As we rolled out onto the track for the first time and waited for a clear spot to enter, the thunderous roar of 4-strokes pelted us harder than the flying roost. The number of those bikes that were 450cc machines was impossible to tally as the number of riders harnessing the ungodly power of these big-bores is mind-boggling - but for good reason. Whether you're one of the elite, a local pro or weekend-warrior schmuck there's almost no reason to not have a 450F. If you don't then you'll be passed by someone who does, and if that doesn't matter a whole lot to you then at the very least you can ignore all kinds of good habits like corner speed, clutch technique and finesse. Simply bend your right wrist and the possibilities are endless. Don't worry, though, we're guilty too - just like you.

As you'll find in this test, there was no shortage of competition among our four Japanese players - reigning champion Kawasaki KX450F, Honda CRF450R, Suzuki RM-Z450 and last year's no-show, the Yamaha YZ450F.

We sound tested the machines at the end of our testing so that each had a chance for the muffler packing to break in. Two SoCal tracks of varying terrain and layout were used to help break down and analyze the components of each bike. We started in the high desert at Hesperia's Competitive Edge and progressed to the power-hungry layout of Glen Helen's National track to round out the riding impressions.

When we weren't logging motos at Comp Edge or Glen Helen, we spent the rest of our waking hours running the bikes across electronic scales, rear-wheel dyno and past sound-measuring equipment. To accompany the empirical data would require equally telling riding impressions which were collected from a thick spread of experienced testers. (For more info on our testers, follow this link to the Rider Bios.)

With our company dyno in the final stages of installation, we turned to the generous Kerry Bryant over at Area P to help us once again crank out some dyno curves. After swapping all the stock tires for dyno-applicable street versions, we spooned on four sets of Pirelli's new Scorpion MX 454 - the new mid/hard tire developed specifically for the American market - so we could begin testing on equal footing.

Our sport has been evolving at an incredible pace in the last decade, and each new model year brings out something different. The changes to the 2007 450F motocrossers are significant, but not so much as to light the world on fire with an all-new development. Granted, we didn't have the e-start KTM. But, with the Japanese foursome ready to rock, we set out to discover what another 365 days of Darwinian Theory has done to the baddest motocross bikes on the planet.

 

Suzuki RM-Z450

Now the only Japanese OEM to use a 4-cog tranny, the Suzuki was under extra scrutiny as the black sheep of our test. As everyone knows, the opportunities to use fifth gear on a motocross track, even long outdoor venues like the ones we visited, are scant. Even riders like Zalamea who typically enjoy rowing trannies like a collegiate coxswain found the easy-going Suzook gearbox to his liking.

"The transmission was smooth and the shifting easy," he admits. "It seemed like I stayed in two gears, third and fourth, just shifting between the two, but I didn't mind at all."

Nobody really minded considering the bike is a moto-specific weapon, but nobody liked it enough to go to bat for it in the score sheets and the gearbox ranked last in category scoring. Suzuki is the last manufacturer not to offer a 450cc off-road/enduro racebike. It will soon, and when that happens there is a high likeliness that it will include another cog. One thing that Suzuki engineers won't have to change about their machine during off-road conversion is the muffler. The RM-Z blew a mellow 96 on our dB meter, which is less than some 250F machines.

"I know a lot of guys that like to take a rip out in the desert," muses the Las Vegas resident, Sun. "Sometimes a 4-speed is a bit limiting, but I know what the manufacturers are going for - they want a very specific, competitive (MX) motorcycle. One thing about the 5-speed is that it makes for a nice transition if you want to take it for a buzz out in the desert."

Another last-place component rank in braking was detrimental to the RM-Z's overall score but Suzuki was able to keep our testers happy by delivering class-best low-end power to the ground via a light, buttery and sensitive clutch. Though its peak HP numbers aren't anything mind-blowing, the power curve off the bottom and into the midrange easily distinguishes itself from the rest on the dyno chart and racetrack alike. It challenges the Kawasaki for the best torque and falling a tad short still comfortably outclasses the Red and Blue machines. The engine's willing and brisk response allowed for riders to bury a deep berm and explode out for a point-and-shoot style. Conversely, it could also provide smooth, early acceleration out of corners thanks to the muscle down low.

