CRF250R

CRF250R Rubber-mounted Renthal 971 bend aluminium handlebar Compact new Honda Progressive Steering Damper (HPSD) smoothes handling for easier control and reduced fatigue Dual-muffler exhaust system with lightweight stainless steel header and repackable aluminium silencers Washable two-stage foam air filter for optimal engine protection and easy maintenance Long-travel, 47mm Showa inverted twin-chamber cartridge-type fork Pro-Link rear suspension system features fully adjustable Showa rear with new settings Dunlop 742FA front and 756 rear tyres offer optimal traction and cornering feel Removable rear sub-frame allows easy maintenance Front disc brake cover helps protect rotor and calliper from damage HRC Works-type rear brake Compact dual-piston calliper front brake with anodised aluminium pistons and lightweight rotor Swingarm features dual-axis, double-taper design with a large cast aluminium cross-member Wide, cleated, self-cleaning stainless steel footpegs Powerful 249cm3 liquid-cooled 4-stroke 4-valve Unicam engine with magnesium ACG cover, clutch cover and cylinder-head cover Lightweight and rugged twin-spar aluminium frame HRC Works-type aluminium spoke nipples for reduced unsprung weight All specifications are provisional and subject to change without notice. 2008 I CRF250R I Press Information CRF250R 2008 Press Information EU-EN – 1/7 CRF250R - 2008 Introduction Features and Benefits Featuring blazing 4-stroke engine performance and a unique dual silencer exhaust system, the hard-charging CRF250R delivers up a potent blend of quick-revving, race-bred 4-stroke performance and crisp, responsive handling that dominates the motocross circuit’s tight berms and big air jumps with confident ease. New for 2008 The CRF250R charges out of the corners riding a wide band of useable power cranked out by its high-revving liquid-cooled 4-valve Unicam engine. Its lightweight and rugged aluminium frame and fully optimised suspension systems have been tuned for race-winning performance, and are now complemented by an amazing new Honda Progressive Steering Damper (HPSD) that extends one’s riding capabilities with smoothly assured handling through the roughest track conditions, providing amazing control that smokes the competition right out of the box. A pure-bred performer that’s always one step ahead of the pack, the new CRF250R proudly assaults the circuits as living proof that at Honda racing always improves the breed. Colours • Extreme Red (with White number plate and sidecovers) • New piston with 13.1:1 compression ratio. • New cylinder head porting for improved power. • New lighter-weight valve train components raise rev limit to 13,500 rpm. • New lighter weight counter-balancer shaft and drive gears. • New exhaust system for stronger power. • New camshaft timing for added power. • Revised carburettor jetting gives smooth power delivery under all riding conditions. • Engine torque now reaches maximum at 8,500rpm. • New clutch features judder spring for smoother engagement. • Lightweight and compact new Honda Progressive Steering Damper (HPSD) developed by Team Honda for improved cornering ability and reduced rider fatigue. HPSD features a compact and rugged hydraulic damper attached between the steering head and the lower triple-clamp to augment more aggressive steering characteristics and assist straight-line handling. The damper’s progressive damping action smoothly increases with handlebar deflection, which produces very natural steering characteristics and feel. • New front fork triple-clamps feature 22mm offset for improved cornering. • New Showa fork features a larger cartridge rod and new cartridge oil piston for improved oil flow and less friction, plus stiffer springs for improved mid-stroke action. • New rear damper valving matches changes to front fork. • New Works-style front and rear brake rotors reduce unsprung weight. • New rear fender shape for improved mud protection. EU-EN – 2/7 CRF250R - 2008 • New larger left-side engine guard. Engine/Drivetrain • Powerful 249cm³ liquid-cooled 4-stroke 4-valve Unicam engine designed to produce power across a wide rpm range for easy-to-control operation. • Unicam valve train provides both the light weight of a compact single-cam drive and an optimum combustion chamber shape for maximum power at all engine speeds. • Unicam valve train features a single carburized camshaft directly actuating two 31mm titanium intake valves. The camshaft’s centre exhaust lobe actuates two 26mm steel exhaust valves via a low-friction forked roller rocker arm. • Lightweight and compact internal auto decompressor and handlebar-mounted hot-start system provide superb operation, hot or cold. • Lightweight titanium intake valves permit use of smaller valve springs, reducing overall engine height. • ACG cover, clutch cover and cylinder-head cover made of magnesium for reduced engine weight. • Forged slipper piston