25YM HONDA CRF250R


New Model: Improved cornering stability especially on rough circuit conditions – with zero loss of steering agility – is the outcome of development for the new HRC-inspired 25YM CRF250R, which shares a chassis with its new 25YM CRF450R sibling. A 70% new mainframe, alongside a variety of cycle part updates plus completely new Showa suspension and a two-piston Nissin front brake caliper are the main changes driving the performance upgrade. The engine features revised crankshaft, enhanced throttle connection, mid-range torque feel, and power past peak via revised intake/exhaust and PGM-FI settings. Electronic specification for 25YM now includes new 3-level Honda Selectable Torque Control (HSTC) in addition to Launch Control and Engine Mode Select Button (EMSB). New plastics and updated CRF family graphics treatment signify the model change while a Honda wing on the front mudguard is the finishing touch.

 

A new CRF250RWE will also be available, featuring parts that further enhance its performance and appeal.

 

Contents:

1 Introduction

2 Model overview

3 Key features

4 Technical specifications

 

1. Introduction 

The MX2 class is a relentless, close-quarter battle. And Honda’s CRF250R has proved itself a worthy weapon for the fight. Competition has led its evolution over time, through increments and steps, into a platform that the amateur MX enthusiast – as well as the pro-racer – can extract the utmost out of, every metre of every lap.

 

And it’s been on a massive development journey. In 18YM the CRF250R underwent a ground-up redesign that inherited the direction of the 17YM CRF450R, sharing its seventh-generation frame, revised geometry and Showa suspension. It was also armed with a brand-new DOHC engine and switchable engine mapping; rider-focused ergonomics ensured it remained an MX machine that the hobby rider could exploit to their individual level of ability.

 

The 19YM CRF250R received a boost to low-rpm torque, through extensive intake and exhaust development plus HRC launch control, revised front brake caliper and adjustable-position Renthal Fatbars. In 20YM it moved forward once again, with the frame and swingarm of the 19YM CRF450R and more mid-range for the engine.

 

For 22YM it made a significant performance with major chassis upgrades inherited from the 21YM CRF450R, improving both ability and agility. It also received stronger low-rpm torque to make best use of the new chassis, with improved toughness and durability.

 

Unchanged since then, for 25YM the CRF250R comes out of the gate charging hard and, just like the 25YM CRF450R, has a brand-new chassis plus harder hitting engine.

 

2. Model Overview 

Enhanced stability and control – especially over the roughest track conditions – were goals for the 25YM CRF250R. The aluminium twin-spar frame is 70% new, with a completely revised rigidity balance alongside new subframe attachment points, top/bottom yokes and stem, front wheel axle/clamp and Pro-Link ratio.

 

The Showa suspension has been completely remade (with 250-specific settings) and aims to deliver consistent damping and suspension reaction from bottom to top stroke. Both 49mm front forks and the rear monoshock feature new settings; the shock is also now much easier to remove. HRC provided the blueprint for the new front brake caliper, which now features new machining for the body, plus new pistons and seal grooves to resist heat fade over race distance.

 

For enhanced throttle control, drive and power past peak output the DOHC 4V engine employs a straighter path for airflow on the intake side, a straighter exhaust pipe route and revised PGM-FI settings. The muffler meets new FIM noise regulations.

 

Crisply redesigned side covers, radiator shrouds and CRF family graphics mark out the 25YM CRF250R, alongside a Honda Wing on the front mudguard.

 

3. Key Features

 

3.1 Chassis

 

  • 70% redesign of aluminium twin-spar frame improves overall stability
  • New top/bottom yokes and front wheel axle clamp and spindle
  • Brand new Showa front/rear suspension delivers smooth, consistent damping control
  • Revised Pro-Link shock linkage structure and ratio
  • New HRC-design front brake caliper resists heat fade

 

The 25YM CRF250R – well established as a fast-steering, lightweight tool – shares the exact same chassis as the 25YM CRF450R and pushes handling ability further, loading with increased straight line and cornering stability, bump absorption, and feel for front and rear grip.

 

The twin-spar aluminium main frame features a 70% redesign, with the aim of enhanced overall chassis stability on the roughest of track conditions. A new front down tube, stiffener spars and side gusset stiffener combine with new pivot plates, upper shock mount and tension bracket to generate 8% more torsional rigidity – improving stability. The torsional/lateral rigidity ratio is 5% greater, elevating cornering performance.  

 

Vertical torsional rigidity increases 4%, suppressing deformation and enhancing high-speed stability; the rear subframe now mounts on the high-rigidity pivot plates (rather than the frame spars). This change reduces the transmission of energy (and subsequent movement) from the back of the machine to the rear head pipe section by 27%.

 

A great deal of work has gone into the top/bottom yoke and steering stem to get a more consistent and stable suspension stroke. Alongside revised fork outer tubes and new front axle bolt the 25YM setup is more rigid, equalling a reduction of 6% in rigidity change during the stroke. The 585.2mm aluminium swingarm is unchanged.

