Organisers have named the competitor killed during last night's Southern 100 practice session.
He was 46 year old Douglas man David Jukes who leaves a partner Cath and a young son.
Mr Jukes died following an incident at Ballakaighan corner during the qualifying session for the 600 cc event.
In a statement this morning organisers have extended their sincere sympathy to family, relatives and friends at this very sad time.
A full investigation into the circumstances of the accident is taking place and the Coroner of Inquests has been informed.
Police are appealing for witnesses to the accident.
If you saw what happened and haven't already spoken to police or organisers you can ring Port Erin police on 631 520 or police headquarters on 631 212.