When the word came in last June that Suzuki would finally be introducing an RMX450Z off-road bike to go head to head against its Japanese and European competitors, yellow fans from around the globe were excited.

It’s been a long wait for Suzuki to introduce a model that’s based on its lightweight 450cc RM-Z450 Motocrosser, however the wait’s over and MotoOnline.com.au was lucky enough to get our hands on one this week at the Australian launch.

A 3.5 hour drive north to Dungog, near Newcastle in New South Wales, saw me arrive at the destination with six RMX450Z models available for the domestic press to thrash, all staged on a beaut bit of land with multiple trails and Motocross tracks to make up our test grounds.

Making the launch all the better was the fact that we had Suzuki Australia’s championship-winning Motocross and Supercross effort, Jay Foreman’s Rockstar Motul Suzuki team, on hand and available to make any changes that we may have requested during the test.

First things first though, note that this particular model doesn’t meet ADR compliance for 2010 as Suzuki plans monitor the potential of the model first due to the current economic climate and the cost of compliance modifications for an Australian specification model.

What that means is that it won’t be street legal or be able to be registered in standard trim, coming in as a competition bike for serious enduro competitors and riders while Suzuki will still sell the popular DR-Z400E in registered trim. You can get recreational registrations for the RMX in selected states though, which really should be the case in all states if we lived in a perfect world for off-road riding.

That being the case, the RMX doesn’t have any rego plates, mirrors, or hand guards, making for a neat look aesthetically – potentially confusing it with an RM-Z with a light bolted on the front! As we are about to find out though, there’s much more to it than that.

Enough with the introduction, plus you can see all of the technical info below, by now you’re probably anxious to find out what it’s like to ride on the single track!

Upon sitting on the RMX450Z and setting the sag, you can feel its seat height is slightly lower than its RM-Z Motocross brother (5mm to be precise). It doesn’t feel bulky at all, and both models share the same ergonomic feel largely thanks to the Renthal Fatboy handlebars fitted as standard equipment.

Starting up the RMX is a cinch thanks to the electric starter motor, simply enabling riders to climb aboard, turn on the ignition via a simple push button located on the dash and then fire it into life with the start button mounted on the throttle side of the ’bars.

While on the subject of the instrument panel, it’s easy to read, great to operate and I like the idea of having two separate modes – one for competition use, or one for recreational use. The orange fuel warning light is a handy feature, too.

My first impression of the RMX out of the box in de-restricted trim is that it has a bucket load of bottom-end grunt. The 449cc, four-stroke, single-cylinder, liquid cooled, DOHC, four-valve, EFI engine sounds pretty loud compared to other enduro bikes I’ve tested, and aggressive in its power application on dry, hard-packed dirt during a hot and humid test day.

If you’re one for pounding through soft soil or sand, tight or wide open, you’ll absolutely love the power of the RMX – it’s the closest enduro bike with a power output that’s close to its Motocross sibling that I’ve experienced to date.

However, if you’re a rider who goes in search for the most technical obstacles and sections, you’ll need to bring your A-game in throttle control because the aggressive power output can make certain obstacles somewhat tricky.

The engine is toned down with revised cam profiles, a reduced compression ratio at 11.6:1 (compared to 12.2:1 on the RM-Z) and taller gear ratios, but there is still a massive amount of power on tap – 49 horsepower and 36ft-lbs of torque.

It makes riding a blast and power hungry or large blokes will really appreciate the power on hand, but there’s no doubt you could get somewhat more fatigued over a long ride than what you would on the softer powered bikes.

The thing to take note of with the RMX450Z’s power is that although there’s a lot of power, it’s so smooth with a broad spread throughout the range, building from the bottom in a burst and then featuring a wide power band as you accelerate through the rpm.

Its horsepower in restricted form as it comes from the dealer is around five less than when de-restricted, with almost six foot-pounds less torque that’s delivered in a more abrupt fashion being what you’ll have to play with until you remove the throttle screw, air filter cap and silencer end pipe – requiring you to purchase a Yoshimura Power Up system for around $120.

Shifting is typical Suzuki with smooth and effective gear changes at the top of its game, while the lever feel for the clutch and also the brakes are exactly as you would expect from an RM.

Speaking of the brakes, the front doesn’t have so much initial bite in the hot weather after an army of journos tortured them on some of the steep descents around our test property, but they do pull up very effectively under almost any circumstance. Same goes with the rear, it’s not too touchy, but gets the job done consistently.

In the handling department, Suzuki has hit the nail on the head at its first attempt in most instances.

You can feel the additional weight over the Motocrosser at 123.5 kilos, however it’s a balanced feeling that isn’t all over the front or the rear, which is a good thing overall. This is also a critical fact if you like a bit of airtime. To be perfectly honest, if you’re looking for an enduro bike that you can also do a bit of Motocross circuit riding on from time to time, it’s hard to go past the RMX450Z.

The trail is eight millimetres steeper, wheelbase 10mm shorter, an 18-inch rear wheel instead of 19 and it has a ground clearance of 30mm less – including a bash plate in case of any clashes with logs or rocks out in the bush.

What all that means is that it’s designed with enduro riding in mind, developed for slower riding than the RM-Z and proving easier to turn sharp at low speed as you work your way through the ever-changing obstacles in the sticks.

Specifically speaking, this one section of uphill continuing switchback single track corners was epic on the RMX, flowing through the rutted turns precisely as I made my way around the 12 minute course – the longest of three options including nine and five minute courses. Dodge a tree in the scrub or hit a berm hard and you’ll appreciate its steering prowess once you get it set-up for you.

The good news is that it isn’t lacking stability at speed despite the adjustments, although being a shorter rider I would prefer a lower set of handlebars at times when negotiating steep climbs and certain objects.