Our test riders' personal likes and dislikes of motor characteristics vary between tons of over-rev, midrange monsters or arm-stretching grunt, so the Suzook engine didn't please everyone. But we all came together on the Suzuki's suspension package. Everyone agreed that the RM-Z was able to outclass the rest of the bikes' suspension with its do-all Showas. Each of our five riders ranked the fork and shock separately, and the Suzuki received a first- or second-place score in 7-of-10 votes. The 47mm front and 50mm rear provided the best all-around bottoming resistance and plushness on smaller hack.

"For my weight the Suzuki was better for me. It tracked a lot smoother through the corners," says our fly-weight intermediate, Ian Martin.

On the opposite end of the weight spectrum, our former open-class champ took refuge from the abusive racetracks on the 'Zook.

"A very predictable front end," mirrors Sun, "you can really do a lot with it. While the rear end is dancing around, the front end sticks."

Only our novice rider wasn't able to get totally comfortable on the RM-Z. Softening the compression damping front and rear helped significantly, but he still felt constantly on-edge with the handling. Much of that was due to the aggressive steering geometry and ergos. The Suzuki utilizes 25 degrees of rake, almost two degrees less than the closest Japanese competitor, which is an integral part of generating the hallmark, knife-like handling on Yellow bikes. It also has the shortest wheelbase and seat height which can give larger riders a cramped feeling.

Overall Rank: 4th

Categories Won: Suspension

RM-Z450 Notepad:
Only bike with gripper seat on sides, not top
Hardest to kick through the stroke (but still lights easily)
No sight window for oil level
Only bike without skidplate
Lowest MSRP at $6799 

 

Kawasaki KX450F 

Kawasaki was the heavy favorite coming into this battle of bruisers. As last year's clear-cut winner, the bull's-eye was clearly painted in green and black. Certainly the accolades earned in the past year through the media and at the professional racing level have proven the 2006 version to be a rock-solid starting point in Kawi's new 450 Thumper endeavors, and James Stewart has already taken the 2007 machine to all-new heights.

The big news that everyone's been talking about is the new 5-speed transmission and a motor that won't take any crap. Obviously, the two are tightly intertwined, but starting with the engine, we found out right away at Area P that the KX-F makes a boatload of power. Last year's mark of 49 peak ponies was third best but still super close to the highest mark set by the Honda. It churned out an identical HP figure this year (different dynos, mind you), but once it hit the track we could tell the Kawi engineers had this bike on a workout regiment during the off-season. It isn't a roids-injected difference, but Creatine shakes and a high-protein diet were certainly part of the equation.

Power comes on strong shortly off idle after a small lull was noted by several of our riders. Once past it thrums into the high rpm without any signs of abnormally aggressive behavior. Note the term "abnormal." Deciding where the optimal rpm range lies is hard to pin down since the entire powerband is aggressive and very linear.

"The power was very linear and this would have won the motor category (for me), but when we went to Glen Helen I found that the bike was a little hungry for power down low," says Zalamea. "Sometimes I would come into one of the sandy berms and try to mash the throttle to get me out and it would have a little hiccup."

The KX hits its peak at 8300 rpm, but the trip up isn't something you'll miss. What makes the bike a true rocketship is the amount of torque it produces. Again topping the dyno charts, a full 33 lb-ft barks out of corners and hustles you around the track in short order. Only one of our pro riders thought the Kawi could use a little extra through the midrange and top.

Sun called the Kawi a "berm-shot weapon" thanks to its stout, tractable motor and stable handling.

"It has a sweet, nice, broad powerband that's very workable," he elaborates. "The Suzuki has more bottom, the Yamaha has more top, the Honda has more midrange, but this (KX) probably is the most linear. It doesn't win in any one of those categories but maybe it will give you the quickest lap time at the end of a moto. People always forget that a usable powerband all the way through is what gets you through a moto with the least amount of energy expense and good lap times."

Interestingly enough, the KX-F didn't tally the highest marks in the motor category from our testers scorecards. In fact, it finished last, but its engine was continually one of the first comments made about the bike, which should give you an idea of how good the rest of these machines are.

