2021 HONDA CRF450R

Model updates: For 2021, every part of the CRF450R is new save for the wheels and engine, with the comprehensive update benefiting directly from knowhow gained through HRC development and the bikes championship-winning history. The new frame and swingarm, plus changes to geometry and suspension, save weight and greatly improve cornering performance. The engine receives intake/exhaust upgrades, new decompression system plus single exhaust muffler to boost and smoothen low-mid-range driveability. A larger hydraulic clutch offers greater control with lighter lever pressure. More compact plastics and a smaller seat unit increase freedom of movement.

Contents:

1. Introduction
2. Model overview
3. Key features
4. Technical specifications

1. Introduction

The Honda CRF450R has been the benchmark motocrosser since its introduction in 2002. The package it offers has become a byword for balance and agility, and as such has consistently offered its rider - whether an amateur enthusiast or pro-racer - total control and the chance to get the very best from their ability. Plus, of course, it’s built with the quality, durability and reliability that Honda has long been famed for.

It’s a machine that has constantly evolved, with every upgrade - large or small - drawing on lessons fed back from Honda’s racing programmes around the world. In 17YM, under a development concept of ‘ABSOLUTE HOLESHOT!’, the open-class MX machine was given a ground-up redesign, with completely new chassis and a major top end power boost from a brand-new engine.

Standard-fit electric start was a convenient addition in 18YM and, for 19YM, an HRC-developed cylinder head upped peak power and torque considerably. HRC launch control was also added along with revised rigidity balance for the frame and swingarm, a new front brake caliper and adjustable-position Renthal Fatbars.

And finally for 20YM, the CRF450R gained Honda Selectable Torque Control (HSTC).

2. Model Overview

For 21YM the CRF450R receives a wide array of improvements and upgrades under a development theme of ‘Razor-sharp Cornering’. Firstly, it is 1.5 kg (3.4 lb) lighter, thanks to a revised frame and subframe. The new frame and swingarm’s rigidity balance, combined with tighter chassis geometry, heightened ground clearance and suspension changes, are all targeted at creating optimal cornering performance and allowing enthusiasts of all ability levels to consistently post optimal lap times.

The engine also benefits from HRC’s knowhow to give a strong focus on low- to mid-range torque. The decompressor has been relocated, airbox volume is up, throttle body redesigned, and exhaust ports re-shaped. The exhaust downpipe is new and a single muffler replaces dual mufflers.

A larger-volume hydraulic clutch has an even lighter lever action, while other weight-saving details include a smaller fuel pump and optimised magnesium cylinder head cover. New plastics, too, are lighter and slimmer to aid rider freedom and the seat is a smaller unit, lower at the back. A smart new graphic scheme completes this major update.

3. Key Features

3.1 Chassis

• Narrower main spars and new rear subframe saves weight, drawing on HRC knowhow
• Narrower swing arm spars and swingarm pivot point, with revised swingarm rigidity balance
• Geometry changes combine with the above to improve cornering ability
• Re-valved front suspension with an extra 5 mm stroke matched with re-valved rear shock
• Improved ergonomics from smaller new seat, and more compact, redesigned plastics

The CRF450R’s twin-spar aluminium frame was unchanged in 20YM; for 21YM it is completely renewed – with direct input from the HRC race team – to elevate every aspect of cornering ability.

Thanks to narrower main spars, at 8.4 kg (18.5 lb) it weighs 700 g (1.5 lb) less than the previous design, while a redesigned subframe also saves 320 g (0.7 lb) weighing 910 g (2 lb). The chassis dynamic is also new: while torsional rigidity is maintained, lateral rigidity has been reduced by 20% to increase corner speed, traction and steering accuracy. The aluminium swingarm has a new rigidity balance tuned to match the frame, with narrower arms and pivot point. The Pro-Link ratio is also revised.

Both top and bottom yokes are revised, with more flex, for quicker steering and feel. Fully adjustable, the 49 mm Showa USD coil spring fork is a version of the Showa ‘factory’ fork supplied to MX race teams in the Japanese championship. With the target of improved, smoother cornering performance, the forks have been revalved, the stroke lengthened by 5mm, to 310 mm (12.2 in) and the axle clamps’ rigidity increased. The Showa rear shock’s main piston valve is enlarged for faster response and improved bump absorption. Its spring also uses the world’s lightest steel - to save 200 g (0.44 lb).

