Dale Earnhardt Jr. is reflecting on his relationship with Kyle Busch in the wake of the NASCAR champion’s sudden death.

Kyle Busch, who died on May 21 at age 41, was coughing up blood at a General Motors facility in Concord, N.C., according to the 911 call obtained by USA Today.

“A future Hall of Famer, Kyle was a rare talent, one who comes along once in a generation. He was fierce, he was passionate, he was immensely skilled and he cared deeply about the sport and fans,” the...