Friday 15nd October 2021

Slimmer & lighter: 2021 Honda CRF450R Motocross!

Reading time approx. 11 Minutes

Honda CRF450R 2021 6 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

All parts of the CRF450R are new for 2021 except for the wheels and engine. The comprehensive update benefits directly from the know-how that HRC was able to gather through the development of Tim Gajser's factory machine, with which he drove to the world championship title in 2019. The new frame and swingarm as well as changes to the geometry and suspension save weight and improve cornering performance considerably. The engine receives improvements to the intake and exhaust system, a new decompression system and a single muffler - together this leads to a smoother response and improved drivability in the lower and middle speed range. A larger hydraulic clutch provides more control with less leverage. More compact plastic parts and a smaller bench increase freedom of movement.

2021 Honda CRF450R Motocross

Honda CRF450R 2021 7 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

The Honda CRF450R has been around since its introduction in 2002 of the company The benchmark for motocross motorcycles and, in the sum of their properties, became the epitome of balance and maneuverability. It offers the driver - whether amateur or professional racing driver - always total control and thus the opportunity to bring their skiing skills to the slopes in the best possible way. In addition, of course, the CRF has the very high quality, durability and longevity for which Honda has long been famous. In addition, the CRF450R is a machine that has been constantly evolving, with each upgrade based on experience from Honda's global involvement in racing. After this 17-year success story, Europe's most popular MX machine has now become the open class with the development concept "ABSOLUTE HOLESHOT!" completely redesigned - including a completely new chassis and a significant increase in performance in the upper speed range thanks to a brand new engine.

standard electric starter

Honda CRF450R 2021 9 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

The standard electric starter was already a practical addition to the 2018 model, and in 2019 a cylinder head newly developed by HRC increased the peak power and torque considerably. Further updates were the launch control from HRC as well as a revised stiffness balance for the frame and swingarm, a new brake caliper at the front and a fat bar handlebar from Renthal with adjustable mounts. For the 2020 season, the CRF450R also got the Honda Selectable Torque Control (HSTC). This traction control already worked in the CRF450RW HRC racing machine that was driven by Tim Gajser (# 243) for the 2019 MX GP World Championship. The CRF450R of the 2021 season is based in many areas on the experience that Gajser and HRC have gained on their long path to overall victory in 2019.

Model overview

The 2021 model of the CRF450R has a wide range of improvements and upgrades, all of which can be summarized under the development theme of "razor-sharp turning". First, thanks to a revised frame and sub-frame, the machine is 2 kg lighter. In addition, the stiffness balance of the new frame and the swing arm in connection with a tighter chassis geometry, greater ground clearance and changes to the suspension are all geared towards optimal cornering behavior. The findings from Tim Gajser's 2019 world championship season reduce driver exhaustion and enable enthusiasts of all performance levels to consistently achieve optimal lap times.

The engine also benefits from HRC's know-how: it now places a strong focus on torque in the lower to medium speed range. The decompression unit was relocated, the volume of the airbox increased, the throttle valve housing revised and the outlet openings re-shaped. The exhaust manifold is also new, and a single silencer replaces the previous twin silencers.

There is also an enlarged hydraulic clutch including reduced manual force and other weight-saving details such as a smaller fuel pump and an optimized cylinder head cover made of magnesium. The new plastic parts are also lighter and slimmer to support the driver's freedom of movement. The bench has also been changed, it is now smaller and shaped lower at the back. An attractive new graphic design - completely in red - completes this comprehensive model update.

Undercarriage of the Honda CRF450R Motocross

  • Narrower tubes on the main frame and a new rear subframe save weight, using HRC's know-how
  • Narrower tubes and swing arm pivot point on the rear swing arm, including revised swing arm stiffness balance
  • Geometry changes in combination with the changes mentioned above improve the turning behavior
  • Front fork with new damping valves and 5 mm more suspension travel, combined with a rear shock absorber that also works with new damping valves
  • Improved ergonomics thanks to a smaller, new bench and more compact, newly designed plastic parts

The CRF450R's double-loop aluminum frame remained unchanged on the 2020 model. For the 2021 season, it has now been completely renewed with direct input from the HRC racing team in order to improve every aspect of cornering behavior.

Thanks to the narrower tubes, the main frame, at 8,4 kg, now weighs 700 g less than its predecessor, while a newly designed subframe, now weighing 910 g, also saves 320 g. The chassis dynamics are also new: while the torsional rigidity is retained, the lateral rigidity has been reduced by 20% in order to increase cornering speed, traction and steering accuracy. The aluminum swing arm has a new rigidity balance that is tailored to the frame with narrower tubes and pivot point. The pro-link ratio has also been revised.

Honda CRF450R 2021 4 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

Both the upper and lower triple clamps have been redesigned. They now offer more flex for faster steering and a better steering feel. The fully adjustable 49mm Showa USD suspension fork is a variant of the Showa “factory” fork supplied to MX racing teams in the Japanese championship. The forks were redesigned with the aim of improving, smoother cornering behavior: the spring travel increased by 5 mm to 310 mm and the stiffness of the axle clamps was increased. The main piston valve on the Showa rear shock absorber has been enlarged for faster response and improved shock absorption. Its spring also uses the lightest steel in the world - this saves another 200 g in weight.

