Model updates: Honda’s MX2 machine receives 48mm
Showa USD air forks, new rear mufflers and the same Engine Mode Select
Button as the CRF450R – with choice of three engine maps – plus 260mm
front disc and detail updates.
Contents:
1 Introduction
2 Model overview
3 Key features
4 Technical specifications
1. Introduction
Skirmishing in a close fought arena of competition,
Honda’s CRF250R has consistently proven itself a polished performer. Its
blend of power – and the fluid way it produces it – and razor-sharp
handling agility combine to create a potent MX2 tool.
In 2014 HRC’s engineers upgraded the CRF250R with
the same aluminium beam frame and over-arching design philosophy of
mass-centralisation as the CRF450R. The new 2015 CRF250R expands on this
direction of development with chassis and engine upgrades that tie it
even closer to its larger capacity sibling, enhancing further its
ability to cut lap times in the hands of both professional and amateur
riders alike.
2. Model Overview
The 2015 model year sees the CRF250R receive 48mm
Showa air forks. As it essentially uses the CRF450R chassis developed in
conjunction with the pneumatic spring forks (made by Kayaba), the 2015
CRF250R now has front suspension to fully exploit the increased
performance potential on offer.
The Separate Front Function AIR (forks) with Triple
Air Chamber (SFF-AIR-TAC) unit has been developed specifically for the
unique demands of a 250cc competition machine. It’s much lighter than
the steel sprung fork it replaces and separates the damping and
compressions functions between the right and left fork legs. A new
spring material for the Showa rear shock is both stronger and lighter.
And like the 2015 CRF450R, the CRF250R gets the
Engine Mode Select Button (EMSB) that gives a choice of 3 riding modes
for the rider to select from the right side of the handlebar. Mode 1
delivers the standard combination of ECU maps, Mode 2 serves up smoother
throttle control and Mode 3 returns a more aggressive power delivery.
The twin rear mufflers feature bigger bore internals
and combine with new PGM-FI settings to improve throttle response
throughout the rev-range, with sharper low-to-mid rpm reaction. Finally
it also features a 260mm front disc, new graphics package and Dunlop
MX52F/MX52 tyres.
3. Key Features
3.1 Chassis
The SFF-AIR-TAC front suspension has been developed
for the CRF250R by Showa to unlock the frame’s extra performance
potential and shaves 1.3kg weight compared to the 14YM. The fully
adjustable right fork leg controls both compression and rebound damping
force while the left fork leg compresses air using a damper-less
structure. This distribution achieves a controlled right/left balance,
enhancing reaction over bumps and stability while hard on the front
brake.
Three chambers are employed by the left fork leg to
manage effective ‘spring’ rate. The Balance chamber operates from the
off and at low speed; the Inner chamber is responsible for the mid-range
stroke and the Outer Cylinder chamber is used as the forks near their
bump stops.
Static sag and preload is changed by adjusting air
pressure in the Inner and Balance chambers via a Schrader valve on the
fork cap, and changing the oil volume in the Outer chamber.
There are no changes to the CRF250R’s sixth
generation aluminium-twin beam frame, originally revealed on the 2013
CRF450R. The steering geometry of 27.23°, with 116.7mm trail and
wheelbase of 1,489mm works directly with the new Showa fork’s
performance and gives a superb connection to the front tyre with
increased feel for available side-grip on the limit. In combination with
the low centre of gravity, this means side-to-side transitions – in
the air or on the ground – require reduced rider input. All-up kerb
weight is down to 105.2kg.
A CRF250R-exclusive lower cradle houses the engine.
Careful packaging of equipment around the frame contributes to mass
centralization; the electrical components (ECU, condenser, regulator and
wiring harness) save weight and are centrally located below the
throttle body. Efficient, lightweight radiators – specific to the
CRF250R – mount low.
The compact Showa shock also mounts low within the
frame spars and uses a new spring material for 2015; it’s stronger and
lighter by 220g with no change in spring rate. The aluminum swingarm
features deep beam height in the front and centre sections, minimising
rut deflection and improving rear tyre traction on corner exit.
Honda’s Pro-Link rear suspension linkage operates
CRF250R-specific ratios and allows 31.7cm of travel. Fully adjustable,
the rear shock features 17-position rebound adjustment; compression
damping is separated into 13-position (low-speed) and 3.5 turns (high
speed).
The 2015 CRF250R’s bodywork maintains Honda’s man
maximum/machine minimum ethos that’s built around a rider’s needs, first
and foremost. Efficient riding ergonomics are at the heart of the
CRF250R shape. The radiator shrouds, side covers, lightweight seat and
fuel tank offer a slim, smooth and continuous transition allowing the
rider huge freedom and flexibility of movement.
