1. Magneto Ignition Systems

2. 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

3. 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.

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

5. Different Types • MBI – Mechanical Breaker Point Ignition • CDI – Capacitive Discharge Ignition • TCI – Transistor Controller Ignition

6. 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.

7. 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.

8. MBI in Use Image courtesy of http://web.telia.com/~u85306919/1912.jpg

9. 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.

10. 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.

11. CDI in Use Image courtesy of www.dansworkshop.com

12. 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.

13. 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.

14. TCI in Use

15. 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.

16. Image courtesy of http://home.howstuffworks.com/how-to-repair-small-engines3.htm

18. 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?

19. 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?

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