The seat is now shorter, lighter and 10 mm lower at the rear; to aid the rider’s freedom of movement. It’s also much easier to remove and install. Maintenance is also easier, as the number of 8 mm bolts securing the bodywork goes from 6 to 4 on each side. The new machine is also slimmer by 70 mm (2.8 in) (50 mm on the left, 20 mm on the exhaust side), and the plastics thinner, while the tank cover has been removed.

Rake and trail are now tighter, 27.1°/114 mm (from 27.4°/116 mm), and wheelbase marginally shorter at 1481 mm (58.3 in) from 1482 mm. Ground clearance goes up 8 mm to 336 mm (13.2 in), and the bottom yoke now sits 6.1 mm higher at 928 mm (36.5 in). The radius arc from swingarm pivot point to rear wheel spindle increases by 0.9°, to 14.5° while distance between the pivot and front spindle goes up 1.8 mm, to 914.6 mm (36 in). Curb weight 110.5 kg (243.6 lb); a full 1.5 kg (3.4 lb) lighter than the previous model.

Designed with Computational Flow Dynamics (CFD) for maximum flow-through of air, the radiator shrouds are now constructed from one piece of plastic, rather than two and include a lower vent while the radiator grills are optimised for airflow. Holding 6.3 L, the titanium fuel tank has also been redesigned.

Standard-fit, lightweight Renthal Fatbar flex for optimal comfort; the top yoke features two handlebar-holder locations for moving the handlebar rearward and forward by 26 mm (1 in). When the holder is turned 180°, the handlebar can be moved an additional 10 mm (0.4 in) from the base position, resulting in four unique riding positions. When it comes to weight saving, small contributions accumulate (‘with enough dust, a mountain can form’ as the Japanese saying has it); with that in mind, balanced control cable wiring saves 100 g (0.2 lb).

Up front, the twin-piston brake caliper employs 30 and 27 mm diameter pistons and 260 mm wave-pattern disc; along with low-expansion rate brake hose it gives both a strong feel and consistent stopping power. The single-piston rear caliper is matched to a 240 mm wave-pattern disc.

DID aluminium rims, with directly attached spoke pattern layout are finished in black; the front is a 21 x 1.6 in, the rear a 19 x 2.15 in. The rear wheel is both stronger and lighter for 21YM and now Dunlop’s MX33F/MX33 soft-terrain tires are fitted as standard equipment.

A striking new graphic treatment complements the 21YM CRF450R’s sharper lines.

3.2 Engine

• Larger airbox plus revised throttle body and exhaust ports for bottom-end drive
• New exhaust downpipe with single muffler boosts torque and saves weight
• Larger volume hydraulic clutch replaces cable operation for consistent and light lever feel
• Revised decompressor system gives improved stall resistance

Having received a boost in peak power, more torque and a stronger bottom-end for 19YM, in 20YM the development of the 449.7cc four-valve Unicam engine centred around refinements and optimisation of the PGM-FI mapping and HRC Launch Control, plus the addition of Honda Selectable Torque Control. For 21YM the focus - with upgrades derived directly from the championship-winning machine - is on drivability in the low to mid-range, and weight saving, further enhancing cornering performance.

A significant increase in peak power above 5,000 rpm is accompanied by a stronger low-rpm torque feel, the result of an air box increased in size by 1.8L, to 4.1L on the ‘clean’ side. The new air box - which can now be accessed simply with the removal of one side shroud bolt - feeds a redesigned, lighter 46 mm throttle body, which optimises intake efficiency and makes active use of latent heat vaporisation in the inlet ports.

The injector angle, have gone from 30°, to 60°, spraying fuel all the way back to the butterfly valve to improve intake efficiency, cooling off the charge and all-important throttle feel. The decompression system is also new: its counterweight is moved from the right of the camshaft to the left, giving more stable operation at low rpm with increased stall-resistance.

