We flogged the 2008 Suzuki RM-Z450 at a recent WORCS round to see how the fuel-injected motocross weapon handled itself off the MX track.
We all know that motocross machines spend as much, likely more, time off the track than skimming groomed whoops at the local MX park. Even manufacturers admit their highly-tuned, MX-specific weapons are more often put away wet and dusty after a long day on the trails. One such cross-over motocross machine is the fuel-injected 2008 Suzuki RM-Z450
, so we took the new Zook for some serious off-road testing at a recent WORCS round.
Motocrossers like the RM-Z can make awesome off-road bikes for its owners with little or no modifications, depending on the rider's stud level. Hard-hitting power, stiff suspension and a lack of electric amenities such as headlights and starters are the major obstacles that prevent MX bikes from going off-road. However, a good mill, aggressive chassis and usable ergonomics are all desirable traits regardless of where you ride, so the moto machines have a distinct advantage right from the get-go.
made three major changes to the RM-Z450
that led us to tap it out for WORCS racing. These primary areas, fueling, transmission and chassis have put some wind in the sails of off-road yellow riders. It's fairly common knowledge that the RM250 2-strokes were pretty damn good rides with a few mods, but Suzuki has finally caught up a bit with the thumper revolution. It is currently the only OEM in the Big 5 that doesn't offer an off-road version of the 450 and 250cc 4-strokes. Though we fully expect a RM-Z450(X) perhaps as early as 2009, the reason for such is that the 2008 bike is a new generation bike and perfect starting point for a cross-over.
Being the impatient fools that we are, we couldn't wait for Suzook to bust out another all-new trail model. The fuel-injected, five-speed moto version was close enough for our tastes. We took the 2008 MotoUSA 450 Motocross Shootout
runner-up and put it through a month of off-road testing to see how well it adapts to multi-purpose (read real-world) use. Trail riding was our primary target but we entered a round of WORCS racing at Pacific Raceways in Auburn, Washington just for kicks. We didn't do any more than dress it up with a set of bark busters, drop 10 bucks for an Oregon OHV permit and head in the opposite direction of the nearest motocross track.
With a combination of moto and off-road, the WORCS race we attended was a pretty good blend for this bike. Some of the rounds further south would have been even better with more space for the big 450 to stretch.
From Pacific Raceway's 300-foot elevation to nearly 5000 feet in Jackson County, Suzuki's new fuel injection system worked flawlessly. We would've liked to have taken the bike twice as high but we ran out of mountains. Still, throughout our testing regimen there wasn't a single hiccup or stutter. Even during the max-rev thrashing we gave it up the 3600-ft hills of Cahuilla Creek MX during the shootout, the bike managed without a single complaint.
Also worthy of note is that we never had any problems with water infiltrating the system during our rabid power-washing sessions, and we didn't go easy on it either, hosing the system directly from all angles. Though it seems trivial, we were super-pumped on this because this has been a problem with other bikes in the past. During our 2006 450 Enduro Shootout
, our Sherco test bike left us stranded out in the woods thanks to water splashing into the EFI. Not having to worry about faulty fueling or needing to change jets for altitude offers good peace of mind. We were worried, though, about whether or not there was enough fuel to get home. The 1.6-gallon tank is excruciatingly small, but the fuel usage appears to be comparable to any 1.9-gallon carbureted machine. Desert guys will definitely need to go bigger for serious stints, but options are limited for now. IMS has recently developed a 2.7-gallon model which is used by the factory riders.
Even though the massive power killed our arms in the tight trees of Washington, the environment also gave a good demonstration of the EFI's other strength, low-end power. We noted in our moto testing that the yellow bike can pull a gear from lower in the rpm than any other, and that translates to great chugability in slow-going woods riding. We didn't even bother to change the final gearing, but the 12-hole injectors and well-tuned battery-less system kept us moving forward even when arm pump left our hands utterly worthless at the throttle. The bike simply refuses to stall, and it's a good thing too, because getting the Suzuki
to start is a real chore. It routinely takes us 4-6 kicks to get the bike started, and the stroke is much harder to push through than other equivalent-sized machines. Basically it wore us out.
Trail riding the RM-Z is especially fun thanks to the luggable, torquey motor and thin ergos. Besides, the easy-going pace allows for a break when the hard seat and stiff suspension start to wear you down.
The older RM-Z wasn't exactly porky, but the new chassis makes the rider feel like their knees are going to touch. Even compared to the other Japanese machines we tested in the MX shootout, this skinny-minnie is obviously one of the thinnest 450's around. Proper off-road technique requires increased standing compared to MX and the thinness allows for the bike to become even more agile as we adapted to life on the pegs. Despite being one of the heavier 450s, the RM-Z hides its weight exceptionally well, and dropping the center of gravity by standing up only increases the sensation.
