Ignition SystemHigh Voltage Components

Objectives Understand the parts and operation

of spark plugs Understand the Kill Switch How to identify spark plugs

Spark Plug Wire And Spark Plug Spark Plug Wire

• Used to transfer electricity from secondary winding to spark plug

Spark Plug• The part that

receives electricity and transfers it into a spark in the combustion chamber

Spark Plug Construction Terminal

• Connects the Magneto to plug

Insulator • Ceramic covering to

prevent leaked electricity Electrode

• Center of the sparkplug that transfers the electricity

Ground electrode • provides a gap for the

spark to jump and allow combustion

Flashover When Electricity

escapes the plug• Happens when the

sparkplug is too wet or dirty

Electric current can jump from the terminal to the ground plug • The Distance that the ribs

provide between the two prevents most flashover

Can caused a fouled spark plug

Plug Operation Electric enters the spark

plug and goes down the terminal jumps to the ground terminal.

The plug only sparks when it comes in contact with the fuel mixture

Plug gaps • The smaller the gap the less

voltage needed and vise versa As a engine gets older it will

build up oil and corrosion causing a higher voltage to spark

Kill Switch In order to stop an

engine power must be removed • The best way to do this is

remove the combustion Kill switches are used to

remove the spark • Small engines have the

kill switch connected to the ground wire

• When of there is no connection between the ground and magneto removing the complete circuit

Plug Heat Range Spark plugs can

reach temperatures above 2,000o F• At high temp the end

will glow red and ignite the mixture at the wrong time Loss of Power

• At low temp. Oil and residue will not burn off Fouled Plug

Plug Types J Gap Surface Gap Retracted Gap Plugs are coded by

their size and type of gap and size of threads

Safety Interlocks Used to kill the

equipment during unsafe conditions

On a riding lawnmower when the blade is on, getting of the mower will kill the engine

Releasing the handle form the walk behind • Kill switch and safety

interlocks are the same in our engines