2019 CRF450RX

Model updates: Like the CRF450R moto-cross machine, the cross-country CRF450RX receives a major boost of top-end power and torque for its engine, which is also stronger everywhere in the rev-range; it also gets 3-level HRC Launch Control plus durability upgrades. The chassis features a revised rigidity balance and new suspension settings, plus Renthal Fatbar handlebar.

Contents:

1 Introduction

2 Model overview

3 Key features

4 Technical specifications

1. Introduction

For 17YM Honda introduced an all-new, competition-ready cross country machine into its off-road line up; the CRF450RX. And it took as its rock-solid base the engine and chassis package of the 17YM CRF450R – Honda’s first totally new 450cc moto-crosser in eight years.

The CRF450R - Honda’s flagship off-road racer - has an engine that produces hard-hitting, useable power and a chassis that allows the rider to put that power to the best possible use. All of which makes it the perfect platform to expand, giving the CRF450RX both the pure moto-cross DNA to deal with any special enduro stage and the confidence-inspiring competence to handle flat-out trails, challenging climbs and tight, tricky sections with ease.

And, just as the 19YM CRF450R is updated with HRC-led improvements, the 19YM CRF450RX follows suit and upgrades its riding package – creating a formidable off-road weapon that’s both devastatingly fast over the ground, and easy to live with over the years of ownership.

2. Model Overview

For YM19 the CRF450RX’s performance parameters expand again; considerably more power and torque has been extracted from the engine – via HRC-led head, intake and exhaust tuning – without sacrificing low-rpm tractability.

3-mode HRC Launch Control is a significant addition, helping any rider from beginner to expert to hit the mark out of the gates every time. A shift sensor enables the use of specific ignition maps for each gear, and PGM-FI has been optimised to inject twice per cycle. Oil pump capacity has been uprated, and the clutch lifter and pressure plate redesigned.

The aluminium twin-spar frame has been optimised for rigidity, as has the swingarm. A new front brake caliper shaves vital grams. Revised oil and spring/damping settings for the 49mm Showa USD fork enhance reaction, complemented by a ‘Super Finish’ process for the rear shock’s damper, plus revised Pro-Link ratio.

The new Renthal fatbars can also now be adjusted through four positions on the top yoke; a revised sidestand replaces the previous design.

3. Key Features

3.1 Engine

• +1.8kW power, +2Nm torque and considerably stronger from 3,000rpm up
• Revised cylinder head, intake and exhaust plus tailored ignition maps
• 3 level HRC Launch Control optimises start performance
• Durability improved with 5-hole piston jet and larger-capacity scavenge pump

While the architecture of the YM19 CRF450RX’s 449cc four-valve Unicam engine remains essentially unchanged, a host of detail changes deliver the increase in power and torque.

And while the peak boost is significant - 1.8kW more power at 9,500rpm and 2Nm more torque at 7,500rpm - it has not been achieved at the expense of low-down performance: the strength of the YM19 engine’s power and torque curves from 3,000rpm up are well above the previous design, and corner-to-corner over-rev has also been enhanced.

Bore and stroke remains 96mm x 62.1mm with compression ratio of 13.5:1. Combustion chamber squish has been revised, as has the piston skirt profile, piston ring and conrod; both right and left engine cases have been optimised for strength versus weight.

A new air cleaner element base has more than double the surface area, and flows much more air as a result; revised PGM-F1 settings make use of upgrade and injects fuel twice per cycle. In step with the improved engine output, a revised radiator grill improves air flow for maximum radiator efficiency. A gear position sensor allows the use of three specific ignition maps for 1^st and 2^nd, 3^rd and 4^th, and 5^th.

The exhaust too now uses differing, larger diameter bores where it splits from the downpipe; 35mm right and 42mm diameter left (both were 31.8mm before). And the total length of the left side exhaust – from port to tip – has been increased 187mm, with the right muffler tube 98mm longer.

It’s not all about performance. Reliability is a crucial element of the CRF450RX’s appeal. A new 5-hole piston oil jet replaces the 4-hole design and the scavenge pump, which used a single, 16mm diameter pickup drum now employs twin 12mm drums, resulting in greater capacity. The clutch lifter and pressure plate are redesigned for improved durability, and a lighter load at the lever. Final drive is via 13T front and 50T rear sprockets.

