Magneto Ignition System, Parts, Working, Advantages & Disadvantages

Magneto Ignition System is unique kind of Ignition system which has its own basis to generate necessary amount of energy for an automobile or a vehicle to work. It replaces all component of battery ignition system except spark plug. Today we will study about this Magneto Ignition System, function, parts, working, advantages and disadvantages.

Functions of Magneto Ignition System

There are several types of Magneto Ignition System used on small engines. These systems are classified by types of switching device they us to control primary current to coil. Mechanical breaker point ignition (MBI systems use mechanical breaker points to control current ignition coil. This type of system is used until development of solid state ignition system. Here is list of parts that are used in it.

  • Magneto
  • Distributor
  • Spark Plug
  • Capacitor

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Parts of Magneto Ignition System

Magneto Ignition System is Magneto gives energy to system. Generally, Magneto is small electric generator that works on electricity. When magneto is rotated by engine, it produces very high voltage. This magneto does not need battery as source of external energy. There are two types of winging in it that is primary binding and secondary binding.

In addition to this, magneto has 3 types based on its engine rotation. Such as armature rotating type, Magnet rotating type and Polar inductor type. In armature rotating type, armature rotates between stationary magnets. On other hand, magnet rotating type, armature is stationary and magnets are rotating around armature. In polar inductor type, both magnet and windings remains stationary but voltage is generated by reversing flux field with help of soft iron polar projections called inductors.


Distributor is used in many cylinder engines to adjust spark in correct series in each spark plug. It distribute ignition surge in spark plug in correct series. There are two types of distributor. One is called as carbon brush type and other is gap type. Check Brake System Types, Functions, and Types of Brakes in automobile

In carbon brush type, brush passed by rotor arm sliding over metallic part and set in into distributor cap or molded insulating material. This makes electric connection with spark plug. In gape type distributor, electrode of rotor arm is close but does not make contact with cap. So there is no wear of electrode.

Spark Plug

Generally, spark plug has tow electrodes which are divided with each other. And high voltage flows through it which makes spark and ignite combustion mixture in cylinder. It consists of two electrodes like steel shell and an insulator.

This central electrode linked with supply of ignition coil. Also, it is well lined with outer steel shell which is grounded. There is small air gap among steel shell and central electrode, between which spark is generated. Usually, electrode is made by high nickel alloy so it can withstand with high heat and resistance. Also Read Manual Vs Automatic Transmission


It is simple electrical capacitor in which tow metal plate are divided by an insulating material with distance. Commonly, air is used as insulating material but for particular technical needs and some high quality insulating material is used. Also you want to know about Difference between Diesel and Petrol Engine

Working system of Magneto Ignition System

Working system of Magneto Ignition System is same as battery ignition system but in Magneto Ignition System Magneto is used to make energy except battery.

  • First when engine starts in system it help magneto to rotate which make a very high voltage.
  • Therefore, ignition capacitor connected in similar with contact breaker. One end of magneto is also grounded through contact breaker.
  • Wherever the breaker open, current flows into condenser, which charged the condenser. And cam control contract breaker.
  • As condenser is acting like charger the primary current falls and magnetic field fall down in the system. This will make much higher voltage in condenser.
  • Now this high voltage in condenser will act as an EMF thereby spark produce at correct spark plug through distributor.

At starting, engine speed is low and current generated by magneto is quite small. As engine speed high then flow of current also high. Thus with magneto ignition system there is always starting problem and sometimes for stating separate battery needed. This ignition system is suited at high speed so it is used in aircraft engines, racing cars etc.

Advantages and Disadvantages of Magneto Ignition System

Main advantages of Magneto Ignition System over other ignition system do not require any external source to generate energy. On other hand, it is managed at low tension and high tension. In high tension, more amount of voltage is creating using in step-up transformer also can be used for engines like airplane engine. And low tension can manage this voltage it flows in smallest part of wiring and this avoids outflow too.

  • This system is more useful at medium and high speed
  • It is useful because no battery is used
  • It needs maintenance less


  • It has starting problem due to low rotating speed of engine while starting
  • It is more expensive when measure up to battery ignition system
  • There is risk of misfire due to leakage because variation of voltage in wiring can occur high voltage