2008 RACE TESTSUZUKI RM-Z250

March 4, 2008
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We don’t expect you to remember the intricate details of RM-Z250 development, which is why the MXA wrecking crew is here to help. Released in 2004, the RM-Z250 started off as a clone of the 2004 Kawasaki KX250F. Developed under the short-lived Suzuki/Kawasaki alliance, the RM-Z250 wasn’t just similar to the KX250F?it was the 2004 KX250F. The RM-Z shared the cranky handling characteristics, overheating problems and low-to-mid powerband of its green brother. In 2005, the green and yellow twins got some durability improvements, but real change was still on the horizon.
In 2006, Kawasaki made a boatload of improvements to the KX250F. The green crew offered Suzuki a chance to buy the new aluminum-framed bike, but Suzuki didn’t want to get bogged down in a long-term contract with Kawasaki. So, for 2006 Suzuki sold the same-old, same-old steel-framed RM-Z250 (and it was looking old by this time).
Then, like a phoenix rising from the ashes, the Suzuki RM-Z250 was reborn in 2007. No longer tied to Kawasaki, Suzuki had the opportunity to go to an aluminum frame and completely overhaul the engine. The end of the alliance was a blessing for the RM-Z250, as it was transformed into the best-handling bike on the track.
The MXA wrecking crew wasn’t expecting any major changes to the 2008 RM-Z250. Suzuki had invested heavily in the redesign of the 2007 model. Manufacturers prefer to use engine molds and chassis extrusion for at least three years before making major investments in a new design (it has something to do with the bottom line).
All the consumer could hope for in 2008 was an assortment of minor changes to the 2007 model. And that is exactly what Suzuki did. The $64,000 question is whether the minor mods were enough to boost the Suzuki RM-Z250 up in the 250F rankings.

Q:HOW MANY CHANGES WERE MADE TO THE 2008 RM-Z250?

A:Two dozen, to be exact. The most noticeable changes are to the RM-Z’s outward appearance. The wave rotors, right-hand hot-start lever, gold axle blocks, gripper seat cover and gold-tone chain are all obvious to the naked eye.

Q:IS THE 2008 RM-Z250 ENGINE IDENTICAL TO THE ’07?

A:No, but don’t get too excited. It isn’t the same, but it also isn’t dramatically different. Suzuki’s engine was the low-to-mid horsepower king in 2007, but fell flat on top and hung in the over-rev. That is still a fairly accurate description.
After listening to rider’s complaints, Suzuki put a Band-Aid fix on the mid-to-top power. How? By adding Bat Wing winglets inside the carburetor throat, narrowing the exhaust port and revising the muffler construction.
Do these mods pump up the power to epic proportions? No. If you have a sensitive side, you could feel a modicum of improvement from the middle on up. But, it essentially the same powerband as last year.

Q:IS THE 2008 RM-Z250 FASTER THAN THE 2007 RM-Z250?

A:We want to say yes, but it is a qualified yes. Don’t get us wrong, the 2008 RM-Z250 has a stronger mid-to-top than the 2007, but it’s nothing worth wasting a stamp on to write home about. Yet, mid-to-top power isn’t what the RM-Z250 is all about. Its focus is lower in the powerband. Thankfully, the blissful low-to-mid power remains as joyous to use as it was last year. Pros will want more meat on top, but for the vast majority of riders, the chunky bottom end is easy to use.

Q:HOW GOOD IS THE SHOWA SUSPENSION?

A:It’s sad for the MXA wrecking crew to see good suspension that is set up for such a small audience. As it sits, the 2008 RM-Z250’s Showa suspension is geared towards minicycle transplants, which leaves riders of average build out in the cold. Suzuki stiffened the valving, but since they were so far off on the clickers last year, that was more remedial than improvement.

Q:WHAT ABOUT THE JETTING?

A:Suzuki’s engineers made slight revisions to the jetting for 2008. We liked it. Here are the stock 2008 RM-Z250 jetting specs (2007 specs in parentheses):
Main Jet: 162 (162)
Pilot Jet: 42 (45)
Needle: NLCT-3 (NLCT-3)
Leak jet: 40 (40)
Fuel screw: 1-1/2 turns out (1-1/2)

Q:WHAT ARE MXA’S
RECOMMENDED RM-Z250 FORK SETTINGS?

A:Here is what the MXA wrecking crew ran in its 2008 RM-Z250 for hard-core racing:
Spring rate: 0.46 kg/mm (0.44 stock)
Oil height: 370cc
Compression: Ten clicks out
Rebound: 12 clicks out
Fork leg height: 2mm up
Notes: The forks are sensitive to fork height adjustments. For tight tracks, we slide the forks up in the clamps, and for fast tracks we slide them down. Even a minor fork height change will alter the handling.

Q:WHAT IS MXA’S RECOMMENDED RM-Z250 SHOCK SETTING?

A:Here is what the MXA wrecking crew ran in its 2008 RM-Z250 for hard-core racing:
Spring rate: 5.6 kg/mm (5.4 stock)
Race sag: 100mm
High compression: Two turns out
Low compression: Eight clicks out
Rebound: Eight clicks out
Notes: The shock is very sensitive to high-speed compression adjustments. Move the dial in 1/8th increments only.

