Suzuki has reasserted itself in the battle for Lites-class supremacy. Yellow riders have been waiting a long time for this machine.
The 2006 250F machines were a rip-snorting batch of technological advancement across the board, save for the efforts of one sore-thumb manufacturer. After the fall-out deal with Kawasaki to jointly produce the KX-F and RM-Z250 models, Suzuki
found itself a step behind and elected to utilize the same machine in '06 as it had the year before. With Kawi's triumphant introduction of its independent 250F design, Suzuki cut its losses for the year to now deliver a haymaker punch for 2007.
In the years since 250F machines began trashing the 125cc class, Suzuki hasn't been making headlines like some of the other manufacturers. That, however, doesn't mean Yellow tiddlers haven't spent their share of time in the victory circle. During the recent press introduction of the 2007 RM-Z250, Suzuki PR representatives were quick at pointing to 30 combined 125cc MX/SX titles hanging from its wall. From Gaston Rahier's 1975-77 trifecta of World MX championships to Branden Jesseman's AMA 125cc Eastern Region SX title in 2003, small-bore Suzukis have been gathering accolades. But not one of them has come on a 4-stroke.
Yellow riders in 2007 will be much less inclined to switch to the RM-Z450 mid-season the way Mike Brown and his Rockstar Suzuki teammate Ryan Mills have in the recently concluded outdoor Nationals. The new Z250 is all-new from the meats to the motor, and it received a healthy dose of influence from its big brother.
The frame looks just like one supporting Suzuki's RM-Z450, but a few dimensional changes adapt the aluminum unit to suit the smaller machine.
As the only Japanese manufacturer to use a steel frame in '06, Suzuki pulled the aluminum technology from its proven RM-Z450 and adapted it to the smaller machine. Switching to the twin-spar, alloy design shaved 2.4 pounds off the chassis weight from last year. This undoubtedly plays a large part in the one-pound overall weight savings at the claimed dry measurement of 203 lbs.
Analyzing the spec sheet shows this new chassis is smaller in nearly every category except for ground clearance when compared to the steel-framed '06 version. The 250 actually has more in common with the big-bore RM-Z, being virtually identical aside from a half-inch shorter wheelbase (57.7 vs. 58.3). However, spec sheets only convey so much. Knowing that, we sat down with Suzuki's Motocross Engineering Manager, Tetsuro Matsumura, to find out a little more about this all-new chassis.
Matsumura revealed that the small-bore's chassis is indeed more compact, which was accomplished by moving the steering head 15mm rearward. To avoid cramping the riding position, the footpegs were shifted roughly 10mm rearwards as well. Overall the 250's frame is just over a pound lighter than the 450. It also appears daintier with its smaller frame spars, though the thickness of the aluminum walls was increased to compensate for the reduced width.
As always, the goal was to keep the chassis forgiving while retaining a balance of rigidity. Cast, extruded and forged components are utilized to achieve the desired equilibrium. The swingarm is straight off the 450, as is the Showa suspension instead of the 250's Kayaba springs of '06. A 47mm fork takes a full 12.2 inches before bottoming out, while the 50mm shock piston comes with a larger reservoir than last year and increased flow volume. Both ends get altered damping to suit the smaller bike.
Suzuki says the new bodywork creates a speedy and energetic image, but what do you think? We tend to agree.
The RM-Z powerplant retains the 77 x 53.6mm bore/stroke in the 4-valve, DOHC configuration. Our dyno aches to run out horsepower and torque figures, but for now those numbers are shrouded in a mysterious yellow fog. What we do know is that changes have been made internally to improve performance and boost reliability. The combustion chamber has been smoothed out to provide less-turbulent air-and-fuel intake. Additionally, the intake and exhaust ports are massaged to further smooth the transitions of fuel mixture and exhaust.
Extra tidbits for the internal engine mods are lighter valves and camshaft and changes to the transmission. Shifting the 5-speed tranny is performed by a link-type mechanism in place of the old gear style, and the ratios between third and fifth have been tightened to help keep the bike pulling through the meat of the power range.
As with any high-performance machine, the new RM-Z comes equipped with special acronyms for that hi-tech flavor. Suzuki's nifty nickname for the nickel-phosphorus-silicon-carbide cylinder coating is SCEM; short for Suzuki Composite Electrochemical Material. Besides sounding really cool, the SCEM treatment actually does make the RM-Z cooler. Heat transfer is said to be faster while also providing weight savings and higher durability. Suzuki Advanced Sump System (SASS) keeps those moving parts lubed up while allowing the motor's center of gravity to remain as low as possible for optimal handling characteristics.
Bodywork and styling are also based on the 450, but gone is the Excitebike-whoop-section rear fender from last year's big-bore. The styling is still a touch angular for a Japanese bike, with the newly-shaped radiator shrouds giving it a sharp appearance, or as Suzuki describes it, "a speedy and energetic image." Function has been incorporated into the shrouds as well, with larger vents that are said to aid in cooling. Combined with larger radiators, Suzuki claims heat dissipation is up 20% from 2006. Larger blades on the water pump impeller also contribute.
Track Impression: The Middle Man
Blasting through loamy corners is a hoot with Suzuki's new powerplant. The new RM-Z won't knock your socks off with sheer power, but the motor feels strong and very competitive.