and rings are lighter than conventional designs, revving quickly while maintaining excellent cylinder sealing, high 13.1 : 1 compression ratio and high-rpm power. • Lightweight NiCaSil cylinder lining ensures cooler and quieter operation for extended engine life. • 40mm Keihin FCR carburettor features four rollers on flat slide, resulting in very light throttle effort, smooth operation, crisp throttle response and excellent rideability. • Carburettor features a Throttle Position Sensor (TPS) that helps maintain linear throttle response throughout the rev range and new jetting for smoother power response. • Twin-sump lubrication system separates oil supply to crankshaft, piston and valve train from clutch and transmission. This ensures a steady supply of cool oil to the clutch, eliminates clutch and transmission material contamination of the engine oil, and reduces the amount of circulating oil, which permits the use of a smaller oil pump. • Dual-muffler exhaust system centralises mass and reduces turning inertia to improve the CRF250R’s lightweight feel. • Dual-muffler exhaust system also increases low-rpm torque. • Exhaust system uses a lightweight stainless exhaust header and repackable aluminium silencers. • Gear-driven balancer reduces vibration while also driving the water pump. • Rugged eight-plate clutch provides ample surface area 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. Chassis/Suspension • Fourth-generation twin-spar aluminium frame derived from Honda’s CR series of champions. Forged aluminium steering head and tapered down-tube section designed to optimise frame rigidity, while tall swingarm pivot plates and thin frame spars create a narrow overall frame cross-section for superb rider comfort and manoeuvrability. • Swingarm features dual-axis, double-taper design with a large cast aluminium cross-member. • Front and rear wheels feature lightweight HRC Workstype aluminium spoke nipples for reduced unsprung weight. • Front wheel features large-diameter front axle and wide wheel-bearing span for excellent rigidity. EU-EN – 3/7 CRF250R - 2008 • Rear axle diameter of 25mm and large-diameter bearings provide significant rigidity to withstand torturous track conditions. • Lightweight, 47mm Showa inverted twin-chamber cartridge-type fork with aluminium dampers. Fork offers 315mm of travel and 16-step rebound and compression damping adjustability. Front fork outer-tubes receive same inner surface honing treatment as Works bikes for low-friction operation. • Pro-Link rear suspension system features single fully adjustable Showa rear damper with new damper settings and 313mm of wheel travel, separate low-speed (13step) and high-speed (3.5 turns) compression damping adjusters and 17-step rebound damping. • Large 50mm-diameter rear damper piston provides consistent performance under demanding riding conditions. • Link-type front brake master cylinder provides strong braking control in combination with a lightweight brake rotor. • Compact dual-piston front brake calliper, anodised aluminium brake pistons and lightweight front brake rotor minimise unsprung weight for improved turning and handling. • HRC Works-type rear brake system integrates the rear master cylinder and fluid reservoir, eliminating conventional external reservoir and hose. • Large, Works-style 240mm front and rear disc brake rotors. Additional Features • Frame design allows airbox sidecovers to have larger intake ducts, contributing to excellent airflow in the mid- and upper-rpm ranges. • All plastic body components (radiator shroud, sidecovers, rear fender, seat base, fuel tank, front fender and front number plate), offer a slim, aggressive style and light weight. • Rider ergonomics optimised by adapting handlebar, seat and footpeg height to place the rider’s legs at the narrowest cross-section of the frame for improved comfort and handling feel. • Dunlop 742FA front and 756 rear tyres provide improved traction and cornering feel. • Front disc brake cover helps protect rotor and calliper from damage. • Removable rear sub-frame allows easy maintenance. • Washable, two-stage foam air filter for optimal engine protection and easy maintenance. • Comfortable, durable controls and high-quality fasteners. • Stainless steel clutch cable for long-life operation. • Cleated rear brake pedal and folding shift lever made of lightweight aluminium and designed to complement the riding position. Brake pedal features optimised ratio to match integrated rear-brake master cylinder design. • Wide, cleated stainless steel footpegs are selfcleaning, corrosion-resistant, provide excellent grip and fold for extra ground clearance. • Aluminium Renthal handlebar (971 bend) rubbermounted to reduce rider fatigue and improve comfort. • Honda Racing-inspired colours and graphics. Honda Progressive Steering Damper A revolutionary application of steering damper technology creates a new level of agile