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Old 03-18-2010, 08:14 PM
exavid exavid is offline
Motorized Bicycle Elite Member
Join Date: Dec 2009
Location: Medford, OR
Posts: 163
Default Re: ignition timing adjustment methods

The diagram looks right to me, a brief description of how the circuit works might be of some use to those who aren't familiar with a CDI system. The capacitor is charged through the diode on the positive half of the sine wave coming from the magneto coil. At this point the "zero crossing trigger" which is an SCR (Silicon controlled rectifer) is an open circuit from the capacitor to the ignition coil. When the negative half of the sine wave appears at the top of the diode it prevents the capacitor from discharging back into the magneto coil. At the same time the reversal of the magneto polarity voltage at the SCR triggers it so that it suddenly changes from an open circuit between the capacitor and ignition coil to a closed circuit. The sudden pulse of current is applied to the ignition coil which is actually a transformer stepping up the voltage from the magneto to a high enough value to arc across the spark plug.
Goldwing 1500, Silverwing 600, Schwinn 49
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