NGK 90398 LMAR8E-J Standard Spark Plug — 2020-2021 Yamaha WR250F & YZ250FX

NGK Spark Plugs — Precision Ignition, High-Performance Heat Transfer, and OEM Quality Reliability

Maintain the high-revving performance of your Yamaha competition machine with the NGK 90398 (LMAR8E-J) Spark Plug. Specifically engineered for the modern 2020-2021 Yamaha WR250F and YZ250FX, this plug features a long-reach threaded design and a projected center electrode. The "Factory Quality" construction ensures a perfect fit within the deep-seated cylinder heads of these advanced four-stroke engines, providing a consistent, powerful spark for maximum throttle response.

The LMAR8E-J is built with NGK's signature trivalent metal plating, which offers superior anti-corrosion and anti-seizing properties, making maintenance easier even after extreme heat cycles. Featuring a pure alumina silicate ceramic insulator for exceptional strength and better heat transfer, and a copper core to rapidly pull heat away from the tip, this plug prevents overheating and ensures longevity on the track or the trail. The unique double ground electrode configuration provides enhanced ignitability and durability under high-compression loads.

• Double ground electrode configuration for improved spark consistency and durability.
• Long 26.5mm thread reach specifically designed for modern Yamaha 250cc engine heads.
• Trivalent metal plating provides elite protection against corrosion and seizing.
• Copper core center electrode aids in rapid heat removal to prevent pre-ignition.
• Triple seals prevent combustion gas leakage for consistent engine compression.

Moto-House MX Pro Tip:

The 2020+ Yamaha WR250F and YZ250FX engines are high-performance tools that rely on precise ignition timing. Because these models use a specialized long-reach plug with a 14mm hex, always ensure you are using the correct thin-wall spark plug socket during installation. We recommend changing your LMAR8E-J plug every 15-20 hours of hard riding to ensure you aren't losing power to electrode wear. A fresh plug can be the difference between a first-kick start and being left on the line.

Year	Make	Model Fitment
2020-2021	Yamaha	WR250F
2020-2021	Yamaha	YZ250FX

FAQ Questions

Q) What is the correct spark gap for the LMAR8E-J?
A) This plug features a specialized 0.4mm (0.016") gap. Due to the double ground electrode design, use extreme care if you are checking or adjusting the gap to avoid damaging the electrodes.

Can I use a standard 5/8" or 16mm socket for this plug?
A) No, this plug requires a 14mm hex socket, and due to the tight clearance in Yamaha heads, a thin-wall socket is highly recommended.

 

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