The effect of this could be significantly mitigated if the DMV made it legal for dirtbikes without streetreg to traverse paved roads in national forest areas and such. The would prevent high polluting dirtbikes from being used as commuters, while still allowing dirtbikers to ride trails that traverse paved roads, which is the primary reason that most folks that I know get a street reg on their bikes. I'm not one to defend SUVs, but just because they guzzle gas doesn't mean that they pollute heavily. You can pretty much guarantee that a dirtbike with absolutely no emissions controls of any kind will produce quite a bit more pollution than any reasonably recent SUV, regardless of size. Still, considering their numbers, it hardly seems like it will make a dent in our air quality one way or another.
The lack of notice, on the other hand, is unconscionable. What about the poor guy who spent thousands on a green sticker dirtbike over the weekend who intended to make it street legal. His bike is now worthless for riding in many areas of California, but he can't just return the thing ad buy a dual sport.
--sam