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2021 Honda CRF450RX Dirt Bike Review Specs

The CRF450RX is well-suited for closed-course off-road racing like GNCC, WORCS, and NGPC and has been raced by Phoenix Racing Honda, SLR Honda, and JCR Honda at the national championship level. It’s better than ever for the 2021 year, with the same significant performance improvements as the motocross-focused CRF450R plus off-road-specific features, including customized ECU and suspension settings, an 18-inch rear wheel, and an aluminum side stand. The CRF450RX is new for 2021, and it comes with hand guards and a 2.1-gallon gasoline tank that narrows the bike width at the radiator shrouds. A result is a racing machine capable of chasing arrows and ribbons through routes from coast to coast.

2021 Honda CRF450RX Dirt Bike – Features and Specs

2021 Honda CRF450RX Dirt Bike

Engine / Drive Train

The CRF450RX engine has been updated to improve bottom-end and middle power, resulting in a linear delivery that is powerful yet controlled even when the rider tires. Furthermore, peak power has increased by—eight horsepower above 5,000 rpm.


The counterweight for the decompressor system has been moved from the right end of the camshaft to the left end of the camshaft in the Unicam® cylinder head. It helps to strong-but-manageable power delivery in corner exits, as well as stall resistance, by improving combustion stability at very low RPMs. For weight reductions, the magnesium cylinder head cover has been constructed with a thinner material.


The downdraft intake system of the CRF450R produces mighty, efficient power. Still, the air boot has been significantly increased, resulting in improved torque at low rpm. In addition, the rubber ring has been removed to make filter cleaning more accessible, and an exterior frame has been added to guarantee a good seal. A single side-panel bolt must now be removed to access the airbox.

2021 Honda CRF450RX Dirt Bike


The CRF450RX will go from two to one muffler in 2021, saving weight and increasing bottom-end torque delivery. The exhaust system as a whole now weighs 8.5 pounds, down 2.7 pounds from the prior generation.

The exhaust header has been moved 74 mm closer to the engine on the right side, and the single right-side muffler has been redesigned to relocate its outer surface 13 mm inboard, thanks to the engine’s new centralized exhaust-port arrangement. Consequently, the whole vehicle body (including exterior pieces) is thinner, allowing the rider more freedom of movement.

Two resonators (one behind the front U-bend and the other at the muffler’s upstream end) improve power and minimize noise, and the heat shield has been removed to save weight.


Engineers raised clutch capacity by 27%, added an eighth clutch plate, and used firmer springs to boost clutch longevity. A friction spring was also installed to control resonance and increase power delivery significantly. According to a chassis dynamometer, these adjustments minimize clutch slip by 85 percent at peak power.

A hydraulic clutch, similar to the HRC factory machines, is now used to assist clutch activation and promote consistent performance. As an outcome, less force is needed to lift the handlebar lever. Even with the firmer springs, the decrease may be as high as 10% compared to the previous generation, depending on where the measurement is done in the lever stroke.

2021 Honda CRF450RX Dirt Bike


The employment of three different ignition maps for first and second, third and fourth, and fifth gears is possible thanks to a gear-position sensor. Standard, Smooth, and Aggressive ignition maps are also available, selectable through a separate handlebar-mounted switch, allowing easy customization according to rider choice or course circumstances.

Furthermore, Honda Selectable Torque Control still has three intervention levels. To enhance rear traction, HSTC monitors rpm spikes and reacts by momentarily decreasing torque by retarding ignition timing and adjusting PGM-FI.

Chassis / Suspension

To enhance handling, some substantial chassis improvements were made. Geometry has changed due to these changes: The wheelbase has been reduced by one millimeter (to 58.3 inches), and the rake has been softened. The swingarm angle is.9o steeper (at 14.5o), the seat height is 5 mm higher (at 38.0 inches), ground clearance is improved by 8 mm (now 13.2 inches), and the distance between the front axle and the swingarm pivot is 1.8 mm longer (now 114 mm) (at 36.0 inches). The vehicle’s heaviest components are still positioned in the center and as low as practicable, like previously.

Consequently, turning is enhanced without compromising high-speed tracking, and squat under acceleration and pitching during heavy braking is decreased.

Frame / Swingarm / Subframe

The new frame has thinner main spars, a revised downtube, and repositioned reinforcing ribbing on the underside of the pivot plate, all of which contribute to a weight reduction of 1.54 pounds, resulting in a frame that weighs just 18.5 pounds. While vertical stiffness is maintained, lateral rigidity is lowered by 20%, resulting in a flexible feel that aids handling.


