The crankshaft drives an intermediate multifunctional shaft on the side, which in turn drives the coolant pump and the two camshafts via the cam chain, while also acting as a counter balancer. A hydraulic chain tensioner ensures reliable chain tension to achieve highly precise valve timings.
The 6-speed gearbox is specially matched to the power delivery of the 350cc engine and any kind of Enduro duty. It is distinguished by easy and precise shifting.
The engine is equipped with a kick starter as well as an electric starter as standard. Well protected behind the cylinder, the electric starter is connected to the starter freewheel on the ignition rotor via the starter drive in the ignition cover.
The 350 EXC-F engine is equipped with a 196 W AC generator with integrated starter freewheel. The generator provides sufficient energy for the fuel injection, lighting and other electrical loads. Compared to the 350 SX-F, the oil-cooled rotor has a larger diameter with a bigger flywheel mass and requires a larger ignition cover.
Engine Management System (EMS)
The Engine Management System by Keihin with electronic fuel injection and a 42mm throttle body ensures a spontaneous response and maximum engine performance. With an optional map-select switch from the Power Parts program, the EMS can allow the rider to select different engine characteristics. In addition, the optional User-Setting-Tool can provide the facility to readout engine data with a laptop and change the ignition and injection mappings with a few mouse clicks.
The 350cc 4-stroke engine with a state-of-the-art electronic fuel injection system offers a very wide power band and is distinguished by a dynamic but fatigue proof power delivery. At over 45hp of maximum power, the 350 EXC-F is strong enough to beat any 450 in the E2 class.
The single-piece basket of the DDS clutch (damped diaphragm steel) is machined from solid high-tensile steel in one piece together with the primary drive gear. This process guarantees unbeatable reliability and, together with the thin steel linings, contributes to the narrow engine width due to its compact rivet-less design. The diaphragm spring makes it possible to implement an additional rubber damping system inside the clutch hub, which guarantees reliability for the transmission and good traction. Finally, the hydraulic clutch mechanism by Brembo in conjunction with the diaphragm spring provides a very light operation and good controllable modulation of the clutch.
The DOHC cylinder head contains four ultra-lightweight titanium valves (intake 36.3mm, exhaust 29.1mm), activated by two overhead camshafts via very small, DLC coated followers that weigh only 8g. The super lightweight design allows for extremely high engine speed levels of up to 12,000 rpm. The camshaft timings are perfectly tuned for performance in the Enduro specific low rev range.
Compared to the 350 SX-F, the 350 EXC-F has a heavier crankshaft in order to achieve a more even power delivery and better traction through the greater gyrating mass. The crankshaft employs a plain big end bearing. Two force-fitted bearing shells run directly on the crank pin. The necessary oil feed for this bearing is ensured by the engine’s pressure lubrication. This design increases the engine’s long-term durability and lengthens crankshaft service intervals, which is a customer benefit in terms of time, effort and cost.