Q:HOW DOES THE RM-Z250 HANDLE?
 
A:You don’t know what a bike should feel like until you race an RM-Z250. The RM-Z250’s handling is second to none, and the handling is what truly makes this bike shine.

Q:WHAT ARE THE BEST TRAITS OF THE 2008 RM-Z250?

A: There are two very significant attributes of the ’08 RM-Z250.
 Handling: Once the Kawasaki/Suzuki alliance was squashed, Suzuki went back to the drawing boards and designed their own RM-Z250 frame. It was good for the consumer and bad for every other 250F on the market. Suzuki’s aluminum frame handles like a dream. It corners, jumps and turns with ease. It can run circles around a Yamaha, Honda, KTM or Kawasaki. It’s that good.
Low-to-mid power: While top-end power is weak on the 2008 Suzuki RM-Z250, it is more than made up for by the stellar bottom-end. This baby will crank out of corners and sing through the middle of the powerband. Thanks to the modest improvements in mid-to-top power, the overall powerband is more effective than it was in 2007. Miss a rut? Roll on the throttle. Blow out a berm? Roll on the throttle. Immediate jump following a tight turn? Roll on the throttle. Suffice it to say that the 2008 RM-Z250 barks like a starving pit bull outside a meat-packing plant.

Q:WHAT ARE THE WORST TRAITS OF THE 2008 RM-Z250?

A:There are two significant problem areas on the ’08 RM-Z250.
Top-end: Although improved over last year’s model, the 2008 RM-Z250 could use more over-rev. Don’t get bogged down in semantics, the RM-Z250 revs, but it doesn’t make horsepower in the upper ranges. It hangs. MXA test riders had to shift often, and Pro riders often found themselves tapped out in fifth gear on long straights (straights that didn’t use up fifth gear on the other brands). When riding the RM-Z250, make sure that your clutch hand and left foot are swift on the shift.
Suspension setup: Last year Suzuki set the RM-Z250’s suspension up for a 140-pound Novice. It was so finely sprung that when a 141-pound rider raced it, it would bottom. For ’08, Suzuki stuck with the same springs, but revalved the Showa units to slow down the damping. Suzuki’s aim was to target the suspension for a 150-pound Intermediate, but it’s still too soft. If you are fast or heavy, you will need to go stiffer on the springs on both ends.

Q:WHAT CHANGES WOULD WE MAKE TO THE 2008 RM-Z250?

A:There are only a few must-have parts on our wish list for the ’08 RM-Z250.
Exhaust system: An aftermarket exhaust system boosts the flat-as-a-board top-end.
Gearing: The MXA wrecking crew had problems with the stock 12/48 on the ’08 RM-Z250. The vast majority of racers, except those who race on fifth-gear tracks, would benefit from an extra tooth on the rear sprocket. A 12/49 allowed the test riders to short-shift and get the most out of the more closely spaced gears?especially third gear.
Stiffer springs: The suspension is too soft (front and rear). We replaced the stock 0.44 kg/mm fork springs with 0.46s and the 5.4 kg/mm shock spring with a 5.6.

Q:WHAT DID WE HATE?

A:The hate list:
(1) Spring rates: Suzuki needs to account for the fact that most 250F riders weigh more than a postage stamp. Up the spring rates and erase our nightmares about landing short off jumps.
(2) Gearing: We complained last year, and we’ll complain again. The 12/49 combo is much better than the 12/48 stock gearing.
(3) Clutch: Suzuki has the weakest clutch out of the Big Five. Use it sparingly. Thankfully, the RM-Z250 clutch doesn’t need to be fanned that often, as the engine takes care of business.

Q:WHAT DID WE LIKE?

A:The like list:
(1) Engine: As much as we complain about the lack of top-end, the RM-Z250s engine is still dynamite from bottom-to-mid. The engine is fun, manageable and competitive.
(2) Hot start: For 2008, Suzuki repositioned their hot-start lever to the throttle side to keep riders from twisting the throttle and flooding the sensitive four-stroke. Very nice.
(3) Handling: The RM-Z250 handles like a dream. What more can be said?
(4) Details: Suzuki spiced up the RM-Z250 by adding a gold-colored chain and axle blocks. Additionally, the new saddle has a 100-percent gripper seat cover. Way cool.
(5) Wave rotors: The RM-Z250 has joined the wave-rotor bandwagon. These rotors help dissipate heat and are self-cleaning.
(6) Rims: We know that Excel rims came on last year’s bike, but we still love ?em. They are bulletproof rims.
(7) Handlebars: Renthal FatBars?now that’s hot.

Q:WHAT DO WE REALLY THINK?

A:We might as well tell you the truth right up front. The 2008 Suzuki RM-Z250 isn’t going to win the ’08 250F shootout. It needs more overrev and stiffer suspension to jump to the top of the heap. But, and this is the big but, whether it wins the shootout or not, the RM-Z250 is the bike that many MXA test riders choose to race (warts and all). Why? You can always make a slow bike fast, but you’ll never get a YZ250F, CRF250, KX250F or KTM to handle this well. o

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