handling If you think you already know a lot about steering dampers, get ready to think again. With a stroke of fresh engineering insight, the hard-working minds at Honda have created the Honda Progressive Steering Damper (HPSD), a new application of steering damper technology designed specifically to augment more aggressive turning characteristics rather than only assisting straight-line handling, as has been the case with steering dampers in past applications. EU-EN – 4/7 CRF250R - 2008 With the integration of Honda’s new HPSD, the 2008 CRF450R and CRF250R both demonstrate a higher level of front-end traction with significantly enhanced steering feel, specifically a more “planted” feel in turns for better front-wheel control, especially under dry, hard-packed track conditions. Net result: greater cornering speed, a higher level of front-end confidence and reduced rider fatigue thanks to this damper’s astounding new turning ease. Additionally, HPSD enhances handling in whoops and fast sections of the track, all of which combine to speed up lap times over the entire course of a race. The earliest versions of HPSD first saw action aboard the American Honda Racing Team’s CRF450R and CRF250R race bikes during the 2004 AMA Supercross series. Initial response from team riders was overwhelmingly positive. Additional testing confirmed just how versatile the system could be under a wide range of tracks and riding conditions. From here the stage was set for the prototype HPSD to see action at the highest levels of Supercross and Motocross racing for the entire 2004 season. Thus equipped, the CRF450R found remarkable success in AMA Supercross and went on to sweep every AMA motocross win during the 2004 outdoor Motocross season, a high-water mark in the history of the sport. Ongoing development work saw HPSD installed on Honda Works motocrossers through the 2007 season, including Europe’s highly successful World Motocross contenders, Team Martin Honda. This intensive four-year period of development and testing of various damper settings under top-level racing conditions led to a finalised design and integration on the 2008 model year CRF450R and CRF250R. HPSD has given Honda’s engineers the ability to create more aggressive chassis geometry for increased agility without compromising machine stability. Accordingly, the CRF450R and CRF250R both feature revised steering geometry for 2008, thanks to a change in fork offset via their new triple-clamps. For example, the change from 24mm of offset to 22mm alters the CRF450R’s steering trail from 109.4mm on the 2007 model to 111.4mm for 2008, which reflects the front-end being tucked in 2mm closer to the engine. This change also shortens the wheelbase by 2mm. This change results in even quicker turning characteristics and improved front-end traction, thus allowing the rider to hold the line more easily in tight corners. Moreover, while in mid-turn—and virtually everywhere else on the track—HPSD damps out a lot of the jarring that normally tries to deflect the front wheel. Subsequently the rider doesn’t need to work as hard to hold a line. In the past, pulling 2mm from the steering offset and shortening the wheelbase might have sacrificed handling, but with HPSD, riders get the best of both worlds: quicker steering and better handling, especially at higher speeds. HPSD consists of a very compact and very clever damper mounted behind the front number plate. Weighing a mere 6.5 ounces, it attaches between the lower triple-clamp and the steering head. The damper offers 15 clicks of adjustability and is also completely rebuildable. Its small size permits it to be tucked behind a newly styled number plate that protects it from flying debris. To complement the addition of HPSD, the steering head was completely redesigned and re-tuned for correct flex/ stiffness properties, and an HPSD mounting lug was incorporated. Likewise, the triple-clamps were newly designed to yield the correct degree of stiffness, given the new forces imparted by the steering damper system. Given the interrelated nature of the forces acting on this latest iteration of Honda’s highly sophisticated fourthgeneration aluminium frame, every force input was carefully calculated and matched so that the chassis, suspension and HPSD all worked in concert as one system. In short, HPSD is not merely a bolt-on damper. EU-EN – 5/7 CRF250R - 2008 As the name Progressive Steering Damper infers, the damping action of the unit increases over the range of travel. From the steering head’s neutral position to approximately five degrees of movement in either direction (which are very small off-centre changes), HPSD exerts minimal damping force, resulting in neutral steering during straight-line running. As handlebar movement increases and further extends the damper rod, damping force smoothly increases to produce very natural steering characteristics and feel. To