KTM 250 EXC TPI 2018:Speed injected
When the smoke clears, you’ll be the last rider standing. The KTM 250 EXC TPI is one of the best pound-for-pound fighters in the world of Enduro, pummeling its more complex 4-stroke rivals. All muscle, no fat: this groundbreaking, fuel-injected 2-stroke machine is as lean as it is powerful.
The KTM 250cc engine is known to be the most powerful
and most competitive 2-stroke engine of the class.
And things get even better. For MY18 the KTM 250 EXC
(EU model only) is fitted with newly developed TPI
(transfer port injection) fuel injection system, a unique
feature when it comes to sporty 2-stroke race bikes. The
patented EFI system with two injectors mounted on
the transfer ports of the cylinder makes the engine much
smoother to ride and reduces the fuel consumption drastically,
a global game changer in terms of technology. On top
of that, the KTM 250cc powerhouse features a modern shaft
arrangement that’s beneficial in terms of mass centralization,
a well-protected E-starter, a balancer shaft for low engine
vibrations, a 6-speed Enduro transmission and a hydraulically
operated DDS clutch. This is a song of belly tingling 2-stroke
symphony when keeping it pinned on the pipe, while still
being able to deliver ultra-smooth and reliable
drive when you need it.
The KTM 250 EXC TPI cylinder has a bore of 66.4mm
and is fitted with the sophisticated power valve
providing smooth and controllable power characteristics.
For the EFI application the new cylinder features two lateral domes,
which hold the fuel injectors supplying fuel into the rear transfer ports.
Thus the loss of unburnt fuel is reduced for less emissions,
a more efficient combustion and reduced fuel consumption.
A little tube in the back of the cylinder is connected
with an intake pressure sensor, which supplies pressure data
to the control unit. Furthermore, it’s possible to change the bike’s
mood in seconds thanks to two supplied power
valve springs. Limitless settings for different tracks and preferences
are up for grabs.
Pre-mixing 2-stroke fuel is a thing of the past for
KTM EXC TPI owners. An electronic oil pump feeds
oil from the oil tank via the throttle body into the engine
intake, and ensures a perfect fuel-oil mix in all conditions
and engine speeds. The system, which reduces up to
50% of the smoke from the exhaust system over
previous models, is managed by the control unit based on
the engine’s revs and load measured by the
TPS (throttle position sensor). The oil capacity
of approximately 0.7 liters is enough for 5-6 refills
of fuel, giving you more time to ride, less time measuring things out.
For optimal mass centralization the lightweight
die-cast crankcases hold the clutch shaft and
the crankshaft in a high position close to the center
of gravity. Which is nice if you care about sweet handling.
In addition, it allows the implementation of a balancer 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: the engine covers
feature a smart surface structure that reduce the
wear caused by the rider’s boots.
This 6-speed Enduro transmission features an Enduro-specific
wide-ratio specification and provides precise and easy shifting.
Keeping safety in mind, an advanced ´No Dirt´ gear shift
lever design prevents muck from blocking the joint.
Because even dirt lovers hate mud when it’s in the wrong places.
Say goodbye to numb feet and hands. This engine
design allows the implementation of a lateral
balancer shaft in order to keep the vibrations to
a minimum. You know what that means: more comfort,
less fatigue, bigger smiles.
The KTM 250 EXC TPI employs the KTM-developed DDS
clutch (damped diaphragm steel) with a wear-free steel basket,
extremely heat resistant clutch plates and new, nitrated steel liners.
This clever design employs a diaphragm spring instead of the usual
coil springs, making for considerably easier clutch action.
A diaphragm spring also leaves sufficient space for a damping
system to be integrated into the clutch hub. The goal is traction,
but durability is as well. Light operation and telepathic amounts
of control are standard with this hydraulic Brembo actuated clutch.
This nickel-plated pipe is produced by WP Performance
Systems. It is taken over from the carburetor model
and designed for an optimal power band and maximal
performance of the engine. A modern 3D production
process guarantees top precision and reliability of the
pipe, so this screamer is as tough as it is strong.
The TPI engine is fitted with a newly developed throttle
body made by Dell`Orto. It features a diameter of 39mm.
The airflow is regulated by a butterfly connected with a twin-cable
throttle cam, which is operated by a new handlebar throttle assembly.
A throttle position sensor provides airflow data to the control unit,
while a bypass screw allows the regulation of the idle speed.
The cold start device also opens a bypass supplying more air.
Via an oil intake tube oil supplied from the oil pump is mixed with
the incoming air to lubricate crankshaft bearings and cylinder/piston etc.
The TPI models are fitted with a stronger generator delivering
196 W (the same as their EXC 4-stroke brothers) to meet
the needs of the engine management system in terms of energy
supply. The new regulator is taken over from the EXC-F models.
Engine management system
The engine management system (EMS) of the TPI
models features a new control unit located below the seat.
The control unit determines the ignition timing and the amount
of fuel to inject is based on several sensor readings such as intake and
ambient air pressure, throttle position, oil and water temperature.
Thanks to altitude and temperature compensation the rider
does not need to worry about fiddling around with the jetting anymore.
KTM engineers just love dropping weight year after year.The result:
the 2018 KTM EXC models are the slimmest, lightest dirt bikes out there.
