Suzuki RM 250 – First Test & Review – Dirt Rider

Stealth technology makes warplanes all but invisible to the enemy. They’re smooshed before they know the airplanes are in the neighborhood. Suzuki is practicing its brand of stealth technology with the 2003 RM250. It’s sort of hide-in-plain-sight stealth. The ’03 model is sitting right in showrooms and will be on starting lines loaded with newfound firepower, and externally no clues hint at its potential. That’s why Dirt Rider is calling a glowing yellow motocrosser a “stealth” weapon. Aside from the usual bold new graphics, it will take a careful eye to notice major changes. Trained scouts will pick up on the new hole pattern in the brake discs and note production versions of the sidepanel vents that Suzuki’s works bikes sported this year. Once you look inside the bike, though, you’ll conclude the engineers were way too busy on the inside to change the outside.The entire engine received far-reaching changes, and the on-track performance confirms that every change was dead on target. This bike is an easily guided missile, with propulsion superior to any past RM. Suzuki sent reinforcements to the ergonomic division, and even though they only perfected the seat, the end (pardon the pun) result is appreciated. We’d have been satisfied with RM’s battle readiness if Suzuki had stopped there, but it ordered Kayaba to accomplish covert operations within the support units.Suzuki is betting it has the weaponry to rule the moto battlefield, and after this initial skirmish, we aren’t counting the company out. In fact, we’ve looking forward to the war games (AKA our annual shootout) to learn the final outcome.Suzuki chose to debut the ’03 machine near the Northern California town of Susanville at Larry Wosick’s Honey Lake motocross track. The largely natural-terrain track has soft dirt over a hard base that offers good traction, as well as many uphill pulls that test the engine very well. Additionally, there is a massive uphill that makes the one at Mammoth Mountain seem like a mole hill! Suzuki was confident in the boost factor of the new bike, or it would have turned around and gone home after seeing the track. Its confidence is understandable. Even with aggressive Bridgestone M70 rear tires on the bikes (temporarily in place of the M601/M602 stockers) the RM has instant throttle response and pulled hard in the deep dirt. The bike runs strong in each gear, and from gear to gear. The one headache was the giant uphill. The RM would pull fourth up the hill, but with a 200-pound rider it was necessary to wind third gear tight before shifting to get strong acceleration in fourth gear. That’s pretty amazing performance since the steepest grade started at 4200 feet elevation–and climbed another 400 feet in elevation!On any part of the track that resembles a normal motocross track the engine picked up each gear effortlessly with the stock gearing.So for turns and jumps the bike has plenty of hard-hitting but tractable power. There were some jump sections as well, and the new motor has all the snap the heroes will want to clear technical stadium-type jumps. At the same time, the hit isn’t too violent for novice pilots.

Part of the congeniality of the new powerplant is due to the changes in the transmission and clutch. The gear shifting–always a Suzuki strength–is very slick and crisp with zero missed shifts.

Honey Lake’s uphill straights tempted riders to rev the engine until it went flat, and then they experienced a slight reluctance to shift without backing off. There were no hitches with the clutch. The new plates engage smoothly but totally, and the clutch never seemed to get hot or temperamental. A side benefit is that the shim included in the 2002 clutch pack is no longer needed, so clutch rebuilds should be needed less frequently and be easier to accomplish when they are required.

Honey Lake has corners with big banked berms, and others that cut up into ruts and smaller berms. The RM chassis–like last year’s–is king of the tight, grooved turns, yet the suspension control keeps the bike calm in the faster banked turns.

Even with the track prepped, Honey Lake had excellent examples of acceleration chop and gnarly braking bumps, and the RM was serene and capable over both. Some of the worst braking bumps were on the downhills, so we went two clicks stiffer on the fork compression and one click in on the shock rebound. Those were the only suspension changes that a 195-pound novice and a 180-pound intermediate required. Nice.Even with the suspension doing an excellent job, the RM chassis is an inherently quick handler. The bike is best suited to riders who aren’t sloppy or reckless in their approach to bike input. No question, though, that this RM250 has the widest range of rider appeal of any RM250 in a decade or more. The package is a complete and well-rounded one. It has no glaring faults on the negative side, and on the positive side of the equation are the great motor, supple, well-controlled suspension and comfy ergonomics for a wide range of body types. Who cares if you can’t see the changes from the outside? Let’s hear it for stealth!What’s Hot!
•Engine performance is strong with good torque feel everywhere in the rpm range
•Throttle response is excellent
•New seat makes changing rider position easy and saves rider from abuse
•Handling is quick and precise with excellent turning
•Suspension is more supple, yet has nicer bottoming feel
•Bike feels light and slim for easy handling
•Graphics are thicker, so they last longer

