Q: FIRST AND FOREMOST, IS THE 2015 KTM
250SXF BETTER THAN THE 2014 KTM 250SXF?
A: Yes. KTM focused on refining the 250SXF
for 2015, with an eye on decreasing weight (nearly a
1-pound savings) and improving the suspension. These
updates are enough to push the 2015 model past the
Q: WHAT’S THE BIG NEWS ABOUT THE 2015
A: KTM unveiled the first 250SXF four-stroke in
the middle of the 2005 model season. Every year since
then, KTM has dealt with a suspension package that has
never impressed the MXA wrecking crew. The WP forks
were plagued by mid-stroke harshness so severe that
we would wake up in cold sweats from nightmares of
racing the 250SXF. KTM dropped their no-link design in
2011 and joined the linkage bandwagon, but link or no
link, the shock was never the problem; it was always the
setup of the WP forks.
There seems to be a disconnect between the powers
that be at WP and the American motocross racer. The
Austrians were pleased with the suspension performance
of the WP units, which were tuned for European circuits.
American racers were not pleased with the suspension
performance of the WP units—and hadn’t been for a
KTM USA was hoisted on their own petard—if they
were blindly loyal to WP, they would suffer in the show-
rooms. If they went against WP’s preferred setup, which
would be the same old, same old, they would be biting
the hand that feeds them. What to do? Who to please?
Luckily for American racers, KTM USA chose to chart
their own path with an all-new 4CS fork. The new fork
is tested, developed and spec’ed for American riders and
tracks. As for European riders, they get the old WP
bladder forks again.
Q: HOW DOES THE WP 4CS FORK WORK?
A: The 4CS (Four Chamber System) fork is comprised
of four uniquely distinct chambers. The left fork leg
contains the compression damping, while the right leg
controls the rebound damping with adjustment dials on
top of the fork caps. This design allows for simple, virtually on-the-fly adjustments. Additional benefits of the 4CS
fork include improved damping and lighter overall weight.
How does the four chamber work? Read on.
Outer tube chamber. The outer tube chamber con-
tains the main spring and air chamber. This is the same
design in both fork legs, except that the left leg houses
the compression damping, while the right leg is responsi-
ble for the rebound damping. The advantage of keeping
the spring in a separate chamber is that changing spring
rates is considerably easier than with a traditional system.
A bleed screw on each fork cap can release built-up air
pressure from the outer chamber. The main spring guide
rotates inside the top cap and allows the fork spring to
rotate for decreased friction and binding within the fork.
Inner chamber. The inner chamber contains the
cartridge, as well as a sealed chamber full of oil. With the
old WP closed-cartridge fork, it was possible to force oil
out of the air-bleed screw hole in order to lessen
2015 KTM 250SXF
Big news: KTM
updated the 250SXF
with myriad changes
the WP 4CS forks are
the biggest news.