When Suzuki last updated the RM-Z250 engine, the goal
was to reduce drag and increase overall performance output of the 249cc, liquid-cooled, DOHC, four-valve, fuel-injected engine. Engineers did this by giving the piston a
different finish and a redesigned L-shaped ring. The crank
was lightened up. The cams received new lift and timing,
while the valves were changed to a flat-face design. The
throttle body and intake angle would also be changed, with
Suzuki eliminating the hot-start system altogether. At the
time, these changes gave the RM-Z250 improved response
down low and made the bike a little easier to start.
Suzuki returns with the S-HAC system, which is their
version of launch control. As with the other manufacturers’ systems, S-HAC A-Mode alters ignition timing at
the moment of launch and during the ride over the gate
to reduce wheel slip, providing a smoother take-off. The
S-HAC also has a B-Mode that delivers more aggressive
power. Just as in previous years, the 2018 RM-Z250 has
two additional quick-change EFI couplers—one with richer
fuel settings and one with leaner.
Compared to the prior-generation RM-Z250, the main
frame weighs 2. 5 percent less, and the chassis rigidity
has been changed to improve cornering. Kayaba suspension components are standard issue on the 2018 model.
The KYB Pneumatic Spring Fork (PSF) uses air chambers
in place of steel springs. This is KYB’s answer to the
Showa Triple Airs that were found on the 450 models
prior to 2018. The air fork is lighter than a spring version
and has seven different clickers for adjustment.
The Kayaba shock is a nitrogen-charged piggy-back-style, featuring a top-mounted adjuster system for
fine-tuning of the high- and low-speed rebound and high-and low-speed compression damping. Preload is still
adjusted by a threaded collar on the main shock body.
Just as with the fork, the shock seems to have clickers
everywhere—three on the top and one on the bottom.
The brakes, plastics, aluminum gas tank, tires, handlebars, levers and general overall package are identical to
last year’s model.
There was one thing that surprised us with the 2018
RM-Z250—we had forgotten how stiff the bike is when
it’s brand new. Our faster riders pushing 200 pounds
had no issues with either end bottoming hard, but for the
average 150-pound 250F rider, it needed some adjusting.
Everything else is the same old song and dance. The
2018 RM-Z250’s strong point is cornering and overall
handling. Engine performance is okay, but in the 250
class where horsepower is king, the Suzuki is definitely
Top inset: The 2018 engine is identical to the 2017, and for
less aggressive riders, this is not a bad thing. Intermediate
to pro-level riders are left wanting. Bottom inset: The
RM-Z250 rear shock has more adjustment clickers than
any mere mortal can comprehend using.
MX TEST: 2018 SUZUKI RM-Z250