| Attribute | Specification |
|---|---|
| Production Years | 2019–2020 |
| Engine Oil | Yamalube 4 (10W-40); API SG+; JASO MA (0.95 L) |
| Front Tire | 90/90-21 54M (1.0 bar / 15 psi) |
| Rear Tire | 130/90-18 69M (1.0 bar / 15 psi) |
| Spark Plug | NGK LMAR8G |
| Battery | HJTZ5S-FP-C (Lithium-Ion) |
The 2019-2020 Yamaha WR 450 F (internal codes CJ28W and BDB8) represents a pivotal moment in enduro engineering. While its predecessors were often viewed as ‘tamed’ versions of the YZ motocrosser, this generation utilized a unique reverse-cylinder-head engine architecture. By positioning the intake at the front and the exhaust at the rear, Yamaha engineers achieved a centralized mass profile that remains a benchmark for handling in tight, technical terrain.
Technical Analysis: Engineering the CJ28W
The CJ28W iteration saw a complete overhaul of the bilateral beam frame, specifically tuned for enduro flex characteristics. Unlike the rigid YZ450F frame of the same era, the WR 450 F’s chassis was designed to absorb the high-frequency vibrations of off-road trails while maintaining precision. The integration of the 449cc liquid-cooled DOHC engine with the smartphone-enabled Power Tuner app allowed riders to adjust fuel mapping and ignition timing wirelessly—a first for the enduro class.
Maintenance Guide & Fluid Specifications
Maintaining the high-performance nature of the WR 450 F requires strict adherence to fluid intervals. The engine utilizes a semi-dry sump lubrication system. For standard oil changes, 0.95 Liters of Yamalube 4 (10W-40) is required. Ensure the oil meets JASO MA standards to protect the wet multi-plate clutch system.
Ignition and Electrical System
The CJ28W uses a high-efficiency NGK LMAR8G spark plug. Due to the compact nature of the reverse-head design, access to the plug requires removal of the fuel tank. For the electrical system, Yamaha transitioned to a lightweight HJTZ5S-FP-C Lithium-Ion battery, which significantly reduces the bike’s center of gravity but requires a LiFePO4-compatible charger for maintenance.
Tires and Traction
The factory-specified tire sizes are 90/90-21 for the front and 130/90-18 for the rear. For optimal enduro performance across mixed terrain, a standard pressure of 1.0 bar (15 psi) is recommended. Riders in extreme rocky conditions may drop this slightly, though rim locks must be inspected regularly to prevent tube shearing.
Editor’s Verdict
The Yamaha WR 450 F (2019-2020) is a masterclass in mass centralization. It offers the raw power of a 450cc motocrosser with the finesse required for the world’s toughest trails. For the owner, meticulous maintenance of the air filter and frequent oil changes are the keys to longevity for this high-revving power plant.