What’s Not!
•Engine likes careful jetting. One clip position made the difference between clean or raspy throttle response
•Stock bar feels a little low
•Front brake could be a little more powerful
Highlights
•Reshaped main port with increased downslope
•Sub exhaust ports are now square instead of rectangle
•Scavenging ports are all moved and/or reshaped
•Boost port separated from the intake port
•Intake port is reshaped and the reed-valve intake passage is narrowed from 82 to 70mm
•The intake manifold is changed to match the new reed valve The exhaust valve system is nearly all-new with cam-operated side exhaust valves. The main and side exhaust valve now open at different times
•The exhaust valve governor is redesigned for more precise control
•The piston is now domed (instead of flat-topped) with a single large intake cutaway in the skirt in place of two wider-spaced holes.
•The crankshaft is heavier for more tractable power delivery
•The crank end is smaller (38 to 28mm) for reduced seal friction
•The water pump is designed to be more efficient, lighter and simpler
•Airbox is 20 percent larger with a shroud to prevent radiator-heated air from entering, and with a cool-air slot in each sidepanel. Cooler air to the engine generates better throttle response
•Driven clutch plates are thicker (3.15 to 3.00mm) and fiber plates have new material for less chatter
•Shift pawl pin is now shouldered to extend into the pressure spring rather than sit on top of it
•The transmission shafts now have involute splines (18 and 23 smaller, slightly rounded splines in place of six large rectangular splines on each shaft) for more precise shifting
•Minor changes to the subframe were necessary to fit the new airbox and improve airflow
•The mounting point for the new brake pedal is raised for increased ground clearance in turns
•KYB fork no longer has bladder or hydraulic bottoming control. A bump-stop bottoming system is used, and travel is reduced 10mm
•The fork’s compression-damping piston has straighter oil passageways
•A small oil passage from the compression adjuster to the shock body is eliminated for better damping at low shaft speeds
•Brake discs have holes rather than slots•Footpegs are 10mm longer, drain better and have a single, wide mounting boss
•Front rim is thicker at the edges and in the middle for more durability
•The front wheel spacer has a lip to make putting the wheel back on easier
•Rear master cylinder is lighter
•Seat cover is thicker (from 0.9 to 1.1mm) and seat foam is eight percent stiffer.
Opinions
It’s been many years since Suzuki offered a 250cc motocrosser this flawless. Most years the weakness has been in the power output, but there were years I didn’t get along with the suspension. The ’03 motor is an easy-to-ride rocket. It pulls hard everywhere in the powerband. It will pull a tall gear or rev equally well. The suspension keeps the track abuse at bay, and the new seat is a great place to spend some moto time. It could find a place in my garage with no problem.
–Karel Kramer/6’1″/195 lb/Novice

Having ridden an ’02 RM250 almost the entire season last year, I have a sensitive feel for the characteristics of that bike. When I jumped on the ’03 machine, I instantly noticed the increased boost in the bottom and midrange power. For this year’s introduction, Suzuki took us to Honey Lake motocross track, which is located in high elevation and is dominated by the biggest uphill on any MX course I’ve ever ridden. The Suzuki had no problems and almost pulled fourth up the entire massive hill. Top-end was about the same, but due to its low-end bark, the ’03 is happiest when ridden in a taller gear. The suspension is also improved over last year’s with plush action front and rear. On hard slap-down landings the ’03 fork was much plusher, absorbing more of the shock. The chassis feels similar to the ’02 bike’s and features the same comfortable ergonomics. With a couple of rides under my belt, I think the new RM250 could be a major shootout contender.
–Jason Webb/5’10″/175 lb/Intermediate