The photos, and the text that follows, in this article are taken from the European press materials released by Honda concerning the 2004 CRF450R motocross machine. Highlights of the changes are listed at the beginning of the press materials below, but include, most notably, production Renthal handlebars (not the oversize bars, but the traditional Renthal bars in a 971 bend), an engine with increased compression for improved torque, quick adjuster on the stock clutch, honed fork sliders for reduced friction (similar to the set-up on factory motocross bikes), and a three pound weight reduction (described as 1.5 kilograms in the European materials).

Interestingly, the 450 continues with the third generation aluminum frame, while the new 250cc four-stroke motocrosser will receive a fourth generation frame (more about that later). Here is the text from the press materials, with all the details:

Features and Benefits

New Features

• New piston shape for increased compression and improved torque over entire rpm-range.
• New exhaust system layout allows muffler to be moved forward 50mm for optimum
  centralization of mass.

• New Renthal Bars as standard equipment (971 Bend).
• New clutch lever with quick adjuster.
  

• The inner surface of front fork slide pipes use same process as works bikes to mechanically
  hone for less friction. First time on a mass production motocrosser.

• New footpegs for less mud build-up.
• Improved carburetor settings for sharper throttle response.
• New seat cover with improved gripping bumps.
• New front fender and front number plate for slimmer more aggressive look.
• Overall lighter weight by 1.5kg.
• New ACG cover made from new magnesium material reduces heat build-up and
  weight.

Engine/Drivetrain

• Powerful engine churns out 41.5kW/9,000rpm and 50.7N-m/7,000rpm. Power is produced
  across a wide rpm-band for easy-to-control operation.

• Auto decompression and hot restart system make starting easy in all conditions.
• Liquid-cooled four-valve SOHC 449cc engine produces more than 120hp per liter while
  maintaining Honda’s legendary dependability and simplicity.

• Compact, lightweight engine assembly weighs only 29kg.
• Unicam(tm) valve train provides the light weight of a compact single-cam drive and the
  optimum combustion chamber shape for maximum power at all engine rpm.

• Unicam valve train features a carburized single camshaft that directly actuates two 36mm
  titanium intake valves. The camshaft exhaust lobe actuates two 31mm steel exhaust valves via
  a forked, low-friction, roller rocker arm. A separate cam holder contributes to the compact
  design, which allows a remarkable 21.5° included valve angle and saves weight over a
  comparable DOHC system.

• Lightweight titanium intake valves permit use of smaller valve springs, reducing overall engine
  height and saving 15.2g per valve compared to a steel valve design.

• Unique, pin-rotation-type auto decompressor produces a lightweight, compact system that
  provides superb cold-starting and hot-restarting operation.

• Crankshaft is made of high-strength, low-carbon steel with carburized main journals for
  maximum durability at sustained high-rpm operation.

• Forged, 12.0:1 compression slipper piston is more than 130g lighter than a conventional
  design, revving quickly while maintaining excellent cylinder sealing and high-rpm power.
  Compared to its predecessor a weight reduction of 17g is obtained.

• Double-carburized connecting rod utilizes a big-end needle bearing for maximum high-rpm
  performance and durability.

• Nikasil(r) cylinder lining is lightweight and provides cooler and quieter operation for
  extended engine life.

• Press-fitted spark plug pipe fits between forked exhaust rocker arms, further contributing to
  compact cylinder head design.

• 40mm FCR-type carburetor features four rollers on the flat slide, resulting in very light
  throttle effort, smooth operation, crisp throttle response and excellent rideability.

• An 8-bit digital CPU incorporates the capacitive discharge ignition (CDI), producing
  immediate data calculation and extremely accurate ignition for maximum performance.

• Twin-sump lubrication system separates the oil supply for the crankshaft, piston and valve
  train from the clutch and transmission. This ensures a cool supply of oil to the clutch, eliminates
  clutch and transmission material contamination to the engine oil, and reduces the amount of
  circulating oil and the required size of the oil pump.

• Vertically split crankcases feature a built-in oil pump, reducing weight 145g compared to a
  conventional design.

• Exhaust system uses a lightweight titanium exhaust header and repackable aluminum muffler
  with stainless steel pipe.

• Dual radiators provide significantly more surface area and more effective heat dissipation
  compared to a single-radiator design.

• Gear-driven balancer reduces vibration and drives the water pump. Eight clutch plates
  provide the surface area necessary to handle the engine’s massive torque, while carefully
  matched clutch springs provide a light feel at the lever.

