KTM’s wheel spacers can seize inside
the wheel bearings if not lubed.
The KTM clutch has butterfly-shaped
rubber bumpers. They can wear out.
If your rear brake pedal spring looks like
this, it’s on backwards. Flip it over.
KTM has awesome wheel spacers.
Unlike on a lot of motocross bikes,
KTM’s wheel spacers run on the
bearings, which means that the front
and rear wheels can accept different axle sizes just by changing the
wheel spacers. This makes older KTM
wheels compatible as spare wheels
on new-model KTMs (and vice versa).
There is a caveat to KTM wheel spacers. The wheel spacers need to be
greased for two reasons: (1) Because
the wheel spacers live in the dirtiest
place on a motocross bike, they can
seize to the bearing and wheel. In
this case, when you try to get the
wheel spacers off the wheel, the
bearing and seal will come out also.
Not good. ( 2) Since the wheel spacers run against the seal, they need
a dab of grease to keep the spacers
from wearing away the rubber on
the seals. Both of these problems are
solved by regular maintenance and a
DUNLOP MX3S WARNING
The MXA wrecking crew loves the
MX3S (previously called MX32) tires
that come stock on the KTM 450SXF,
especially the front in comparison
to the MX52 that came as OEM
equipment on earlier models. But, be
forewarned; if you push the MX3S
front out of its intermediate terrain,
you will begin to lose side knobs off
the front tire. Oh, don’t get us wrong;
the MX3S works well on hard terrain,
but just not for long. If the side knobs
tear off and you don’t notice, you will
lose the front end without any warn-
ing. These are race-quality premium
tires—and when used on the wrong
terrain they will wear prematurely.
Although KTM runs Dunlop tires,
the bikes come with ultra-thin Pirelli
tubes. These tubes have a high failure
rate on rough tracks. We replace them
with STI Heavy Duty tubes.
Additionally, almost every tire manufacturer specs a 120/90-19 rear tire
on its 450cc four-stroke, including
KTM, but every MXA test rider prefers
to run a 110 rear tire. Why? A 120 is
harder to roll over in turns and makes
the bike stand up more in ruts.
LONGER SHOCK LINKAGES
KTM’s Belleville washer-operated
diaphragm clutch is a thing of beauty.
It lasts twice as long as any Japanese
clutch, self-adjusts, and rarely needs
new plates; however, we do two
things to help our 450SXF clutches.
(1) We change the cush-hub rubber
bumpers every four months. These
rubber bumpers take the shock loads
out of the clutch when the rear wheel
is jolted in whoops, in jump landings
or by errant shifts. ( 2) Given that the
KTM 450SXF clutch has a one-piece
CNC-machined steel basket, which no
aftermarket company wants to try to
duplicate, we do the next best thing
and run a Hinson inner hub and pressure plate (along with a stiffer Hinson
Belleville washer). The Hinson parts
tighten up the actuation and provide
more bite under drive.
Turn your rear brake pedal spring
around so that the tang on the spring
closest to your foot faces inward. If
it faces outward, you can hit it with
your boot and unhook the spring. If
you’ve ever had a KTM brake-pedal
spring disappear, it is because the
spring was on upside down. We also
crimp the tangs once they are turned
around to make them fit tight to the
pedal. The MXA wrecking crew has
broken a lot of KTM rear brake-pedal
springs. To avoid this problem, we
run brake-pedal springs with rubber
sleeves over the coils. It is easy to do.
Take a section of clear gas line. Cut
it to the length of the brake spring’s
coils. Heat it with a torch and slide it
over the spring. We don’t know if this
is the ultimate solution, but we haven’t broken any brake-pedal springs
since encasing them in rubber.
HOW TO REMOVE THE STOCK
Believe it or not, you can’t remove
the exhaust pipe until you remove
the rear shock. This is a major hassle
because the KTM shock is not the
easiest part to remove from the bike.
There is a trick to doing this. (1) We
swing the shock linkage rearward by
removing the bolts on the front of the
link arm. ( 2) Then, we drop the shock
down through the opening in the
swingarm as far as it will go before
the piggyback reservoir hits. ( 3) Once
the shock is moved down, we rotate
it clockwise and pull it out through
the rubber mud flap. It helps to have
a friend raise and lower the swingarm