From the California DMV web page:

Off highway vehicles (OHV) subject to off-road registration.
OHVs are vehicles such as racing motorcycles, trail bikes, mini bikes, dune buggies, all-terrain vehicles, jeeps, and snowmobiles. These vehicles are operated exclusively off public roads and highways on lands that are open and accessible to the public. They do not require regular registration, but must display an identification plate or device issued by DMV.

It is not necessary to register a vehicle for both on-highway and off-highway use. Valid on-highway registration allows the vehicle to be operated on and off the highway. Vehicles registered for on-highway use only may be subject to a "use fee" if operated in OHV parks.

To change a California registered vehicle from on-highway use to OHV, you will need to:

Visit a DMV office. Make an Appointment(s) for faster service.
Provide the California Certificate of Title.
Pay the original off-highway vehicle application fee (registration fee).
To register an OHV that has never been registered and was purchased from someone other than a licensed California dealer, you will need to:

Visit a DMV office. Make an Appointment(s) for faster service.
Complete an Application for Title or Registration (REG 343) (PDF).
Have a DMV representative, licensed vehicle verifier, or peace officer complete a vehicle verification (on the REG 343 form).
Provide evidence of ownership such as a bill of sale, out-of-state title, or Manufacturer's Certificate of Origin.
Surrender any on-highway license plates.
Pay the original off-highway vehicle application fee (registration fee).
Pay the use tax.
Original and renewal registrations are good for 2 years and expire on June 30th of the second year. Renewal notices are mailed to owners. A penalty fee is due if the renewal is late.

Visit the California State Parks Off Highway Motor Vehicle Recreation website for additional information and the Green Sticker Vehicle Newsletter.


The above is halfway down the page on this site: http://dmv.ca.gov/vr/vr_info.htm

Lee
Tustin, CA