achieve this natural steering feel, HPSD’s damping rates differ in the two directions of travel; under extension when the handlebar is turned away from centre, damping forces are significantly greater. Under compression as the handlebar returns to the straight-ahead position, HPSD offers less resistance. In addition, at about the one-third point on the extension throw, a position-sensitive damping circuit opens and progression of the damping action lessens. This additional passageway, which in cutaway view looks like a small channel machined into the damper body, moderates the damping force under more extreme handlebar angles. In addition, the damping mechanism is speed sensitive, relative to the speed of handlebar movement and wheel deflection; as sharp impacts cause the front-end to rapidly deflect, HPSD provides proportionally greater damping force. Yet when the rider places steering input through the handlebar, the damping action feels negligible and entirely natural. In addition, Team Honda riders have discovered that use of HPSD permits the use of distinctly stiffer front suspension settings than had been possible without the steering damper. The addition of HPSD offered riders another opportunity to fine-tune their machines in new ways to match various riding conditions. Proof once again that the entire chassis is a highly tuned system that must be designed and adjusted as a whole. Subsequent testing for the 2008 CRFs confirmed this for production bikes as well, and, as a result, the new CRF450R and CRF250R both feature slightly stiffer springs and revised compression and rebound damping rates in the fork. With HPSD, the 2008 CRF450R and CRF250R feel just as stable through fast whoops as the 2007 model did with its more conservative fork offset, yet steering for both new bikes is markedly quicker, and remarkably easier on the rider. When the front-end impacts an obstacle off-centre and the handlebar begins to kick out in response, HPSD automatically lends a steadying degree of damping. As a result, these 2008 models feel distinctly easier to ride; not only offering precise steering action that inspires confidence, but also remarkably smooth and responsive, allowing the rider to more easily steer in and out of ruts and take other lines at will. In short, the Honda Progressive Steering Damper reflects once again the benefits of innovative engineering. By fundamentally moderating the manner in which outside forces affect a bike’s steering, HPSD now extends Honda’s ability to elevate the sport to the next level. The location of the HPSD unit also creates what is in effect a rising-rate mechanical stroke for the damper rod travel without the need for a complicated linkage. As the handlebar arcs toward the steering stops, the increased degree of turning produces increasingly larger amounts of travel from the shock on the extension stroke. Hence, a rising rate relationship in shock stroke versus handlebar movement. Net result: a very natural steering feel along with the bonus of added damping assistance as the handlebar moves farther from center. EU-EN – 6/7 CRF250R - 2008 Specifications General Suspension Model CRF250R Mold Type ED-type Front 47mm inverted Showa leading-axle twinchamber cartridge-type telescopic fork with 16-step adjustable compression and rebound damping; 315mm axle travel Rear Pro-Link with single Showa damper, adjustable low-speed (13-step) and highspeed (3.5-turn) compression and 17-step rebound damping; 313mm axle travel Type Front Aluminium rim/wire spoke Rear Aluminium rim/wire spoke Rim Size Front 21 x 1.60 Rear 19 x 1.85 Front 80/100 21 (51M) Rear 100/90 19 (57M) Front 240mm x 3mm hydraulic disc with dual-piston calliper and sintered metal pads Rear 240mm x 4mm hydraulic disc with singlepiston calliper and sintered metal pads Type Engine Type Liquid-cooled 4-stroke 4-valve SOHC single Displacement 249.4cm³ Bore x Stroke 78 x 52.2mm Compression Ratio 13.1 : 1 Max. Power Output 32kW / 11,000min-1 (95/1/EC) Max. Torque 29.3Nm / 8,500min-1 (95/1/EC) Wheels Fuel System 40mm Keihin FCR flat slide carburettor with throttle position sensor (TPS) Carburation Fuel Tank Capacity Tyre Size 7.3 litres Brakes Electrical System Ignition System Computer-controlled digital capacitor discharge with electronic advance Starter Primary kick Type Drivetrain Transmission 5-speed Primary Reduction 3.166 (57/18) Gear Ratios 1 2.142 (30/14) 2 1.750 (28/16) 3 1.450 (29/20) 4 1.227 (27/22) 5 1.041 (25/24) Final Reduction 3.923 (51/13) Final Drive #520 roller chain Frame Type Semi-double cradle; aluminium twin-spar Chassis Dimensions (LxWxH) 2,170 x 827 x 1,277mm Wheelbase 1,477mm Caster Angle 27° 50' Trail 125mm Seat Height 965mm Ground Clearance 362mm Kerb Weight 101.2kg All specifications are provisional and subject to change without notice. EU-EN – 7/7
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Related manuals
Download PDF
advertisement