스크랩 2010 Honda CRF250R Preview

[윤태호/돈키호테]

Introduction 

2010 Honda CRF250R

The reason why we talk about Honda revolutionizing the dirt bike segment is the entirely new 249cc liquid-cooled single-cylinder four-stroke engine that this new motocrosser gets, one that is more compact and fed through a PGM-FI fuel injection system. This makes it more powerful and the fact that the quarter-liter motor is now repositioned on the also new frame lowers the bike’s center of gravity. This shows how engineers clearly aimed towards more speed and sharper cornering in an attempt to leave the competition behind.

Furthermore, the new generation model features Honda’s Progressive Steering Damper, a new and specially designed 48 mm fork, a redesigned airbox that is larger and allows easier access to the air filter and a new exhaust silencer supposed, together with the lighter, central shock, to improve mass centralization. The longer swingarm of the new CRF250R enhances stability.

All the bodywork pieces have been redesigned to resemble those of the bike’s bigger sibling. 

History

Forty-Plus Years of Four-Strokes

Think the new CRF(tm)450R and CRF250R are starting a four-stroke revolution? Wrong-Honda(r) fired the first shot more than four decades ago.

It’s easy to think Honda’s new CRF motocrossers are the first really successful four-stroke dirt bikes. But you couldn’t be more wrong. Because, with only a short look back, you’ll discover a whole string of revolutionary and successful Honda four-strokes-so many that the two-stroke Elsinore(tm) and its CR(r) progeny might seem just an anomaly in Honda’s history of four-stroke dominance.

One could start with the Super Cub(r) back in 1959, a bike countless thousands of baby boomers used as their first dirt bike. But set that aside, and look toward one of the most significant off-road motorcycle feats of the post-war generation: Dave Ekins’ and Bill Robertson’s first ride through Baja in 1962 on a pair of Honda CL72 Scrambler 250s. These were high-pipe four-stroke twins that, to today’s eyes, look far more like street bikes than state-of-the-art dirt machines. But state-of-the-art is exactly what they were at the time. Ekins and Robertson set off to do the unimaginable—no one else believed motorcycle could possibly travel the length of Baja to La Paz nonstop without suffering numerous breakdowns. But that’s exactly what they did, due in large part to their bikes’ superior four-stroke engine design.

By showing what a virtually stock Honda could do-and even by the standards of the day those two CL72s were painfully stock-Ekins and Robertson and the CL72s paved the way for the annual Baja 500 and 1000 races we have grown accustomed to, just as we have grown accustomed to a Honda XR(tm) winning the overall every year, handily besting the monster trucks, one-off race buggies, and every two-stroke in the field.

Honda adapted the CL72 from a street bike, the 1961 CB72 Hawk(r) 250. And by 1969 Honda was ready to introduce its next-generation dirt bike, a machine in which street bike and dirt bike again shared the overall engine design: the SOHC 350 twins. The resulting dirt bike, the SL350, was the motorcycle that really opened up Baja. Custom shops in Southern California latched on to them and produced machines that flat-out blew off the heavy desert sleds that had dominated the desert racing scene. If anything the 350s were better, faster, and more reliable than the CL72s had been.

But the best was yet to come. In 1972 Honda unveiled the most radical concept yet: the XL250 Motosport 250, the first of the long XR and XL lines. Here at last was a motorcycle still recognized as the defining formula for four-stroke off-road bikes, one that’s lasted for more than 30 years: a lightweight single-cylinder engine with a single overhead camshaft, upswept exhaust system, high fenders, long travel (for the era!) suspension, and capable off-road handling. Yes, those original XL-series machines were street-legal. But unlike the machines before them the XLs had been designed as dirt bikes first, then simply equipped with the necessities to make them civil road bikes, not the other way around. Just as important, they were as tough as a Baja steak.