As far as the transmission and gearing goes, our Kwacker got knocked a bit for its comparatively stiff and notchy action at the toe. Unfortunately, as the interface between man and machine the somewhat clunky application overshadows some of the transmission's positives. The gear ratios proved to be a highlight as they allowed the motor to keep dishing out the power in an extremely usable way. There was some concern that the new bike wouldn't tolerate lazy shifting as well as the old 4-speed, but to our pleasant surprise the Kawasaki will still carry that extra gear or stretch to the next corner without necessitating additional shifts.

The largest complaint about the Kawi, literally, is that it feels heavier and bigger than the rest of the bikes. MotoUSA's electronic scales proved that our testers weren't a bunch of crack-monkeys and revealed that the engineers' muscle-building program brought some additional weight. The bike is 4 pounds heavier than last year's model and 1-7 pounds more than our other test bikes. Several testers believe its weight is carried high on the machine and gave it a top-heavy feel. The complaints tended to come from our smaller, lighter riders who struggled not only with the weight but straddling the Greenie as well. With a seat height of 38 inches only the Yamaha is taller (38.9").

"It feels big - kind of heavy and a little wider," explains the 150-pound Horban. However, our heavier riders had a less negative opinion on the issue. Though noticeable, that extra poundage and girth at the knees was hardly detrimental to the bike's smooth, stable nature. The chassis and suspension components did an admirable job of handling the weight deftly and with grace. But, while the laziest rake and greatest amount of trail in our test plays a large part in keeping the Green bike on course, it's also a contributor to our riders' interpretation of weight.

"It was very plush and predictable, so I could do whatever I wanted with the bike," says an enthused Sun. "It didn't do anything strange of funny, and you could change directions any time you wanted. Besides, I like to have something to hold onto with my knees."

New Diamond-like Carbon coating (DLC) protects the fork sliders and eliminates stiction, which not one rider complained of. It also scores huge points in the style category. Though forcing the burly KX-F into an inside rut wasn't as easy as, say, the 229-lb Honda, it made up for it with high-speed stability and a confidence-inspiring attitude. It takes a much larger obstacle to shake the Kawi than most other bikes, and it's capable of handling almost anything across the motocross spectrum. Unfortunately, a strong, smooth and stable package isn't enough to keep it on the same course charted in 2006, and it's surprising how it fell in our '07 rankings.

Overall Rank: 3rd

Categories Won: Braking

KX450F Notepad:
E-Z adjust throttle cables
Choke knob impossible to reach.
DLC fork is wicked
MSRP $6899 

 

Honda CRF450R

Two things come to mind when thinking about modern Honda motocross bikes - durability and aluminum. Honda is the OG of light, shiny twin-spar chassis and, though Kawasaki and Suzuki have virtually cloned the CRF450R frame, years of refinement by Honda's engineers have kept it on the cutting edge with a seriously competent, nimble and fun chassis.

"The Honda has really come a long way," says Chuck Sun, who won a 500cc National title for Honda back in the early 1980s. "I found a little difficult of a time with the quick steering of the Honda, (initially) figuring it was more of a pro/expert bike. But within the first few laps I found it was very predictable in the way you plant it and get your weight on the front end."

Our largest rider felt right at home with the layout and his 5'11" frame, although the mechanical jockeys among our crew found the CRF450R's ergonomics outside of their dinky comfort ranges.

A diminutive weight of 229 pounds is the most balanced at a standstill, with 50% of its weight distributed on each wheel. A revised subframe helps tuck the muffler in closer to the motor, all a part of Honda's master plan for ultimate mass-centralization.

"The bike lays over very well into corners," says intermediate test rider, Ian Martin. "It's easy to throw around but still tracks super-straight in the turns."

The CRF is easy to move around on the track and is even distinguishable from the rest when hoisting onto a bike stand back at the truck. Light weight is one of the key ingredients in motocross and the Honda has it covered. Another is power.

"It didn't lack anywhere," says Alvin Zalamea of the 450R's powerplant. "It had good bottom-end and once you get into the middle part to crack the throttle wide open it will just explode."

The hard-driving motor was enough to garner the nod from Sun. In fact, it was so strong and usable that he launched into a lengthy anecdote about his old 500cc, 2-stroke Honda motors back in the day - the five-hundy he calls it. Somewhere amid his moto narrative was an enthusiastic two thumbs up for the motor which "immediately impressed with the ease of use and great midrange boost that got me up and over step-up jumps better than all the others."

