3 Thumpers
3 THUMPERS
Two of Japan's best vs. an Austrian with an electric personality
RYAN DUDEK
WHY ARE WE ONLY TESTING THREE BIKES?” ASKED ONE OF our test riders. “That’s all I could fit in my truck,” was my immediate response.
Okay, just joking. But the truth is that after all the major revisions the four Japanese 450cc MX bikes had received last year, the 2007 models weren’t much different. They all boasted refinements that looked good on paper; but in actuality, they didn’t seem to have enough improvements to move any of them ahead of Honda’s CRF450R, the bike that has kicked butt in this category five straight times, including last year.
CW COMPARISON
There was one possible exception among those four, however: the Kawasaki KX450F. Though it looks very much like the ’06 model, the new KX-F has undergone more than 50 changes in an effort to unseat the Honda as the king of the 450s. So we decided to include it, along with the Honda, obviously.
And we absolutely had to make the KTM 450 SX-F part of the comparison, as well. It’s a new-from-the-ground-up bike its Austrian creators hope will offer a serious challenge to the Japanese 450s that have so far owned the class. Plus, the 450 SX-F even has electric starting; on that basis alone, we couldn’t possibly leave it out. And that’s how we settled on just three 450s for this test.
Plus, only testing three bikes allowed us to spend a little more time with each one. We did all the routine maintenance, played with spring preload and damping adjustments to make sure the bikes were properly set up for each rider, and spooned on Michelin Cross Competition S12 tires when the originals starting going bald. Throughout the entire test,
we handled these bikes as though they were our own, just as any privateer might do.
Starting with the most interesting bike of the trio, the KTM has no trouble, er, starting. Up until now, the idea of an electric-start motocross bike hasn’t been taken
KTM
450 SX-F
Price .$7198
4ps
A All-new design A Pushbutton starting A Traction king
Downs
T Ultra-hard seat ▼ Rear tire still hits muffler T Hydraulic clutch is Stifter than cable clutches
very seriously. After all, MX riders are real men, and real men don’t need crap that just adds extra weight, right? But the 450 SX-F weighs one pound less than the KX450F (6 more than the Honda) and doesn’t feel any heavier. And after the first time you stall it in a corner and have to restart in a hurry, you’ll never again call The Button “crap.” I was quickly sold on the KTM’s electric starting, and so were our other testers.
Besides, that wasn’t the only part of the 450 SX-F that got every rider’s attention. The frame is a totally new design with fat, oval-section rear downtubes on the main chrome-molysteel structure, and the triangular backbone is integrated with the cooling system; less weight, fewer parts. A new aluminum swingarm provides revised geometry for the PDS shock, yielding 1 Omm of additional travel and a more-progressive suspension rate.
KAWASAKI
KX450F
!rice.$6899
Ups
▲ DLC on fork lowers A Now a five-speed A Butter-smooth clutch
Downs
▼ New suspension doesn’t help handling
▼ Fork and shock too soft
▼ Hard-to-control power
Up front, a 48mm WP inverted fork uses the latest “closed cartridge bladder” technology. This involves a separate damper in each leg that is under pressure, which helps reduce foaming of the fork oil and provide more-consistent damping. The upper of the CNC-machined triple-clamps has two handlebar-mount offsets that provide four-position adjustability for the bar. Add black rims fitted with redesigned machined hubs and lighter spokes, and you have KTM’s best MX chassis ever.
Nevertheless, the 450 SX-F ranked second to the Honda in overall handling among these three. When the surface is anywhere between smooth and mildly rough, the SX handles as well as any other motocross bike and better than most. But when the track gets really rough, the bike has a tendency to headshake and swap on bigger bumps. Not ideal.
Under all track conditions, though, the SX-F tracks better out of comers than either the Honda or Kawasaki, thanks mostly to the new motor. In fact, when it comes to acceleration, the KTM even surpasses the Honda. Though its power output isn’t super-aggressive, the Katoom’s dohc motor allows the rear wheel to hook up and launch the rider out of turns or off the starting gate. The powerband is very controllable and easy to use, even though the SX is the fastest of these three. Really, the only complaint anyone had about the bike came from one rider who wished the four-speed KTM had another gear when motoring down a long, fast straightaway.
He didn’t have that problem on the Kawasaki, though, thanks to the KX450F’s new five-speed gearbox. First gear is taller than on last year’s four-speeder, while second through fourth remain the same and fifth, obviously, is new.
