Air forks may be dead at the Japanese brands, but they are
alive and kicking at KTM. These are very effective forks.
Every 2018 KTM comes with an hour meter, but they don’t
get to stay at 2. 2 hours for very long.
We switched the stock 50-tooth rear sprocket for a taller
49-toother. It broadened out the midrange powerband.
on a four-stroke, you can crank into on a two-stroke. It can
make instantaneous cuts, break off berms midway through a
turn and slice and dice past the guy in front of you in places
he never imagined possible.
You haven’t lived until you’ve mastered two-stroke handling, and the KTM 250SX is the best all-around handling
smoker on the track. It handles instinctively. You just have
to think about choosing a line and it takes it. There is one
caveat—you have to fiddle with the fork-leg height to dial in
the balance to perfection. One millimeter in either direction
can make a noticeable difference, and it’s not unusual for an
MXA test rider to come in from a race and slide his forks
down to change the cornering habits for the next moto.
Q: HOW GOOD ARE THE WP AER AIR FORKS?
A: The problem with air forks, especially the Kayaba
PSF and Showa TAC forks, was that consumers didn’t understand the relationships between the various air chambers.
Not only that, but the riders didn’t want to mess with their
forks every time the sun came out. Air forks died because
they were too complex.
KTM’s WP AER air forks are still around because they are
amazingly simple to live with. Here is how to make the most
of AER forks. First, when you get the bike from your friendly
local dealer, put two hours of riding time on it before you
make any judgments. Forks, like pistons, need to break in.
Second, set the single Schrader valve on top of the left fork
cap to the recommended air pressure. The pressure is listed
on a sticker on the fork stanchion. Most MXA test riders run
lower air pressures than what is suggested by WP. Third, put
an O-ring or zip-tie around the right fork leg and go out and
ride with the clickers set on 12 and 12. Fourth, after doing a
couple laps, come back into the pits and look at the zip-tie. If
it is not within 1-1/2 inches of bottoming, lower the air pressure by 2 psi and ride again. Keep lowering the air pressure
until you get within 1-1/2 inches of bottoming. Fifth, write
down this air pressure number and turn your attention to the
compression clickers. Don’t be afraid to make big swings in
the number of clicks. Try everything from 6 out to 25 clicks
out. Somewhere along the way you will find your sweet spot.
The key is to find your best air pressure. Think of this pressure as being the same as whatever coil springs you used
to race with back in the day. Did you ever change your coil
springs between motos? Didn’t think so. Thus, find the right
air pressure for your speed, weight and track, and stick with
it. From that point on, all adjustments should be done with
We think that once you take the time to find your personal
setting, you will love these forks—and not just because they
are 3 pounds lighter than the forks on a 2018 Honda, Yamaha
Q: WHAT DID WE HATE?
A: The hate list:
(1) Handlebar clamps. In a crash, the bar mounts twist,
which deforms the rubber inserts and eventually bends the
top one-piece bar mounts.
( 2) Fork compression clicker. If the clicker arms were
longer, the compression could be adjusted with one finger.
( 3) Seat height. Modern motocross bikes are too tall.
Every bike made should be 1 to 2 inches lower.
( 4) Shock collar. The KTM nylon shock collar is such a
bad idea that Suzuki copied it.
( 5) Air-fork Schrader valve. The position of the WP
AER fork’s air valve is hard to reach, and the valve-stem cap
almost always falls in the recessed cap.
( 6) Front master cylinder hose. If you hook metal
tie-down hooks onto your handlebars and hit a bump in the