01. Engine & Exhaust
Engine
The KTM 300 EXC TPI engine leads the field in offroad competition with innovative electronic fuel injection that sets a new standard in offroad 2-stroke racing. Its modern architecture includes high-end features, like the well-protected E-starter, a new cylinder with two injectors and an adjustable power valve. A 6-speed enduro transmission and hydraulically operated DDS clutch transfer truckloads of tractable power to the back wheel.

Cylinder
The KTM 300 EXC TPI cylinder has a bore of 72mm and is fitted with the sophisticated power valve, which provides really smooth and controllable power characteristics. For the EFI application the cylinder features two lateral domes that hold the fuel injectors supplying fuel into 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 for less emissions, a more efficient combustion and reduced fuel consumption. A little tube in the back of the cylinder is connected with an intake pressure sensor, which supplies pressure data to the control unit.


Crankcases and engine covers
For optimal mass centralization the lightweight die-cast crankcases hold the clutch shaft and the crankshaft in a high position close to the center of gravity. Which is nice if you care about sweet handling. In addition, it allows the implementation of a balancer shaft. So your ride will be as relaxed as it is rapid. Plus, your new favorite engine will keep looking as fresh as the day you bought it: the engine covers feature a smart surface structure that reduce the wear caused by the rider’s boots.


Transmission
This 6-speed Enduro transmission features an Enduro-specific wide-ratio specification and provides precise and easy shifting. Keeping safety in mind, an advanced ´No Dirt´ gear shift lever design prevents muck from blocking the joint. Because even dirt lovers hate mud when it’s in the wrong places.


Engine management system
The engine management system (EMS) of the TPI models features a control unit located below the seat. The control unit determines the ignition timing and the amount of fuel to inject is based on several sensor readings such as intake and ambient air pressure, throttle position, oil and water temperature. Thanks to altitude and temperature compensation the rider does not need to worry about fiddling around with the jetting anymore.


Cylinder and piston
Inside the cylinder, with a bore of 78mm, thumps a reliable box-type piston made by CP. Its crown geometry is adapted perfectly to the high-compression combustion chamber (12.8:1), where its rigid structure and low weight maximize performance. Thanks to low oscillating masses, the engine revs freely with plenty of power.


Balancer shaft
Say goodbye to numb feet and hands. This engine design allows the implementation of a lateral balancer shaft in order to keep the vibrations to a minimum. You know what that means: more comfort, less fatigue, bigger smiles.


Clutch
The KTM 300 EXC TPI employs the KTM-developed DDS clutch (damped diaphragm steel) with a wear-free steel basket, extremely heat resistant clutch plates and nitrated steel liners. This clever design employs a diaphragm spring instead of the usual coil springs, making for considerably easier clutch action. A diaphragm spring also leaves sufficient space for a damping system to be integrated into the clutch hub. The goal is traction, but durability is as well. Light operation and telepathic amounts of control are standard with this hydraulic Brembo actuated clutch.


Oil pump
Pre-mixing 2-stroke fuel is a thing of the past for KTM EXC TPI owners. An electronic oil pump feeds oil from the oil tank via the throttle body into the engine intake, and ensures a perfect fuel-oil mix in all conditions and engine speeds. The system, which reduces up to 50% of the smoke from the exhaust system over carburettor models, is managed by the control unit based on the engine’s revs and load measured by the TPS (throttle position sensor). The oil capacity of approximately 0.7 liters is enough for 5-6 refills of fuel, giving you more time to ride, less time measuring things out.


Throttle body
The TPI engine is fitted with a 39mm throttle body made by Dell`Orto. The airflow is regulated by a butterfly connected with a twin-cable throttle cam, which is operated by the handlebar throttle assembly. A throttle position sensor provides airflow data to the control unit, while a bypass screw allows the regulation of the idle speed. The cold start device also opens a bypass supplying more air. Via an oil intake tube oil supplied from the oil pump is mixed with the incoming air to lubricate crankshaft bearings and cylinder/piston etc.


Cooling
KTM’s proven cooling system routes the coolant from the cylinder head through the frame triangle, directly to aluminum radiators made by WP. The additional KTM PowerParts radiator fan that riders can add to this fuel injected 2-stroke is now regulated by the control unit, no thermo switch is required anymore. Thanks to flow optimized internal circulation and CFD-calculated ventilation, the system is superbly efficient. In addition, the radiator protectors improve heat dissipation. Especially in the mud. They are also integrated into the front part of the shrouds to protect the radiators in a crash.


Exhaust
This nickel-plated pipe is produced by WP Performance Systems. It is designed for an optimal power band and maximal performance of the engine. A modern 3D production process guarantees top precision and reliability of the pipe, so this screamer is as tough as it is strong.

CNC-parts