 

Rake and trail are set at 28°24’/117mm with 1,483mm wheelbase and 330mm ground clearance. Dry weight is 102kg (107kg wet) with a 48.6/51.4% front/rear balance (wet).

Even more development has gone into the suspension. The aim has been to make fork stroke smoother, by removing any obstructions, while adding appropriate friction – 200% more friction force – throughout the entire stroke, with consistent damping force from top to bottom.

 

The Showa 49mm USD coil spring forks are effectively brand new with each component part – from outer rigidity to all internals – remade to deliver enhanced control from the initial movement all the way through. It employs a 310mm stroke and the oil specification is also new, to enhance low-speed damping. There are 16 adjustment positions for both of rebound and compression; all settings have been revised for 25YM.

 

Matching the forks the Showa rear shock has been remade to deliver consistent, uniform control anywhere in the stroke, with friction reduced in the bottom. There are 17 adjustment positions for rebound and 3.5 turns for high and 13 adjustment positions for low-speed compression, all revised for 25YM. A revised Pro-Link structure is 11% more rigid, with ratio and axle travel optimised to deliver smoother bump control. Axle travel is 308mm

 

The 25YM CRF250R has also been designed to make shock removal/replacement quicker, with only four parts needing removal, cutting time to change in half.

 

Drawing from parts employed by HRC’s factory race bikes, the re-machined, two piston front brake caliper uses new pistons and piston seal grooves. The new design reduces lever play by 57% when caliper temperature is high, while the caliper itself reduces rigidity change when hot by 25%, improving brake lever linearity and reducing rider fatigue. The 260mm wave-pattern disc is unchanged; a single-piston rear caliper is matched to a 240mm wave-pattern disc.

 

DID aluminium rims, with directly attached spoke pattern layout are finished in black; the front is a 21 x 1.6in, the rear a 19 x 1.85in. Pirelli’s MX32 tyres are fitted as standard equipment, sized 80/100-21 front and 100/90-19.

 

Minimal bodywork aids rider movement around the machine. The shrouds and side covers have been updated for 25YM, using the consistent CRF design philosophy focussed around weight reduction, mass centralisation and rider-friendly ergonomics. A flat knee trajectory, front to back of the machine, has been maintained.

 

All the 25YM CRF family members feature new family graphics that denote the model change, and the CRF250R features a Honda Wing on the front mudguard. The titanium fuel tank holds 6.3L.

 

Standard-fit, lightweight Renthal Fatbar flex for optimal comfort; the top yoke features two handlebar-holder locations for moving the handlebar rearward and forward by 26mm. When the holder is turned 180°, the handlebar can be moved an additional 10mm from the base position, resulting in four unique riding positions.

 

3.2 Engine

 

  • More direct airflow intake route improves throttle connection and torque feel
  • Smoother, straighter exhaust pipe boosts mid- to top-end acceleration range
  • New crankshaft is more rigid around crank pin with improved moment of inertia
  • Power UP past peak output

 

The CRF250R’s 249.4cc 4V DOHC engine has long established a top-end that’s one of the best on track, but it also builds torque and power from low rpm. The aim for 25YM was to improve power output past peak rpm, generate more mid- to high-rpm torque – thus acceleration – and smooth the throttle connection.

  

A newly redesigned crankshaft features increased rigidity around the crank pin and an improvement in the moment of inertia, allowing it to spin up faster. In conjunction the airflow route – through intake, airbox, intake funnel and throttle body – is more direct than the previous design, reducing resistance and improving throttle control.

 

A redesigned exhaust pipe also uses a straighter, smoother path for gas flow than the previous model which improves acceleration in the mid- to high-rpm range. The muffler is constructed from heat-treated aluminium to better stand up to the rider’s boot; it meets the new FIM 109dB noise regulation.

 

The intake cam sprocket is press-fit, saving weight and increasing rigidity. Double springs for the intake valves give extra high-rpm control. The oil’s pathway to the camshaft journals – and a rigid camshaft holder and head – reduce journal friction.

 

Precise alignment of the rocker arm shaft position aids high-rpm performance while the piston and connecting rod design maximise efficiency. Bore and stroke are set at 79 x 50.9mm, with a 4.5mm cylinder offset to reduce friction and compression ratio of 13.9:1. The valves are titanium; 33mm inlet and 26mm exhaust.

 

Extra levels of reliability are built in. The water pump gear design deals efficiently with high-temperature oil while pressure to the cylinder head ensures greater oil flow. A 5-hole piston oil jet maintains optimum piston cooling and ignition timing.

 

The combined oil pump/drive gear is on the right-hand side of the engine, with the oil filter and oil way on the right side – the oil’s path around the engine is short and straightforward and the oil also lubricates the clutch and transmission, with a total oil capacity of 1.25L.

