Service manual

G420F(FE) Service Manual Chapter 4. Engine Electrical System 125
3. Check the spark plug as below.
1) Insulator broken
2) Terminal worn
3) Carbon deposit
4) Gasket damaged or broken
5) Porcelain insulator of spark plug clearance
4. Check the plug clearance using a plug clearance
gauge and if the value is not within the specified
values, adjust it by bending the ground clearance.
When installing a new sparkplug, install it after
checking the uniform plug clearance.
Spark plug clearance 0.7~0.8mm
5. Install the spark plug and tighten it to the specified
torque.
Take care not to over tighten it to prevent cylinder
head threads from damage.
Tightening torque 2~3kg·m
Spark Plug Analysis
State
Contact point is
black
Contact point is
white
Description
• Density of the
fuel mixture is
thick
• Density of the
fuel mixture is thin
• Lack of air
intake
• Ignition timing is
fast
• Spark plug is
tight
• Lack of torque