The first thing you notice about any bike is the motor. Even as you simultaneously adjust your goggles, try to decide what exactly is different about the cockpit and give your knee guards a final twist, the mind is abruptly torn away with a blip of the throttle. Your brain is consumed with analyzing what the motor is doing between your legs. Whether it furiously rips out of corners or gives an all-show-and-no-go routine, the first few laps around the track are inescapably focused on engine performance and power delivery.
newest Thumper definitely runs strong and clean. Zaca Station MX Park was plowed deep and thoroughly saturated during the early going. While not necessarily the best time to test suspension and handling, the deep loam provides an excellent test of the motor. Plowing through the heavy soil demonstrated that the little Z has plenty of juice. As you would expect from a modern 4-stroke, power delivery is smooth across the board. Corner-exiting grunt isn't mind-blowing, but the RM-Z will tolerate a fairly healthy dose of lugging. Once the engine starts breathing is when the fun starts.
Midrange power is the most thrilling attribute of the engine curve. Keeping the bike in its sweet rpm range pays dividends with a responsive, controllable thrust of roost-chucking bliss. The motor keeps pulling into the top end before signing off way, way out there. Even on the lengthy Zaca Station course with several elevation changes, I never found the rev limiter. To be honest, I didn't really want to.
A narrow, comfortable design and roomy cockpit make it easy to move around and give good reason to do so with responsive handling characteristics. Suzuki is known for sharp handling and cornering prowess and the smallest RM-Z hasn't fallen far from the tree.
Even though it revs forever and has the top-end power to maintain momentum, high-rpm power output isn't as effective as up-shifting and keeping the motor a tad lower in the revs. As the track dried out and formed alternate lines, the motor demonstrated its do-all ability. There was enough power down low to run a gear high and still get out of corners and over obstacles, yet could eliminate an extra shift by stretching the upper limits. Keep in mind, this impression is coming from a 190-pounder. It was impossible to finagle the RM-Z's exact figures from Suzuki techs, but they confirmed the '07 makes more power than its predecessor. Hopefully their tight-lipped smirks and vigorous nodding will translate into impressive dyno numbers.
Choosing the right cog to keep the motor at its happy medium was easy to do with no gaps anywhere in the close-ratio tranny. This is the first bike that I have ridden where I didn't miss a single shift. Not one. All day. The distance between gears is so small, and the new shift mechanism is quick, accurate and dependable. My only grievance was the constant struggle to find neutral. I was like a virgin in the dark, and the elusive neutral led to difficulties starting the machine as well.
The RM-Z doesn't like to start in gear, and it wasn't until the last half of the day that I began to regularly fire the machine with less than five strokes. After stalling the high-strung motor, lighting the 13.4:1 compression was never an easy task. Even letting the bike sit for a full hour while I ate lunch still required the hot-start lever. In fact, I don't recall ever lighting the bike without it. It got to the point where I had to ask if there was a trick, but the techs offered nothing and I never discovered a successful routine. This was the hardest-starting 250F I've ever ridden.
It's common knowledge that Suzukis rule the inside line, which can suit a rider's style or not. Either way, the manufacturer is proud of its nimble machines, and the '07 version refused to deviate in the slightest. Engineers actually added over a half-degree of rake to the steering geometry, now boasting rake/trail figures of 27.2 degrees and 4.5 inches. The KTM 250 SX-F has a sharper angle at the steering head (26.5 deg), but whether or not the Orange machine can match the Suzook's turning prowess will have to be settled in our 250F MX shootout. As far as the RM-Z is concerned, the new machine has the one trait now synonymous with the Yellow brand: razor-quick handling.
This rear brake is an underrated asset on the new machine. Rave reviews about Suzuki's binders aren't as abundant as say those for Honda, but Yellow engineers have found a near-perfect blend of strength and compliance.
Suspension on the '07 Suzuki is impressive. As the dirt changed from loam to silt and I started conquering more obstacles, not once did I need to adjust the suspension. When I showed up the sag happened to be dialed in at 105mm and the rest was history. Front and rear did exactly what I wanted it to in all areas of the track. The only thing missing from the gamut of testing was heavy braking bumps that never really developed. I'm pretty heavy for a 250F, but the Showas were predictable and plush and I never felt any hint of harshness. I tend to come up short on jumps quite a bit, but that isn't a problem with the Suzuki.
A few things that make riding the bike more pleasant are the brakes and rider layout. Even though the chassis has shrunk compared to last year's bike, it still fits my 5' 11" frame. The relationship between the pegs and new-for-'07 Renthal Fatbars is a comfortable one, and the gripper seat offers extra friction but doesn't lock you down.
Often, having great control over the rear brake requires the foot control of a karate sensei or riding in sneakers. Trying to modulate the pedal through heavy boots while getting bounced all over the place makes it easy to lock up the rear wheel when a gentle application would be sufficient. Spongy brakes can ease the harshness, but then a rider sacrifices braking power. Suzuki has done an excellent job of providing a powerful and responsive single-piston caliper on the rear. Up front is an equally good dual-piston caliper that gives riders just what they need. It is neither grabby nor soft, but once again right at that happy medium. Both rotors are straight off the 450, and even though I went into this test determined to pick apart the braking system, the Suzuki completely shut me down.
Jumping the RM-Z was one of the most enjoyable things about riding the yellow 250. Light and well suspended, Suzuki should be a favorite among the anti-gravity crowd.
Suzuki's whole marketing gig for this machine is a "Return to Dominance" theme. The successes enjoyed throughout the past have surely been a rewarding experience for the Yellow manufacturer and it is hungry for more. Suzuki has never been at the forefront of this new 250cc 4-stroke movement, but I don't predict seeing riders jump ship to the bigger 450 in 2007. The concentrated effort from Suzuki's engineers should pay off well, so Suzuki's plan of returning to championship form might not be that far away.
It's hard to say if this bike will prove to be the best 250F on the market, but everyone knows that the machine is only 50% the battle. It was a tough stretch for RM-Z riders last season, but Suzuki will be holding up its half of the bargain in '07.
It's a year late, but the new RM-Z250 is finally here. Talk about it in the forum