Getting a California license plate for a motorized bicycle is the easiest thing in the world!!
Here's a link to print the form... http://www.dmv.ca.gov/portal/wcm/con...df?MOD=AJPERES
fill it out & mail it in with a check to the 'CA DMV' for $20 & they'll mail you back a real license plate & registration card for your bike.
This is what it should look like when it's filled out correctly, (just substitute your info onto it).