Yamaha EF3000iSE, EF3000iSEB Spark Plug

  • These spark plug service and replacement procedures apply to Yamaha EF3000iSE and EF3000iSEB inverter generators.

A spark plug is an electrical device inserted in the cylinder head of an internal-combustion engine. It delivers electrical current from the generator’s ignition system to the combustion chamber. An electric spark emits between the electrode gap—from the centre electrode to the ground electrode. The electric energy transmitted through the spark plug gap ignites the explosive air and fuel mixture so as to convert energy into power.

Spark plug maintenance

Periodic spark plug maintenance is important. If a spark plug does not fire properly various generator issues will arise. If the spark plug is not replaced it will deteriorate over time and cause possible engine damage. Spark plug upkeep is key to good performance and fuel efficiency. The factory maintenance interval chart advise to check, adjust and clean the spark plug every 3 months or after 50 operating hours, whichever comes first. Replace a worn or damaged spark plug if necessary.

Spark Plug Maintenance Interval for Yamaha EF3000iSB EF300iSEB Gas Generator
*: Items related to the emission control system.

Spark plug service

Do not perform repair work or routine maintenance around the cylinder head until the engine has completely cooled down. Before the spark plug is removed, put on safety goggles and use compressed air to blow the cylinder head cover clean of dirt and debris that could potentially enter the spark plug hole while it is removed.


  1. Remove panel (12). See illustration.

    How to remove spark plug EF3000iSE EF3000iSEB EF 3000 EF3000 iSE iSEB
    Remove panel marked (12).
  2. Detach spark plug cap and extract spark plug.
  3. Inspect spark plug electrode (1) for damage or wear. Check insulator color (2). The insulator should be brown or grayish-tan around the side electrode.

    Inspect spark plug for worn electrode or damage and insulator color. Measure gap.
    (1) Electrode. (2) Insulator.

Measure gap:

When replacing a spark plug be sure to gauge the opening between the ground electrode and centre electrode.

  1. Use a spark plug cleaner, wire brush or spray-on spark plug cleaner, if necessary.
  2. Use a feeler gauge or a coin-style spark plug gap gauge to measure gap thickness.
  3. Adjust gap if needed.

    Yamaha EF3000iSB EF3000iSEB spark plug gap.
    Spark plug gap: 0.7 ~ 0.8 mm (0.028 ~ 0.031 in)


Before installing the generator’s spark plug, clean the plug surface and gasket surface. To prevent cylinder head damage, finger tighten (a) spark plug before using a torque wrench to tighten it to its specified torque (b).

  1. Install spark plug.
  2. Install spark plug cap.

    Torque spec spark plug Yamaha generator EF3000iSB EF3000iSEB
    Torque plug: 18 Nm (1.8 m · kg, 13 ft · lb)
  3. Reinstall panel (12).

Spark plug type

Yamaha spark plug size and brand for generator

The manufacturer requires the spark plug to be replaced with a NGK BPR4ES standard spark plug. Do not install the wrong type of plug. A plug that is too long could result in serious engine damage.

Richard Potter

Hi, I'm Richard, small engine mechanic with a combined 20 years experience in small engine service and repair. I fix everything from all-terrain vehicles, dirt bikes, scooters, and, generators, both gas, and diesel. Have a mechanical issue? Submit a detailed description of the problem in the comment box below. I will answer it ASAP.

Leave a Reply

Your email address will not be published. Required fields are marked *