| Quick Specs: Yamaha YZ 450 F (2018–2019) | |
|---|---|
| Model Code | CJ21C / BR92 |
| Engine Oil | Yamalube 4-S 10W-40 (0.69 L) |
| Spark Plug | NGK LMAR8G (Gap: 0.7–0.8 mm) |
| Front Tire | 80/100-21 51M (1.0 bar / 15 psi) |
| Rear Tire | 120/80-19 63M (1.0 bar / 15 psi) |
| Battery | Skyrich HJTZ5S-FP-YI (Lithium-ion) |
The 2018 release of the Yamaha YZ 450 F (CJ21C) marked a watershed moment in motocross history. It was the first production motorcycle to integrate a smartphone-based engine tuning system, allowing riders to adjust fuel and ignition mapping wirelessly via the Yamaha Power Tuner app. This leap in digital integration, paired with the unique rearward-slanted cylinder design, solidified Yamaha’s position as a pioneer in mass-centralized performance engineering.
Technical Overview: The CJ21C Revolution
Building on the “Reverse Cylinder” concept, the 2018–2019 models featured a completely redesigned frame, a more compact electric starter, and a lighter lithium-ion battery. The 449cc liquid-cooled DOHC engine was optimized for a more linear power delivery, while the KYB® Speed-Sensitive System (SSS) front forks remained the gold standard for suspension performance in the 450 class.
Maintenance Essentials
Lubrication System
The YZ 450 F utilizes a high-performance lubrication system that requires precise fluid management. For the CJ21C/BR92 generation, Yamaha specifies 0.69 Liters of Yamalube 4-S 10W-40. It is imperative to use oil meeting JASO MA standards to ensure the wet clutch operates without slippage. Due to the high-revving nature of this engine, oil changes should be performed every 7.5 to 10 hours of operation under racing conditions.
Ignition and Electrical
The ignition system relies on the NGK LMAR8G spark plug. Ensuring a precise gap of 0.7–0.8 mm is critical for consistent combustion under high compression. To support the electric start system without adding excessive weight, the bike utilizes a Skyrich HJTZ5S-FP-YI lithium-ion battery. Owners should use a lithium-specific charger to maintain the battery during off-season storage.
Chassis and Tires
For optimal traction and handling stability, the YZ 450 F is equipped with an 80/100-21 front and a 120/80-19 rear tire. While terrain dictates specific pressures, the factory baseline is 1.0 bar (15 psi) for both ends. Maintaining this pressure is vital for preventing rim damage and ensuring the tire carcass flexes as intended over obstacles.
MotoSpecsLab Editorial Verdict
The Yamaha YZ 450 F (2018–2019) remains a formidable machine on the used market and a favorite for amateur and professional racers alike. Its combination of technological innovation and mechanical reliability makes it a benchmark for the modern 450cc motocrosser. Proper adherence to the maintenance intervals outlined above is the key to preserving the “Blue Crew” performance legacy.