KTM 250 SX‑F 2013: BETTER PERFORMANCE
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ENGINE
A completely new design, without kickstarter, in a new engine case, manufactured in a die-casting process. What's all this for? To save weight. A new, elastic and simultaneously high-strength, aluminium alloy provides additional damage protection for the engine on the KTM 250 SX‑F 2013.
CYLINDER + PISTON
The stroke-bore ratio of the KTM 250 SX‑F 2013 has been defined as somewhat shorter-stroked for the benefit of higher peak power, with the new cylinder now boasting a bore of 78 mm (previously 76 mm), hence providing space for larger valves. Despite the larger diameter, the box-type, forged piston is lighter in weight. This reduces the moving masses and enables higher engine speeds as well as more power.
BALANCER SHAFT
The goal was less vibration in spite of increased revs. That's why the new KTM 250 SX-F engine also has a laterally positioned balancer shaft, which also serves as the drive wheel for the timing chain and the water pump.
CYLINDER HEAD
Those wanting to know what drives a winner to victory will find the answer here. The heart of the newly developed DOHC engine is the redesigned cylinder head with twin overhead camshafts and DLC-coated cam followers that actuate the titanium valves. Larger, flow-optimised ducts in conjunction with the more generously dimensioned intake valves (intake 32.5 mm, exhaust 26.5 mm) guarantee 10% more gas flow and therefore significantly improved performance. The new camshafts on the 250 SX‑F 2013 have also been designed (new valve timing, larger stroke) for achieving a huge increase in performance compared with the predecessor model, above all at the top end of the rev range (max. 14,000 1/min, previously 13,400 1/min).
NEW INJECTION SYSTEM
The Keihin engine management system with electronic fuel injection has been improved significantly on the KTM 250 SX‑F 2013. Even more performance has been achieved with greater air flow through a new throttle body - featuring a 44 mm instead of a 42 mm port - in conjunction with the new injector nozzle. The throttle position sensor (TPS) is harder wearing and protected from stone impact with a plastic protector. The connectors are now enclosed in rubber grommets to protect them from steam-jet pressure. The wiring harness has been simplified and the quality of cables and connectors optimised. Additional engine characteristics can also still be activated with an optional map-select switch on the handlebars.
