It was New York's first home loss of the season and its first setback anywhere since Aug. 3.
Kansas City opened the scoring in the 12th minute on a play set up when Graham Zusi's free kick bounced off the crossbar and back into the field of play. Matt Besler collected the ball and sent it to Spaong, who turned in the middle of the penalty area and fired a shot past goalkeeper Bill Gaudette.
Kamara then headed in a corner kick from Zusi in the 19th minute.
Kansas City (16-7-6) is unbeaten in its last seven games and is atop the Eastern Conference. New York (14-8-7) is in third place in the East.