Ignition system for two-cylinder engines

An ignition system for a two-cylinder engine comprising a first ignition signal generator, a first ignition coil controlled by said first ignition signal generator, a first pair of spark plugs connected in series with said first ignition coil, a second ignition signal generator operable independently of said first ignition signal generator to generate ignition signals at time instants different from those of said first ignition signal generator, a second ignition coil controlled by said second ignition signal generator, a second pair of spark plugs connected in series with said second ignition coil,

• a first ignition time control means including a first centrifugal advance device operable in response to the number of rotations of the engine and a first vacuum advance device operable in response to an intake negative pressure, said first centrifugal advance device and said first vacuum advance device being coupled to said first ignition signal generator for varying the time of ignition signal generation by said first ignition signal generator in accordance with the number of rotations of the engine and the intake negative pressure, and
• second ignition time control means being adapted to operate entirely independent from said first ignition time control means and including a second centrifugal advance device operable in response to the number of rotations of the engine and a second vacuum advance device operable in response to the intake negative pressure, said second centrifugal advance device and said second vacuum advance device being coupled to said second ignition signal generator for independently varying the time of ignition signal generation by said second ignition signal generator in accordance with the number of rotations of the engine and the intake negative pressure.