Cycle News - Archive Issues - 2000's

950 Rally for extra stability while rac- throttle over each little sand berm in swear KTM had lightened the crank Take it from me, after survlvmg ing flat-out along sandy desert tracks, a way you don't need to do on a sin- quite considerably to do this, as the Sahara and riding the KTM LCa in it's a no-no off-road and is one rea- gle-cylinder rally bike, he says. The indeed it has - but it has done so its perhaps esoteric but undoubtedly responsiveness of the LCa motor just without sacrificing any torque, and lightens the front wheel enough to that's the measure of the Austrian counter the weight imbalance, albeit company's achievement in develop- at the cost of higher fuel consumption ing this sweet, responsive, powerful - but I could tell how good a motor yet muscular V-twin engine, which at son Yamaha went for a parallel-twin in designing the XTZ Super Tenere all those years ago. Hence one reason I kept washing effective first application, I'm convinced this is the debut of an extremely significant powertrain design, which will set new standards out the front until Sala showed me this will be when fitted in a city bike, the same time is small, light, com- for V -twin engineering that others will how to counter this by consistently because it's so eager-revving and pact and versatile, in spite of its near- have to take very seriously. Can't gassing it up and then backing off the crisply responsive on pickup. You'd 1000cc capacity. wait to ride the streetbike version ... eN [?[?@[fJiJ [§)D f?f1 a@ @a[?@@a Although the LC8, liquid-cooled, DOHC. eight-valve, 75degree. V-twin engine (right) will only reach production for customer purchase this September - initially in 950 Adventure rally-replica guise, then later in 2003 in the V2 Duke streetrod - KTM has been thinking for most of the past decade about how to expand its single-cylinder, dirt-derived model range into multi-cylinder tarmac territory. Those plans first found expression shortly after KTM boss Stefan Pierer and his colleagues took over the insolvent company early in 1992 and began the spectacular tumaround that has seen KTM go from bust to boom. That year, a oneoff special called the Bepono, built for the German BoTT series by two engineering students by combining a pair of KTM LC4 cylinders on a special crankcase, was displayed on the KTM stand at the Cologne Show. That was just a teaser, though - as was the second time around in 1996, when the company's stock-market flotation prospectus and investor meetings were spiced up by the revelation that the Stuttgart-based design office Kraft Technik had been commissioned by KTM to produce a design for a Vtwin Hard Enduro, possibly using the 60-degree V-twin RSV900 engine Rotax was then developing for Aprilia. The Italian company, however, refused to share it with its Austrian neighbors, even for an off-road bike. Another altemative for KTM was the Swedish Folan 60degree V-twin motor that already existed, consisting this time of two Husaberg cylinders on a special crankcase, albeit without provision of any balance shaft to eliminate the considerable vibration. Even though KTM by now owned Husaberg, this, too, was aborted once KTM had been successfully floated on the stock market. In early 1998, as the company grew in size and the need for expansion became a priority, Pierer commissioned KTM's chief engineer, Wolfgang Felber, to make preliminary studies of twin-cylinder engine formats and vehicle concepts. "Our idea wasn't so much to build a better V-twin, but to develop a versatile twin-cylinder engine concept, which had the potential to be used in off-road bikes as well as on the street, without any compromises in either application," says 39-year-old Felber, himself a former Grand Prix road racer. "In fact, we made studies of several other concepts, including not just many kinds of V-twins but also some that might seem a bit strange, like a horizontal as well as vertical parallel twin, crossways and lengthways Boxer motors, and even a tandem-twin like the 250cc GP bike I used to race! But, eventually, we concluded that a 75-degree V-twin was the best option, especially in terms of following KTM's established policy of going racing successfully first with a prototype version, then bringing an identical product to the marketplace in succeeding years. Plus, it had the extra advantage that we could build a V-twin not like the others!" Indeed, for compared to a 90-degree format as practiced by Ducati, Honda and Suzuki, the 75-degree format offered a more compact layout, which in tum allowed KTM to place the engine wherever they wanted in the chassis. (The 60degree option as preferred by first Harley-Davidson, then Aprilia, presented potential difficulties with inlet design, throttie-body location and vibration.) "We would have needed to install twin counter-balancers, as Aprilia has done, and this was not acceptable either in terms of power loss or, particularly, weight," Felber says. "But we also wanted to make sure there was no lost space in the engine, and so to meet the demands of what we called our 'box measurement' - assessing how small a box would be needed to contain the entire engine and throttle bodies we decided the best solution was to place the electric starter between the cylinders, as well as the balance shaft and water pump, for which we needed more space than on a 60-degree or even a 72-degree V-twin." So, by August 1998, the decision was made to go with a 75-degree V-twin design, but with special emphasis on light weight and a compact build. KTM decided to assume the entire R&D process in-house, and hired Claus Holweg as Project Manager for the LC8. Holweg was fresh from Austrian