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
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement