From high-speed NGPC and WORCS tracks to the technical woods riding of GNCC, the CRF450RX is a versatile, yet refined machine that is perfectly equipped for the variety of terrain found in closed-course off-road racing. To improve corner-exit acceleration and handling, the this model receives the same chassis and engine updates as its motocross-focused relative, the CRF450R. Built with off-road specific features like dedicated ECU and suspension settings, an 18-inch rear wheel, an aluminum side stand, a large 2.1-gallon fuel tank and hand guards, the championship-proven CRF450RX is ready for the track or trail, which is why it’s the motorcycle of choice for a variety of off-road racers, including the SLR Honda and JCR Honda teams.
UPDATES FOR 2023
- Narrower intake-port shape and longer intake funnel, for improved engine response and torque, resulting in improved acceleration on corner exits.
- Cam profile is changed, further increasing torque.
- Throttle body diameter is reduced from 46 mm to 44 mm, for smoother power deliver at low speeds.
- Frame rigidity optimized by increasing material thickness at joint where horizontal braces meet down tube, and at upper shock mount, enabling freer functioning of front and rear suspension.
- Engine hangers changed from aluminum to steel, to match frame changes and improve front traction.
- Because changes to frame rigidity allow freer suspension movement, shock damping could be made stiffer without introducing harshness.
- Fork setting changed to match rear suspension and ensure front/rear balance.
- Muffler is quieter thanks to change of inner-pipe design. Switch of aluminum material (A6061-T6) of muffler body increases strength without increasing overall weight.
- Radiator shroud graphics feature new HRC logo.
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 12 mm 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 and for a strong-but-manageable power delivery on corner exits, for example, as well as resistance to stalling. For 2023, engineers followed the direction of Team Honda HRC by updating the cam profile for better low-end torque. As before, the cylinder head cover is magnesium, with a thin-wall design for weight savings.
Intake: The CRF450RX features a downdraft intake design that delivers strong, efficient power, and a large air boot (4.1 liters on the clean side of the air filter) achieves in strong torque at low rpm. Following feedback from HRC, the throttle body has a smaller diameter (44 mm instead of 46), for smoother power delivery at low speed. In addition, the intake port has a narrower shape, while the air funnel is longer, a combination that results in increased low-end torque and improved throttle response. The air box 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, optimizing exhaust efficiency and torque characteristics. With the engine’s central exhaust-port location, the exhaust header and muffler are positioned close to the vehicle’s centerline for a slim profile, contributing to freedom of movement for the rider. For 2023, the muffler has a new inner-pipe design to reduce noise without affecting power or weight (the entire system weighs 8.5 pounds). In addition, the muffler body is now made from a new aluminum material called A6061-T6, which is five times more resistant to impacts. As before, two resonators (one after the front U-bend and another at the upstream end of the muffler) boost power and reduce 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: 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 an all-new handlebar-mounted switch, enabling simple tuning depending on rider preference or course conditions.
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. The three different modes differ in drive-management level, for differing riding conditions or rider preferences:
- Mode 1: The system intervenes most lightly 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 CRF450RX’s handlebar-mounted switch allows selection between three modes, depending on conditions and rider preference. The HSTC system can also be switched off completely.
HRC Launch Control provides the best option for a strong start and also has 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
The Engine Mode Select Button (EMSB) alters the engine’s characteristics and three maps are available to suit riding conditions or rider preference:
- Mode 1: Standard
- Mode 2: Smooth
- Mode 3: Aggressive
CHASSIS / SUSPENSION
The motorcycle’s heavier components are positioned centrally and as low as possible for precise cornering without sacrificing high-speed tracking, and to achieve minimal squat under acceleration and negligible pitching during hard braking. For 2023, updates to the suspension settings and frame improve stability and turning.
Frame / Swingarm / Subframe: The frame uses narrow main spars and features optimized reinforcement ribbing on the backside of the pivot plate, contributing to the low frame weight of just 18.5 pounds. For 2023, frame rigidity has been optimized by increasing the thickness of the aluminum material at the joint where the twin horizontal braces meet the down tube, from 4 mm to 6 mm. Similarly, the material at the upper shock mount has been increased from 4 mm to 6 mm. These changes allow the front and rear suspension components to move more freely and avoid binding, improving stability and bump absorption. In addition, the engine hangers are now made from steel instead of aluminum, a switch that works with the revised frame rigidity to improve front traction.
As before, the subframe features a simple design that weighs just 2.0 pounds. The swingarm is narrow, providing good clearance in ruts, with rigidity tuned to maximize rear traction and cornering.
Suspension: As before, the Pro-Link® rear-suspension system uses a Showa shock absorber with adjusters on the right side and an ultra-light steel shock spring. Because of the updates to the frame rigidity, the shock now moves more freely, which allowed the switch to a stiffer spring rate (from 54N/mm to 56N/mm) without introducing harshness. Hold-up is improved as a result, for better performance in ruts.
Front suspension comprises a 49 mm inverted Showa® coil-spring fork and a gas-liquid separation structure. For 2023, the fork setting has been updated to the changes to the shock, for proper front-rear balance. The upper and lower triple clamps are designed to offer a good rigidity balance for optimum handling and feel through corners.
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 rugged AT81 tires, designed for all around performance across a variety of off-road terrain.
DESIGN
As before, both versions of the CRF450RX have slim bodywork, with a smooth junction of the radiator shroud and side panel, facilitating rider movement and cornering. Each radiator shroud is produced in a single piece instead of two separate parts, and Computational Fluid Dynamics (CFD) were used to design air-outlet vents in the shrouds. The radiator grills optimize the number of fins and their angle, maximizing cooling performance.
The seat base has rearward-facing tongues and front-located mounting tabs, easing installation, and using acceleration forces to keep the seat securely in place. The larger polyethylene fuel tank holds 2.1 gallons
Only eight fasteners are used to secure all of the main bodywork components—both radiator shrouds, both side panels and the seat, and all of the bolts for the main bodywork parts have 8 mm heads, simplifying maintenance.
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 26 mm.
Off-Road Features: The CRF450RX comes with a number of off-road-focused features that set it apart from its motocross-focused CRF450R sibling.
Softer suspension settings enhance performance over rocks and roots while the dedicated ECU map optimizes power delivery for low-traction off-road conditions. The 18-inch rear wheel allows for a taller tire sidewall, improving compliance over rough terrain and the 50-tooth rear sprocket (compared to the R's 49) adapts the gearing for increased torque. A 2.1 gallon resin tank increases range between fuel stops.
Lightweight plastic handguards provide knuckle coverage from brush and roost and can be easily removed. The CRF450RX is also equipped with a forged-aluminum side stand for convenient on-trail parking.
