Kuchar notched seven birdies and no bogeys at Riviera Country Club in Palisades, Calif.
Sergio Garcia carded a 6-under 65 to ending the day alone in second place.
Brandt Jobe fired a 66 for third place.
Rookie James Hahn, David Lynn and Charlie Beljan each carded a 4-under 67 to share fourth place before play was suspended.
Benedict Cumberbatch's dramatic reading of R. Kelly lyrics is just what you need
Beyonce flaunts bikini body, Blue Ivy in vacation pics