The biggest change is to the twin exhaust ports: like the CBR1000RR-R Fireblade their exit is oval rather than round in shape for improved efficiency, and the 5.08 kg (11.2 lb) 2-1-2 exhaust design of the previous model has been replaced by a single 3.84 kg (8.5 lb) downpipe and muffler (which also does away with a heat shield) saving a full 1.24 kg (2.7 lb). The downpipe also tucks in 74 mm (2.9 in) closer to the centre line (improving rider ergonomics) while the pressed muffler features twin resonators that reduce noise while boosting power.

One big update for 21YM is the addition of a hydraulic clutch. This improves both control and feel at the lever (it’s 10% lighter) as well as delivering consistent lever clearance under arduous riding conditions. The clutch capacity has been increased by 27% with an extra plate - from 7, to 8 - and works with an extra friction spring to maximise power transmission and durability. Slippage has been reduced by 85% at peak power.

Bore and stroke remains 96 x 62.1 mm with a compression ratio of 13.5:1. A gear position sensor allows the use of three specific ignition maps for 1st and 2nd, 3rdand 4th, and 5th.

Rock-solid reliability has always been a big factor in the CRF450R’s success and a 5-hole piston oil jet and dual 12 mm drum scavenge pump manage lubrication.

Saving more precious grams, the magnesium cylinder head cover has been redesigned with thinner material and the fuel pump made smaller – it secures with 4 bolts instead of 6, saving 120 g (0.26 lb) and offers the same pressure and filter life as the previous design.

3.3 Electronics

• Honda Selectable Torque Control (HSTC) with 3 riding modes (plus OFF)
• HRC Launch Control offers 3 start options
• Engine Mode Select Button (EMSB) features 3 maps to adjust output character
• HSTC button now rationalised into the left-hand switchgear
• HRC setting tool updated for changes to Aggressive and Smooth modes

The CRF450R gained HSTC in 20YM and the system is unchanged for 21YM. It works to minimise rear wheel spin (thus wasted forward drive) and maximises traction. It doesn’t use a wheel speed sensor, and critically maintains feel at the throttle while managing power; ignition timing is retarded and the PGM-FI controlled when the rate of change of rpm is detected to have gone over a set amount.

The three Modes differ in drive management level for different riding conditions:

In Mode 1 the system intervenes most lightly, and after the longest time ­– useful for reducing wheel spin and maintaining control in tight corners.

Mode 3 has the system intervene more quickly and strongly, and is therefore useful in more slippery, muddy conditions.

Mode 2 naturally offers a mid-point between 1 and 3 in terms of speed and strength of intervention.

An obvious update for 21YM is the rider controls and display switchgear. The Launch Control indicator, EFI warning, EMSB mode button and LED indicator - are sited on the left handlebar, with HSTC button now incorporated.

Pressing and holding the HSTC button for 0.5s will cycle the system to the next mode, with a green LED indication - 1 blink for mode 1, 2 for mode 2 and 3 for mode 3 - to confirm selection.

The HSTC system can also be switched off completely. When the engine is turned on, the system uses the last-selected setting.

HRC Launch Control gives any rider the best option for a strong start and also has 3 modes to choose from:

Level 3 – 8,250rpm, muddy conditions/novice.

Level 2 – 8,500rpm, dry conditions/standard.

Level 1 – 9,500rpm, dry conditions/expert.

Activating HRC Launch Control is easy: to turn on, pull in the clutch and push the Start button on the right. The purple LED will blink once for Level 1 selection. Push the Start button again, for 0.5s or longer, and the LED will blink twice for Level 2. Repeat the process and the LED will blink 3 times, indicating that Level 3 has been chosen.

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.

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

Gaining a 21YM mapping update the HRC Setting Tool can deliver a much more easy-going Smooth mode, with gentler throttle response for novice riders. It can also inject Aggressive mode with a hyper-sensitive throttle reaction and engine response for race conditions.

4. Technical Specifications

All specifications are provisional and subject to change without notice.

Honda Canada Motorcycles
Honda Canada Inc. was established in 1969 and is the sole distributor of Honda motorcycles, scooters, ATVs and side-by-sides in Canada. The Honda Canada Motorcycle Division is responsible for sales, marketing, and operational activities for these products through authorized Honda dealers. For more information on Honda Canada powersports products, please visit: https://motorcycle.honda.ca/.

# # #