The subframe has a streamlined design that eliminates the need for separate seat support, resulting in an overall weight of about 2.0 pounds, down from over.7 pounds before.

The swingarm is also smaller, allowing for more clearance in ruts, and has been rebalanced to match the frame to enhance rear traction and turning.


The front suspension consists of a 49 mm inverted Showa® coil-spring fork and a gas-liquid separation mechanism, the same as the 2020 CRF450RX. Still, the suspension stroke has been extended by 5 mm to absorb rough terrain better while minimizing pitching. Additionally, the axle holders have been changed to improve stiffness. The top and lower triple clamps have also been modified, with revised reinforcing ribs rebalancing stiffness and offering enhanced flex characteristics for better corner handling and feel.

The Pro-Link® rear-suspension system employs a Showa shock absorber with adjustments relocated from the left to the right side to cope with the redesigned frame. By converting to a lightweight steel shock spring, the weight was also reduced.


Black D.I.D. Rims, like previously, provide long-lasting performance and a beautiful appearance. Heat is dispersed via petal-style brake rotors, and a low-expansion front brake hose offers a robust feel and sustained stopping force.

Dunlop’s renowned Geomax AT81 tires are standard on the 2021 CRF450RX, providing all-around performance and high levels of toughness for off-road racing.


The CRF450RX’s technical modifications allowed for thinner bodywork, which aids rider mobility. The absence of a left-side muffler, for example, allowed for a 50-mm inboard side panel, while the revised muffler form also allowed for a 20-mm inboard right side panel. The adjustments result in a 70 mm decrease in width at the back of the bike, which significantly improves rider mobility and, as a consequence, handling. The transition between the radiator shroud and the side panel is smoother, which aids rider mobility.

The radiator shrouds are also new, and instead of two distinct sections, each is now made in one piece. New air-outlet vents in the blankets were designed using computational fluid dynamics (CFD). The radiator grills have been redesigned to optimize the fins and their angle, resulting in a 5% increase in cooling performance. At the same time, the vehicle width is 17.7 mm narrower at the front of the shrouds, thanks to a redesigned 2.1-gallon polyethylene fuel tank with only—1 gallon less capacity than before.

The new seat base features rearward-facing tongues and front-located mounting tabs, while the old seat was mounted by sliding it forward onto the subframe and then attaching it at the back. It makes it easier to secure the seat, and the acceleration forces retain it in place.

Engineers worked for and took advantage of every chance to reduce weight for better handling throughout the model’s makeover. For example, instead of the usual 12, just eight screws are required to hold all of the essential bodywork components—both radiator shrouds, both side panels, and the seat. In addition, all of the primary bodywork bolts now have 8 mm heads, making servicing easier.

2021 Honda CRF450RX Dirt Bike

2021 Honda CRF450RX Dirt Bike – Price

The new 2021 Honda CRF450RX Dirt Motorcycle is available for $9,899 only.

2021 Honda CRF450RX Dirt Bike – Technical Specifications


Type 449.7cc liquid-cooled 10º single-cylinder four-stroke
Valve Train Unicam® OHC, four-valve; 38mm intake, steel; 31mm exhaust, steel
Bore x Stroke 96.0mm x 62.1mm
Compression Ratio 13.5:1
Induction Programmed fuel-injection system (PGM-FI); 46mm throttle bore
Ignition Full transistorized
Starter Push-button electric starter
Transmission Constant-mesh 5-speed return; manual
Clutch Multiplate wet, hydraulically actuated (6 springs)
Final Drive #520 sealed chain; 13T/50T

Suspension System

Front 49mm of fully adjustable leading-axle upturned telescopic Showa coil-spring fork having 12.2 inches travel
Rear Pro-Link system; fully adjustable Showa single shock including 12.32 inches travel


Front 2-piston caliper (30mm, 27mm) hydraulic; solo 260mm disc
Rear 1-piston caliper hydraulic; solo 240mm disc


Front Dunlop Geomax AT81 90/90-21 w/ tube
Rear Dunlop Geomax AT81 120/90-18 w/ tube


Rake (Caster Angle) 27°7’
Trail 114mm
Length 85.9 inches
Width 33 inches
Height 50.5 inches
Ground Clearance 13.2 inches
Seat Height 38 inches
Wheelbase 58.3 inches
Fuel Capacity 2.1 gallons
Color Red
Curb Weight 251 lbs.

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