But Delvene Manning, the meet manager, said Tuesday that Keown reached a top average speed of more than 141 mph on a milelong run, followed by a 133 mph run.
Two back-to-back runs are averaged together to determine the speed entered into the books. Keown's effort on her first day racing topped the record set last year by Serge Martin, another Harley of Glendale rider. He had reached 137.65 miles per hour on one run and averaged 135 mph.
Keown saw that she had reached 140 mph when she started the timed one-mile portion of the five-mile sprint.
"I just got as low and crouched on the bike as humanly possible, and that pushed me up that one extra mile," she said.
When she saw her record time as she finished the run, she said, "I was shouting in my helmet. I was pretty excited."
A Missouri native who lives in Atwater Village, Keown moved to Southern California in 2008 to work in the movie industry. But last year she joined the staff at Harley-Davidson of Glendale, watched her first races and began to ride with her colleagues.
Glendale Harley-Davidson owner Oliver Shokouh and his crew helped Keown prepare for the event with months of tips and training.
"She's a novice," Shokouh said. "We taught her all the techniques we knew. She's a good listener, she listened; she has the right attitude and she put it to work."
Shokouh decided to sponsor Keown after members of his staff suggested she had the right stuff.
"I felt that she had it in her," he said. "She really wanted to do this, and some people can just get out the first time and do miracles. Some can stay on and never achieve anything."
Keown said a new challenge emerged on the second half of her record run, by which time a 14 mph side wind had arisen. Instead of easing off the throttle, Keown said she leaned into the wind, cranked it a little higher and reached 133 mph.
"It has been an incredible experience," she said. "I've been able to surprise myself out here."