Kamara's right-wing cross in the game's 5th minute was collected by C.J. Sapong, who volleyed it past goalkeeper Jon Busch for a quick Kansas City lead.
Kamara doubled the advantage in the 39th when he got on the receiving end of a left-wing cross from Michael Harrington, which he headed into the net from seven yards out.
Kansas City improved to 8-3-1 after starting the season 7-0-0.
Simon Dawkins scored for the Earthquakes (8-3-3).