Modified Suzuki RM-Z250
You know the face people make when something smells really, really bad? Whether it's rotten eggs or dirty moto socks, we, as humans, are automatically programmed to wrinkle our noses and half-open our mouths in disgust at the slightest trace of stink. Well, that's the face most of our test riders were making when discussing the performance of the 2008 RM-Z250's fork after our last day of shootout testing. Yes, the RM-Z is a great bike and, no, the suspension isn't bad fresh off the showroom floor, but after several days of hard testing on some seriously rough tracks, the Suzuki's front end had seen more break-in than a hotel room full of O.J. Simpson memorabilia. The bottoming resistance went out the window, and the bike's original vote of confidence was beginning to dwindle right along with the ride height. Something had to be done.
Barely cooled down from one last day of evaluations with our schoolboy testers (see the featherweight impressions in the March issue of Mini Rider), the Suzuki was dropped off at RG3 Suspension for a pick-me-up. Along with fresh oil in both ends, the suspension was revalved to accommodate heavier pilots, with the end goal being to maintain the original settling in turns while doing something about the awful clank-clank that resulted from landing a bit off target. To complement the new setup, an RG3 rear link was also installed to reduce the dead blow to the shock on hard hits.
After tooling with the suspension, I found it prudent to try to fi x some of our other complaints about the yellow thumper. Since I feel that the stock Renthal Fatbar has a cramped bend that doesn't complement the rest of the Suzuki's ergos very well, it was off with the old and on with the new 997 Twinwall bar and half-waffle grips. The tires were fairly well burned after all the testing, which meant that some new meat was in order-I went with the Maxxis Maxxcross IT on both ends. Next, I turned my attention to the motor, mostly out of curiosity rather than complaining since engine performance is actually one of the RM-Z's high points. Personally, I like my four-strokes to run a tad stronger on the mid and top-end, so I got my mitts on a pair of Leo Vince exhaust systems to see what they could do as far as boosting the power. I then bumped the gear ratio from 4.00 to 3.92 with a fresh 47-tooth Renthal rear sprocket and installed a Twin Air Dual Stage filter, which is designed to increase airflow and enhance the overall response. To finish things off, I slapped on some fresh Throttle Jockey graphics and a gripper seat cover, just so the 'Zook didn't feel left out next to Jimmy's howling death-monkey stickers.
It took about half of a lap aboard the RG3 suspension to realize how much better the RM-Z was working. Two more days of riding confirmed that even with some break-in, the new setting had the machine riding higher up and using more of the stroke without all the bottoming hassles seen previously. Due in part to the RG3 rear link, the suspension took on a plush feel with quick-acting resistance in all the right places. The change was just what I was hoping for-not drastic enough to botch the original strengths, but super improved all the way around.
The slightly faster gearing, Maxxcross tires and new Renthal bar were all an instant hit, but I hit a virtual wall when it came to the exhaust. Jumping right to the titanium full Leo Vince system, golf partner/testing homie Ryan Orr and I were less than stoked on the changes to the power. A great supercross pipe, the full system gave the bike a quick-revving, narrow-windowed power that didn't work well on any of the three outdoor tracks that we rode. Feeling the poopy-face coming on again, we were happy to find success with the stock header/ Leo Vince stainless steel slip-on combo, although the broadened power and better mid was accompanied by boggy response and sporadic hesitation. The golden ticket ended up being in the spark arrestor tip, which calmed down the throttle response issue while only slightly suppressing the newfound power, ultimately adding more meat on both ends and boosting the midrange considerably over stock. We rotated through all of the combos-including stock-once more to make sure we were happy, and then settled upon the slip-on can with S/A screen as the final choice.
In my opinion, the revised RM-Z250 makes for one heck of a race package. By stepping up the suspension performance, opening up the cockpit, slightly tweaking the gearing and broadening the power throughout, we transformed the entire feel of the bike. What's more, I didn't once have to remove the motor from the frame or crack the carb to fiddle with the jets. All of these mods were completed without breaking the bank, and thanks to the spark arrestor, the bike is now much quieter and-best of all-off-road-able. You know that face that people make on the 4th of July whenever a huge bundle of colorful fi reworks explode in the shape of a massive, awesome peace sign? Well, I'm making that face now.
Parts List
Leo Vince X-3 stainless slip-on exhaust
Throttle Jockey graphics and gripper seat cover
Renthal 997 Twinwall handlebar, dual-compound half-waffle MX grips, 47-tooth rear chainwheel
RG3 linkage tie arm and cam with bearings, front and rear suspension revalve
Twin Air Dual Stage filter
Tires
Maxxis Maxxcross IT front and rear tires