• Durable five-speed close-ratio transmission now features a new hardening process for
  second and third gears, adding even more durability in demanding conditions.

Chassis/Suspension

• Twin-spar aluminum frame is a third-generation design derived from Honda’s CR series. Tall
  swingarm pivot plates and thin frame spars create a narrow overall frame cross-section for
  superb rider comfort and maneuverability.

• Semi-double-cradle design features a single, large-diameter tapered downtube. Two rugged
  box-section rails attach to the base of the downtube and support the engine. A forged
  aluminum steering head provides a compact and extremely durable mount for the frame spars
  and engine downtube.

• The aluminum frame design is matched to rider ergonomics to maximize handling and control
  operation.

• CR-type swingarm features a dual-axis, double-taper design with a large cast aluminum crossmember.
  End piece has been redesigned for a weight savings of almost 30g.

• CR-spec front and rear wheels feature HRC works-type lightweight aluminum spoke
  nipples. Compared to last year, front wheel unsprung weight is reduced by over 150g.
  Together with a revised rear wheel, hub and spoke design, rear wheel unsprung weight
  compared to a conventional design is reduced 450g.

• Front wheel features large-diameter front axle and wide wheel-bearing span for excellent
  rigidity.

• Optional 20-inch front wheel improves cornering traction and rider comfort.
• Rear axle diameter of 25mm and large-diameter bearings provide significant rigidity to
  withstand torturous track conditions.

• Lightweight, 47mm inverted Showa(r) twin-chamber cartridge fork with aluminum dampers
  is derived from the CR250R and features settings unique to the CRF. The fork offers 315mm
  of travel, 16-position rebound and 16-position compression damping adjustability. The inner
  surface of front fork outer-tubes receives same honing treatment as works bikes for lowfriction
  operation.

• CR-type Pro-Link(r) single-shock rear suspension system features a fully adjustable Showa
  rear damper and 319mm of wheel travel, separate low-speed (13 positions) and high-speed
  (3.5 turns) compression damping adjusters and 17-position rebound damping.

• Rear shock’s damper piston diameter is 50mm for consistent performance under demanding
  riding conditions.

• Compact dual-piston front brake caliper has been redesigned for a weight savings of over
  30g, anodized aluminum brake pistons and lightweight front brake disc minimize unsprung
  weight for improved turning and handling.

• HRC(r) works-type rear brake system integrates the rear master cylinder and fluid reservoir,
  eliminating the rear master cylinder reservoir and hose.

• Large, 240mm front and rear brake discs.

Additional Features

• Frame design allows sidecovers to have larger air-intake ducts, contributing to significant
  airflow in the mid- and upper-rpm range.

• Rider ergonomics are optimized by adapting the handlebar, the seat and the
  footpeg height to place the rider’s legs at the narrowest cross-section of the frame, for
  improved comfort and handling feel.

• Seat cushion uses multi-density foam construction that follows the shape of the fuel tank,
  providing a smooth transition to increase rider mobility and comfort.

• New seat cover has been designed with larger grip bumps for improved rider control.
• Brake pedal and shift lever are designed to complement the riding position. Brake pedal
  features optimized ratio to match integrated rear-brake master cylinder design.

• Wide, cleated stainless steel footpegs have been re-designed to improve self-cleaning, resist
  corrosion, provide excellent grip and fold for extra ground clearance.

• Cleated rear brake pedal and shift lever are made of lightweight aluminum.
• Adjustable front brake lever.
• New Renthal handlebar is rubber-mounted to reduce rider fatigue and improve comfort.
• CR handlebar holders provide three different mounting positions: standard CRF450R holder
  (CR125R-type) provides +/- 3mm fore or aft position to match rider preference, and optional
  holder (CR250R-type) provides neutral position.

• Works-type handlebar grips add to rider comfort.
• Chain guide has been redesigned for a weight savings of almost 20g.
• Front disc brake cover helps protect rotor and caliper from damage.
• Removable rear subframe allows easy maintenance.
• Washable, two-stage foam air filter for optimal engine protection and easy maintenance.
• Re-packable silencer for maximum performance and minimal noise.
• Comfortable, durable controls and high-quality fasteners.
• Stainless steel clutch cable for long life.
• Honda Racing-inspired colors and graphics.

Consult owner’s manual for optional racing parts.
All specifications are provisional and subject to change without notice.

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