Here is an official link for Los Angeles knife laws
http://www.amlegal.com/library/ca/losangeles.shtml Click on "Municipal code" (left side under the seal), and then type "knife" into the quick search box.
Los Angeles municipal code section 55.10 clearly states that it is illegal to openly carry ANY knife with a blade 3" or longer, this includes folders. Whether or not a visible pocket clip makes a folder "openly carried" will be up to any individual cop, prosecutor, or jury. I would advise being on the safe side and carrying ones folder deep-pocket if the blade is 3" or longer.
It should also be noted that in LA there is no length limit on folders that are carried CONCEALED. Odd but true.
Assisted openers are legal.
There are exceptions to the open-carry blade length limit in LA law. If you are carrying the knife for work related purposes, or legitimate recreational related purposes, and can prove it, then there is no length limit on the knives you can openly carry (section 55.10 c).
It's always a good idea to read the actual laws for yourself rather than just take the word of a bunch of strangers on the internet.