Dyno results didn't reflect our seat-of-the-pants testing but there is no denying the response of all five testers that the new 41mm Keihin carburetor and 1mm-smaller exhaust valves on the Unicam engine are part of a better package for 2007.

Suspension on Big Red was stiff to the point of being harsh. For the slower riders it was blatantly abusive on chatter and even jump landings lacked the finesse of some other machines. However, as the speed of our test riders rose incrementally, the more we heard positive feedback. Our 20-year-old pro rider, Mike Horban, put what the rest of us were thinking into words.

"It had the stiffest feel but was really good the more aggressive I was," he notes. "The harder I pushed the better it worked."

Our other pro, Zalamea, was equally optimistic about the CRF's competitive potential if a rider can match the potent requirements.

"If I was in shape and wanted to compete in the Nationals, the Honda suspension could work for me," he says. "The fork was really good in that I had confidence to hit jumps with steep faces and feel comfortable coming down on landings. They just bothered me coming into small chop or braking bumps."

The base package caters to a higher-skilled rider and rewards rough treatment. It's no secret the masochistic machine has become a privateer favorite on the professional circuits, and for good reason.

Overall Rank: 2nd

Categories Won: Chassis/Handling; Transmission/Clutch/Gearing

CRF Notepad:
Gripper seat is one of the best
Separate oil supplies for added durability
Rear-facing petcock a hassle
Highest MSRP at $6999 

Yamaha YZ450F

Under most circumstances, upstanding men such as us would scorn any sneaky, undermining behavior, but as it relates to this particular case we found nothing but delight in the mischievous Yamaha. The YZ-F's bag of tricks includes its motor, ergos, exhaust and suspension - a deviant through and through. The odd thing is how much we like the way it misbehaves.

Our testers paired the Yamaha with the Kawasaki as the two smoothest machines in the test, but no one mistook the vastly different motor characteristics. Our least experienced rider, and heaviest, found the bike sluggish with its relative lack of low-end tug, but the speedier pilots were able to utilize the upper-rpm powerband. What everyone did agree on in terms of the motor is that it is deceptively fast.

Again, the eloquent Sun lays it out in easy terms. "Somebody might think that it doesn't have enough power on the bottom, but in many ways it delivers the right amount of power at the right time in the turn and delivers more as you exit. Consequently it takes much less energy to ride the bike," he said. "The YZ-F's more of a revver even though you don't have to get it up there before it delivers the power."

While the Yamaha wasn't blowing anybody's socks off on Day 1 of our test, a few minds had been changed by the time we closed the petcocks for the final time. Three of five riders picked the YZ-F's motor first. Is it coincidental that the same ratio voted the Yamaha best overall? We'd say not. Motor is what 450s are all about. After all, these are the new open-class bikes.

Not only does it have a misleading motor but everyone thought for sure it would be the quietest in our emissions test. Perhaps just looking at the tiny exhaust opening in the muffler influenced our brainwaves, but it was a unanimous consensus among the testers. We could have argued day and night about which barks the loudest (Kawi), but the Yamaha seemed to be a shoe-in for the silent-but-deadly award. As it turns out, the Yammie will pass AMA rules for motocross and supercross racing, but just barely at the legal limit of 99 dB. The Honda and Suzuki are both quieter, but Blue's exhaust note is much different from the remaining trio in that it whines more than it barks. The comparison is much like a contrast between a zingy Ferrari and the throaty roar of an overbuilt Mustang.

After riding the perimeter-framed Honda and its two copycats, Yamaha's unique take on the aluminum chassis was refreshing and enjoyable. Many riders felt the YZ-F's frame is the slimmest between their legs which contributes to a light, nimble feel in the air. The bike tips the scales at 232 lbs, which is less than the Suzuki (235) and Kawasaki (236) but slightly more than the ultra-light CRF (229). The biggest difference between the three is where the Yammie carries its weight.

Engineers made a concerted effort to reduce the weight on the front end by lightening the triple clamps, upper fork tubes, wheels and brake rotors. It worked because with a full tank the Yamaha has eight more pounds on the back of the motorcycle - the highest weight ratio placed on the rear wheel out of all the bikes. The goal was to produce a lighter-steering machine, but what most of our testers found was that it put more turning influence on the rear wheel. Not everyone prefers that setup, but it was very suitable to our faster riders.

