No endorsement intended by this but here is a partial list from 2014 compiled by the President of the SoCal Norton Owners Club. Personally, in no order of preference, I have had good experience with Phil Radford at Fair Spares, Dean Collinson, Steadfast, and Jim Schmidt at JS Motorsports. As for the others, I have heard good things but I have no experience, and so cannot comment.
4 Aces Cycle Supply
12734 Branford St. #16, Pacoima, CA
(818) 834-1060
Century Cycles
1640 S. Pacific Ave., San Pedro, CA
(310) 832-6190
Dean Collinson Motorcycles
9211 Elizabeth Lake Road, Leona Valley, CA
(818) 288-2539
Fair Spares America, Inc.
1137 N. Los Olivos Avenue, #3A, Los Osos, CA
(805) 534-9248
Garage Company
956 W. Hyde Blvd., Inglewood, CA
(310) 330-9933
Glory – Sales and Service
4659 Hollywood Blvd, Los Angeles, CA
(323) 644-5679
JRC Engineering
3110 Indian Avenue, Unit 1E, Perris, CA
(951) 940-5410
Omo and Son Motorcycles
1570-B Pine Street, Oxnard, CA
(818) 701-1010
JS Motorsports
4480 North Academy Avenue
Sanger, CA 93657
Phone/Fax: 559 875 0659
Steadfast Cycles
26516 Reuther Ave, [HASHTAG]#210[/HASHTAG], Santa Clarita, CA
(661) 252 2274
Symonds Cycles
12206 Foothill Bl vd., Syl mar, CA
(818) 897-4738