The seat is now shorter, lighter and 10 mm lower at the rear to support the driver's freedom of movement. It is also much easier to remove and install. Maintenance has also been simplified as the number of 8mm screws securing the bodywork has been reduced from 6 to 4 per side. The new machine is also 70 mm slimmer (50 mm on the left side, 20 mm on the exhaust side) and the plastic parts are thinner, and the tank cover has been saved.

The values ​​for steering head angle and caster are now lower at 27,1 ° and 114 mm (previously 27,4 ° / 116 mm) and the wheelbase is also slightly shorter at 1481 mm (1482 mm). Ground clearance increases by 8mm to 336mm, and the lower triple clamp is now 6,1mm higher at 928mm. The radius from the pivot point of the swing arm to the rear wheel axle holder increases by 0,9 ° to 14,5 °, while the distance between the pivot point and the front axle holder increases by 1,8 mm to 914,6 mm. The dry weight is 105,8 kg, which is a full 2 ​​kg lighter than the previous model.

Honda CRF450R 2021 6 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

Designed with Computational Flow Dynamics (CFD) technology for maximum air flow, the radiator shrouds are now made from one instead of two plastic parts and have a lower vent, while the grille is optimized for airflow. The 6,3 liter titanium fuel tank has also been improved.

A light Fatbar-Flex handlebar from Renthal is standard for optimal comfort. The upper triple clamp has two handlebar brackets that can be used to move the handlebars back and forth by 26 mm. If the holder is rotated 180 °, the handlebar can be moved a further 10 mm from the basic position, resulting in four individual driving positions. When it comes to weight savings, many smaller amounts also lead to success (“A mountain can form from enough dust”, as a Japanese proverb says); In this sense, the machine's cabling, which has now been optimized again, saves a further 100 g.

A double-piston brake caliper with 30 and 27 mm piston diameters and a 260 mm wave disc is used at the front. Together with the brake hose with a low expansion rate, the system offers both an optimal pressure point and maximum stability. The rear single-piston brake caliper works in conjunction with a 240 mm wave disc.

The DID aluminum rims are painted black; the front wheel rim is 21 x 1,6 inches and the rear wheel rim is 19 x 2,15 inches. The rear wheel on the 2021 model is both stronger and lighter. Dunlop MX33F / MX33 cross tires are fitted as standard.

A striking, new and completely red graphic concept underlines the now even sharper lines of the 2021 CRF450R.

Honda CRF450R motocross engine

  • Larger airbox plus redesigned throttle body and exhaust ports for more power in the lower speed range
  • New exhaust manifold and new individual silencer increase torque and save weight
  • An enlarged, hydraulic clutch replaces the cable actuation and ensures smooth operation and little manual effort
  • Revised decompression system reduces the risk of death

After a power increase of 1,8 kW at its peak, plus 2 Nm more torque and more power in the lower speed range in the 2019 model, the further development of the 449,7 cc four-valve Unicam engine for 2020 concentrated on optimizing the PGM-FI -Mappings and the HRC Launch Control as well as the integration of the new traction control Honda Selectable Torque Control (HSTC). With the new machine for 2021, the focus is on upgrades that are directly derived from Tim Gajser's HRC world champion machine: They bring significant improvements in drivability in the lower to medium speed range as well as weight savings to further improve cornering performance.

A significant increase (up to 0,6 kW) in peak power above 5.000 rpm is accompanied by a more noticeable torque at low engine speeds, which is the result of an airbox that has been increased by 1,8 l to 4,1 l. This is now easily accessible by removing a side panel screw and feeds a newly designed, lighter 46 mm throttle body. It optimizes the efficiency in the intake tract and actively uses the latent heat of vaporization that arises in the intake ducts.

Honda CRF450R 2021 10 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

The injection nozzle angle was increased from 30 ° to 60 °, which means that the fuel is sprayed in the opposite direction to the intake air in the direction of the throttle valve. This improves the intake efficiency, the cooling of the mixture and the important "throttle valve feeling" for the driver. The decompression system is also new: its counterweight is shifted from the right side of the camshaft to the left, which results in more stable operation at low engine speeds with less risk of death.

The biggest change concerns the dual exhaust ports: like the CBR1000RR-R Fireblade, its exit is oval instead of round to improve its efficiency. The 5,08 kg 2-1-2 exhaust system of the previous model has now been replaced by a single, only 3,84 kg system of manifold and silencer (which also eliminates a heat shield), which saves a total of 1,24 kg. The manifold is also mounted 74mm closer to the central axis (which improves driver ergonomics), while the muffler is equipped with double resonators that both reduce noise and increase performance.

