If your unit is not starting, does not produce spark, misfiring and/or running rough it could very well be your CDI box.
A Capacitor Discharge Ignition or CDI is an electronic ignition device that stores an electrical charge and then discharges it through an ignition coil in order to produce a powerful spark from the spark plugs in a petrol engine. Here the ignition is provided by the capacitor charge. The capacitor simply charges and discharges within a fraction of time making it possible to create sparks CDIs are commonly found on motorbikes and scooters.
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