The new KTM 250 SX with its all-new engine has one of the best power-to-weight ratios in the world of dirt, forming the ultimate fist against more complex 4-stroke rivals. With the grunt to devour all sorts of tracks and terrains, and a lightweight chassis keen to skim the surface, this lovechild of KTM’s R&D and Motorsport departments is born to lead the next pack of winners into a hazy blue future.
The engine of the 250 SX has been known and
respected for being the most powerful 2-stroke
engine in its class. But we thought the segment
could use an extra push and a solid statement:
2-strokes have a future at KTM. Their
outstanding power-to-weight ratio, low cost and
simplicity see to that. Putting our money where
our mouth is, we gave the 250 SX engine an all
new architecture with a new shaft arrangement
for better mass centralization, a new cylinder
with twin-valve controlled power valve, a new
counter balance shaft for less engine
vibrations, a 5-speed transmission and a
hydraulically operated DDS clutch. This
compact firecracker truly outshines the
competition with its ripping performance and is
the right choice for lovers of low purchasing and
maintenance costs. Oh, and of course don’t
forget that belly tingling 2-stroke symphony
when you’re on the pipe.
The newly developed cylinder of the 250 SX -
with a bore of 66.4mm - has all-new ports and
is fitted with an overhauled power valve system.
This system features a sophisticated
mechanism for the lateral support exhaust
ports, providing smooth and controllable power
on tap. Furthermore, it’s possible to change the
bike’s mood in seconds thanks to two supplied
powervalve springs. Limitless settings for
different tracks and preferences are up for
grabs. Throw everything you have at it; new
water jackets in the cylinder and head will take
care of excess heat and reworked lateral
cylinder head brackets allow a more efficient
fixation of the engine to the frame via
lightweight head stays. Yes, this is a serious
piece of kit.
These all-new die-cast engine cases feature a
8mm higher clutch shaft and a 27mm higher
crankshaft, resulting in better mass
centralization. Which is nice if you care about
sweet rideability. In addition, it allows the
implementation of a counter balance shaft. So
your ride will be as relaxed as it is rapid. Plus,
your new favorite engine will keep looking as
fresh as the day you bought it: redesigned
engine covers feature a smart surface structure
in order to reduce the wear caused by the
The 250 SX employs the KTM-developed DDS clutch (damped diaphragm steel) with a
wear-free steel basket and extremely heat resistant clutch plates. This clever design employs a
diaphragm spring instead of the usual coil springs, which makes for a considerably easier clutch action.
A diaphragm spring also leaves sufficient space for a damping system to be integrated into the clutch hub.
The goal was traction, yes, but durability as well. On top of that, it is fitted with a lighter basket, a
reworked inner hub and a pressure plate providing better oil supply and unsurpassed cooling.
Of course, light operation and telepathic amounts of control are what make this particular clutch,
a hydraulic Brembo clutch.
COUNTER BALANCE SHAFT
Say goodbye to numb feet and hands. The new
engine design allows the implementation of a
lateral counter balance shaft in order to reduce
the vibration level drastically (50% lower level
on handlebar and foot pegs). You know what
that means: more comfort, more smiles.
This reworked 5-speed gearbox has the same
gear ratios as its predecessor, but our
engineers took a close look at the mechanism
in order to provide you with more precise and
easier shifting. Keeping safety in mind, an
advanced ´No Dirt´gear lever design prevents
muck from blocking the joint. Because even dirt
lovers hate mud when it’s in the wrong places.
The engineers meticulously tuned the
expansion chamber for maximum power. An
advanced 3-D production process now
guarantees higher precision manufacturing, so
this little screamer is as tough as it is strong.
Its 72mm stroke stayed, the rest is brand new. Rebalanced, revamped and
set-up with a counter balance shaft to kill vibrations, not your vibe.
As of model year 2017, all KTM 2-stroke
models are fitted with new MIKUNI TMX
carburetors, replacing the Keihin products. This
38mm flat slide carb lives to provide smooth
and controllable power all the way up to the
limiter. And it’s less sensitive to different
altitudes and temperatures, so you can pin it
KTM engineers just love dropping weight year after year. The result: the 2017 SX
models are the slimmest, lightest dirt bikes out there.
The airbox design offers maximum protection of the air filter against soiling,
while ensuring maximum airflow. The large twin-air filter is mounted in a stiff cage,
which at the same time holds the system in place. This design is so simple,
you could still pop a fresh one in with a face full of mud. Without tools. In seconds.
The cast aluminum design offers low weight and a perfect flex behavior.
The single-component casting process eliminates any inconsistencies
and inherent weak points created by welding. It’s better looking too.
Tailored to meet the needs of the world’s fastest backsides, this durable
seat offers great comfort. For MY2017, a new cover pampers its riders
even more with better feel and grip.
The high-tech, lightweight chrome-moly steel frame has a knack for easy
handling, outlandish rideability, precise cornering and excellent stability.
You can also count on high torsional rigidity and low longitudinal stiffness.
This results in better absorption of the energy created from the front and rear
suspension, sucking up jumps and bumps. In short: more comfort and less
rider fatigue. Laterally attached, lightweight engine head stays
(the connection between cylinder head and frame) contribute to precise
cornering and a reduced vibration level. The engineers were able to pull
off all that, while making their frame a big fat kilogram lighter than that of
the lightest competitor on the market. In addition, it is easier to maintain,
easier to work on and supplies more space for the tank and other
components. The bike also features an extra-light subframe made of stable aluminum profiles,
which tiptoes the scales at less than 900g.
