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Engine
Lots of changes in
these engines: For 2003, the 400cc models are, in line with the new rules,
enlarged to a displacement of 450cc.
The motocross
versions as well as the 250 EXC engine were modified, especially with
regard to achieving higher peak r.p.m. levels.
The EXC models are
equipped with both electric starter and kick-starter. On all models, the
weight of the outer clutch hub has been reduced by 100 grams.
The transition from
a sand-cast to a die cast case has reduced the weight of all three
engines.
450 EXC Racing
4-Stroke
This engine is based
on the 2002 400cc racing engine. The bore of the world champion 400cc
engine from 2001 was maintained while its stroke was increased from 46 to
72 mm. KTM’s goal for this model was to develop a 2003 450cc 4stroke
with the performance of the 2002 520cc bike.
A modified 4-speed
transmission that has already been used in the 520 SX saves weight and
accommodates the increased power of the 450cc engine.
A new
short-stroke-type bore/stroke ratio of 95: 63,4 was designed. Due to its
reduced inertia weight and the lighter balancer shaft, the extremely
lightweight new 450 SX crankshaft has a lower weight, which significantly
improves the engine’s response and power development. A new Lightweight
connecting rod contributes to these improvements.
A new cylinder head,
whose port cross-section has been increased from 39 to 41 mm, and a new
Keihin FCR-MX 41 carburetor with hot-start knob, plus lighter valve
springs increase peak power and reduce the oscillating masses.
In conjunction with
re-designed camshaft profiles, extremely lightweight titanium valves
increase performance over the whole power band. At the outlet end, a
chromium-plated single-pipe exhaust features a new, lighter motocross main
silencer.
Chassis/Suspension
Chassis innovations
on all models have their focus on improved handling with many general
improvements on all models.
In 2003, all SX/EXC/MXC
models will come with the White Power USD 48 mm forks.
The WP PDS
suspension strut was modified considerably. A bigger compensating tank and
a larger oil volume prevent premature fading. Changed flow cross-sections
for the oil stream and new tuning setups provide better progression.
All SX, EXC and MXC
models come with a new front-wheel axle enlarged from 20 to 26 mm. The
front-wheel hub was also given a new design and its diameter increased
from 36 to 52 mm.
The rear-wheel hub
was reinforced from 48 to 64 mm.
All 4-stroke EXC
models with a 12mm Magura handlebar of identical design to the Renthal
used in the SX and 2-stroke EXC models. All 2003 EXC/MXC models will be
fitted with the broader footrests of the SX machines.
To prevent damage
all models are fitted with flexible steel clutch hoses.
All 125, 200 and 525
SX models are equipped with a rear-brake caliper piston diameter reduced
from 28 to 26 mm. The model 450 SX comes with a completely new caliper,
whose weight was reduced by about 250 g, and with a piston diameter of 26
mm.
Plastic
Components
The new series look
for 2003 is taken from KTM’s title winning 2002 GP Team. A new, seamless
seat cover creates an ideal surface.
A full-width
radiator guard (on the 4-stroke racing KTM’s) provides for optimum air
guidance and efficient cooling. A new, seamless seat cover creates an
ideal surface.
All EXC models boast
a new tank with the “SX“ look. Also the shape of the tank shrouds is
made uniform for both models. The advantage for the Enduro models is a
more ergonomic tank/seat contour and thus a better sitting position. All
tanks come in a basic orange with the EXC models slightly transparent. The
EXC tanks are equipped with new fuel cocks. A recess in the tank allows
riders to operate the choke and warm start knob with easily.
The EXC models come
with a highly functional digital odometer with a control unit which, as an
option, can be arranged away from the odometer at the end of the
handlebar.
Graphics
Design/Colors
In 2003 the rear
mudguard and the side paneling are orange, the shrouds, lamp mask, and the
front mudguard is also orange. The seat is all black. The KTM shroud logo
was given a new design so as to cover the entire shroud. Frame and the
hubs are power-coated in a gold hue, matching the color of the fork.
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