What Is a Magneto on a Small Engine

The magneto is a self-contained generator of high voltage that provides ignition to an engine through spark plugs. … The moment the contact points open, a rapid magnetic flow generates a high voltage in the secondary coil, which ignites the spark plug, thus firing the engine.

How do I know if my magneto is bad?

Holding the plastic handle of the screwdriver, bring the metal area of the screwdriver close to a metal part of the engine, being careful not to touch it. Have someone start the mower. If you don’t see a spark between the screwdriver and the engine, the magneto is bad.

What causes a magneto to fail?

The voltage generated across magneto coils is quite high, in the order of 20,000 volt if no spark plugs are in place. … The high voltage will simply arc across the gap. The gap will widen as the wire ends melt further apart and soon the adjacent turns will be affected so the coil will eventually fail.