A teenager died hours after walking away from a crash in which the trial bike he was riding hit a car on a village road.
Scott Blair was just 16 when he lost control of the 200cc machine he was delivering to his father, Allan, who had bought it.
At his inquest at Stamford Magistrates Court on Thursday, South Lincolnshire Coroner, Prof Robert Forest, said the collision with a red Fiat took place in Sandygate Lane, Horbling, close to his home in Stow Lane on Monday, July 23, at about 4.30pm.
Prof Forest said Scott was able to ride away from the scene but was later taken ill.
When paramedics arrived Scott was struggling to breathe.
Scott became calmer and was taken to Pilgrim Hospital in Boston, where he suffered a heart attack and died.
Consultant pathologist Dr Michael Harris said Scott had received fatal lacerations to his liver that led to an abdominal haemorrhage.
He said the bleed would have built up over a period of time which is why it was not evident at the time of the crash.
Driver of the Fiat Belinda Hay said she saw Scott coming towards her from about 100 yards.
She said: “When he lost control and hit the floor his helmet came off straightaway. I was braking hard but could not stop before the impact.
“When I opened the door he was under the car - it’s hard to say how long it was before he got up.”
Accident investigator PC Mark Brown, said: “The motorcycle was for off-road use only and it was not road legal. The 200cc engine was too powerful for someone with little experience.”
Scott’s sister, Linda, said she could confirm his grandfather had told him not to ride the motorbike.
Recording a verdict of accidental death, Prof Forest said it was a tragic accident. He said: “He was told by his grandfather not to ride the motorbike but he did.”