Denso 4002 Spark Plug

U-Groove Spark Plug Design

This Denso spark plug uses a U-Groove ground electrode design to improve ignitability and support more efficient combustion. It is a conventional secondary ignition component for a wide range of small-displacement Yamaha, Kawasaki, and Honda applications.

• U-Groove ground electrode design for stronger ignitability.
• Copper center electrode core with nickel tip for stable spark delivery.
• Nickel ground electrode tip and standard ground configuration.
• Flat seat, 14.00 mm thread diameter, and 12.70 mm reach.
• Pre-gapped to 0.7 for straightforward service replacement.

Fitment and Application

Compatible with Yamaha XV250 V Star 250, 2008-2010. Compatible with Yamaha XC125 Riva 125, 1985-1989 and 1991-2001. Compatible with Kawasaki KLF110 Mojave, 1987-1988 and Kawasaki KLT110, 1986. Compatible with Honda Z50R, 1979-1981; Honda Z50A, 1972-1978; Honda C70M, 1971; and Honda PC50, 1970. Denso 4002 is also cross-referenced to DENSO Auto Parts U20FS-U for the same application.

What It Helps Address

• Hard starting caused by worn spark plug electrodes.
• Weak or inconsistent ignition performance.
• Rough running from degraded secondary ignition components.
• Reduced combustion efficiency in service-worn engines.

Installation Notes and Quality

Verify thread diameter, reach, seat type, and heat range before installation. Confirm the plug gap matches the engine specification if adjustment is required. Denso’s U-Groove Conventional line focuses on ignition efficiency through electrode geometry and durable electrode materials. Part number 4002 identifies this spark plug for ordering and fitment reference.