It happened at 10:05 p.m. Wednesday in the 5200 block of Montezuma Road, according to San Diego police Sgt. Michael Tansey.
After turning onto Montezuma Road from 54th Street, the rider accelerated, soon hitting 90 miles per hour and losing control of the motorcycle, Tansey said.
The motorcycle crashed and slid on the ground until it struck a sign post. The man was transported by paramedics to Mercy Hospital with life-threatening injuries but is expected to survive, although he will probably lose the use of both legs, Tansey said.