Naraku Racing AC CDI with adjustable timing for customized tuning on 50 to 150cc GY6 engine based vehicles. The timing adjustment screw is set in the middle from the factory and has approximately 12 to 13 turns (up to 15 turns) in either direction to advance (clockwise direction) or retard the timing (counter clockwise direction). The screw clicks when you reach the stop point. Please note: This is only compatible with AC charging systems. Please confirm plug connection is correct for your vehicle. Returns are not accepted on electrical items. Please see our Warranty & Returns Policy.