We have been anticipating this Suzuki off-road 450 for quite some time. There were plenty of questions about the bike and its arrival even before it emerged, and now that it is here a whole new set of questions are coming along with our first ride and test, starting with, "What exactly is the RMX450Z for?"
Times are tough and no other segment has felt this pinch as hard as the higher-performance side of the trail and off-road riding market. Simple economics have put many of the riders who are buying these types of bikes on the sidelines. Most don't need a new machine every year, and for sure the performance of their old bike can carry them along for another skinny year. Suzuki says this is only a serious off-road machine, not sold or designed to be a racer. And a lot of the other Japanese manufacturers are not making 2010 releases of their own 450cc off-roaders so as an off-road guy, you have to give Suzuki credit for making a bike for you.
That said, we darted off to the tacky dirt of Northern California for the introduction of the bike then got it back at our offices for a more thorough shakedown on familiar turf. After a few hundred miles on the bike we're still asking the same question: "What exactly is this bike for?"
The one thing we know is the RMX is a very finicky bike. It is sold in a corked-up form with a throttle stop, a snorkel in the airbox and a very restrictive muffler, making it green sticker-legal. Since we rode it on closed courses, we removed the throttle stop and pulled the snorkel out of the airbox but did not remove the muffler diffuser since the bike becomes obnoxiously loud. Plus, it runs crappy when the muffler flows too much, since the bike is set up lean. Stock, the engine side of the bike is tame. The suspension and chassis side of the machine have a totally different nature to them. The shock and fork act very stiff with resistant valving and light springs. The chassis is moto rigid. It is thin, looks lean and rides mean. The motor and chassis are from two separate sects. But this is what we were given so we went forward and tried to tune it to a happy place.
On the scale the bike tips the meter at an average weight for an off-roader, that is 275 pounds with its 1.6-gallon fuel tank full, if you can call that a full tank in the first place. All of the ritualistic modifications that take a frontline motocrosser and turn it into a trail-capable machine add close to 25 pounds to the RMX, with the electric starting being the best of the additions. New to the game is fuel injection for Japanese off-road bikes, but somehow this RMX is fighting a battle here, too. Emissions compliance necessitates a very lean fuel setting and, compounded by a clutch leverage ratio that makes complete disengagement very difficult, stalling of this light-flywheeled Suzuki is common and restarting is best done in neutral.
Once running, and it usually takes some cranking on the electric starter and some finesse with the throttle to bring her to life, the bike will idle fine and respond cleanly most of the time. It is not the best FI we've experienced. Once into gear, the wide-ratio five-speed is a simple shifting machine provided you have the clutch set with minimal to nil free-play. The engagement is long and smooth and we didn't have any issues with the clutch getting grabby, the drag and long pull were its Kryptonite. The RMX will chug right along at low rpm and has plenty of torque, as long as the throttle is open. But when it's shut, the bike is stall-prone. The clutch action doesn't help, but turning up the idle does. When you're rolling and into the throttle you'll not be disappointed with the power delivered for such a quiet bike. It has some aggression in the delivery, more snap than is common with FI bikes and it revs out decently, enough for close to 90 mph on flat dirt. Way up top is not where the meat of the power is, so just shift up and let the bottom and mid do the work for you. It is easy to lift the front wheel with just the throttle. Fuel delivery-wise there was a fluttery spot when trying to get extremely technical with the throttle and there are lean backfires in the muffler on long deceleration drags, but for the most part the almost-instant throttle response overrides the downfall in mapping. We also tried a Yoshimura Cherry Bomb, which plugs into the wiring loom under the sidepanel, along with a sound-responsible Akrapovic full exhaust system. Since the Cherry Bomb is designed to run with an aftermarket exhaust, it richens up the FI mapping. Then the motor's pull really broadens out and the bike becomes a little less prone to stalling. It gains more torque earlier in the throttle at all rpm and makes more power on top and revs further. Internally this motor is not true RM-Z spec. It has different cams, a different throttle body and its own unique mapping for the FI and ignition.