Even though the handling and ergonomics are very good, the bike doesn't stick to the trail as well as we'd like for race situations due to the moto suspension. We were able to tame some of the deflection and harshness, but this thing was designed to land big jumps, not soak up roots, bump over logs and gorge on wet rocks. Our testing crew thought the Zook was on the plusher side in our shootout evaluation, but a plush moto ride isn't the same as a plush off-roader. The bike does perform better at higher speeds, but the Showa units just don't react well to sharp impacts. We even had our buddy at Watson Performance
try his hand and the result wasn't as encouraging as we'd hoped. The factory team uses RG3, but some kind of aftermarket mods will be required. As expected, this was the biggest weakness for the RM-Z.
The front brake, which got knocked for requiring too much effort at the lever during moto testing, doesn't have such a negative effect off-road. It still requires a stiff pull, but because you don't typically ride the front brake as much compared to riding a motocross track, the sensation is far less annoying. However, there is one thing that is amplified in the transition from moto to off-road - the rock-hard seat. Thankfully, as mentioned before, we spend more time standing up off the MX track, but the brutal saddle is anything but comfortable. Skinny and hard, none of our riders could stand it for very long no surprise there.
In order to test the Suzuki RM-Z450's off-road racing credentials, of course we had to blatantly take someone down in the corner.
So there're a few good and bad things, but just how competent is the bike off the track? New Zealand's Paul Whibley snared the first major off-road win for the bike at the Wiseco John Penton GNCC in Ohio aboard a FMF Suzuki Factory RM-Z450
. Granted, that bike was heavily modified, but that's exactly the point we were trying to prove - the stock bike is a good starting point for something great. Not only did Whibley take the win, but he was followed by his teammates, 450-mounted Josh Strang and Jimmy Jarrett on a RM250. Last year, three of the top-10 GNCC Pro XC1 point holders, Jarrett, Strang and Glenn Kearney, were aboard Suzuki 2-strokes, but the tide has begun to change since the new RM-Z came out.
has found success in the WORCS format as well. Nathan Woods signed on this year to take the place of former MX hero Ryan Hughes. Ryno never could stay healthy enough to make his Zook's successful, but as the winningest rider ever in the WORCS series, Woods has a good chance at bringing victory to the Suzuki camp. When he made the move, Woods left behind the powerful KX450F, so you can bet he didn't want to hop on the ol' 2-smoker.
Now that we've established that the new Suzook is a bona fide trail bike, the rest is up to you to make it into a full-blown, target-specific off-road warrior. The factory wasted no time in putting it to good use with the FMF Suzuki Factory Off-Road teams. The RM-Z450
is certainly a motocrosser first and foremost, but we, and the rest of the off-road community, were happy to see that the new changes carry sizeable benefits for non-moto use. Everything that you would expect to be problem areas, like abrupt power delivery, hard suspension and a lack of amenities need to be addressed, but the bike definitely didn't move backwards in terms of developing an overall package. Suzuki states in its promotional material that the Z450 was designed for fun weekend use, and it's clear to us that it knows not everyone spends each Saturday and Sunday at the motocross track.
Stock Specs: RM-Z450
Even with its stiff MX suspension the Suzuki RM-Z450 proved to be a capable beast out on the trails.
449cc, 4-stroke, single-cylinder, liquid cooled, DOHC, 4-valve
Bore & Stroke:
96 x 62.1mm
Electronic Fuel Injection
Telescopic, cartridge-type fully adjustable rebound, compression and pre-load settings
Link-type, spring preload fully adjustable rebound, compression and pre-load settings
Single hydraulic disc
Single hydraulic disc
Fuel Tank Capacity:
Rider: Nathan Woods
Mechanic: Dave Dye
Nathan Woods is the man at the helm of Suzuki's WORCS program. If it weren't for an injury early on, Woody would have been challenging for the series title.
Works Connection clutch perch, hot start, custom one piece skid plate/engine guards, engine plugs, front/rear master cylinder cover, holeshot device, oil fill plug
RG3 20mm triple clamps
RG3 rear suspension link
Showa kit suspension
Acerbis plastics, carbon disc guard, hand guards
Bib Mousse tubes
Renthal dual grips, 999 Twinwall handlebars and front and rear sprockets
IMS oversized tank 2.7 gallon
Zip-Ty axle spacers, axle blocks, shark fin brake guard
T.M Designworks chain guide
Mectec Titanium bolt kit
N-Style graphics and gripper seat cover
Fast Co. brake clevis
FMF Mega Bomb header
FMF Factory 4.1 exhaust
Zip-Ty oil filter cover, case saver
Twin Air filter
Suzuki Offroad ECU mapping
Engine internals are stock: cylinder head, crank, cams, piston, valve train, etc
GNCC RM-Z450K8 and RM250K8
Paul Whibley is one of the RM-Z450 riders contesting the ultra-competitive GNCC series.
The same as WORCS but GNCC runs production suspension revalved by RG3 (Softer settings than WORCS), bark buster Acerbis hand guards and FMF pipe and silencers on the 2-strokes.
Paul Whibley/Josh Strang
Dan Schuller/Chris Wolf
Charlie Mullins/Jimmy Jarrett
Shane Nalley/Rod Harris
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