An innovation that was derived directly from Gajser's World Championship motorcycle is the installation of a hydraulic clutch. This improves both control and the feel of the lever (it works 10% lighter) and ensures an even lever spacing under difficult driving conditions. The clutch capacity has been increased by 7% with an additional disc (from 8 to 27 discs) and works with an additional spring to maximize power transmission and durability. The slip was reduced by 85% at peak power.

Honda CRF450R 2021 3 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

Bore and stroke remain at 96 x 62,1 mm with a compression ratio of 13,5: 1. A gear position sensor enables the use of three specific ignition maps for gears 1 and 2, 3, 4 and 5. The legendary reliability has always been a major factor in the success of the CRF450R. When it comes to lubrication, a 5-hole jet nozzle for oil cooling of the piston and a double 12 mm drum suction pump for the oil supply are used.

In order to save even more precious weight, the magnesium cylinder head cover was redesigned with thinner walls and the fuel pump was made smaller. It is now secured with 4 instead of 6 screws, saves 120 g and offers the same pressure and the same filter life as the previous design.

Electronics of the Honda CRF450R Motocross

  • Honda Selectable Torque Control (HSTC) with 3 driving modes plus OFF
  • The HRC Launch Control offers 3 start options
  • The Engine Mode Select Button (EMSB) has 3 maps for setting the engine characteristics
  • HSTC button now integrated in the left handlebar fitting
  • Improved HRC setting tool for changes to the "aggressive" and "smooth" modes

The HSTC traction control introduced for the 2020 model year on the CRF450R is unchanged in the 2021 version. It minimizes the spinning of the rear wheel (and thus the loss of propulsion) and maximizes traction. It doesn't use a wheel speed sensor and maintains the driver's feel for the throttle while controlling the power. As soon as the system detects that the speed change has exceeded a specified value, the ignition point is delayed and the injection control is checked via PGM-FI.

Honda CRF450R 2021 3 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

The three modes of the HSTC differ in the management of the drive for different driving conditions:

  • In mode 1 the system intervenes least and late - this is useful to reduce wheel spin and maintain control in tight corners.
  • In mode 3 the system intervenes faster and stronger and is therefore mainly used in more slippery, muddy conditions.
  • Mode 2 naturally offers an average value between modes 1 and 3 in terms of speed and strength of the intervention.

An eye-catching update for the 2021 model year are the driver controls and the display switchgear. The start control display, the EFI warning, the EMSB mode button and the LED display are located on the left handlebar, with the HSTC button now also being integrated here.

By pressing and holding the HSTC button for 0,5 seconds, the system switches to the next mode, whereby a green LED display - one flashing for mode 1, twice for mode 2 and three times for mode 3 - confirms the selection.

Honda CRF450R 2021 8 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

The HSTC system can also be switched off completely. When the engine is switched on, the system uses the last setting selected. HRC Launch Control offers every driver the best option for the best possible start. Here, too, there are three modes to choose from:

  • Level 3 - 8.250 revolutions per minute, muddy conditions / beginners.
  • Level 2 - 8.500 RPM, dry conditions / standard.
  • Level 1 - 9.500 RPM, dry conditions / expert.

The HRC Launch Control is easy to activate: switch it on, pull the clutch and press the start button on the right. The purple LED flashes once to select level 1. After pressing the start button again for 0,5 s or longer, the LED flashes twice for level 2. After repeating the process, the LED flashes three times, indicating that level 3 has been selected.

The selection button for the motor mode (EMSB) changes the properties of the motor. There are three maps available to take into account the driving conditions or the driver's preferences:

  • Mode 1 - Default
  • Mode 2 - soft
  • Mode 3 - Aggressive

The LED also shows the selected mode, but with a blue light.

With an update to the 2021 mapping, the HRC setting tool can now activate a much more easily drivable smooth mode, including a smoother throttle response for beginners in this performance class. It can also program the aggressive mode into the engine management system with a very sensitive throttle response and direct engine response for racing conditions.

Photos: Honda

Technical specifications

Type4-stroke single cylinder, Uni-Cam, liquid-cooled
capacity449,7 cc
Bore / stroke96,0 62,1 mm x mm
compression ratio13,5:1
mixture preparationinjection
Tankinhalt6,3 l
ignitionDigital CDI
ClutchMulti-disc clutch, wet
ÜbersetzungClaw gear
Final driveChain
TypeAluminum double loop tubular frame
Dimensions (L´B´H)2.182 827 x x 1.267mm
wheelbase1.481 mm
Steering head angle27,1 °
trailing114 mm
seat height965 mm
ground clearance336 mm
Weight:105,8 kg (dry) - 110,6 kg (ready to drive)
your Front Wheel.Showa 49mm USD fork
behindShowa monoshock with Honda Pro-Link lever system
your Front Wheel.Aluminum spoked wheel
behindAluminum spoked wheel
Front tire80/100-21-51M Dunlop MX33F
Tire behind120/80-19-63M Dunlop MX33
your Front Wheel.Single disc brake 260 mm
behindSingle disc brake 240 mm

Honda CRF450R 2021 11 Slimmer & Lighter: 2021 Honda CRF450R Motocross!

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