Which statement about impulse coupling timing during starting is correct?

Which statement about impulse coupling timing during starting is correct?

• A. The magnet is locked while the engine starts, preventing rotation.
• B. The coupling winds up and then releases to spin the magnet, producing a hot and retarded spark.
• C. It increases engine RPM.
• D. It cools the spark plug.

Answer: (B)

Impulse coupling timing during starting relies on a spring-loaded impulse unit that stores energy as the crank is turned. When released, that stored energy drives the magneto rotor to spin momentarily faster, producing a much stronger spark. That spark is described as hot and its timing is retarded relative to normal running, which helps ensure ignition occurs reliably at the low RPM of starting. It doesn’t lock the magnet to prevent rotation, it doesn’t purposefully increase engine RPM during starting, and it doesn’t cool the spark plug. The device’s function is to provide a high-energy, properly timed spark to light off the mixture during starting.

Impulse coupling timing during starting relies on a spring-loaded impulse unit that stores energy as the crank is turned. When released, that stored energy drives the magneto rotor to spin momentarily faster, producing a much stronger spark. That spark is described as hot and its timing is retarded relative to normal running, which helps ensure ignition occurs reliably at the low RPM of starting. It doesn’t lock the magnet to prevent rotation, it doesn’t purposefully increase engine RPM during starting, and it doesn’t cool the spark plug. The device’s function is to provide a high-energy, properly timed spark to light off the mixture during starting.