"The first thing I noticed about this bike is that it's a rear-end turning bike," noted Zalamea. "I love that. With Comp Edge's intermediate-to-hard terrain I felt like the front end wanted to wash out on me in off-camber or hard-pack turns, but the straights and whoops were really stable."

Our novice also noticed the long feel of the Yamaha. By no means raked out, and with less than a half-inch more wheelbase than the other bikes, the sensation stems from the low handlebars, roomy ergonomics and a front fender that seems to stretch out in front. The ProTaper handlebar raises the grips 8mm compared to last year but it still sits down in the rider's lap more than the threesome of Renthals on the others.

The soft setup on the Kayaba suspension drew rave reviews for its plush action. Utilizing its entire stroke, the fork and shock compliment one another and helped boost the YZ-F's rating once we took it to the choppy, bone-jarring Glen Helen circuit. The first day seemed to favor the stiffer suspensions of the CRF and Suzuki with a relatively chatter-free track and big jumps - which our notes reflected as several riders commented about bottoming the YZ-F. However, what Glen Helen lacked in big air it made up for in big braking bumps. Soaking up the abusive obstacles is what these Kayabas do best. Fortunately it still provides enough bottoming resistance to let a rider get away with minimal tinkering and more riding.

A really well-balanced package," says our Hollywood stuntman, Zalamea. "If you're like me and don't like to change your clickers too often, then this suspension is for you."

"When I first rode it I thought the suspension may be too soft," sums the 190-lb Sun. "But as the track got rougher the suspension was ideal for my speed, and I think a pro can get along with it too. Basically when you're not thinking about the suspension and you're doing more (on the track) and you want to keep riding, that's kind of an indicator that good things are going on."

The Yamaha certainly has a lot of good things going on as it handily won the overall crown. It took us the full test to sort out the true nature of this Blue beast, but once we did we were sure happy with the results. Not only does the Yamaha serve the widest variety of riders, but it has the most distinct feel of the Japanese squad. It only took top honors in one category but again YZ-F wiled its way into the shootout win. There's nothing deceiving about the fact that a unique feel and top-level product is a damn good combination.

Overall Rank: 1st

Categories Won: Motor

Yamaha YZ450F Notepad:
Blue plastic looks haggard on short notice
No sight window for oil level
Bolt sizes have been standardized for easier maintenance
Optional white plastic gives a little variety
Highest MSRP at $6999/$7099 (white)  

The Verdict

As always, we ran all the bikes through a gauntlet of individual riding sessions, but before ever throwing a leg over these bikes we knew the decision-making process of today's bike buyers is heavily influenced by personal preference, favorite color and brand familiarity. Our testers' widely varying responses proved how true this can be and how close these bikes really are. In terms of performance, yes, these machines are all very close, but we were surprised at how differently each displayed its personality.

The big-bore specialist, Sun, put it simply when he says "They're all good. I was thinking they'd be really similar to each other because the bikes have kind of morphed into the same thing, but they each have their own personality which is something I really appreciate. I was really pleased to see that it's not all homogenized."

All of our testers agree that the differences between bikes makes for a better buyer's market and reinforces the bottom line that any of these machines could ultimately be your next open-class motocrosser. Each bike was deemed the best in one category or another. Lucky for you, getting access to these machines won't be as difficult as it was for us. Your nearest dealer won't require any more than a down payment, and maybe not even that.

The biggest problem you'll have is trying to set your mind on only one machine - it isn't deciding which 2007 bikes you don't like, but which one you like most.

Check out the following links for some extra tidbits about our shootout.

- Rider Bios
We ride, therefore we are.

- For My Money
See what each rider would do if they had to drop almost seven grand out of their own pockets.

- Full Score Sheet
Want to see how your favorite bike did in the grand scheme of things? Check out our primary testing categories.

- Glen Helen Track Map (Google Earth file)
Look at our lines as we spin a few laps around the famed Glen Helen circuit with our GPS. If you don't have Google Earth installed, click here to get the free download. Otherwise just hit this link to view it in your regular web browser.


Let us know what you think about this comparo in the MotoUSA Forum.