Honda’s four-stroke XR and XL dominance continues to this day. Along the way the XRs got revolutionary Radial Four-Valve Combustion chamber (RFVC) heads, tons more ground clearance, and single-shock rear suspensions. In 2000 they also broke new ground by debuting the first liquid-cooled four-stroke XR engine, one wrapped in an aluminum frame to create the XR650R. This latest incarnation of Honda’s four-stroke off-road line is its most sophisticated, with a flawless racing pedigree. The XR650R has won every Baja 500 and Baja 1000 it’s entered, as well as the once-in-a-lifetime Baja 2000—all in totally dominant style.

But of course we’ve saved the best for last—the Honda CRF450R and now the CRF250R. The 450 has turned the world upside-down when it comes to prejudices against four-strokes. In 2003 Honda’s Ricky Carmichael’s incredible win streak in AMA 250 motocross—21 overall victories in a row—was finally broken by the only bike up to the task, the four-stoke CRF450R. Flat track racers have discovered the CRF for short-track events, and it’s hardly unusual to see the first two and even three rows mounted on the big CRFs. And the newly rediscovered Supermoto? Owned by CRF riders, who won the inaugural event.

Sure, the CRFs use Honda’s revolutionary aluminum motocross frames. But a peek inside the engine provides the real answer. In many ways, the CRFs are the most sophisticated engines Honda offers for sale to the public. Then there’s the CRF’s unique Unicam cylinder head. It features a single camshaft that directly actuates two intake valves, and employs a forked, low-friction roller rocker-arm. It’s a setup that’s compact, light, strong, and revs like a four-cylinder sport bike’s engine.

While the new CRFs might be sitting in the spotlight today, you can see that rather than standing out, they simply stand at the head of a long, line of Honda four-strokes that have risen to greatness and shown the way in off-road riding. The new CRF250R? In many ways, it is the most advanced of the bunch.

Competition

2010 Yamaha YZ250F

Honda built the 2010 CRF250R, like all of their previous generation models, with winning in mind and the models they plan to beat are true opponents. Starting with the Japanese range, the 2010 Yamaha YZ250F stands out as probably the fiercest opponent thanks to the five-valve engine. This is followed by the 2010 Kawasaki KX250F and Suzuki RM-Z250. From the old continent, we mention the KTM 250 SX-F and the Husqvarna TC250.

None of these dirt bikes feature fuel injection yet, but most of them are still 2009 model years. If they carry on like this, we don’t have to mention which model gets the 2010 Bike of the Year award in this class.

Exterior 

2010 Honda CRF250R

Although claimed to be the most potent bike in its class, the 2010 Honda CRF250R doesn’t scream to be noticed and stays faithful to the Red/White color scheme. The plastics have been redesigned and remind us of those on the new CRF450R, meaning that the aggressive lines are there to cope with the bike’s aggressive nature.

Everything is designed to look like it was made from one piece, so the fenders, number plates, body panels, seat and even the gas tank stay in perfect communion to contour the overall narrow body. The graphics are quite simple, just like Honda got us used to.

Price

Another aspect that needs to be covered before calling this a winner on the market is price. Starting at $7,199, this is currently the most expensive 250cc dirt bike among the 2010 models considering that the 2010 Yamaha YZ250F starts at $6,990 or $7,090 and the 2010 Kawasaki KX250F comes with a $6,999 MSRP.

Conclusion 

2010 Honda CRF250R

We’ll still have to ride the thing before a final verdict, but we must admit that this is the only 250cc motocross bike to start our interest this year so far.

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SPECIFICATIONS 

2010 Honda CRF250R

Model: CRF250R

Engine and Transmission

Engine Type: 249cc liquid-cooled single-cylinder four-stroke

Bore and Stroke: 76.8mm x 53.8mm

Compression ratio: 13.2:1

Valve Train: Unicam, four-valve; 30.5mm intake, titanium; 25mm exhaust, steel

Induction: PGM-FI, 50mm throttle body

Ignition: Full transistor with electronic advance

Transmission: Close-ratio five-speed

Final Drive: #520 chain; 13T/51T

Chassis and Dimensions

Suspension Front: 48mm inverted Showa 16-position rebound and 16-position compression damping adjustability; 12.4 inches travel