That’s just one of the KX’s many changes for 2007. Quite a few were made to the engine, the goal being to improve low-rpm torque and throttle response for better starting-line performance and stronger drive out of corners.
The engineers hoped to accomplish this through revised cam and ignition timing, a reworked intake port and a different taper on the header pipe.
While those changes have given the motor more punch, the power now comes on too strong, making it difficult to get and maintain good traction. The power hits hard at low rpm and the delivery is not as smooth as it is on the two other bikes, so it’s harder to manage on most surfaces.
You can blame the chassis for some of the Kawasaki’s trac tion problems, though, despite numerous suspension changes for 2007. The KYB shock has been redesigned to have more consistent damping and a wider range of adjustment, and it now works on a revised linkage. Up front, a new fork, also by KYB, boasts larger cartridges and a bigger compression piston, and the lower fork tubes have a Diamond-Like Coating (DLC). DLC is intended to reduce stiction, improve fork action and be more scratch-resistant.
Unfortunately, the fork and shock both are set up too soft, so it’s difficult to experience the benefits of those upgrades. The suspension is so soft and springy that the bike bounces around in the rough stuff and doesn’t want to stay planted on the track, giving it a very nervous feel. We got the Kawi to carve through turns more accurately and easily by sliding the fork tubes down through the triple-clamps about 5mm, but we were never able to find good suspension settings
HONDA
CRF450R
Price.............$6999
Ups
▲ Same great bike
▲ New Dunlop D742FA front tire
▲ Even smoother power delivery
▲ Refined and proven Downs
T Same great bike (looks like the ’02)
▼ New suspension a tad stiff
using the available adjustments.
Even the defending champ, the Honda CRF450R, had some suspension concerns of its own. But in this case, it was the opposite problem, with the bike being too stiff on one particular track that had a lot of choppy terrain. Ironically, one of the very few chassis changes made to the 450R for ’07 was the fork valving, claimed to improve the front end’s bump absorption. And overall, the suspension worked exceptionally well everywhere but at that particular track, and nothing we did with the clickers was able to remedy the problem.
Otherwise, the CRF’s handling was fantastic, by far the best of the bunch. The chassis has an exceptional balance of agility and stability, requiring rider input to be a simple, three-step process: look, point, go. As a result, the Honda gives its rider the confidence to hit any bump, rut or landing and stay upright and aimed straight.
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Actually, handling wasn’t Honda’s main concern when developing the ’07 CRF450R. Instead, the focus was to make the engine crank out more power while keeping the output smooth and usable throughout the entire rpm range. So for better low-end and midrange urge, the engineers used smaller (30mm vs. 31) exhaust valves and reshaped both the intake and exhaust ports. And to prevent top-end power from being compromised, they increased carb size from 40 to 41mm and redesigned the accelerator pump for sharper throttle response.
Although those changes seem small, they get the job done. The CRF has a never-ending flow of strong, even power from one end of the rev range to the other.
It’s power that’s easy for the rider to control, whether hammering over rough terrain, powering out of corners or getting just the right amount of drive for an upcoming double. The KTM is a bit faster in terms of outright acceleration, but the Honda generally can do faster laps because it has a superior chassis.
What’s more, because the CRF is six years old, Honda has had time to make lots of
refinements that help the bike stay at its competitive best.
For 2007, these include a link-type front-brake master cylinder (claimed to improve braking power by 15 percent), a stronger clutch basket and inner hub, a different muffler placement (for better mass-centralization) and the use of Dunlop’s new D742FA front tire (for improved turning). I can’t say much about the effect of the clutch and exhaustsystem improvements, but I can tell you that the front brake gives better feedback than it did on previous 450Rs, and our testbike turns more precisely, too.
So, who wins this three-way? If you haven’t already guessed, it’s the Honda-for the sixth year in a row. It offers the best handling, the best steering and the best overall feel, and its power is second-best only by a hair. The KTM comes home a close second with the best motor and-as much as we hate to admit it-an electric-starting system that’s actually a nocompromise advantage. And the Kawasaki, despite all of its model-year changes, crosses the finish line third, thanks to its abrupt, twostroke-like power delivery and mushy suspension.
1 Kind of makes you wonder if any bike will ever manage to unseat the CRF450F as the king of 450s.
The KTM and Kawasaki are definitely in the hunt, but until they resolve some handling issues, they’re not likely to stand on the top step of the podium. □
