01. Engine & Exhaust
Thanks to state-of-the-art engineering, innovative 2-stroke design, and revolutionary TPI fuel injection technology, the 150 cc 2-stroke powerplant is as surprising as it is effective. Delivering class-leading power throughout the entire rev range, the benefit to this compact, lightweight 2-stroke is down to its approachable rideability, making it a great option for those looking to delve into more extreme action, without the intimidation of a bigger 2-stroke.
The KTM 150 EXC cylinder has a bore of 58 mm and with refined port timings and the aid of a sophisticated power valve, provides really smooth and controllable power characteristics. For the EFI application the cylinder features two lateral domes which hold the fuel injectors that supply fuel to the rear transfer ports. The downstream injection guarantees excellent atomization of the fuel with the upstreaming air. Thus, the loss of unburnt fuel is minimal, resulting in less emissions, a more efficient combustion and reduced fuel consumption. A small tube in the back of the cylinder is connected with an intake pressure sensor, which supplies pressure data to the control unit. The cylinder features a power valve unit with a sophisticated mechanism for the lateral support exhaust ports. The exhaust port layout increases engine performance, while the upper contour of the exhaust port has been machined to ensure more accurate port timing. The new cylinder, with TPI technology, produces outstanding performance over the entire range with significantly increased torque compared to its predecessor.
Crankcases and engine covers
These compact engine cases are manufactured using a high-pressure die-cast production process which helps with weight reduction but maintains strength and durability. This design also allows for optimal shaft arrangements close to the center of gravity, resulting in ideal mass centralization and ride-ability.
The KTM 150 EXC is fitted with a robust 6-speed transmission made by PANKL RACING SYSTEMS, and make use of enduro-specific wide-ratio gears, with precise and easy shifting. An advanced ´No Dirt´ gear shift lever design prevents mud and dirt from blocking the joint. Because even dirt lovers hate mud when it's in the wrong places.
The KTM 150 EXC is fitted with a DS (diaphragm steel) clutch. It features a one-piece clutch basket and primary gear made of high-strength billet steel. Its compact rivet-less design guarantees unbeatable reliability. The clutch is fitted with extremely heat-resistant steel carrier friction discs which ensure excellent disengagement of the clutch and are pre-tensioned by means of a diaphragm spring, substantially reducing the lever force required by the Brembo hydraulic system.
The standard electric starter on the KTM 150 XC-W 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.
Engine management system
The engine management system (EMS) of all 2-stroke EXC models features a control unit located below the seat. The ECU defines the ignition timing while the amount of fuel to inject is based on several sensor readings such as intake air pressure, throttle position, water temperature , and ambient air pressure. Thanks to altitude and temperature compensation, re-jetting is a thing of the past, meaning more time twisting throttles and less time turning screws. Should the rider decide to mount a radiator fan from the KTM PowerParts, it will be controlled directly by the EMS without needing to add an additional thermal switch.
Pre-mixing 2-Stroke fuel is a thing of the past for KTM XC-W owners. The 2-Stroke enduro range is fitted with a frame-mounted oil tank featuring flexible mountings, which greatly improves durability and reliability. In addition, a mesh filter prevents dirt from getting into the oil pump and into the fuel. This works in conjunction with the oil pump, which delivers the lubricant directly to the throttle body, where it is mixed with the incoming air to lubricate the piston and crankshaft. Using engine speed and throttle position sensor data, the engine management's precise electronic control of the oil pump ensures that the ideal amount of oil for any given conditions is used. With an average fuel-to-oil ratio of 1:80, an oil capacity of about 0.7 liters is sufficient for roughly five tanks of fuel.
The KTM 150 EXC engine is fitted with a 39 mm throttle body made by Dell`Orto. These regulate the airflow via a butterfly connected with a twin-cable throttle cam, which is operated by the handlebar throttle assembly, supported by a throttle position sensor that provides airflow data to the control unit. What all this means is, riders can precisely set the idle speed via the bypass screw, as well as easier cold starts.
In order to accommodate the power requirements of the engine management system, all KTM EXC models are fitted with a powerful 196 W alternator and voltage regulator to ensure all systems are always powered up.
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. The radiators also benefit from plastic protection fins that serve as protection from flying rocks and debris, as well as a brace that disperses energy around the radiators in the event of an impact.
When it comes to improved power delivery and performance, the new exhaust plays a key role and packs a punch that is hard to beat. The pipe is produced with the latest 3-D stamping technology and has an optimized shape. The silencer also features a reworked design that includes a new perforated inner tube and lighter wool. The new exhaust works perfectly with the new TPI engine, producing excellent enduro-specific performance with significantly better bottom end power than its carbureted predecessor. Last but not least the plastic mounting system of the muffler is replaced by 2 welded, aluminium brackets that help reduce the weight of the muffler by 60 g.