Motorcycle specifications HondaCRF 450 R 2021 Drawing on experience

for its 2021 model year, the Honda CRF 450 R benefits from a long list of improvements. To begin with, 2 kg have been saved on the frame and rear clamp. Next, work has been carried out on the balance between frame and swingarm stiffness, new - and more responsive - geometry, increased ground clearance and changes to the suspension, all aimed at making the bike more efficient in corners. Feedback from Tim Gajser's victorious season has also been used to tweak various aspects of the bike to reduce rider fatigue, enabling professionals and amateurs of all levels to improve their performance with every lap.

the engine has also benefited from HRC's experience, focusing on low- and mid-range torque values. At the same time, the decompressor has been relocated, the airbox volume increased and the throttle body redesigned, as have the exhaust ducts. The manifold is also new, while a single silencer replaces the dual system used up to now. Finally, a hydraulically-operated clutch provides smoother lever action and reduces rider fatigue.

weight savings are concentrated on the fuel pump (more compact) and the magnesium cylinder-head cover, while the new, lighter and thinner plastics on the bodywork make it easier for the rider to move around. The seat is also smaller and lower at the rear.

part-cycle

the ^{7th-generation} double-beam aluminum frame equipping the big CRF had already been extensively revised for 2019. At HRC's instigation, the 2021 model has been extensively reworked to further improve cornering performance.

thanks to narrower beams, the new aluminum frame boasts a total weight of 8.4 kg, down 700g, while the new rear buckle drops 320g to 910g. Dynamic characteristics have also been reworked: while torsional rigidity is unchanged, lateral rigidity has been reduced by 20% to increase cornering speed, traction and ease of turning. The distribution of stiffness zones on the aluminum swingarm has been adapted accordingly, with narrower spars and less width at the frame anchorage point. The gear ratio of the Pro-Link system has also been modified.

at the front, the upper and lower tees have been made more flexible, to enhance steering responsiveness and feedback.

fully adjustable, the Showa ø 49 mm inverted fork with springs is simply a version equipped with the Showa factory kit supplied to official Japanese MX Championship teams.to improve cornering smoothness, the valves have been changed, the travel increased by 5 mm (310 mm) and the rigidity of the axle mounts reinforced.the valves on the rear shock's main piston have been enlarged for greater responsiveness and shock absorption, while the spring is made from the lightest steel currently available, saving 200g on this component alone.

the saddle is now shorter, lighter and 10 mm lower at the rear, making it easier for the rider to move around. It is also much easier to remove and reinstall. Maintenance is also easier overall, since the number of screws needed to secure the trim components has been reduced from 6 to 4 on each side.

more generally, the bike is 70 mm narrower at the side plates (50 mm on the left and 20 mm on the right, on the exhaust side), the plastics are thinner and the tank cover has been removed.

caster angle and drag are set at 27.1° / 114 mm (vs. 27.4 and 116 mm previously), while wheelbase is 1,481 mm (- 1 mm vs. 2020). Ground clearance has increased by 8 mm to 336 mm, while the lower tee has risen by 6.1 mm to 928 mm. The angle described by the swingarm tilt increases by 0.9° to 14.5°, while the distance between the swingarm axis and the front wheel axis increases by 1.8 mm to 914.6 mm. Dry weight is 105.8 kg, 2 kg less than the previous model.

the Renthal Fatbar handlebars are fitted as standard, contributing to riding comfort thanks to their flexibility. The upper fork crown is designed to allow the 26 mm handlebar mounts to be moved forwards or backwards. When the mounts are rotated by 180°, the handlebars have an additional 10 mm of latitude, bringing the number of positions available to the rider to 4.

considering - as a Japanese saying goes - that with enough dust you can make a mountain, the various control cables have been lightened, saving 100g on total weight.

in terms of braking, the front brake caliper uses two pistons, ø 27 and 30 mm, combined with a low-expansion hose to improve braking feel and maintain power at a constant level. This caliper acts on a ø 260 mm petal disc. At the rear, the ø 240 mm disc is slowed by a single-piston caliper.

the DID aluminum rims (1.60 x 21 at the front and 2.15 x 19 at the rear) are black anodized, and the rear unit is lighter and stronger than the part it replaces. Both are fitted with Dunlop MX33F/MX33 rubber.

