With an ideal blend of motocross performance and trail-focused features, the CRF450RX is a highly capable machine for closed-course off-road series like GNCC, NGPC and WORCS. With features like a larger nylon fuel tank, handguards, a side stand and dedicated suspension and ECU settings, this motorcycle is a popular choice with teams like SLR Honda, Phoenix Racing Honda and JCR Honda.
HISTORY
Introduced for model-year 2017, the CRF450RX was based on the CRF450R motocrosser but developed for closed-course off-road racing. The model was updated for 2019, with a new cylinder head, a refined oil-management system, new ECU settings, HRC launch control, a Renthal® Fatbar® handlebar, black rims and redesigned fork protectors. For model-year 2021, the CRF450RX benefited from improved power and handling, plus the addition of handguards and a revised fuel tank. Honda gave most of the CRF Performance family a makeover for 2025, with updates to the CRF450RX focused on chassis-rigidity optimization, plus a new airbox, header pipe, ECU mapping, suspension valving and bodywork.
OFF-ROAD-SPECIFIC FEATURES
Compared to the CRF450R motocrosser, the CRF450RX has the following differences:
- A resin 2.1-gallon fuel tank (instead of the R model's 1.7-gallon titanium cell) provides enough range to compete in closed-course off-road competition.
- Front and rear suspension have dedicated settings developed specifically for the closed-course off-road application, for good compliance over technical terrain like rocks and roots.
- The CRF450RX's ECU features a different fuel-injection map, with settings that deliver a smooth spread of power, maximizing traction in slippery, off-road conditions.
- Whereas the CRF450R has a 19-inch rear wheel, the CRF450RX has an 18-inch rear wheel, for a taller tire sidewall that better absorbs obstacles typically encountered off-road. In addition, front and rear tires are Dunlop Geomax AT81, which offer all-around performance, plus high levels of ruggedness for off-road racing and riding.
- The CRF450RX comes standard with plastic hand guards, to help fend off trailside bushes and brush.
- A 50-tooth rear sprocket (compared to the R's 49) adapts the gearing for technical off-road conditions.
- The model also has an aluminum side stand, which facilitates parking away from the pits but tucks out of the way when not in use.
STYLING / DESIGN
The standard CRF450R is known for its excellent ergonomics; the CRF450RX retains those, but adds features designed specifically for closed-course off-road racing. The radiator shrouds and side plates promote freedom of movement thanks to a smooth, flat surface, and although the bike is notable for its slim profile, the side-plate profile is wide enough to provide good contact for gripping the bike. Cooling the CRF450RX's engine is crucial to maintaining performance and overall durability. Computational fluid dynamics were used to design the air-outlet vents in the shrouds, and the radiator grilles are optimized in terms of both the number of fins and the fin angle. Each radiator shroud is produced in a single piece. The 2.1-gallon fuel tank is made of resin.
The seat base has rearward-facing tongues and front-located mounting tabs, an arrangement that eases installation, and acceleration forces keep the seat securely in place. Maintenance is simple, with only eight fasteners used to secure the main bodywork components, including the radiator shrouds, side plates and seat, all with 8mm bolt heads.
A single switch cluster addresses several functions: engine stop, ride-modes and Honda Selectable Torque Control (HSTC). The starter and HRC launch control are on the right side of the Renthal® Fatbar® handlebar. There are two locations for the handlebar clamp, and the clamp can be turned 180º; as a result, four different mounting positions are possible, through a range of 26mm.
ENGINE / DRIVETRAIN
The CRF450RX engine boasts exceptional bottom-end and midrange power and torque, making for a linear delivery that is strong but manageable, even as the rider tires, while peak power is also very good. A five-hole piston oil jet and dual 12mm drum scavenge pump manage lubrication.
Cylinder Head
The design of the Unicam® cylinder head, with the decompressor system's counterweight on the left end of the camshaft, contributes to combustion stability in the extremely low rpm range for strong-but-manageable power delivery on corner exits, as well as resistance to stalling. The cam profile is optimized for low-end torque. The cylinder-head cover is magnesium, with a thin-wall design for weight savings.
Intake
The airbox has a direct pathway for airflow, resulting in precise throttle control and excellent top-end power. A large air boot (4.1 liters on the clean side of the air filter) achieves strong torque at low rpm. Following feedback from HRC, the 44mm throttle body ensures smooth power delivery at low speed. In addition, the narrow intake-port shape and long air funnel result in strong low-end torque and crisp throttle response. The airbox is accessed with the removal of a single side-panel bolt. The 60º fuel-injector angle enables the spray to reach all the way to the back of the butterfly, thus cooling the upstream side of the intake path for maximum intake efficiency and torque feel.