In common with the CRF450R, new Black CRF decals and
detailing mirror the factory racer’s look. Another detail change is the
use of black radiator grilles in a hard-to-clean area. A new simplified
fuel hose design helps with cleaning and maintenance; fuel capacity is
6.3 litres.
A larger 260mm wave-pattern front disc improves heat
dissipation, power and feel from the two-piston brake caliper working
it; a matching 240mm wave-pattern disc and single-piston caliper is at
the rear. The new fork protectors and two-piece disc cover are finished
in White, while the front and rear brakes guides are now Black.
Lightweight aluminium rims reduce unsprung weight.
Both now wear top-specification Dunlop MX52F/MX52 80/100-21 front and
100/90-19 rear tyres which offer superb grip over a variety of
conditions, with block-within-a-block knobs for more progressive
side-grip and cornering, superior bump absorption from the sidewalls and
recessed carcass design plus increased durability.
3.2 Engine
In 2014, Honda’s 249cc MX power plant gained a
redesigned cylinder head and inlet exhaust porting, with increased
compression ratio of 13.5:1. At this point in development HRC’s
engineers focused on the rider’s ability to easily adjust the engine to
suit conditions and riding style, plus exhaust efficiency and throttle
feel.
The four-valve Unicam unit (with bore and stroke of
76.8mm x 53.8mm, 30.5mm dia. titanium inlet/25mm dia. steel exhaust
valves) has always impressed with its broad spread of useful power no
matter the revs, plus sharp throttle response.
Adding Honda’s EMSB to the mix has increased its
usability further. This is a bonus for the club racer in particular;
rather than set up during the week and hope for matching condition at
the weekend (or take a laptop to the track), the rider just has to stop
with the engine at idle and press and hold the button for just under a
second to select the next map in sequence.
A highly visible LED built into the lightweight
button signals the map in use with a quick press and number of
subsequent flashes. 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 designed for use in slippery, muddy conditions and is all about
throttle control, giving easy-to-manage feel that hunts out every last
shred of traction. Mode 3 hits all-out hard with aggressive and
responsive top-end power to drive through deep, soft sand. Mode 2 and 3
can be further tailored via the existing HRC mapping hardware and
software.
Improved throttle response throughout the rev-range
with crisper top-end and sharper snap off the bottom and through the
middle have been achieved through use of redesigned mufflers and
internals; the right inner diameter grows from 22 to 23.8mm, the left
from 23.4 to 26.6mm.
PGM-FI Dual Fuel Injection is fed by a CRF450R
specification airbox married to a dedicated CRF250R air boot and
features revised mapping to suit the free-breathing exhaust. It uses a
lighter throttle return spring on the 46mm throttle body to reduce
effort. In FIM form peak power of 28kW arrives @ 11,000rpm, with peak
torque of 26.5Nm delivered @ 8,500rpm.
A variety of maintenance packs will be available for the 2015 year model.
4. Technical Specifications
ENGINE |
|
Type |
Liquid-cooled 4-stroke single cylinder uni-cam |
Displacement |
249cc |
Bore x Stroke |
76.8mm x 53.8mm |
Compression Ratio |
13.5 : 1 |
Max. Power Output |
28kW @ 11,000rpm |
Max. Torque |
26.5Nm @ 8,500rpm |
Oil Capacity |
Engine oil 0.85 litres / Transmission oil 0.75 litres |
FUEL SYSTEM |
|
Carburation |
Fuel injection |
Fuel Tank Capacity |
6.3 litres |
ELECTRICAL SYSTEM |
|
Ignition |
Full transistor |
Starter |
Kick |
DRIVETRAIN |
|
Clutch Type |
Wet multiplate |
Transmission Type |
Constant mesh |
Final Drive |
Chain |
FRAME |
|
Type |
Aluminium twin tube |
CHASSIS |
|
Dimensions (LxWxH) |
2,181mm x 827mm x 1,271mm |
Wheelbase |
1,489mm |
Caster Angle |
27 °23' |
Trail |
116.7mm |
Seat Height |
951mm |
Ground Clearance |
322mm |
Kerb Weight |
105.2kg |
SUSPENSION |
|
Type Front |
Showa 48mm inverted SFF-TAC air fork (310mm stroke) |
Type Rear |
Showa monoshock using Honda Pro-Link system (317.6mm stroke, 133mm axle travel) |
WHEELS |
|
Type Front |
Aluminium spoke |
Type Rear |
Aluminium spoke |
Tyres Front |
80/100-21 Dunlop MX52F |
Tyres Rear |
100/90-19 Dunlop MX52 |
BRAKES |
|
Front |
260mm hydraulic wave disc |
Rear |
240mm hydraulic wave disc |
All specifications are provisional and subject to change without notice.
By press release Honda motors
Aucun commentaire:
Enregistrer un commentaire