A lightweight polyethylene tank with a capacity of 7.0 liters of juice.
The filler cap has an inside thread, which makes for easy and reliable closure.
KTM’s proven cooling system routes the coolant from the cylinder head
through the frame triangle, directly to aluminum radiators made by WP.
Due to flow optimized internal circulation and CFD-calculated air ventilation,
the system is superbly efficient. In addition, well thought-out radiator
guards integrated in the front part of the spoilers provide protection
in case of crashes. Which is also pretty cool.
Sophisticated ´No Dirt´ footpegs prevent smudging up the pegs,
even when digging in deep ruts. Looking for a higher riding position?
Then just mount the footpegs of the MY2017 EXC models, which are 6mm
higher than the SX versions.
KTM engineers sure know how to handle handlebars. This tapered one,
made of high-strength aluminum by NEKEN, is fixed in damped rubber
mountings and has two different positions. From MY2017 onwards, the lower
handlebar clamps are separated, while on the upper side a new bridge-type
clamp guarantees more torsional stiffness. It’s also easier to replace the
bar in case it gets twisted in a nasty crash. An ODI volcanized grip sits on
the right, while on the left side of the bar a comfortable ODI lock-on grip is mounted,
which does not require any wire or glue to be fixed.
Featuring lightweight, CNC machined hubs and high-end Excel rims, they
guarantee maximum stability and minimal unsprung weight.
The wheels are shod with the latest Dunlop Geomax MX 3S tires.
The WP monoshock has been developed with the entire frame and swingarm
architecture in mind, including the linkage system and the WP AER 48
front forks. It features machined and black anodized components and
is a valuable, high-end product compared to roughcast reservoirs.
A new setting and a softer spring perfectly match the reworked front-end
set-up and its sparkling WP color scheme lets everyone know you
have excellent taste in suspension.
You couldn’t brake any harder, better, faster or stronger. These high-tech Brembo
babies are combined with lightweight wave discs made by Galfer. For MY2017,
the rear brake features a 10mm longer brake pedal and you get new,
less aggressive brake pads all round.
The lightweight WP AER 48 front fork, a 48mm USD air-sprung fork developed
by WP in close collaboration with KTM, is a split fork with separate functions
for each leg. That means damping functions are on the right side, whereas
the air spring is in the left. This left leg features a two-chamber system
with a capsuled air cartridge to prevent loss of air pressure. Should the outer
seal start to leak, the internal cartridge pressure will keep the bike in position.
The air spring is easy to adjust to any rider weight via a single air valve.
No special tools are required; the air pump supplied with the bike will do just fine.
The right fork leg integrates a damping cartridge that tailors to all your damping needs.
It can be adjusted to the track conditions and the rider’s preferences with
a twist of a dial (compression from the top, rebound from the bottom, 30 clicks each).
For MY2017, the AER 48 also features redesigned outer tubes with better bending
characteristics, smoother operation and less friction. Plus: they’ve lost some weight
(265g). Right off the dealer floor, these forks are more comfortable and more sensitive than ever.
But you can still hammer the hell out of them
Top quality, CNC machined triple clamps have been something of a
KTM trademark for years. Ensuring a precise handling, they perceptibly
support the flex characteristics, and with it the action of the forks. For
MY2017, the upper triple clamp specifically features a redesign in conjunction
with the new fork tubes. The rubber damped handlebar fixation has also
been reworked and the lower handlebar clamps are now separated, while
on the upper side a new bridge-type clamp guarantees more torsional
stiffness and can easily be replaced in case it gets twisted due to a crash.
In addition, an hour meter is fitted at the upper triple clamp in order to
let the rider know it’s time for a service. Or a cold drink.
KTM R&D, Kiska Design and all our factory riders had their say
in shaping the plastics. Their goal: complete harmony between
rider and bike. And so it turned out. Perfect ergonomics and contact points,
maximum freedom of movement, a low seat height and sweet comfort,
especially in the rear part of the seat. The I-beam structures of the front
and rear fenders are prime examples of such an intelligent design, guaranteeing
maximum stability and a low weight thanks to well thought-out construction
and mounting. Plus: they stay cleaner for longer.
A new, tailor-made kit, fit for a king. Because in this sport, champs deserve to look
the part regardless of the dirt.
|Design||1-cylinder 2-stroke engine|
|Secondary gear ratio||14:50|
|Clutch||Wet, DDS multi-disc clutch, Brembo hydraulics|
|Frame||Chrome-molybdenum steel central-tube frame|
|Front suspension||WP-USD, AER 48, Ø 48 mm|
|Rear suspension||WP shock absorber with linkage|
|Suspension travel Front||310 mm|
|Suspension travel Rear||300 mm|
|Brake system||Disc brakes|
|Brake discs - diameter Front||260 mm|
|Brake discs - diameter Rear||220 mm|
|Chain||5/8 x 1/4"|
|Steering head angle||63.9 °|
|Wheel base||1485 ± 10 mm|
|Ground clearance (unloaded)||375 mm|
|Seat height (unloaded)||960 mm|
|Total fuel tank capacity approx.||7 l
Unleaded premium fuel (95 octane), mixed with 2-stroke engine oil (1:60)
|Weight without fuel approx.||95.4 kg|