| Specification | Detail |
|---|---|
| Production Years | 2017 – Present (PE07 Series) |
| Engine Oil | Pro Honda GN4 SAE 10W-30 (API SG, JASO MA) |
| Oil Capacity | 1.04 L (2017–2020) / 1.10 L (2021–Present) |
| Front Tire | 90/90-21 54M |
| Rear Tire | 120/90-18 65M |
| Tire Pressure | 1.0 bar (15 psi) F/R |
| Battery | Eliiy Power HY85S-P (Lithium-Ion) |
| Spark Plug | NGK SILMAR9A9S |
A pivotal moment in Honda’s off-road history occurred in 2017 with the introduction of the PE07 series. Unlike previous conversions, the CRF 450 RX was the first time Honda engineered a dedicated “closed-course cross-country” weapon directly alongside the CRF450R motocrosser. This resulted in a machine that retained the aggressive Unicam engine architecture but integrated a pioneering 8.5-liter resin fuel tank and a specialized 18-inch rear wheel for superior compliance on technical terrain.
Engineering Overview
The Honda CRF 450 RX is built upon the high-performance PE07 chassis. At its heart lies the 449cc liquid-cooled single-cylinder Unicam engine. The engine’s mapping is specifically tuned for the RX to provide a smoother power delivery compared to its MX sibling, essential for maintaining traction in enduro and GNCC-style racing. The transition to a Lithium-Ion battery (Eliiy Power HY85S-P) in later iterations significantly reduced top-heavy weight, enhancing the bike’s flickability in tight woods.
Maintenance Guide & Technical Specs
Lubrication System
Correct lubrication is critical for the high-revving Unicam valvetrain. Honda recommends Pro Honda GN4 SAE 10W-30. Note the capacity change between generations: 2017–2020 models require 1.04 Liters, while the updated 2021–Present models require 1.10 Liters. Always check the oil level with the bike upright on level ground after a 3-minute warm-up.
Ignition & Electrical
The RX utilizes a high-performance NGK SILMAR9A9S iridium spark plug. This plug is designed to withstand the extreme heat cycles of off-road racing while providing a consistent spark for the fuel injection system. The electrical system is supported by the Eliiy Power HY85S-P battery, which requires a dedicated Lithium-compatible charger to maintain longevity.
Tires and Traction
For optimal cross-country performance, the PE07 uses a 21-inch front (90/90-21) and an 18-inch rear (120/90-18). The 18-inch rear wheel is a signature RX feature, allowing for a taller tire sidewall which improves bump absorption. The standard recommended pressure is 1.0 bar (15 psi) for both ends, though riders may adjust based on terrain (e.g., lower for mud, higher for rocky high-speed sections).
Expert FAQ
Q: Can I use 10W-40 oil instead of 10W-30?
A: While 10W-40 is acceptable in hotter climates, Honda specifically recommends 10W-30 (JASO MA) for optimal flow through the internal oil jets that cool the piston under-crown.
Q: Why does the 2021+ model take more oil?
A: The 2021 redesign featured a new hydraulic clutch and updated crankcase internals, necessitating the slight increase to 1.10 Liters for total system lubrication.
Q: What is the benefit of the NGK SILMAR9A9S plug?
A: The “SIL” prefix denotes a laser-welded Iridium center electrode and a Platinum ground electrode, offering maximum durability and resistance to fouling during low-speed technical maneuvers.