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Understanding the working of magneto ignition system

Magneto ignition being a special type of ignition system that provides a spark in spark-ignition engines, such as petrol engines. it is used to obtain pulses of high voltage for the spark plugs. The system has been in existence for over 100 years and still used today on stationary and portable engines. It’s mostly employed on applications where space for the external battery is restricted.

Today you’ll get to know the definition, functions, applications, components, diagram, and working of the magneto ignition system. you’ll also get to know the advantages and disadvantages of the offer to spark-ignition engines.

magneto ignition system

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Magneto ignition system definition

A magneto ignition system or high-tension magneto is an ignition system that uses magneto to create high voltage for the generation of electricity. The electricity generated is further used to run vehicles and other electrical components in the system.

The magneto is a combination of a distributor and generator built as one unit, making it different from the conventional distributor that creates spark energy without external voltage. There is a series of rotating magnets that break an electrical field, causing an electrical current in the coil’s primary windings. The current charge will then multiply when it transfers to the coil’s secondary windings. This is because there are many more times the number of windings in the secondary circuit compared with the one in the primary circuit, which then causes the multiplied charge magneto to produce a spark at a higher voltage than was created in the primary windings.

In most cases, magneto system can produce voltage as high as 20,000, which result to very hot spark that a conventional distributor can produce.

The function of a magneto system is to use a magneto to provide current for the ignition system which powers the spark plug that further ignites the fuel-air mixture in the combustion chamber. another function of the magneto system is performed by the spark plug as heat can dissipate through the system. the system also causes ionization to be measured in the cylinders.

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Application of magneto ignition system

Below is the application of magneto ignition in various aspect as it generates the electricity needed for ignition:

  • The system is used in two-wheeler vehicles (SI engines.
  • Just as the battery is used to generate power in the battery ignition system, magneto is used for the generation of electricity.
  • Finally, the magneto ignition system is widely used in applications such as tractors, outboard motors, washing machines, marine engines, power units, and natural gas engines.

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Components of magneto ignition system

Below are the functional components that aid the working of magneto ignition system in various applications:


The magneto is the source of energy generation in the magneto ignition system. it’s typically a small generator that works on electricity as it produces a voltage when rotated by the engine. This is to say, the higher the rotation, the greater the voltage produced by the system. The system has no external source of energy and does not need one to start it, the magneto itself is a source for generating energy. The winding in the system is of two types which include; primary binding and secondary binding.

Depending on the engine rotation, the magneto is of three types;

  • Magnet rotating type
  • Armature rotating type
  • Polar inductor type

The difference between the three is just their source of rotation. In the magnet type, the armature is stationary while the magnets rotate around the armature. Whereas in the armature type, the armature rotates between the stationary magnet. Finally, in the polar inductor type, both the magnet and the windings remain stationary but the voltage is generated when the flux field is reversing. This is achieved with the help of soft iron polar projections which is known as inductors.


The distributor components used in the magneto ignition system can also be found in the multi-cylinder engine. This multi-cylinder engines are used for the regulation of spark in the right sequence in the spark plug. It causes the surge of the ignition to be distributed uniformly among the spark plugs.

Distributors are of two types which include;

  • Gap type, and
  • Carbon brush type distributor.

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In the gap type distributors, the electrode of the rotor arm is close to the distributor cap but is in contact. This eliminates the occurrence of wear in the electrode. While in the carbon brush type, the rotor arm sliding over the metallic segment carries the carbon brush that is placed inside the distributor cap or molded insulating material. With this, an electric connection is created with the spark plug.

Spark plug:

The spark plug is a device that is powered by the ignition system to ignite the fuel-air mixture in the cylinder. It has two electrodes that are parted from each other which allow a high voltage to flow through it. These electrodes are made of steel shell and an insulator. The central electrode is attached to the supply of the ignition coil and an outer steel shell. It’s grounded insulating them.

Read full article on a spark plug


A capacitor is also a component in the magneto ignition system. it’s just like the conventional electrical capacitor with two metal plates separated by an insulating material with a distance. Air is commonly used as insulating material on this system, but to reach a particular technical requirement, a high-quality insulating material is employed. The function of this capacitor is to store charge.

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The cam is attached to the north and south magnet.

Contact breaker:

This contact breaker is regulated by the cam, which allows current to flow through the capacitor and charges it when the breaker is open.

Ignition switch:

The ignition switch help to start and off the vehicle ignition system. it controls and set the parallel of the capacitor because it helps to prevent damage of too much air.

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magneto ignition system diagram:

diagram of magneto ignition system

Working principle

The working of a magneto ignition system is less complex and can be easily understood. Its working begins when the engine of the system starts working, when then rotate the magneto. The magneto then creates energy of high voltage. The end of the magneto is grounded at one end through a contact breaker and the capacitor is attached to it parallelly. The cam helps to regulate the contact breaker and current flow through the capacitor and charges it when the breaker is open.

With that, the capacitor act as a charger as the primary current flow is reduced, and then reduces the overall magnetic field created in the system. This increases the voltage in the capacitor, which acts as an EMF, thus producing the spark. This is achieved with the help of the distributor.

When the speed of the engine low at the starting stage, the voltage generated by the magneto is also low. But as soon as the rotating speed of the engine increases, the voltage generated also increases. If this happen, the flow of the current is also increased.

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Watch video on the working of magneto ignition system:

Advantages and disadvantages of magneto ignition system


Below are the benefits of magneto ignition system in its various applications:

  • Less maintenance is required compared to the battery ignition system.
  • Less cost as the battery is not used.
  • Efficient working due to high-intensity spark.
  • The electric circuit is generated by the magneto.
  • It occupies less space.
  • Since the battery is not used, there are no issues with battery discharge or battery error.

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Despite the good advantages of the magneto ignition system, some limitations still occur. Below are the disadvantages of the system in various applications:

  • Poor quality of spark due to low speed at first start.
  • Misfiring may occur due to leakage. This is because the variation of voltage in the wiring can occur.
  • The system is more expensive compare to other types of ignition systems.

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In conclusion, a magneto ignition system is a great development on spark-ignition engines, and other internal combustion equipment. We have look in-depth on the definition, function, and the component of the ignition system. we also covered its working, as well as its advantages and disadvantages where we said it requires less maintenance and no battery is employed. We also saw that it provides poor quality spark at first start because of the low speed it experiences.

I hope you enjoyed the reading, if so, kindly comment on your favorite aspect of this article and free ask questions. We hope to see you next time. Thanks!

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