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A capacitor-discharge ignition system for a two-stroke internal combustion engine has a trigger coil which during forward rotation of the crankshaft discharges a capacitor through the primary coil of an ignition transformer to produce an appropriately timed ignition spark. The discharge and spark oc

A capacitor-discharge ignition system for a two-stroke internal combustion engine has a trigger coil which during forward rotation of the crankshaft discharges a capacitor through the primary coil of an ignition transformer to produce an appropriately timed ignition spark. The discharge and spark occur when a magnet mounted on the flywheel of the engine intercepts the trigger coil at a crankshaft or piston position in the vicinity of top dead center. The trigger coil discharges the capacitor by supplying a trigger signal to the control gate of a silicon controlled rectifier (SCR) located in the discharging path between the capacitor and the primary coil of the ignition transformer. The primary coil, which is connected to the cathode of the SCR, is mounted on a stator core intercepted by the magnet on the flywheel no less than 60°after top dead center. If, for any reason, the crankshaft of the engine should be rotated in the reverse direction, the voltage induced in the primary coil by the magnet reduces the gate-to-cathode bias on the SCR and causes any charge on the capacitor to discharge through the primary. Any ignition spark created is too far in advance of the top dead center position and sustained engine operation in the reverse direction, therefore, is inhibited.

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In a capacitor-discharge ignition system for a two-stroke internal combustion engine having a crankshaft, a spark plug for ignition and a member rotated in synchronism with the crankshaft and the engine cycle, the combination comprising: an ignition transformer having a primary coil and a secondary

In a capacitor-discharge ignition system for a two-stroke internal combustion engine having a crankshaft, a spark plug for ignition and a member rotated in synchronism with the crankshaft and the engine cycle, the combination comprising: an ignition transformer having a primary coil and a secondary coil for producing a spark voltage for the spark plug; a capacitor connected for timed discharging through the primary coil of the ignition transformer; means for charging the capacitor during each engine cycle; switching means connected between the capacitor and the primary coil of the transformer and activated by trigger signals to establish an electrical discharge path between the capacitor and the primary coil of the ignition transformer; triggering means connected with the switching means and including flux-varying means and a trigger coil for producing a first trigger signal from the trigger coil to actuate the switching means and discharge the capacitor through the primary coil in timed relationship with forward rotation of the engine crankshaft to sustain the engine operation, the flux-varying means and the trigger coil being selectively positioned relative to one another in the engine for movement past one another by the rotated member during each rotation of the engine crankshaft to produce the first trigger signal; and suppressing means connected with the switching means and including the primary coil of the ignition transformer and the flux-varying means, the primary coil and the flux-varying means also being selectively positioned relative to one another in the engine for movement past one another by the rotated member during each rotation of the engine crankshaft for producing a second trigger signal from the primary coil to actuate the switching means and discharge the capacitor through the primary coil in timed relationship with reverse rotation of the engine crankshaft to inhibit engine operation.