'Deadpool 2' Dead Stuntwoman Identified as a Professional Motorcycle Racer

The stuntwoman who was killed on the set of "Deadpool 2" has been identified ... and she was a professional road racer.

The victim was Joi "SJ" Harris, a professional motorcycle racer from Brooklyn, NY and the first African-American licensed female in the sport ... her family confirms to TMZ.

She was not a member of the Alliance of Canadian Cinema, Television and Radio Artists -- a Canadian actors union. "Deadpool 2" was also her first film as a stunt driver.

We broke the story ... Harris lost control of her motorcycle during filming in Vancouver, which sent her airborne through a glass window of a ground floor studio. Eyewitnesses say the brakes were never applied ... and she was also not wearing a helmet. She died on the scene.

Weeks before her tragic death, Harris tweeted she had just fully healed from an injury involving her wrist and was ready to ride again. She had also fallen from a motorcycle before and filmed the fall.