NGK
Racing Spark Plug

NGK 4015 Spark Plug

Brand NGK 4015
Resistance 5000
Ground Electrode Tip Design Standard
Ground Configuration Standard
Ground Electrode Core Material Nickel
Electrical Terminal Type Non-removable nut
Center Electrode Core Material Copper
Center Electrode Tip Material Nickel
Pre-Gap Size .024
Ground Electrode Quantity 1
Hex Size 13/16
Insulator Height 55.00
Manufacturer Heat Range 9
Seat Type Flat
Reach .75
Thread Diameter 14.00
Part Number Br9eg solid
Stock Number 4015
Product line Racing Spark Plug
Fits Yamaha · 8 vehicles

Copper core. Promotes stable ignition performance in demanding racing use.

Pre-gapped. Specified at 0.024 inch for the listed application.

Racing plug. Built for secondary ignition service in performance applications.

Cross-references CSF 4015 for the same application. See all 1.

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Overview

NGK Racing Spark Plug 4015 is a performance ignition component built around a copper core center electrode, nickel tip materials, and a standard ground electrode design. It is specified with a 0.024-inch pre-gap and a 5000 resistance value for race kart applications.

Fits 1992-1993 Yamaha YZ125, N/A and fits 1999-2004 Yamaha YZ125, N/A. This NGK YZ125 spark plug is identified by part number 4015 and BR9EG SOLID.

Key Features

  • Copper core center electrode for stable ignition performance.
  • Nickel center and ground electrode tip materials.
  • 0.024-inch pre-gap for the listed application.
  • Standard ground configuration with a flat seat design.
  • 14 mm thread diameter, 0.75-inch reach, and 13/16-inch hex size.

Detailed Description

NGK 4015, also listed as BR9EG SOLID, is a racing spark plug with a non-removable nut terminal and a manufacturer heat range of 9. The standard ground electrode layout and single ground electrode design support consistent spark delivery in demanding secondary ignition use. For buyers searching for a Yamaha YZ125 spark plug or NGK 4015 replacement, this part matches the listed race kart fitment and gap specification.

Common Uses

  • Replacing a worn or fouled racing spark plug.
  • Restoring consistent ignition in race kart use.
  • Addressing misfire caused by incorrect plug gap.
  • Replacing a plug with the wrong heat range or reach.

Installation Notes

Verify the thread diameter, reach, seat type, and pre-gap before installation. Confirm the application matches the listed Yamaha YZ125 fitment and use the specified 0.024-inch gap for the intended setup. Check the ignition system condition and cylinder head threads during service.

This part fits 8 vehicles
Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
YearMakeModelLitersCylindersNotes
2004YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
2003YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
2002YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
2001YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
2000YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
1999YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
1993YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
1992YamahaYZ125-L--Race Kart; Gap 0.024"; Racing Spark Plug
Directly replaces or cross-references 1 part number
Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.
CSF — 4015