Virtually everything about
the 2013 motor was new. It
had a different bore-and-stroke
configuration, with a shorter stroke and a larger
bore than anything in
the class. The head
although it still used
between the double
cams and the four
titanium valves. The
ports and intake valves
were larger. The cams
and the crankshaft were
new, and pretty much everything was redesigned with one thing in mind: revs.
The bike was made to be a screamer. The new redline
was right around 14,000 rpm, which sets the record for any
production dirt bike. KTM also redesigned the bottom end.
The cases no longer had a rough, sandcast finish.
One thing that didn’t change, however, was KTM’s commitment to electric start. On a 250F, this was a fairly bold
move. With a kickstarter, the bike would have been the
lightest in the class. With electric start, it was a little chubby. The 2013 model was even more committed to the electric starter. It had no provision for a kickstarter, whereas
previously you could add one if you purchased the various
gears and parts separately. The new bike got a more compact electric starter, and the six-speed gearbox had slight
differences but the same final gear ratios.
After such a major model change in 2013, the 2014 version is exactly what it should be: a chance to breathe.
KTM’s engineers made small mechanical changes that are
virtually invisible. The one exception is the switch to a five-speed gearbox. This saved 250 grams, which is slightly
more significant than it sounds because all of it is rotating
mass. The other changes are all minor: a new water-pump
cover, new chainguide mounts, a redesigned starter flywheel and new suspension valving.
There are several important features that didn’t change.
At the top of that list is the clutch, which keeps its six coil
springs, while most of the other bikes in the KTM line have
a DDS diaphragm spring clutch.
SCREAM TILL THE DOGS HOWL
Riding the KTM 250 is a scream. Literally. The bike
remains very fast, but you have to tell a new rider where
the power is or he might never find it. The KTM reaches its
peak after most other bikes have long since hit their shift
points. As a result, some riders can race a whole moto
without ever getting into the happy zone. Down low, the
SX-F runs clean and has acceptable power, but nothing
special happens unless you commit to holding it open just
a little longer. The motor keeps on going and going. There
isn’t any turbo kick on top; it’s more of a linear progression
all the way to the rev limiter—and you will hit the limiter
if you go up there. On other bikes, the power dies long
before you reach the electronic stop sign, so you have no
reason to go farther. On the KTM, once you realize there’s
power up there, you tend to keep going all the way. The
power never really tapers off, so the only way you’ll know
that you’re near 14,000 rpm is when the ignition tells you
so. When you chop the throttle at high rpm, the KTM
responds with so much popping that you think something’s
wrong. That’s normal. There are mapping changes that will
reduce the noise, but they tend to steal power. The gear
KTM redesigned the
motor from the bottom
up in 2013. The biggest
change for 2014 is the
switch from a six-speed
gearbox to a five-speed.
The exhaust note isn’t that loud, but the KTM generates a
lot of popping when you chop the throttle.