New graphics complete the lines of the CRF 450 R 2021.

refined powertrain

the increase in power and torque recorded in 2019 on the 449 ^cm3 4-valve Unicam single-cylinder was significant (+ 1.8 kW at 9,500 rpm and + 2 Nm at 7,500 rpm). In 2020, the engine-makers' efforts focused on refining and optimizing the electronic fuel injection system, as well as on the adoption of two devices, one an HRC-based start aid and the other a torque control system (HSTC).

for the 2021 model year, taking advantage of the experience gained on Tim Gajser's factory bike, efforts have focused on weight reduction and optimizing low- and mid-range behavior, in particular to improve cornering performance.

the result is an appreciable increase in power (+0.6 kW) below 5,000 rpm, accompanied by a renewed sense of torque at low revs, thanks in particular to an increase in airbox volume from 1.8 to 4.1 litres on the "clean" side. The new air filter housing - now accessible by removing a simple screw - feeds a 46 mm injection body that has been lightened and optimizes intake efficiency by making greater use of the volume of mixture remaining in the intake ducts.

the injector angle is increased from 30° to 60°, vaporizing fuel right up to the throttle valve for more efficient intake, better cooling of the gas charge and improved throttle response.the decompression system is also new, with a centrifugal system that moves from the right to the left of the camshaft for more stable operation at low revs.

the biggest change affecting the engine is to be found in the 2 exhaust pipes which, as on the last-generation CBR1000RR-R Fireblade, adopt an oval rather than round shape, for the benefit of efficiency. The previous model's 2-in-1-in-2 exhaust system has also been replaced by a single-muffler unit, resulting in a weight saving of 1.24 kg (from 5.08 to 3.84 kg). The single manifold is now some 74 mm closer to the longitudinal axis, improving ergonomics. Finally, the deep-drawn silencer features 2 resonators, limiting noise while enhancing power.

another technology extrapolated from the World Champion bike is the hydraulically operated clutch. This inheritance improves both control - since clearance remains constant whatever the conditions of use - and lever feel, which is improved by 10% less effort. Clutch capacity has been increased by 27% thanks to the adoption of an additional disc (from 7 to 8) and a friction spring to enhance longevity and power transmission efficiency. As a result, slippage has been reduced by 85% in the area of maximum power.

bore and stroke dimensions remain fixed at 96 x 62.1 mm, with a volumetric ratio of 13.5 to 1. The adoption of a sensor on the gearbox selector allows the use of 3 specific ignition maps depending on the gear engaged (first and second, third and fourth, fifth).

reliability has always been an important factor in the CRF 450 R's success. For 2019, a 5-nozzle oil jet has replaced the previous 4-nozzle component to cool the piston, while the oil pump, which previously used a single ø 16 mm suction nozzle, now makes use of 2 ø 12 mm elements, synonymous with greater capacity.

to save a few more grams, the magnesium cylinder head cover is thinner, while the fuel pump is more compact and secured by 4 screws instead of 6, saving an extra 120g while guaranteeing the same feed pressure and filtration quality as the previous component.

a handful of electronics

adopted in 2020, the HSTC remains unchanged for 2021. This torque control system minimizes rear-wheel grip losses (synonymous with lost time) by optimizing grip and traction. With no need for a speed sensor on the wheel, this system maintains full sensitivity to the throttle while managing power. Its effectiveness comes from precise intervention in ignition timing and fuel injection when abnormal variations in engine speed are detected.

the three available modes intervene on the steering according to the following conditions:

- In Mode 1, the system intervenes only very lightly and after a certain delay, which is ideal for limiting wheel spin and maintaining control in tight bends.

- Mode 3 is the one in which the system intervenes fastest and most strongly. This mode is particularly useful in muddy or slippery conditions.

- Finally, Mode 2 naturally offers an intermediary between Modes 1 and 3 in terms of speed and force of intervention.

the CRF 450 R 2021 benefits from a significant improvement in handlebar control. The start-assist indicator, fuel-injection indicator, riding mode selector and LED are positioned to the left of the handlebars, now combined with the HSTC control.

holding down the HSTC button for 0.5 seconds enables the system to switch from one mode to another under the control of an indicator light (green LED): one flash for mode 1, two flashes for mode 2 and three flashes for mode 3.

the HSTC system can also be completely deactivated. When the engine is restarted, the system automatically returns to the last selected mode.

the HRC-developed "Launch Control" start-assist system allows riders to choose from three start modes:

- Mode 3 / 8,250 rpm, particularly suitable for beginners and/or muddy conditions

- Mode 2 / 8,500 rpm, for advanced riders and dry conditions

- Mode 1 / 9,500 rpm, for expert riders and dry terrain

activating the Launch Control system is as simple as activating the clutch and pressing the starter button. A purple LED flashes once to indicate that Mode 1 is active. If the starter button is pressed a second time for 0.5 seconds or more, the LED will flash twice to indicate that Mode 2 is engaged. Press again and the LED will indicate that Mode 3 has been selected.

last but not least, the EMSB (Engine Mode Select Button) map selector lets you adjust engine characteristics. 3 mappings are available to suit rider preferences and riding conditions: Mode 1 (Standard), Mode 2 (Gentle) and Mode 3 (Aggressive). A blue LED informs the rider of the selected mode. Note that the "Gentle" and "Aggressive" mappings have been optimized to allow additional settings (softer or more explosive) via the HRC tuning system.

News and media credits: Honda