2006 450F MX Shootout

JC Hilderbrand | March 5, 2006

We don’t recommend staring down these 450 machines. Make a habit out of it and sooner or later they’re bound to kick your ass. From left, the ATK 450 MX, Suzuki RM-Z450, Honda CRF450R and Kawasaki KX450F.

The bigger the better, eh? Well that is the American way, and motocross in the USA will live and die by that cardinal rule. The 450cc thumpers are the supreme motocross weapon. All the big names have officially traded in their pipey pre-mixers for the booming bikes, and even the race series’ names indicate supremacy; Supercross with a capital S. The biggest stars race the biggest bikes for the biggest purse in what has become the world’s greatest supercross series.

Ride one of these bikes and it’s obvious why they are so highly touted. Their performance is unmatched, and the only thing coming even remotely close is the number of manic grins concealed behind a rider’s chin guard.

MotorcycleUSA wanted to find out what these mean machines are all about, so we rounded a few of them up for a shootout. A few is actually something of an understatement. In reality we put in calls and lined up not only the four Japanese brands, but went ahead and made it the Big Five with the increasingly popular European KTM marque. Just for some additional flavor, and since the best racing in the world now happens within the boundaries of the continental United States, it seemed only appropriate to see what the red, white and blue had to offer. ATK, the only American manufacturer of off-road bikes, lent us a 450 MX to bring our count to six.

The stage was set for MotorcycleUSA’s biggest MX shootout ever, but life has a way of building you up just to knock you down. Unfortunately, we got punked by two manufacturers at the last minute, turning our scheduled six-bike shootout into a scaled-down version consisting of Honda’s CRF450R, the new KX450F from Kawasaki, the Suzuki RM-Z450 and the aforementioned ATK 450 MX. If you’ll notice, there’s a distinct lack of blue and orange in the photo gallery which is by no means the fault of our photographer.

Regardless of the shortcomings we grabbed what we could and ran for the San Bernardino hills, then jaunting over to the drastically changing lakebed soils of Lake Elsinore. Our regular test monkey, Mike Mandahl came out to give the fo-fiddies a spin and brought along his pal Anthony Rondon for a second opinion. Here’s how it all shook down.

We tried to reason with the man  but Ken  left  refused to quit jumping the gate. After this particular display he pronounced himself the Holeshot King and then proceeded to strut through the pits staring down anyone who would look saying  “What bitch  what
After jumping the gate repeatedly on our first day of testing, Ken (left), who was on hand for video duties and the occasional stand in only, pronounced himself the Holeshot King and pranced through the pits shirtless staring down small children saying, “What you looking at punk, what?” We knew right away that it was going to be an awesome test.

Motor Mania

The heart of the 450’s success lies in the motor. Sure, the rest of the bike’s components are important too, but these machines kick 2-stroke tail primarily because they can yard anything except another 450 off the line. Having the power to pull starts, clear jumps and out-drag competitors into the next turn is where 450F pilots will gain huge advantages.

None of the bikes we tested had any problem pulling second-gear starts, and with massive holeshots and welted chests becoming the norm, that’s just a given these days. Where you want to go from there depends on rider weight, track conditions and personal preference. Our guys ranged from 150 pounds to 180, and not one of the bikes liked to keep the front wheel on the ground while ripping away from the gate.

Our test riders put the CRF ahead of the rest in the motor department. There’s no denying that the Honda cranks it out, as it posted the highest horsepower numbers when we revved them out on the Two Brothers Racing dyno. The Honda was consistently above the competition through the entire powerband, maxing at 50.6 hp. From a seat-of-the-pants perspective, our test riders agreed by noting strong performance across the rpm spectrum. Rondon was particularly fond of the red bike’s motor, believing that it makes more down low than it did in ’05.

Our first day of testing was at the tortuous Glen Helen circuit. Battling gusty winds and this gnarly uphill in particular  the brutal racetrack gave us plenty of obstacles to assault.
Our first day of testing was at the tortuous Glen Helen circuit. Battling gusty winds and this gnarly uphill in particular, the brutal racetrack gave us plenty of obstacles to assault.

Honda’s Eric Crippa was the technician on hand to help tweak the bike throughout our testing. From his experience in previous testing and other magazine shootouts, he went ahead and installed different jetting specs that he says should have come stock in the 40mm Keihin FCR carburetor. We take his word for it because the combination in our bike was spot on at both Glen Helen and Lake Elsinore. Crippa replaced the stock 45 pilot jet with a 48 and tossed in a slightly leaner NCVQ needle with the clip in the fourth position along with a #168 main jet.

It’s important to remember the way the power is delivered makes a big difference in a rider’s impression. Two of our four bikes had four-speed transmissions, which meant that power delivery was very different from the others. I too liked the CRF’s motor, but the five-speed transmission wasn’t as useful to me for motocross applications. The KX-F and RM-Z both felt more robust, especially in the low end and midrange, primarily as a result of their four-speed trannies.

Second and third gears on the Kawi and Suzuki were awesome utility gears that allow for riders to get around the track with far fewer shifts. Lugging the four-speeds through corners was no problem, while the CRF was by far the easiest to stall. I never had any stalling problems with the ATK, but the other riders killed the motor on occasion. In either case, it’s hardly worth mentioning because the ATK’s electric start combined with fuel injection meant that it was up and running again faster than any bike on the track.

JC Hilderbrand

Off-Road Editor| Articles | Hilde is holding down the fort at MotoUSA’s Southern Oregon HQ. With world-class dirt bike and ATV trails just minutes away, the hardest part is getting him to focus on the keyboard. Two wheels or four, it doesn’t matter to our Off-Road Editor so long as it goes like hell in the dirt.