Technology KTM LC8 engine

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Technology KTM LC8 engine

Hot phase

KTM starts the hot test phase with the new two-cylinder V-engine. MOTORRAD was able to exclusively take part in test runs.

The representatives of the pure Enduro doctrine had made pilgrimages to the two-wheel mecca Intermot in Munich from everywhere. They flocked to the KTM stand, where they paid homage to the new message from the two-cylinder, looking strictly at Dakar. The new 75-degree V2 presented itself to the fans of the brand from Austria with slim stature and yet athletic.
Now MOTORRAD editors in Mattighofen could hear the 102 HP two-cylinder working on the engine test bench. In addition to the sonorous sound, the engine’s key data also made people sit up and take notice. For example the cylinder angle of 75 degrees. Engine developer Claus Holweg, who once paved the way for the big Aprilia V2 at Rotax: "From the very beginning, it was crucial for us to have the smallest possible box size. "In English, it means: length, width and height. The best compromise had to be found." The 90 degree cylinder angle of the sporty V2 from Ducati, Honda and Suzuki would have taken up too much space, the 60 degrees of the Aprilia caused poor mass balancing. The V-engine with a 75 degree cylinder angle, on the other hand, is compact and, with a comparatively small balancer shaft, creates good vibration behavior, ”explains Holweg.
Other remarkable data: The displacement of 942 cm³, which the 100 millimeter large Mahle pistons displace with a 60 millimeter stroke. When asked why KTM didn’t use up the full liter, Development Manager Wolfgang Felber asks the counter-question: “We wanted to build an All Terrain Enduro that can be driven both on and off-road. Who needs more cubic capacity and power? “For the planned range of models, cubic capacities from 800 to 1000 cm³ can be realized through different bores. By far the smallest stroke of all one-liter V2 is part of the concept. Together with the short connecting rods, this results in extremely compact cylinders and thus a low overall height. Cylinders integrated into the engine housing were out of the question due to the vertical division and the planned modular system.
The vertical division of the motor housing has been carefully considered. This is the only way to arrange the crankshaft and the two shafts of the six-speed gearbox on different levels to save overall length. And the efforts to make the smallest packaging also included details. In the V between the cylinders, a shaft rotates at crankshaft speed to save space, which can be seen as a multi-functional talent. It carries a counterweight on both sides of the cylinder, drives the water pump and the centrifuge of the engine housing ventilation and serves as an intermediate gear for the starter motor and the two timing chains above it.
The inverted tooth chains each lead in a control shaft to the symmetrical cylinder heads, which are rotated 180 degrees against each other, and there they drive another intermediate gear, on which a gear is located. This in turn engages the gears of the two overhead camshafts. Advantage: The necessary two-to-one ratio already takes place in the chain drive, the camshaft sprockets have small diameters. In addition, the camshafts can be removed to adjust the valve clearance without removing the timing chains.
A narrow valve angle of eleven degrees to the cylinder axis ensures compact combustion chambers. Despite the relatively large bore, they enable a remarkably high compression of 11.5 to one. However, with a diameter of 38 and 33 millimeters, the inlet and outlet valves operated by bucket tappets are rather moderate compared to the competition. This also applies to the constant pressure carburetors with a diameter of 43 millimeters from Keihin. Compared to the size 54 intake manifold of the Suzuki TL 1000 engine, they virtually act as a throttle body. But Claus Holweg can calm down those who are always hungry for performance. »With the LC8 Adventure we start with carburetors. Injection is only used when it is fully developed. ”When the time comes, performance for a road model like the two-cylinder Duke will not be a problem. In any box, what is tested is what an accidental and certainly not intended appearance of a test vehicle during the MOTORRAD visit to the KTM factory proved. The new V2 in a TL 1000 chassis hummed past the confused editors.
With the new two-cylinder, the designers use the advantages of dry sump lubrication, such as proper ground clearance and additional cooling of the oil. The two trochoid oil pumps sit on a common shaft under the multi-disc oil bath clutch. The maintenance-friendly oil filter insert is placed directly in front of it. It can be changed with the tool kit. In addition to the specifications of building a compact motor, the specifications also included low weight. This was almost inevitable due to the consistent design. Without using exotic materials? only the valve covers are made of magnesium alloy ?? the engine weighs 56 kilograms without the carburetor. This puts it a considerable 17 kilograms below the Japanese competition and still twelve below the Aprilia Mille. Because of the large overlap of the crank and main bearing journals, the crankshaft can be designed to be stiff and yet light. It only weighs five kilograms. The values ​​of the competition are between seven and nine, and even the shaft of the in-house single-cylinder LC4 weighs half a kilogram more.
B.The only question left is the stability of the unit. The developers are confident. Individual engines have already survived over 50,000 test kilometers and several hundred hours of endurance without complaint. And then there is the ultimate endurance test before the start of series production. At the Paris Dakar 2002, the new two-cylinder has to pass its baptism of fire before KTM delivers the first LC8 to customers in spring 2002. And they should not only recruit themselves from the camp of convinced KTM disciples, but also convert strict believers of other denominations.

Technical specifications

Engine: two-cylinder four-stroke 75-degree V engine, transverse crankshaft, two overhead, chain and gear-driven camshafts each, four valves per cylinder, bucket tappets, dry sump lubrication, constant pressure carburetor, O 43 mm, bore x stroke 100 x 60 mm, displacement 942 cm³ Compression 11.5: 1 Nominal output 78kW (102 HP) at 8000 / min Max. torque 97 Nm (9.9 kpm) at 6000 / minPower transmission: primary drive via gears, hydraulically operated multi-disc oil bath clutch, six-speed gearbox.

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