Final answer:
Gear-reduction starters are typically set to a 4:1 ratio to increase torque output and facilitate starting the engine.
Step-by-step explanation:
The ratio of gear-reduction starters is typically set to 4:1. This means that for every four revolutions of the starter motor, the gear attached to it will rotate one revolution. The purpose of this gear reduction is to increase the torque output of the starter motor.
The starter motor needs to provide enough torque to turn the engine's crankshaft and start the combustion process. By using a gear reduction, the starter motor can generate more torque while operating at a lower speed. This allows the motor to have a smaller size and consume less power.