Rear: Pro-Link Showa single shock with spring preload, 17-position rebound damping adjustability, and compression damping adjustment separated into low-speed (13 positions) and high-speed (3.5 turns); 12.6 inches travel

Brakes Front: Single 240mm disc with twin-piston caliper

Rear: Single 240mm disc

Tires Front: Dunlop 742FA 80/100-21

Rear: Dunlop D756 100/90-19

Wheelbase: 58.8 inches

Rake (Caster angle): 27o15’

Trail: 116mm (4.56 inches)

Seat Height: 37.6 inches

Ground Clearance: 12.8 inches

Fuel Capacity: 1.5 gallons

Curb Weight: 226 pounds

Features & Benefits 

2010 Honda CRF250R

New for 2010

All-new, more compact engine.

Programmed Fuel Injection (PGM-FI).

Progressive Steering Damper (HPSD)-equipped aluminum frame

All-new front and rear suspension, featuring upper and lower fork tubes and a shock body developed exclusively for the CRF250R chassis.

Redesigned higher-capacity airbox for enhanced breathing and increased power also improves filter access.

All-new single-muffler exhaust system improves mass centralization.

All-new bodywork.

Engine/Drivetrain

All-new compact engine.

Liquid-cooled four-valve Unicam? 249cc engine.

Engine completely redesigned for improved power delivery from a significantly more compact package that lowers the center of gravity and enhances mass centralization for improved handling.

New forged slipper-piston material permits a thinner crown. Low-friction surface treatment ensures high-rev potential.

All-new Programmed Fuel Injection system (PGM-FI) utilizes a 50mm throttle body with 12-hole injector fed by lightweight 50-psi pump to ensure optimum fuel atomization and precisely targeted fuel charge. System also improves fuel consumption.

PGM-FI system monitors throttle position, intake air and coolant temperatures and manifold pressure to accurately map fuel charge and ignition spark, significantly improving partial-throttle response and helping to ensure excellent rideability.

AC generator enlarged to service the PGM-FI system. Two crankshaft position sensors quickly determine crank position to provide quick starts, hot or cold.

New mechanical water pump seal improves durability

Kashima coating applied to the clutch basket and clutch center improves clutch life and feel.

All-new transmission ratios match engine power output.

Chassis/Suspension

All-new HPSD-equipped Twin-Spar Aluminum Frame with forged-aluminum steering head. Spar height was reduced (70mm to 66mm) and width was narrowed (27mm to 26mm). Stronger downtubes improve front-end feel.

Steering response and overall handling were improved by positioning the front wheel 15mm farther back and closer to the crankshaft.

Frame, steering head and swingarm modifications permit a reduction in triple-clamp offset (22mm to 20mm).

Removable rear subframe was redesigned to eliminate brackets. Shape altered to improve air filter access and narrow the bike profile.

HPSD features a compact damper attached to the lower triple clamp and the steering head to allow more aggressive steering characteristics and assist straight-line handling. Damping action smoothly progresses as handlebar deflection increases, which produces very natural steering characteristics and feel.

Pro-Link? Rear Suspension features exclusive Showa integrated reservoir with all-new damping and spring settings.

Brake system integrates the rear master-cylinder and fluid reservoir, eliminating the separate reservoir and hose.

Link-type front-brake master cylinder and a lightweight brake rotor provide strong braking.

Additional Features

Engine stop switch features an integrated LED pre-ride check indicator. This confirm‎s the PGM-FI system is operating normally.

All-new higher-capacity airbox improves filter access.

PGM-FI tuning connectors located behind radiator shroud for easier access

Redesigned larger radiators, improve cooling performance

New fuel-tank tether eliminates need to disconnect fuel line to work on top end.

Rider ergonomics are optimized by adapting the handlebar, seat and footpeg height to place the rider’s legs at the narrowest part of the frame for improved comfort and handling feel.

Adjustable front-brake lever for improved control.

Quick-adjust clutch perch for easy cable adjustment.

Aluminum Renthal handlebar (971 bend) is rubber-mounted to help reduce rider fatigue and improve comfort.