Air filter box
The air filter box design offers maximum protection of
the air filter against soiling, while ensuring maximum airflow.
The EXC TPI models get a new intake snorkel designed for the
new throttle body while also hosting an air temperature sensor.
The large Twin Air air filter is mounted on 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.
KTM’s proven cooling system routes the coolant from
the cylinder head through the frame triangle, directly
to aluminum radiators made by WP. The additional KTM
PowerParts radiator fan that riders can add to this fuel injected
2-stroke is now regulated by the control unit, no thermo switch is required anymore.
Thanks to flow optimized internal circulation and CFD-calculated ventilation,
the system is superbly efficient. In addition, new radiator protections improve
heat dissipation. Especially in the mud. They are also integrated
into the front part of the shrouds to protect the radiators in a crash.
Sophisticated ´No Dirt´ footpegs prevent smudging up
the pegs, even when digging in deep ruts. The pegs on the Enduro
models are 6mm higher than the ones used on SX models,
which benefits ground clearance. But you can swap them at will.
This is a lightweight polyethylene tank with a capacity of
9.25 liters. The EXC TPI models incorporate a new integrated fuel
pump system and an additional fuel level sensor so you’ll
always know when you’re running low on gas.
KTM engineers sure know how to handle handlebars.
This tapered one, made of high-strength aluminum by
NEKEN, features a throttle assembly, which now has
a twin-cable for EXC TPI models just like their 4-stroke brothers,
with a new double-cable aluminum body and straightforward free-play
adjustment. A 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. All models can retrofit optional
ignition curve switches at the handlebar for the selection of an
alternative map, so you can be fully prepared for any condition.
The EXC wheels feature lightweight, CNC machined
hubs and high-end Giant rims guaranteeing maximum
stability at minimum weight. The wheels are fitted with
MAXXIS tires – perfect for surefooted performance off-road
and stability on-road.
KTM R&D, KISKA Design and the factory racers had their say
in shaping the plastics with one goal: complete harmony
between rider and bike. Perfect ergonomics and contact
points provide maximum comfort in movement on the EXC TPI.
The I-beam structures of the front and rear fenders guarantee
maximum stability and a low weight thanks to well thought-out construction
and mounting. They also stay cleaner for longer. Clever brake hose
routing on the front number plate prevents wear and tear.
New graphics convey the READY TO RACE character
of the 2018 KTM EXC model line.
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 a reduced vibration level.
Two threaded inserts in the lower cradle tubes allow for safe
fixation of an optional skid plate. The engineers could 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. On the EXC TPI models the upper frame tube
features a slot where the oil filler cap is mounted, which feeds the oil
tank via a hose inside the frame tube. The bike also features an extra-light
subframe made of stable aluminum profiles, which tiptoes the scales at less than 900g.
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.
The PDS is kind of a KTM trademark where the shock absorber is
directly connected to the upper side of the swingarm. This setup
boasts the best possible mounting geometry and provides amazingly
progressive damping. The shock absorber is mounted close to the centerline,
which means nearly symmetrical loads for the swingarm and frame and
more space for the exhaust system. A second piston works together
with a closed cup (instead of a needle) towards the end of the stroke
and is supported by a progressive shock spring for exceptional bottoming
resistance. Various machined and anodized components and a distinctive WP
color trim make this a valuable, high-end product compared to the less
refined shock absorbers of the competition.
The WP Xplor 48 upside-down fork is a split fork developed by
WP in close collaboration with KTM. It is fitted with a spring on
both sides but features separated functions for each fork leg: compression
damping is fitted on the left side, while rebound is on the right. The forks
can easily be adjusted for compression and rebound with the twist of a
dial on the top of the forks. New outer fork tubes and a reworked
setting make for more sensitivity, improved damping behavior and a
reduced weight. In addition, a sealed hydro-stop guarantees
excellent resistance to bottoming-out. Due to high-quality
materials and a state-of-the-art production process, the new
WP Xplor 48 fork – with approx. 300mm of travel – has outstanding
response and damping characteristics. A comfortable preload adjuster can
be retrofitted and allows for a simple spring preload setting
in three steps without tools (standard, +3mm, +6mm).
Fitted with forged triple clamps with an offset of 22mm,
ensuring a solid grip of the fork and precise handling. The
handlebar is adjustable forwards and backwards over 4
positions, so the EXC TPI will fit you like your favorite gloves.
You couldn’t brake any harder, better, faster or stronger.
These high-tech Brembo babies are combined with lightweight
Wave brake discs and are the ultimate solution in braking
technology. First you outrun them, then you outbrake them.
|Design||1-cylinder, 2-stroke engine|
|Starting aid||Kick and electric starter|
|Clutch||wet multi-disc clutch, Brembo hydraulics|
|Frame Design||Chrome-molybdenum steel central-tube frame|
|WP Xplor PDS shock absorber|
|Suspension travel (front)||300 mm|
|Suspension travel (rear)||310 mm|
|Front brake||Disc brakes|
Rear brake disc diameter
Front brake disc diameter
|Wheel base||1482 ± 10 mm|
Steering head angle
|Seat height||960 mm|
Tank capacity (approx.)
|Weight READY TO RACE (without fuel)||103 kg|