The new DOHC (Double Overhead Camshaft) engine of the 350 XC-F features a completely new construction in order to make it even more compact and powerful than before. Fitted with the latest electronic fuel injection system, it has a very wide and usable power spread while still delivering high performance. The new design has made the engine 20 mm shorter than before, while reducing the weight by 2 lbs.
The new cylinder head features an improved combustion chamber geometry, two overhead camshafts with a friction-optimized super-fine surface, new finger followers with a 30 % harder DLC coating and high-flow ports. In conjunction with new valve springs and retainers for the four lightweight titanium valves (intake 36.3 mm, exhaust 29.1 mm) the flow rate has been maximized for an optimal power band with more performance across the entire range, which peaks at 13,400 rpm. The peak performance now is at 58 hp.
Cylinder and piston
In the redesigned and shorter cylinder, with a bore of 88 mm, works a weight-reduced forged bridged box-type piston made by CP. Its new piston crown geometry is adapted to the new high-compression combustion chamber and stands out with its extra rigid structure and low weight. Thanks to the low oscillating masses, the engine is extremely lively. The compression ratio is14:1.
The new 350 XC-F's crankshaft is lighter and features a stiffer design than before. It utilizes a shorter connecting rod, contributing to the compact and light engine with a snappy power delivery. This design is a major prerequisite for the extremely high engine speed levels and the unrivalled maximum power of the 350 cm³ engine. Not only that, it enhances the engine's durability, allowing long crankshaft service intervals.
The new 350 XC-F is fitted with an electric starter as standard, which a clear advantage when it comes to crunch time in the heat of battle. A new starter motor made by Mitsuba (modified for easy disassembly) and a weight reduced starter drive guarantees more efficient and reliable starting.
The highly compact CSS clutch (Coil Spring Steel) features a weight reduced, wear-free steel basket, and now seven instead of eight clutch plates, which are extremely heat resistant due to their steel carrier discs. In addition, a reworked inner hub and a pressure plate guarantees a better oil supply along with even better cooling of the clutch. A smaller master cylinder diameter of the Brembo hydraulic clutch system provides lighter pull and precise modulation.
The new engine is fitted with an all-new and weight reduced, six-speed semi-close ratio gearbox. One of the new and special features on the bike is an advanced "NO-DIRT" gear lever design, which prevents dirt from blocking the joint of the lever and guarantees a safe activation of the transmission.
350 SX-F engine cases and covers
The completely new design of the die-cast engine cases allowed for a much more centralized shaft configuration, raising the crankshaft by 6 mm closer to the bike's center of gravity. Newly designed engine covers made of magnesium feature an advanced surface structure, which reduce the wear caused by the rider's boots.
Engine management system
The completely reworked Keihin Engine Management System, with electronic fuel injection, features an all-new 44 mm throttle body, which provides instantaneous response and maximum performance thanks to a revolutionary injector position. The new ECU (Engine Control Unit) includes a launch control for more efficient starts with the provision of different maps according to the gear sensor selection. In addition, the rider can activate an optional map for a different power delivery via the map select switch on the handlebar.
Counter balance shaft
In order to balance the high-revving engine, the new 350 XC-F engine uses a multifunctional counter balance shaft driving the water pump and timing chain. It features new sprockets fitted to the new timing chain.