01. Engine & Exhaust
The race-proven and fully adjustable WP XPLOR shock absorber has received a re-tune, with factory settings making it firmer, and new conical bushing between the pistons to improve bottoming reserves. This has resulted in reduced fade and improved wear, taking the PDS rear suspension design even further in its quest for podiums.
The KTM 250 EXC-F SIX DAYS engine is fitted with a compact DOHC cylinder head for optimal mass centralization. The head configuration promises efficient power delivery and unrivaled performance. A single overhead camshaft also ensures optimal gas flow, with low-friction rocker arms and timing chain guides guarantee consistent performance throughout the rpm range. The DLC coated finger followers, as well as the lightweight titanium valves they actuate - intake 32.5mm, exhaust 26.5mm -,allow for higher engine speeds.
The KTM 250 EXC-F SIX DAYS crankshaft is located in an ideal position close to the center of gravity, contributing to easier handling. It utilizes a short connecting rod, which makes for an overall compact and lightweight engine with a snappy power delivery. A plain big end bearing with two force-fitted bearing shells runs directly on the crank pin. The engine's pressurized lubrication system provides the necessary oil feed for this bearing.
Crankcases and engine covers
A lightweight engine case design allows for a very centralized shaft configuration while contributing to an efficient centralization of mass. Additionally, the engine covers feature a smart surface structure that reduces the wear caused by the rider's boots, keeping them looking as fresh as the day it rolled off the production line, while a reinforced clutch cover and engine guard mean the engine case is more robust.
The KTM 250 EXC-F SIX DAYS features a robust 6-speed transmission made by PANKL Racing Systems. The gears are made of a strong, forged raw material, ensuring the highest durability and reliability level. All four-stroke engines are fitted with a gear sensor, giving the option of different engine characteristics for each gear.
Engine management system
The state-of-the-art Keihin Engine Management System, with electronic fuel injection, features a 42 mm throttle body with separate systems for cold starting and idle adjustment. The throttle cable mount also allows for easy access and a smooth routing of cables for crisp throttle response, every time.
Cylinder and piston
Inside the short cylinder, with a bore of 78 mm, thumps a box-type piston made by CP. Its crown geometry is adapted perfectly to the high-compression combustion chamber, where its rigid structure and low weight shine. The compression ratio of 13.8:1 delivers an exceptional engine performance and reduces the risk of engine knocking.
The KTM 250 EXC-F SIX DAY makes use of a side-mounted balancer shaft, which does three jobs. It maintains low oscillating masses and reduces engine vibration, drives the water pump, and drives the timing chain.
The KTM 250 EXC-F SIX DAY is fitted with the extremely durable, KTM-developed damped diaphragm steel - or DDS - clutch with a wear-free steel basket and heat-resistant clutch plates. It uses a diaphragm spring instead of the usual coil springs, which results in considerably easier clutch action. Additionally, the Brembo hydraulic system provides easy and precise clutch modulation throughout the entire operating temperature range.
The standard electric starter on the KTM 250 EXC-F SIX DAYS uses a proven starter drive and a strong starter motor made by Mitsuba. As demonstrated time and time again, it provides quick and reliable starting, saving you precious time and energy when you need it most.
Keeping the engine cool when the going gets tough comes courtesy of a pair of radiators, mounted close to the center of gravity. These make use of CFD technology (Computational Fluid Dynamics) and clever coolant circuit routing, achieving optimum engine temperature for the highest performance, in all conditions. Above all, the delta distributor, integrated into the frame triangle, features a large center tube for highly efficient coolant flow, as well as radiator fans as standard on all 4-stroke models.
Packing a punch and delivering an unmistakable engine note, all 4-stroke KTM SIX DAYS models feature an easy-access two-piece header pipe that can be disassembled easily to allow access to the rear shock. An aluminum muffler sleeve has a short and compact profile, which also proudly displays the SIX DAYS logo.