Next year, Kawasaki will attack the off-road segment with a new KLX450R (designated a 2008 model), based on the company’s successful KX450F motocross machine. According to Kawasaki’s press materials, the company’s engineers started with the KX450F and “modified it for the improved durability, comfort and range needed by off-road racers”. These modifications consist mainly of changes to the motor for a more off-road friendly power characteristic, along with increased durability, as well as a wide-ratio 5 speed transmission and some revision of the bike’s ergonomics for greater long-distance comfort. Below is the complete text of Kawasaki’s press release regarding the 2008 KLX450R.

NEW 2008 KAWASAKI KLX™450R MODERN OFF-ROAD DESIGN MEETS WORLD CHAMPION MOTOCROSSER

Off-road toughness, electric-start convenience, motocross performance

Kawasaki’s 2008 KLX450R will soon be making a name for itself amongst the growing legion of off-road racing fans. This purpose-built version of the brand’s World Supercross Championship winning four-stroke KX™450F motocrosser delivers the same high performance features as the KX model, yet modifies it for the improved durability, comfort, and range needed by off-road racers.
Adapted to the rigors of grueling courses, this model’s lightweight engine has been tweaked for more low and mid-range performance delivering a wide spread of responsive, high-traction torque and superior throttle control for low-speed maneuvering. The KLX450R’s gutsy response to hill climbing, mud holes, or other poor-traction, low-speed conditions will put it at the top of every racer’s “want” list.

Kawasaki engineers have combined revisions in cam lift and timing in order to boost low and mid-range torque. Adding to the special characteristics of this engine are a heavier flywheel with double the mass of the KX450F’s unit and a wide-ratio five-speed transmission with gears that have been specifically selected for off-road competition.

Adding an electric starter in addition to its kick-starting capability gives the KLX rider more options in the event of a stall. A high-capacity starter motor and compact, high-output battery helps insure quick and reliable starts under virtually all conditions a racer might face. A simple push of the starter button is all that’s required in the event of a stall and can often be accomplished while still moving.

Given the length of some off-road race courses, being there at the end is just as important as getting there quickly. Kawasaki has engineered-in extra durability for the KLX450R, to help make it the envy of all competitive off-road riders. While the lightweight titanium intake valves from the KX remain unchanged, steel valves are used in place of the KX’s titanium exhaust valves and the radiator is fitted with a reservoir tank to provide efficient cooling during long enduros. The KLX450R also features a sealed chain.

Utilizing the top-of-the-line suspension from the championship-winning KX450F, this new motorcycle puts extreme off-road capability at the top of its must-do list. The Kayaba AOS inverted fork provides superb damping and steering precision with tuning specifically optimized for light, easy handling characteristics. Oil and air are kept in separate chambers for stable damping performance during long events and low-friction seals contribute to smooth fork action.

Rider fatigue can be a significant factor in the outcome of an event, or just a weekend play ride, and Kawasaki has taken steps to minimize this bothersome effect. The KLX450R’s chassis has been specially set-up to be nimble while negotiating narrow trails or maneuvering between rocks and trees. The wider seat with slip-resistant top surface adds both to comfort and mobility, while the 18-inch rear wheel allows for use of a taller/thicker rear tire which is more suited to absorbing sharp-edged impacts and allows the rider to choose from a wide selection of off-road tires.

A lightweight digital instrumentation cluster includes speedometer, twin tripmeter, odometer, and clock. The plastic fuel tank, which meets all environmental regulations, has a 2.1 gallon capacity and the petcock is fitted with a reserve. Illumination equipment is also kept on the light side, with the 35 watt compact headlight using a plastic lens, while the ultra-compact and energy efficient LED tail lamp highlights the part of the KLX450R that most other competitors will see.

Among the other race-ready features of this new motorcycle are: side covers shared with its motocross brother, though purposely lacking any holes so that water can’t seep in; a left-side cover made of two pieces with a special “door” that allows easy access to the air cleaner; engine guards for both sides of the engine; and a works-style aluminum skid plate. All told, this new Kawasaki is ready to get dirty.

This straight-from-the-factory racer has everything needed to both maneuver an open course and find its way to the winner’s podium. Every component found on the new KLX450R has been developed to enhance off-road racing performance while adding as little weight as possible. In fact, a fully-equipped KLX450R only weighs about 22 pounds more than the KX450F.

2008 Kawasaki KLX™450R

Features and Benefits

Ultra-powerful 449cc Liquid-cooled, Four-stroke Single

• 449cc liquid
• cooled, four-stroke single with four valves
• Features improved low and mid-range power delivery for climbing hills, riding in the mud or other poor-traction, low-speed conditions
• Linear power curve offers plenty of over
• rev, for maximum flexibility in choosing shift points

Top End

• Revised cam lift and timing boost low- and mid-range torque
• Camshaft lobes and tappets feature a soft-nitride surface treatment for long wear and high-rpm reliability
• Hand-finished surfaces of the polished intake ports improve intake efficiency at all rpm
• Lightweight 36mm titanium intake valves and aluminum valve retainers reduce reciprocating weight for reliable valve control at high rpm
• 30mm steel exhaust valves replace the KX’s 31mm titanium units for improved durability
• Double valve springs help ensure stable valve operation
• Screw-type automatic cam chain tensioner with oil pressure spring
• Revised ignition timing helps boost power
• Low-friction coating on piston skirt

Bottom End

• Flywheel mass is double that of the KX450F to provide ultra-smooth engine power characteristics
• Crankshaft, rotor mass centralization, oil circulation, and ignition timing have been carefully examined to help ensure ideal engine braking characteristics
• Crankshaft and connecting rod are sintered for additional rigidity

Exhaust

• Large 41mm titanium exhaust header for maximum power
• Tapered exhaust pipe joint helps increase ultra-low rpm power.
• Titanium exhaust pipe heat shield
• Silencer uses long-fiber packing for lower maintenance

Cooling

• High-capacity Denso radiators deliver superior cooling efficiency
• A reservoir tank is fitted to the radiator, for efficient cooling during long enduros
• Slim radiators feature tightly packed cores and fins designed to enhanced heat dispersion
• The KLX radiator shroud design is optimised for a seated position, compared to the KX shrouds

Electric Starting

• High-capacity starter motor is compact, yet offers high-output to help ensure quick and reliable starts under all conditions
• Lightweight battery is located beneath the seat and behind the airbox for optimum mass centralization
• Having both electric and kick starters means the KLX450 can be quickly restarted if the engine stalls during an event
• Features highly reliable auto-decompression system; the dual-weight centrifugal decompression system fitted to the exhaust cam eases starting, and its simple construction helps to ensure reliability

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