They say its the bike that Stefan Everts built and of course the 10 times World Motocross Champion had a lot to do with the development of the 350 SX-F.
In the three years since its launch, the revolutionary 350 SX‑F has proven that it’s possible to win the MX1 World Championship with reduced displacement as well.
Over this period seven times World Motocross Champion Antonio Cairoli has been the dominant force in this class with the 350 SX‑F and the Italian is banking on this ingenious concept of low weight, playful handling and rev-oriented engine characteristics again in the 2013 season. A unique recipe for success, from which professionals benefit just as much as amateurs.
TECHNICAL DETAILS
ENGINE
Design Single-cylinder, 4-stroke, spark-ignition engine, liquid-cooled
Displacement 349.7 cm³
Bore 88 mm
Stroke 57.5 mm
Starting aid Electric starter
Transmission 5-speed, claw shifted
Engine lubrication Forced oil lubrication with 2 Eaton pumps
Primary ratio 24:73
Secondary gear ratio 14:50
Cooling system Liquid cooling system, continuous circulation of cooling liquid with water pump
Clutch Wet multi-disc clutch CSS / Brembo hydraulics
Ignition system Contactless, controlled, fully electronic ignition system with digital ignition timing adjustment
CHASSIS
Frame Central tubular frame made from chrome molybdenum steel tubes
Shock absorber WP Suspension 5018 BAVP DCC
Suspension travel Front 300 mm
Suspension travel Rear 330 mm
Brake system Disc brakes, floating brake calipers
Brake discs – diameter front 260 mm
Brake discs – diameter rear 220 mm
Chain 5/8 x 1/4″
Steering head angle 63.5°
Wheel base 1,495±10 mm
Ground clearance (unloaded) 376 mm
Seat height (unloaded) 992 mm
Total fuel tank capacity approx. 7.5 l
Unleaded premium fuel (95 RON)
Weight without fuel approx. 104.9 kg
CYLINDER HEAD
The DOHC cylinder head excels with ducts dimensioned for optimum flow, which ensure maximum gas throughput and therefore supreme cylinder charging. Ultra-light titanium valves and DLC-coated cam followers allow engine speeds of over 13,000 rpm to be achieved and ensure spontaneous power development plus high peak power that comes very close to that of a 450.
CRANKSHAFT
The crankshaft on the 350 SX‑F is equipped with a plain bearing in the lower conrod eye: Two press-fit bearing shells run directly on the crankshaft’s crank pin. The engine’s direct pressure lubrication system ensures the necessary oil supply for the bearing. This design is a key factor behind the extremely high engine speed and impressive peak power of the 350cc engine. Another decisive benefit for the customer is that it has been possible to extend the service interval for the crankshaft thanks to the plain bearing.
BALANCER SHAFT
To counterbalance the inertia forces, the 350 SX‑F engine is equipped with a balancer shaft that acts as a multi-function shaft, driving timing chain and water pump simultaneously. For the 2014 model year, the engine is provided with a new water-pump cover complete with new gasket for optimising sealing.
STARTER
The 350 SX‑F engine is equipped as standard with an electric starter – an undisputed benefit when the going gets really tough in the heat of battle, even when a slight weight disadvantage has to be accepted as a consequence. A redesigned starter freewheel is employed in MY 2014 for the benefit of greater durability.
TRANSMISSION
The five-speed transmission has been specially designed to match the 350 SX‑F engine characteristics and excels with precise and simple shifting.
CLUTCH
The very compact CCS (Coil Spring Steel) clutch is equipped with a wear-free steel cage and eight lining discs that are extremely heat-resistant due to the steel base material. The hydraulic clutch actuation system from Brembo, with new clutch armature, guarantees smooth and very precise clutch control.
ENGINE MANAGEMENT SYSTEM (EMS)
In conjunction with the revolutionary injector position developed by KTM, the Keihin engine management system, with electronic fuel injection and 44 mm throttle body, ensures spontaneous responsiveness and maximum engine performance. The wiring harness on the 350 SX‑F has been further simplified for the 2014 model year and the quality of cables and plugs improved. Many connectors are now enclosed in new rubber grommets to protect them from steam-jet pressure. Various engine characteristics can also still be selected via the EMS, with a map-select switch available as a PowerPart. Furthermore, a user-setting tool (also available as an option) allows data to be read from the bike by laptop and the mapping, ignition and fuel injection to be modified in a matter of a few mouse clicks.
