Magneto Ignition Systems

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Magneto Ignition Systems
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Table of Contents

• I. Introduction to Magneto Ignition Systems
• What are Magneto Ignition Systems?
• What are the different uses for the Systems?
• II. Different Types of Systems
• MBI
• CDI
• TCI
• III. Summary
• IV. Review Questions

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What are Magneto Ignition Systems?

• The purpose of an ignition system is to provide
  sufficient electrical voltage to discharge a
  spark plug at precisely the right time to ignite
  highly compressed air-fuel mixture.
• Magneto Ignition systems provide current for
  ignition without any outside primary source of
  electricity.

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Different Uses

• The primary uses for Magneto Ignition systems are
  in small gasoline powered engines such as lawn
  mowers.

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Different Types

• MBI Mechanical Breaker Point Ignition
• CDI Capacitive Discharge Ignition
• TCI Transistor Controller Ignition

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Mechanical Breaker Point Ignition

• One of the types of ignition systems, the MBI
  system uses a Condenser to prevent current from
  arcing across the breaker point gap as the points
  open.

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Advantages to MBI

• MBI does not require a primary source of
  electricity in order to produce ignition in the
  engine.
• Through the use of the Flywheel and the
  condenser, a continuous current is generated and
  can be easily broken for stopping purposes by use
  of the condenser.

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MBI in Use
Image courtesy of http//web.telia.com/u85306919/
1912.jpg
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Capacitive Discharge Ignition

• CDI is a solid state ignition system, it is one
  of the newest ignition systems used today.
• CDI is breakerless and the moving mechanical
  parts are replaced with electronic components.
• The only moving parts are the magnets attached to
  the Flywheel.

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Advantages to CDI

• CDI is very easy to troubleshoot, by turning the
  flywheel and watching the sparkplug gap for a
  spark.
• CDI is compact and maintenance free since the
  only moving parts are the flywheel magnets.

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CDI in Use
Image courtesy of www.dansworkshop.com
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Transistor Controller Ignition

• As the Flywheel magnets rotate they pass by the
  ignition coil in the system.
• The magnetic field of the magnets induce current
  in the primary windings of the ignition coil
  creating the charge for the spark.

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Advantages to TCI

• As with CDI, the only moving parts are the
  magnets on the flywheel.
• The timing of TCI is more precise with the use of
  the Transistors.
• Does not use Mechanical Breaker contacts, but
  utilizes semi-conductors instead.

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TCI in Use
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Summary

• The primary purpose of the ignition system is to
  provide sufficient voltage to discharge a spark
  plug.
• The three types of Magneto Ignition systems have
  advantages over the others but have different
  uses for each.
• Small engines most prominently use Magneto
  Ignition Systems for firing the ignition of the
  engine.

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Image courtesy of http//home.howstuffworks.com/ho
w-to-repair-small-engines3.htm
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Review Questions

• 1. Name three components of a CDI system.
• 2. What is the main purpose of the Condenser?
• 3. Which of the systems has the least amount of
  maintenance?
• 4. In the CDI system, what is the only moving
  part?

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Review Questions cont.

• 5. What is the main purpose of an Ignition
  System?
• 6. What does TCI stand for and what makes it
  different from the rest?
• 7. What is an advantage to using an MBI system?
• 8. How can you troubleshoot a CDI system?

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References

• Roth, Alfred C. Small Gas Engines. Tinley
  Park The Goodheart-Willcox Company, Inc., 2004.