Down hills you’ll thank the soft feel of the suspension as it tracts along the rocks and water ruts well, the bike featuring the fully-adjustable Showa suspension direct from the RM-Z albeit with softer springs and revised settings to suit the demands of off-road riding.

We all have experienced the odd stall or two in the bush, and I’m happy to say that the RMX’s electric start will power up on demand, sometimes requiring you to have a couple of goes at the starter when it’s hot, but otherwise proving reliable.

And if you can’t get it started, revert to the old school kick-starter, because it has one of those, too…

The only odd thing is its tendency to stall sometimes when pulling in the clutch at low revs. You’re basically heading for a tight turn or obstacle, pull in the clutch, and the engine stalls out of the blue with no real warning. This happened a number of other testers and I during the day, however I’d say raising the idle speed would be a sure fix in the long term.

At just 6.2 litres, the aluminium fuel tank is over three litres smaller than what’s found on KTM’s 450, however the Suzuki does have EFI that’s said to be more efficient than carburetted bikes.

Suzuki has done a fantastic job at moulding its impressive RM-Z450 into an off-road weapon in the RMX450Z, a great first attempt that’ll prove the perfect sporty upgrade (or addition) to those who already enjoy the top selling DR-Z400.

Welcome to the enduro world Suzuki, but this time it seems yellow ain’t so mellow… I bet we have a factory-backed effort featuring the RMX in the Australian Off-Road Championship in no time!

TECHNICAL INFORMATION
Suzuki’s RMX450Z shares the DNA of Suzuki’s championship winning RM-Z450 Motocross bike, including a fuel-injected 449cc engine, and race-bred frame, suspension and bodywork.

Developed to maximise off-road performance, the new model heads Suzuki’s popular off-road range, which includes Australia’s number selling off road bike in 2009, the street-legal DR-Z400E.

Delivering exceptional power and torque, the RMX450Z is powered by a 449cc, four-stroke, single-cylinder, liquid cooled, DOHC, four-valve, EFI engine, sharing the key technologies of the RM-Z450.

The bore and stroke of the RM-Z and RMX remain the same at 96.00 x 62.1mm, however the compression ration has been reduced from 12.2:1 to 11.6:1.

A modified inlet tract and revised cam profiles enhance low and mid-range power, while the airbox features a hinged lid for quick air filter access, easier maintenance and better dust protection.

To meet the demands of trail riding, the RMX450Z has an extra coolant reservoir tank and relocated filler cap, along with a bash plate.

Wider primary and final drive ratios in the five-speed transmission help riders get the most from the engine in the bush, also featuring an electric starter. The starter and lights’ centrally located battery is charged by a larger magneto-generator.

Based on the RM-Z450, but optimised for off-road riding, an aluminium alloy frame utilises cast and extruded sections in a slim, lightweight, rigid and tough package.

The RMX450Z features a Showa suspension package derived from the championship winning RM-Z450 – the 47mm inverted front forks are fully adjustable for rebound and compression settings, while the rear shock unit offers fully adjustable rebound, compression and pre-load settings.

Spring rates and suspension geometry on the Suzuki have been developed for off-road riding, combining with an 18-inch rear wheel as is the norm for enduro machines.

When comparing the suspension of the RMX vs the RM-Z, the off-road version has a slightly longer spring that is also softer, the sprint rate being 0.47kgf/mm on the RMX and 0.48kgf/mm on the Motocrosser at the front. The rebound and compression can be adjusted via 11 clicks on the RM-Z, compared with eight clicks on the RMX.

The rear shock spring is also slightly longer on the RM-Z, the spring rate again softer on the RMX compared to the RMZ (5.5kg vs 5.8kg).It’s also slightly less adjustable.

While it may seem very similar when looking at the components, vast differences when comparing the RMX to the RM-Z include the overall length being 5mm shorter, its width is 10mm wider, height is 5mm lower, wheelbase 10mm shorter, ground clearance 30mm lower, seat height 5mm lower, and weight 11kg heavier at 123.5 kilos.

The caster of the RMX is 28 degrees and 10 inches compared with 29 degrees and 40 inches on the RM-Z, while the trail has been reduced by 8mm to 122. Its turning radius is 2.3 metres, compared with 1.95 metres on the RM-Z.

Slim bodywork, a low-profile 6.2 litre aluminium fuel tank and a motocross-developed seat gives RMX450Z pilots a functional riding position to focus on the terrain ahead to optimise line selection.

The RMX450Z’s compact instrumentation offers riders the choice between two modes, a sports mode showing the basic information a rider needs in competition, such as a trip meter, timer and average speed, while a standard mode displays additional information including speed, time and information of two trip lengths.

An integrated tyre diameter calculator allows precise fine tuning for different tyres, giving racers accurate live data for speed and distance displays.

Suzuki’s trademark Black/Champion Yellow livery with black, white and red graphics accompanies the aggressive styling of the RMX450Z.

POWER UP!
The RMX450Z comes from dealers in a restricted form, however de-restricting it is a simple and very effective process that either you can do yourself or have your dealer complete.

Stage one is to remove the throttle stop screw, which limits the throttle plate to a maximum opening of 32 degrees.

The second stage is to remove all restrictors, including an air cleaner cap and silencer end pipe, but keep in mind that you’ll first require a Yoshimura Power Up unit for around $120 to complete the job at hand.

And the result? A smoother, broader power curve that boosts horsepower up to a measured 49 ponies compared with the restricted amount of 44, while torque will be increased to 36ft-lbs from 29.

If you’re going to lay down your hard earned dollars on the RMX, this de-restriction process is a given for you to make the most of the ride.