for 2018 went into the new Suzuki RM-Z450, Yamaha
YZ450F and Kawasaki KX250F. Still, KTM has not sat idle
over the last year. Here are the changes made between
2017 and 2018.
(1) WP AER forks. The 48mm WP AER air fork has
been updated with a new air seal, air piston and rebound
spring on the air leg, along with a new piston on the
damping side for improved performance.
2) C4 transmission bearing. The transmission is
outfitted with a C4 bearing that offers more overlap in
the cases for improved reliability at high operating temperatures.
( 3) MIM shift star. The 450SXF gets a Metal Injection
Molded (MIM) shift star to provide better wear characteristics via a stronger surface.
( 4) Nitrided drive plates. The KTM 250SXF, 350SXF
and 450SXF get new metal clutch plates made from nitrided steel for reduced wear on the steel clutch basket.
( 5) Battery. All of KTM’s 2018 four-strokes get a
higher-capacity (but not heavier) battery for improved
cold-weather starting. The Sky Rich HJTZ5S-FP battery
replaces the lighter-duty Samsung C22S battery. It also
gets a new battery tray to hold the upsized battery.
( 6) Shock. The valving on the WP rear shock has been
modified to better match the re-valved front fork.
( 7) Radiator guards. KTM has redesigned the radiator
guards to improve airflow in muddy conditions.
( 8) Frame color. The previously black chromoly frame
is powdercoated in Factory Team Orange and gets orange
frame guards to match.
The 2018 KTM 350SXF is only modestly changed
over last year, but mods were spec’ed to make the
350 a better bike. At 221 pounds, the 350SXF is
lighter than the 450SXF, but not by much.
( 9) Graphics. The redesigned graphics feature more
orange and less white.
Q: WHAT DID KTM CHANGE ON THE WP AER
AIR FORKS FOR 2018?
A: KTM uses its Factory Edition models as stalking
horses for technical changes. As a rule, the late-season
Factory Editions are precursors of next year’s KTMs. Thus,
Factory Editions were the first bikes to get the AER air
forks. But, it doesn’t end there. What KTM’s engineers
learned about the shortcomings of the Factory Edition
forks, they fixed for the later-arriving production model. In
short, the 2017-1/2 Factory Edition fork settings were test
forks for the 2018 WP forks. This is a great research-and-de-velopment project, because it takes testing away from the
cloistered world of the factory’s R&D department and gives
it to the consumers who buy, ride and race the Factory
Editions. KTM got several months of real-world testing
done and was able to incorporate customer input before
finalizing the 2018 fork settings. Thus, the 2018 KTM
350SXF’s forks aren’t first generation; they are well-tested
Here is a quick list of what WP changed for 2018:
(1) Mid-valve. Last year’s mid-valve was constructed
from a special ceramic composite material. Not only was it
lighter than the previous steel mid-valve, but it had wear
qualities that were supposed to make it a big plus. That
turned out to be pie-in-the-sky. Instead, the composite
mid-valve had some reliability issues, and for 2018, KTM
replaced it with a new sintered-steel mid-valve.
( 2) Base valve. The base valve has been redesigned to
produce a more positive feel. While the dimensions remain
the same as last year, the design is different.
( 3) Air seal. From the earliest prototype versions of
the WP air fork, the air seal has been under constant
scrutiny. The original seal could not handle cold tempera-