NGK 2120 Spark Plug

NGK D8EA Standard Spark Plug

The NGK D8EA standard spark plug is built for dependable ignition performance in a wide range of motorcycle, marine, and small engine applications. As part of NGK’s Standard Spark Plug line, it uses a copper core center electrode with nickel tip materials and a standard ground electrode design for consistent spark delivery.

For buyers searching for an NGK spark plug replacement, part number 2120 offers OE-style construction and the fitment characteristics needed for engines that call for a 12 mm thread, flat seat, 0.75 reach, and 18 mm hex. It is a practical choice for routine ignition service on applications such as Honda motorcycle and Yamaha motorcycle models that specify the D8EA plug.

Key Features

• NGK Standard Spark Plug line for everyday ignition service
• Part number 2120, also identified as D8EA
• Copper center electrode core for stable conductivity
• Nickel center and ground electrode tip materials
• Standard ground configuration with one ground electrode
• 1 ohm resistance for ignition system compatibility
• 12.00 mm thread diameter, .75 reach, and flat seat design
• Pre-gapped at .028 for applications that call for this specification

Product Details

NGK has long supplied original equipment spark plugs for domestic and import vehicles in North America, and that OE background is reflected in the D8EA’s straightforward construction and dimensional accuracy. The plug’s heat range 8 specification, stud terminal, and standard electrode layout make it a direct-service replacement where the engine calls for this exact configuration. If you are cross-shopping ignition parts for Honda motorcycle or Yamaha motorcycle maintenance, NGK 2120 is a common reference point for the D8EA application.

This part cross-references DENSO Auto Parts 4099 and Anchor 2120 for the same application.

Common Issues It Can Address

• Hard starting caused by worn or fouled spark plugs
• Rough idle from inconsistent spark output
• Misfire symptoms under load or at higher engine speeds
• Reduced throttle response from degraded ignition performance
• Service intervals where the original plug has reached wear limits

Installation Notes

Verify the engine calls for NGK D8EA / 2120 before installation. Confirm thread diameter, reach, seat type, and heat range against the service specification, then check the gap if your application requires a different setting than the .028 pre-gap. Use proper spark plug removal and tightening procedures to avoid thread damage in the cylinder head.

For fitment-based searches, this spark plug is a direct match for applications that specify the D8EA designation, including select Honda motorcycle and Yamaha motorcycle models. Always compare the part number and engine requirements before service.

Quality Assurance

NGK is a major OE spark plug supplier with more than 80 years of automotive experience, and the D8EA reflects that manufacturing focus on durability and consistent operation. Built to original-equipment standards, NGK 2120 is produced for reliable service across automotive, motorcycle, marine, and small engine applications.