The 250cc 2-stroke engine has for long been the best combination of unsurpassed power and lightweight construction. The simplicity and low maintenance cost of the 2-stroke engine has made it a favourite amongst enduro riders for generations. The TE 250i features an advanced electronic fuel injection system. This comprises of a set of fuel injectors positioned at the transfer ports which deliver the ideal amount of fuel to the engine in every condition. This not only reduces fuel consumption and emissions but also delivers a clean and smooth power delivery giving the revered 2-stroke the edge. Additionally, the TE 250i engine has an advanced construction featuring shaft arrangements precisely positioned for greater mass centralisation, a counter-balancer shaft reducing vibration, a twin-valve controlled power valve and a 6-speed enduro gearbox.
The 66.4 mm bore cylinder in the TE 250i features a twin valve-controlled power valve system which delivers smooth and controlled power throughout the RPM range. Optimal exhaust port timing is achieved with the combination of a state-of-the-art, adjustable power valve drive and machined port window.
Additionally, the cylinder features two inlet positions located on the transfer ports at the rear of the cylinder where a pair of fuel injectors are mounted. The injectors deliver the fuel downwards into the transfer port which guarantees excellent atomisation with the air travelling upward to the combustion chamber. This ensures more efficient combustion resulting in reduced fuel consumption and emissions.
The lightweight piston is perfectly matched to the cylinder and transmits minimal oscillating mass ensuring high levels of reliability and performance.
The TE 250i engine is designed to improve mass centralisation. The engine uses specific shaft arrangements designed to harness the rotating mass of the engine in the ideal centre of gravity. As a result, the lightweight, die-cast engine casings are developed with the shaft arrangements in the ideal position, centralising oscillating mass and improving ride-ability. Additionally, the counter- balancer shaft is integrated in a very compact manner, having little effect on the overall design.
The engine houses a laterally mounted counter-balancer shaft. The balancer significantly reduces vibration resulting in a smoother and more comfortable ride.
The crankshaft features a 72 mm stroke and is balanced in conjunction with the counter-balancer shaft for minimum vibration. By incorporating a heavier ignition rotor, the crankshaft produces more inertia than its motocross counterpart which improves control in the lower RPM range.
A 6-speed Pankl Racing Systems gearbox features enduro-specific ratios while an innovative shift lever reduces dirt build up guaranteeing easy operation in all conditions.
The TE 250i features a DDS (Dampened Diaphragm Steel) clutch. What this means is the clutch uses a single diaphragm spring instead of the more common coil spring design resulting in a much lighter clutch action. This design also incorporates a damping system which increases both traction and durability. Additionally, the light and robust basket and inner hub guarantee optimal oil supply and cooling to the clutch.
Combined with the BRAKTEC hydraulic system this guarantees a light, modulated clutch feel with reduced maintenance and freedom from adjustment.
Oil tank and pump
The TE 250i features an electronic oil pump which feeds vital 2-stroke oil into the engine to keep it lubricated. The pump is located just below the oil tank and feeds the oil via the throttle body meaning the oil is not mixed with the fuel, eliminating the need for pre-mixing as on traditional 2-stroke engines. The pump is controlled by the EMS and delivers the optimal amount of oil according to the current RPM and engine load reducing waste and preventing excessive smoke being transmitted from the exhaust.
The oil tank is located beneath the fuel tank and is connected to a filler hose which runs through the upper member of the frame to a filler cap conveniently located for easy refills. The tank capacity is 0.7 litre and is fitted with a sensor which illuminates a warning lamp visible to the rider when the oil needs to be refilled.