 

3.3 Electronics

 

  • Now equipped with Honda Selectable Torque Control (HSTC) featuring 3 riding Modes (plus OFF)
  • 3-Mode HRC Launch Control
  • Engine Mode Select Button (EMSB)
  • HRC Setting tool tailors Aggressive and Smooth modes

 

The HSTC – as fitted to the CRF450R – works to minimise rear wheel spin (thus reducing wasted forward drive) and maximise traction. It doesn’t use a wheel speed sensor, and critically maintains feel at the throttle while managing power; ignition timing is retarded, and the PGM-FI controlled when the rate of change of rpm is detected to have gone over a set amount.

 

Three Modes differ in drive management level for different riding conditions:

 

Mode 1 intervenes most lightly, and after the longest time ­– useful for reducing wheelspin

 

Mode 2 naturally offers a mid-point between 1 and 3 in terms of speed and strength of intervention and maintaining control in tight corners.

 

Mode 3 has the system intervene more quickly and strongly, and is therefore useful in more slippery, muddy conditions.

 

HSTC can also be switched off completely. When the engine is turned on, the system uses the last-selected setting.

 

The Launch Control also has 3 Modes: Mode 1 has a high rev limit, 2 (the factory setting) uses a middle point with 3 set low. There are 3 Modes available via the Engine Mode Select Button (EMSB) to alter engine character. Mode 1 is the factory setting, 2 smooth and 3 aggressive.

 

The Launch Control indicator, EFI warning, HSTC and EMSB mode button, and LED indicator are sited on the left handlebar. Pressing and holding the HSTC button for 0.5s will cycle the system to the next mode, with a green LED indication – 1 blink for Mode 1, 2 for Mode 2 and 3 for Mode 3 – to confirm selection.

 

CRF250RWE

 

For 25YM, a special CRF250RWE will also be available. Benefitting from all the model upgrades of the CRF250R, the CRF250RWE features additional parts that enhance both its performance and its appeal.

 
Built alongside the CRF250R in Kumamoto, the CRF250RWE features a Yoshimura muffler and TwinAir air filter to improve air flow management. Exclusive ignition timings and unique start mode settings, alongside a new hydraulic clutch to help the rider. The CRF250RWE model now adopts the hydraulic clutch system with a revised clutch slave cylinder. The hydraulic clutch system reduces clutch lever pulling force by 16% when compared to a cable operated system. It also reduces the amount of variation in clutch free play and feel as the clutch temperature increases.

The intake/exhaust ports of RWE cylinder head are hand-finished by specialist craftspeople  in the Kumamoto factory to remove any small steps in the port created in the casting process. This makes air flow smoother and improves power delivery. The laser engraving “CRF WORKS EDITION” is added to the cylinder head to underline its special status.

 

The rear shock features a titanium coated rod for improved wear resistance and rear wheel control, paired to upgraded front forks, which now feature a special dark Kashima coating on the outer tube and a titanium coating on the slide pipe for optimal wear resistance.

 

The CRF250RWE will also feature a striking metallic red engine head cover, black top and bottom bridges, a gold DID DM2 chain, Renthal bar grips, a Throttle Jockey seat, black DID-LTX wheel rims, a black anodised front axle holder as well as updated graphics and laser engraving on the wheel rims and suspension caps. The hand-operated compression adjuster knob on the top of the front suspension provides easier adjustment without the need for any tools.

 

4. Technical Specifications

 

ENGINE

 

Type

Liquid-cooled 4-stroke single cylinder DOHC

Displacement

249.4cc

Bore & Stroke

79mm x 50.9mm

Compression Ratio

13.9:1

Oil Capacity

1.25L

FUEL SYSTEM

 

Carburation

Fuel injection

Fuel Tank Capacity

6.3L

ELECTRICAL SYSTEM

 

Starter

Electric

DRIVETRAIN

 

Clutch Type

Wet multiplate

Transmission Type

Constant mesh

Final Drive

Chain

FRAME

 

Type

Aluminium twin tube

CHASSIS

 

Dimensions (L´W´H)

2,179 x 827 x 1,262mm

Wheelbase

1,483mm

Caster Angle

28°24’

Trail

117mm

Seat Height

955mm

Ground Clearance

330mm

Kerb Weight

102kg (107kg wet) (CRF250RWE 103kg (107kg wet))

SUSPENSION

 

Type Front

49mm Showa (Hitachi Astemo, Ltd) coil-spring USD fork.

310mm stroke

Type Rear

Showa (Hitachi Astemo, Ltd.) Mono shock with Honda Pro-Link

308mm axle travel

WHEELS

 

Type Front

21 x 1.6in Aluminium spoke nipple

Type Rear

19 x 1.85 Aluminium spoke nipple(CRF250R)

19 x 2.15in Aluminium spoke nipple(CRF250RWE)

Tyres Front

80/100-21 PIRELLI MX32 MIDSOFT(CRF250R)

80/100-21 Dunlop MX33F (CRF250RWE)

Tyres Rear

100/90-19 PIRELLI MX32 MIDSOFT(CRF250R)

110/90-19 Dunlop MX33 (CRF250RWE)

BRAKES

 

Front

260mm hydraulic wave disc

Rear

240mm hydraulic wave disc

 

All specifications are provisional and subject to change without notice.

           



Source link

Got an opinion on this? Share it!