FRAME
The modern frame design of the SX models, comprising lightweight, high strength, chrome-molybdenum steel section tubes, combines maximum longitudinal stiffness with optimum torsional stiffness. It guarantees easy handling and precise steering behaviour, as well as excellent ride stability.
SWINGARM
The cast aluminium swingarm has been developed with state-of-the-art calculation and simulation software and constructed, in terms of design and wall thickness, for minimum weight with optimum stiffness and precisely defined flexibility. For the 2014 model year, our engineers have revised the chainguide and its attachment points to the swingarm for the benefit of higher functional reliability, while simultaneously reducing the weight.
SUSPENSION/DAMPING
Both the rear shock absorber and the 48 mm upside-down fork from WP Suspension guarantee ultimate damping and responsiveness. Thanks to optimised tuning, the telescopic fork excels with even higher reserves against bottoming out in MY 2014. Naturally, rebound and compression damping can be adapted individually to the track and rider in no time at all – while high and low-speed compression damping can also be adjusted on the rear shock absorber.
TRIPLE CLAMPS
High quality, CNC-machined triple clamps have long since been standard equipment at KTM. They ensure precise handling and provide a perceptible boost to the flexing characteristics and hence the responsiveness of the telescopic fork.
EXHAUST SYSTEM
The FIM noise limits represent a major challenge for manufacturers of motocross motorcycles, which KTM is confronting with substantial R&D investment. On the 350 SX‑F, hydroformed components and an additional HRS resonator chamber (Header Resonator System) ensure greater torque, while also reducing noise.
BODYWORK
KTM engineers have focussed on designing the bodywork ergonomically and functionally in such a way that the whole motorcycle is in perfect harmony with the rider down to the very last detail. The front fender is a perfect example of how moulded plastic components can gain maximum stability with a well thought out structure and well-conceived attachment.
SEAT
The ergonomically perfectly designed seat is equipped with an improved foam core for the 2014 model year, ensuring both greater comfort and higher stability.
AIR BOX
At the same time, the design of the airbox guarantees optimum protection of the air filter from dirt plus maximum air throughput for the highest performance. Quick replacement of the twin-air filter – without tools and in a matter of seconds – has long since been an unrivalled KTM standard.
FUEL TANK
All models in the SX range are equipped with a new, lightweight, polyethylene, 7.5 litre fuel tank, which has been revised in the area of the filler cap internal thread and can be closed even more easily and reliably with a new filler cap. The fuel pump system used on the four-stroke motocross models is the same as that used on the four-stroke enduro models, thereby allowing optional installation of larger tanks from the PowerParts range or from the enduro models.
HANDLEBAR
All SX models are equipped with the extremely sturdy, tapered Renthal Fatbar 827 handlebar that features an offset specially designed to meet the demands of motocross. In accordance with the proven KTM standard, the handlebar can be fixed in a choice of four positions. A large Renthal crash pad, still in classy black/silver for 2014, provides the rider with effective impact protection.
GRAPHICS
A new, refined graphic design with clear lines underlines the high demands made of a modern, state-of-the-art offroad motorcycle.
WHEELS
The wheels feature CNC-machined hubs, high-end Excel rims and black coated spokes with lightweight aluminium nipples, allowing the highest levels of stability to be achieved while keeping weight to a minimum. The fitted Pirelli Scorpion MX Mid Soft 32 tyres excel with perfect traction and outstanding performance.
BRAKES
High-tech brakes from Brembo® have always been standard equipment on KTM offroad bikes and, together with the lightweight wave brake discs, they are the measure of all things in terms of brake technology. A newly developed handbrake armature has been employed for the 2014 model year, with new remote reservoir, smaller brake piston diameter and new levers with optimised lever kinematics. As a result and thanks to optimised brake pads, performance and application of the front brake have been perceptibly improved again.