Morales scored on a penalty kick in the 10th minute and beat Galaxy goalkeeper Josh Saunders from 20 yards out in the 41st. Morales assisted on Andy Williams' goal in the 2nd minute for RSL, which led 3-0 at halftime.
Paulo Araujo Jr. scored in the 68th minute on a pass from Fabian Espindola.
RSL extended its MLS unbeaten streak to 16 games, three shy of the league record shared by FC Dallas (2010) and Columbus (2004-05). RSL hasn't lost at home in the regular season since May 16, 2009, a span of 26 games.
Both teams were short-handed because of national team duties. The Galaxy played without Landon Donovan, while RSL was missing Will Johnson and Alvaro Saborio (Costa Rica).