Summary: Turn signals are required, must be white or amber in front, amber or red in rear, and must be at least 15 inches above the ground and be visible and understandable to other motorists from 300 feet away.

24951(b): The following vehicles shall be equipped with a lamp-type turn signal system meeting the requirements of this chapter.
24951(b)(4): Motorcycles manufactured and first registered on or after January 1, 1973, except motor-driven cycles whose speed attainable in one mile is 30 miles per hour or less. 

24951(c): Turn signal lamps on vehicles manufactured on or after January 1, 1969, shall be mounted not lower than 15 inches. 

24952: A lamp-type turn signal shall be plainly visible and understandable in normal sunlight and at nighttime from a distance of at least 300 feet to the front and rear of the vehicle... 

24252(a)(1): No turn signal lamp may be combined optically with a stoplamp unless the stoplamp is extinguished when the turn signal is flashing. 

24953(a): Any turn signal system used to give a signal of intention to turn right or left shall project a flashing white or amber light visible to the front and a flashing red or amber light visible to the rear.