The rider controls and displays – engine stop button, EFI warning, EMSB mode button and LED indicator – are all in one place on the left handlebar:

New for YM19, HRC’s Launch Control system gives any rider the best option for a strong start and has 3 modes to choose from:

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

Level 2 – 8,500rpm, dry conditions/basic

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 LED will blink once for Level 1 selection. Push the Start button again, for .5s or longer, and the LED will blink twice for Level 2. Repeat the process and the LED will blink 3 times, indication Level 3 has been chosen.

Honda’s EMSB (Engine Mode Select Button) puts instant engine character adaptability at the rider’s control. With the machine stopped, and engine at idle, a simple press and hold of the button for just under a second selects the next map in sequence.

The LED built into the button signals the map in use with a quick press and number of subsequent flashes (like HRC Launch Control, 1 flash for Mode 1, etc). If a new map is selected the choice is also confirmed to the rider.

Mode 1 uses the standard combination of ignition and fuelling maps to present a balanced power and torque delivery. Mode 2 is more mellow in nature, giving easy-to-manage throttle feel. Mode 3 hits sharply, with aggressive and responsive power. Mode 2 and 3 can be further tailored via the existing HRC setting tool for mapping hardware and software.

3.2 Chassis

• Nearly 1kg lighter; frame and swingarm revised in detail
• New settings for 49mm Showa USD fork and rear shock
• Redesigned footpegs and front brake caliper
• Renthal Fatbars can be adjusted forward/back/up/down

The goal for the seventh generation of CRF aluminium beam frame, debuted in YM17 were clear and defined: improved corenring performance and front-end stability/traction – plus rear wheel drive – while delivering elevated levels of rider feedback and predictability.

And if the focus of YM19 revolves around more power (and its control) from the engine, the CRF450RX’s chassis has also improved in step, with even better balance, turning ability and tracking through a corner. 0.9kg has been shaved from the wet weight (dry weight is now 109.5kg, wet weight 115.6kg) while suspension action front and rear has been revised. Rake and trail are set at 27.4°/116mm, with wheelbase of 1,477mm.

The tapered twin-spar frame design has been optimised for rigidity around the swingarm pivot plates. The swingarm too has been subtly re-shaped and features a lower rigidity balance to improve traction and feel while the right and left cylinder head hangers have also been optimised. A useful detail – that also saves 20% weight – are the footpegs, which now use a 4-web (rather than 6) internal structure to clear mud faster.

The fully adjustable 49mm Showa USD coil spring fork is a version of the Showa ‘factory’ fork supplied to MX race teams in the Japanese championship.

For YM19 spring rate, compression/damping settings and oil weight have been revised. The fully adjustable Showa rear shock has received a ‘Super Finish’ treatment, which improves its stroke action. A revised Pro-Link ratio softens slightly as it reaches full compression.

Also new on the CRF450RX for YM19 is the Renthal Fat Bar (839) aluminium handlebar, reduces the weight of the steering system and flexes for optimal comfort; the top yoke features two handlebar-holder locations for moving the handlebar rearward and forward by 26mm. When the holder is turned 180 degrees, the handlebar can be moved an additional 10mm from the base position, resulting in four total unique riding positions. A Bar Pad is also included.

A new twin-piston front brake caliper uses 30 and 27mm diameter pistons (the previous design used 2 x 27mm pistons). This allows for a lighter body and, along with low expansion rate brake hose, improves brake feel and staying power. It works on a 260mm wave-pattern disc, matched by a rear 240mm wave-pattern disc and single-piston caliper.

Lightweight DID aluminium rims, with directly attached spoke pattern layout are now finished in black; the front is 21 x 1.6in, the rear 18 x 2.15in. Fitted as standard equipment are Dunlop’s bespoke enduro Geomax AT81 tyres: 90/90-21 front and 120/90-18 rear.

The CRF450RX uses a lightweight 8.5L plastic fuel tank; range is approx. 65km. The smooth external lines of the plastics help the rider move easily, and the narrow frontal area and front mudguard directs an efficient funnel of air to the radiator – for YM19 the radiator grills have been redesigned to flow more air.

The bodywork uses durable film inset graphics that cover a wide area with scratch-resistant style.

4. Technical Specifications

**All specifications are provisional and subject to change without notice.