CB350 / CL350 / SL350 Spark Plugs

Spark plugs are available in various heat ranges. Select plugs from a heat range that suits the load and temperature conditions under which your bike will be run. As a rule of thumb, use the highest numbered plug that will not foul.

We recommend the BR8ES (NGK) Spark plug

As of January 2020, NGK has discontinued the B8ES and superseded with the BR8ES. The BR8ES is a resistor plug, which is designed to reduce electromagnetic interference of ignition systems for things like radios and phones while used in automotive applications. It is the new replacement plug for our vintage Honda motorcycles and performs just like the older B8ES spark plug. More info about resistor plugs can be found on the NGK FAQ page.

http://www.common-motor.com/honda-spark-plug-ngk

Spark Plug Gap Specification : 0.7 - 0.8 mm (0.028 - 0.032 in.)

Adjusting Plug Gap :

Adjust the gap by bending only the outside negative electrode. Use a Spark Plug Gap Gauge to check if the distance is correct.

Removal of Spark Plugs :

1 ) Blow any debris that has collected in the spark plug wells to prevent it them from falling into the cylinders while the plugs are removed.

2 ) Gently remove the electrical leads. Don't jerk them, as the wires may disconnect from the insulator boots.

3 ) Back out the plugs with a socket.

Inspection :

The normal color of a spark plug tip ranges from a light tan to a chocolate brown. If the old plugs are to be used again, check them for deposits on the electrodes, cracked insulators, damaged threads or eroded electrodes. If any one plug is found to be unsatisfactory, discard the set.

• Abnormal Tip Conditions 

• • Black Carbon Deposit 
    • Fuel mixture too rich
    • Dirty air filter
    • Prolonged ideling
    • Low heat range
  • Oil Fouling (Wet Tip)
    • Worn pistons or rings
    • Timing off
    • Loose plug
    • Worn valve guides
  • White Crust
    • Fuel mix too rich
    • Timing off
    • Loose plug
    • Hot heat range

Cleaning :

You can clean your spark plugs with a simple wire brush and solvent.