Subsection (f) of the above mentioned Title 13 Section 2412 states the following:
(f) Off-road motorcycles and ATVs, and engines used in such vehicles, that do not meet the emissions standards in subsection (b) above may operate only during certain periods of time at certain off-highway vehicle (OHV) riding areas.
Section 2415 of this Article lists these California OHV riding areas and their associated riding seasons for offhighway recreational vehicles that are subject to use restrictions.
This is relative to the current "Red-Sticker" bikes including 2-Strokes and 4-Strokes. per the defintions section of the document.
(13) “Off-Highway Recreational Vehicle Engines” or “Engines” are identified as: two-stroke or four-stroke, aircooled, liquid-cooled, gasoline, diesel, or alternate fuel powered engines or electric motors that are designed for powering off-road recreational vehicles and engines included in, but not limited to use in, the following: off-road motorcycles, all-terrain vehicles, and golf carts. All engines and equipment that fall within the scope of the preemption of Section 209(e)(1)(A) of the Federal Clean Air Act, as amended, and as defined by regulation of the Environmental Protection Agency, are specifically not included within this category.