Suzuki hasn’t had a serious off-road bike since the RMX250 two-stroke, last offered in 1998. But the company’s days of selling only mild-mannered off-roaders are over, as there is nothing soft about the new-for-2010 RMX450Z. It rocks to the same beat as the fuel-injected RM-Z450 motocrosser from which it was derived, except that the lyrics have been changed to play to a different audience: desert rats, trail hounds and off-road racers.
There’s nothing new about the idea of developing an enduro bike around a motocrosser; most top-level off-road riders compete on modified motocross bikes rather than hopped-up enduros, and some European enduro models roll off the assembly lines that way. Evidently, Suzuki saw enough need in this segment to introduce the MX-based RMX as one of only three true 2010 models in its current lineup.
Outward appearance might have you thinking that the RMX is simply an RM-Z dressed up with the usual enduro gear—lights, 18-inch rear wheel, digital enduro instrumentation, coolant recovery system, quick-access airbox and kickstand. While that is essentially true, there’s more to this bike than that, even if the X does retain much of the Z’s demeanor. The ergonomics match those of the motocrosser, and except for a slight change in the lower cradle, the aluminum twin-spar frame is identical to that of the 2009 Z. The engine is wider only because of the larger cover needed to accommodate the electric start components; any width differences between the rider’s legs are imperceptible. The X even uses the same fuel tank as the Z, even though its 1.6-gallon capacity is absurdly small, especially for serious trail riders. On average, after only 30 miles of riding, the low-fuel light on the dash beams, signaling about a quarter-tank of remaining go-juice.
Talk about the ultimate love/hate relationship: I want a bigger fuel tank, but its smallness helps make this bike unbelievably easy to move around on, especially forward—great for corners, hillclimbs and tiptoeing over rocks. Because the ergos, including the tank size, are the same as on the Z, riding the X feels almost identical. It’s no wonder I felt like Ryan Dungey when powering through turns.
Like Suzuki’s MX models, the RMX has stellar cornering abilities. The front tire almost never slides, the steering is precise and tracking out of corners is exceptional. The swingarm is based on that of the 2010 RM-Z450 but the shock linkage is similar to the ’09 model’s. This mix-and-match is what Suzuki claims worked best during pre-production testing. I can’t argue, as the X eats up fireroads and wide single-track while bouncing over rocks and other trail hazards, yet transmits very little of those jolts to the rider.
Only in extremely tight conditions does the RMX tend to show its weight—263 pounds without fuel, which is right in line with the competition. The Suzuki doesn’t flick side to side as easily as the upside-down-engined Husaberg 450, but it’s not at all like steering a school bus through tight trails, either.
Though the Showa suspension has been softened to give a plusher ride than on the Z, it still retains some of the aggressive nature of its MX ancestry. It cushions the blows enough to make all-day riding a pleasure as long as you don’t mind feeling the wrath of some square-edge bumps. Yet skying off man-made water bars will have both tires scraping the fenders on the landings.
If you find that the RMX is capable of launching far off those kinds of lips and bumps, you can blame the responsive engine. Doubling and sometimes even tripling whoop-de-dos is all part of what this bike can deliver with a quick blip of the throttle. So, as far as throttle response and power delivery are concerned, I had no complaints with the fuel-injection system, which uses a 41mm Keihin throttle body rather than the 43mm unit on the RM-Z450.
Fuel injection and electric starting don’t help the RMX fire quickly, however. The process takes a little patience, sometimes requiring anywhere between 3 and 10 seconds on our test bike. That can feel like an eternity if you’re all amped up for a ride or rebounding from a stall or a tip-over. And on our test bike, the engine tended to stall frequently, even though Suzuki claimed the idle was set at the correct rpm. I cranked up the idle by three clicks anyway, and that not only helped the bike stall less often but also marginally improved the starting.
In terms of pure power, the engine delivers a mix of typical 450cc four-stroke Single enduro-bike acceleration combined with MX-like response at certain rpm. The RMX has a lower compression ratio than the RM-Z, along with milder cam profiles intended to improve the low-end and midrange power. To get the best of what the engine has to offer, I removed the factory-installed throttle stop and airbox snorkel—the RMX is not the first bike to require such uncorking. The end result was steady power all the way through the rev range, even though the delivery was not exactly what I would call “electric.” The bottom-end power is very meaty but can sometimes be a bit too stout to prevent the rear wheel from spinning in tight, slippery conditions. It isn’t on/off light-switch-type power, but it can come on abruptly enough to require some delicate clutch work over slow-paced technical terrain. Manipulating the clutch and keeping the revs up also helps eliminate the previously mentioned stalling, but you shouldn’t have to ride an enduro bike this way. Top enduro competitors and highly experienced riders accustomed to dealing with converted motocross bikes might not mind it, but it’s less than ideal for the average off-road rider.
At the other end of the performance range, the RMX’s outright acceleration is more than most riders will need for trail riding; actually, that’s pretty much the case for all Open-class off-road bikes. Still, it’s nice to know that some extra power is available when needed. Fifth gear in the wide-ratio five-speed gearbox yields a top speed suitable for Baja racing; if you need more, changing the final gearing will allow the powerful RMX to go even faster. And although the engine is pretty potent, its exhaust note is quiet enough that you can exchange words with a riding buddy without having to shut off the engine.
But in the end, the RMX is not quite as enduro-savvy as most other players in the segment, due to it retaining a fair amount of its motocross heritage. Really good riders should be able to cope with the abrupt low-rpm power delivery, but other than replacement, there’s no way around the too-small fuel tank.
On the other hand, the RMX is much more than just a motocrosser with a headlight—a headlight that actually works, by the way. It offers great handling and suspension for overall off-road work, with enough outright engine performance to run with the best in class. Plus, it’s Green Sticker-legal, making it a workable option for riders in California.
So, after a 12-year break, Suzuki is back in the game. The RMX450Z is not perfect, but it’s still a worthy choice for enduro competition and all-around trail riding.