans and the local economy, we recognise the ACU has a strong duty to look at safety and evaluate the risks to riders and spectators in what is a thrilling sport, but not without its dangers.
“Following recent incidents at the track and taking into account the nature of the sport, the council takes the safety of those attending the event very seriously. We have a responsibility to keep people safe at events taking place in the borough and therefore we fully respect the decision the ACU has made.