are the turn signals allowed to be yellow on a motorcycle in CA?
the stock ones are amber

They are supposed to be yellow. Red is only for brake lights.

Front must be amber (yellow) or emit amber light
Rear can be amber or red

Front turn signals shall be white or amber. (Veh C §§ 24953(a), 25109.)
Rear turn signals shall be red, amber, or yellow. (Veh C §§ 24953(a), 25950(b)(2).)

The California Vehicle Code provides in pertinent part:
“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 & a flashing red or amber light visible to the rear.”
“25109. Any motor vehicle may be equipped with two white or amber running lamps mounted on the front, one at each side, which shall not be lighted during darkness except while the motor vehicle is parked.”
“25950…(b) The emitted light from all lamps & the reflected light from all reflectors, visible from the rear of a vehicle, shall be red except as follows…(2) Turn signal lamps may show yellow to the rear.”

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