The complete answer is minimum 7500 miles with a non CA EPA sticker you can bring it in.
If it does have the CA EPA sticker, you can bring it in but as a 'new' bike if under 7500 miles on it.
Otherwise it's a no go.
Best to find one with over 7500 if it doesn;t have a sticker.
Either way it has to have an EPA sticker whether CA EPA sticker or not,
CA DMV wants to see the sticker, the VIN, and the mileage to register either way you go.