Exhaust
The engine's exhaust port is centrally located, has an oval shape and is very straight, creating efficient, usable power in the low-to-mid rpm range. The centralized exhaust-port location enables the exhaust header and muffler to be positioned close to the vehicle's centerline for a slim profile, contributing to freedom of movement for the rider. The muffler is constructed with strong A6061-T6 aluminum for impact resistance and weight savings. A dual-resonator design optimizes power, while simultaneously minimizing noise.
Clutch
The clutch is hydraulically actuated and has eight plates and a large volume for good durability, with minimal slippage and light lever pull.
Electronics
To mimic what Honda-supported off-road teams were seeking, the signature Unicam engine uses selectable ECU maps that offer a smooth delivery while also delivering strong torque and power throughout the rev range.
A gear-position sensor allows the use of three specific ignition maps for first and second, third and fourth, and fifth gears. There are options for Standard, Smooth and Aggressive ignition maps, selectable via a handlebar-mounted switch, enabling simple tuning depending on rider preference or course conditions.
- Mode 1: Standard
- Mode 2: Smooth
- Mode 3: Aggressive
In addition, Honda Selectable Torque Control offers three levels of intervention. HSTC monitors rpm spikes and responds by temporarily reducing torque by retarding ignition timing and controlling PGM-FI to aid rear traction. A handlebar-mounted switch allows selection between modes, depending on conditions and rider preference. The three different modes differ in drive-management level, for differing riding conditions or rider preferences:
- Mode 1: The system intervenes the least and waits the longest to do so—useful for reducing wheel-spin and maintaining control in tight corners.
- Mode 2: A midpoint between modes 1 and 3 in terms of how quickly and assertively the system intervenes.
- Mode 3: The system intervenes most quickly and assertively, which helps in conditions that are slippery or muddy.
The HSTC system can also be switched off completely.
HRC Launch Control provides options for a strong start, with three modes to choose from:
- Level 1: 9,500 rpm, for high-traction conditions and/or advanced riders.
- Level 2: 8,500 rpm, for high-traction conditions and/or average riders.
- Level 3: 8,250 rpm, for slippery conditions and/or novice riders.
CHASSIS / SUSPENSION
The standard CRF450R is known for its precise handling and overall rideability; those characteristics, which are also welcome in the gnarly conditions encountered in closed-course off-road competition, carry over to the CRF450RX.
Frame / Subframe
The mainframe contributes to a comfortable and confidence-inspiring ride. Optimized torsional rigidity contributes to overall stability, while an ideal torsional/lateral rigidity ratio allows for precise cornering. Vertical torsional rigidity is designed to enhance stability in rough track conditions.
Perhaps counterintuitively, a relatively high overall frame rigidity helps give the model a compliant, composed ride character. As with the standard CRF450R, the subframe mounting point is positioned at a rigid location on the mainframe, minimizing energy transmission from the rear of the motorcycle to the front, contributing to excellent stability and comfort.
Suspension
The 49mm inverted Showa coil-spring fork features kit-fork-inspired Bending Control Valves, and provides a consistent feel throughout the stroke, from initial movement to full compression, minimizing any harsh sensations. The outer fork tubes were developed in tandem with the steering stem and front axle to optimize rigidity for excellent bump-impact absorption and front-end feel, resulting in a comfortable, controlled ride.
The rear Pro-Link system has excellent bottoming resistance while preserving comfort over small bumps. The shock spring, reservoir, shaft and oil seal are designed to ensure a smooth, consistent feel throughout the stroke, complementing the frame and fork rigidity for an overall balanced performance. The shock absorber is easy to remove for service and adjustment, only requiring the removal of the side panels, muffler and ECU.
Wheels
Black D.I.D rims deliver durable performance and good looks. Petal-style brake rotors disperse heat, and a low-expansion front brake hose gives strong feel and consistent stopping power. The CRF450RX comes with Dunlop's AT81 tires, designed for all-around performance across a variety of off-road terrain.
Brakes
The front-brake caliper was developed based on feedback from Honda HRC Progressive riders, and it features two pistons (sized 30mm and 27mm), allowing for a smooth, linear feel that's consistent throughout the race. The caliper also features machined accents. The rear brake has a single piston. The brake rotors (sized 260mm front, 240mm rear) have a petal design to disperse heat.
