2015 Honda CRF250R | Development Story

2015 Honda CRF250R | Development Story

2015 Honda CRF250R

Honda’s CRF250R has a long history of winning championships, and the records show that the bike earned another AMA 250 Supercross championship in 2014.

But there’s another story too. In 2014 the CRF250R wasn’t just a winner, it was also the overwhelming favorite choice among Pro AMA Supercross racers. An impressive 53 percent of all main event qualifiers in the 250 class rode CRF250Rs, including an amazing 124 of 198 spots—63 percent—in the SX East series.

A stopwatch will show the CRF250R can turn fast laps. But from the top teams to privateers, racers are also banking on Honda’s legendary durability, quality and reliability that enable them to earn a living racing motorcycles.

These racers also rely on the CRF250R’s unique balance: a great powerband, agile handling and top-level suspension components all combine to give the CRF250R well-integrated performance that makes it great fun to ride whether you’re a weekend warrior or a seasoned pro racer.

And to make a championship-caliber ride even better, for 2015 the CRF250R offers a host of improvements that elevate its performance to even higher levels, including a new Showa air fork, three-setting Engine Mode Select Button, enhanced power characteristics, new brakes and more.

A New-Generation Fork

A new-generation 49mm Showa Separate Function Fork, Triple Air Chamber (SFF-Air) air fork introduces a new level of front suspension performance for 2015. This fork eliminates steel springs for significantly less weight (2.8 pounds lighter) while offering a wider range of adjustments than a conventional spring fork. As its name states, the two fork legs perform separate functions; the right side houses the damper mechanisms for compression and rebound control, while the left side contains a three-chamber pneumatic spring system that completely eliminates the use of steel springs.

This design allows a huge degree of adjustability in damper settings—16-position rebound and 16-position compression damping adjustability—plus convenient spring-rate adjustments. And because this air fork uses high-pressure settings—a maximum of 189 psi—any increases in pressure that may occur as the fork heats up during use represent a negligible percentage change.

Within the air-side fork leg, the balance chamber handles spring force at the initial portion of fork travel and at low speed, while the inner chamber affects spring rate throughout the entire range of fork travel. The outer chamber contains fork oil and air at ambient pressure; adjusting the level of oil in this chamber affects the rate of spring progression during the latter portion of travel when the fork approaches its greatest degree of compression. Together, these three chambers work in concert to provide smooth, more progressive suspension action that aids front-end traction and feel.

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 by changing the oil volume in the outer chamber. As an added benefit, riders can easily alter pressures in the balance chamber and inner chamber with a pump while at the track to fine-tune fork action to match riding conditions; no need to change fork springs, as with a conventional fork.

In back, the Honda Pro-Link® single-shock rear suspension system now incorporates a stiffer spring that is 7.8 ounces lighter than before. Also fully adjustable, the rear shock offers 17-position rebound adjustment, while compression damping is separated into 13-position low-speed settings and 3.5 turns for high-speed adjustment.

The twin-spar aluminum frame was completely revised for 2014, and in keeping with current Honda motocross design it features aggressive steering geometry settings for nimble handling and quick steering. These dimensions work in concert with the Honda Progressive Steering Damper that aids high-speed handling to give the best of both worlds.

The HPSD system features a compact damper that is attached to the lower triple clamp and the steering head to assist with straight-line handling. The HPSD damping action smoothly progresses as handlebar deflection increases, which aids handling while also producing very natural steering characteristics and feel. Net result: exceptional steering response along with excellent high-speed manners.

Engine Mode Select Button

The 2015 CRF250R also incorporates Honda’s new Engine Mode Select Button with three EFI/ignition map settings, an industry-first in the world of motocross bikes. Beginning with Honda’s four-valve Unicam engine already known for its wide powerband and accommodating nature, this new Engine Mode Select system allows the rider to easily select one of three different EFI/ignition maps to modify power delivery. And that’s a huge benefit for matching track and riding conditions.

Mode 1 uses the standard ignition and fueling maps for balanced delivery of horsepower and torque. Mode 2 is designed for use in slippery, muddy conditions and is all about throttle control, producing an easy-to-manage character that places an emphasis on traction—getting power down to the ground efficiently. Mode 3 hits all-out hard with aggressive and responsive top-end power to drive through deep, soft terrain. Peak power remains unchanged for all three settings; only the delivery characteristics change. To add an even greater degree of adjustability and control, the settings in Modes 2 and 3 can be further tailored via the HRC mapping hardware and software.

While on the bike, making these changes is super-simple: the rider merely stops with the engine at idle and presses and holds the button for about a second to select the next map in sequence. A highly visible LED light built into the lightweight button signals the map in use; a quick press identifies the mode with the corresponding number of flashes. When a new map is selected, the choice is also confirmed to the rider.

In addition to the new Engine Mode Select Button, the 2015 CRF250R also comes equipped with a new, larger-diameter exhaust system and new fuel-mapping settings for the Dual-Timing PGM-FI fuel injection system to increase engine performance for smoother acceleration, crisper throttle response, quicker revving and more peak power. Specifically, the inner diameter of the right-side muffler grows from 22 to 23.8mm, while the left sees an increase in diameter from 23.4 to 26.6mm. Also, a new throttle return spring now gives a lighter pull.

By design, this Dual-Timing PGM-FI fuel injection system helps boost power while also delivering even better throttle feel and control at partial throttle openings. During every cycle of the fuel injection system, the Dual-Timing PGM-FI setup injects two charges: the first, short-duration charge is used to cool the intake valve/port area in order to increase the density of the air/fuel mixture; the second charge increases the amount of fuel directed into the combustion chamber to improve power and response.

Unicam Design

Honda’s Unicam design features a single overhead camshaft and four-valve head for a powerful, compact powerplant. Since the single camshaft sits lower and takes up less space in the cylinder head, the overall engine height is shorter and it also contributes to a lower CG. The 30.5mm intake valves are made of light and tough titanium, while the 25mm exhaust valves are durable steel. This SOHC configuration with a forked, low-friction roller rocker arm to actuate the exhaust valves is not only space efficient, it also saves weight over a comparable dual-overhead-camshaft motor and also allows for a narrow included valve angle for excellent flame propagation in the combustion chamber even at higher compression ratios.

Sweating the Details

Close attention to other details make things even better in 2015. The CRF250R now features new front/rear wave-style rotors, with a larger 260mm front disc brake for increased stopping action that’s easily modulated. New-generation Dunlop Geomax MX52 motocross tires front and rear 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 new-design sidewalls and recessed carcass design, plus increased durability. New fork covers offer a different look plus better rock protection, the front brake guide and radiator grill now feature a black finish, and an all-new CRF graphics package tops off its fresh looks.

Building championship-winning bikes is a great achievement. Designing successors to extend that legacy presents new challenges—a process of development Honda has mastered well. By applying innovative engineering and new technology, Honda has once again created a new CRF250R that’s sure to become a favorite in the hands of pro and amateur riders alike.