rival Rotax, where he had headed up the R&D team that developed the freshly launched RSV Mille engine for Aprilia, so he already had several years of accumulated V-twin expertise under his wings. The project was fulfilled with amazing speed: The LC8 engine went from a blank computer screen to its first dyno run on August 11, 1999 in exactly 12 months - and the first time it fired up was in darkness, thanks to Austria's coincidental total eclipse of the sun that very same day! UGHT IS RIGHT The 75-degree KTM (fitted with a single balance shaft) scales just 123 Ibs., compared to 150 for the 60-degree Aprilia/Rotax (complete with twin counterbalancers), 161 for both the 90degree Honda VTR1000 and Suzuki TLlOOO, 165 for an old-style 90-degree Ducati desmoquattro engine (158 for the new Testastretta design), and 167 for the lightest version available of the flat-twin BMW Boxer motor - all with perfect primary balance, so no balance weights. This makes the KTM engine between 17-percent and 26-percent lighter than its rivals, achieved without extensive use of magnesium, which is confined to the cam covers. It's hard not to applaud the extent of the team's achievement in creating such an intelligent, rational, strippeddown design, without compromising reliability or performance. The bike won the 2001 Egypt Rally first time out in the hands of Fabrizio Meoni, then scored a victory in the 2002 Dakar Rally. Joan Roma's win in the Tunisia Rally (on his first time out on the new bike) underlined its worth three out of three ain't bad for an all-new design! GETTING TECHNICAL The dry-sump engine is vertically split, not only to save weight (no need for long engine bolts to hold everything together), but also as the easiest way of arranging the crankshaft and twin gearbox shafts on different planes (to reduce the overall length of the engine). The 3.18-quart oil tank doubles as the oil radiator, positioned ahead of the front cylinder, with twin oil pumps mounted on a single shaft located beneath the multi-plate oil-bath clutch (a wet-sump engine design was never considered because of the 4-inch reduction in ground clearance this would entail). The twin DOHC, four-valve cylinders are evenly located on the crankcase (not rotated as on a Honda or Suzuki Vtwin), which was good for wheel clearance and weight distribution in both dirt and street guise. The LC8 uses a forged, one-piece, plain-bearing crankshaft weighing less than 11 pounds (lighter than one from KTM's own LC4 single, and over 6 pounds less than a Suzuki TLlOOO bottom end) with small, semi-circular flywheels and short, H-section, forged-steel con-rods measuring 125mm in length and mounted on a common crankpin. These carry three-ring forged Mahle pistons that weigh 13.23 ounces each without bolts, deliver 11.5: 1 compression, and have a flat top and short skirt (total piston height is just 46mm). "For sure, we lose a little by having such a light crank," Felber admits, "but from the beginning we tried to create a very responsive engine for sports bike application - doesn't matter whether it's a road bike or off-road bike, it's the same." The crank carries a spur gear on the left side, driving the multi-purpose layshaft positioned between the cylinders. !t not only carries the twin-opposed counter-balancer weights needed to eliminate the primary vibration, it also drives the water pump and centrifugal engine breather, as well as acting as an idler wheel for the starter motor and the composite chain and gear drive to the twin overhead camshafts. A six-speed transmission with gear primary drive is employed on all versions (no five-speed for off-road use, though intemal ratios and overall gearing will vary by application). The LC8 employs all-new, four-valve cylinder heads rather than a pair of those from KTM's existing singles, fitted with bucket tappets and steel valves (38mm inlet and 33mm exhausts), each with double valve springs and sitting at a total included angle of just 22 degrees - very flat, in accordance with best Formula One principles. "Our main target for design of the cylinder heads was always to maximize compactness by having the smallest possible drive-gears on the camshafts, as well as a camdrive mechanism capable of very high revs," says Felber. "We wanted to avoid having the very large cam-wheels needed to achieve a 2: 1 ratio with direct chain drive, like on a Honda Varadero." For this reason, the LC8 employs very short hydraulically tensioned offset cam-chains driven off sprockets mounted at .. either end of the multipurpose layshaft. These run to an intermediate gear located in each cylinder head; the gear, in tum, drives the two small camwheels at the end of each camshaft. The camdrive layout is broadly similar to that of the Suzuki TLl 000 but is far more compact. INJECTION vs. CARBURETION in 950 Adventure form, as well as the V2 Duke guise in which it will make its tarmac debut at Intermot in September, the Le8 engine measures 100 x 60mm for a capacity of 942cc, but the design was conceived to accommodate various capacities ranging from 800 to 1000cc - there's room to increase the bore up to 103mm, for exampie, making an even shorter-stroke 999cc Superbike version a realistic option. The engine is designed to be capable of producing up to 180 hp at the crank, says Holweg, and to rev up to 12,000 rpm. And while Meoni's Dakar-winning dirt sled and its Adventure customer clone both employ 43.5mm Keihin CV carbs and a Denso CDI (with the carbs fitted inside the substantial airbox to liberate extra space under the seat - a first in motorcycles, according to Holweg), KTM will use fuelinjection and a fully mapped engine-management system on the V2 Duke, with throttle bodies ranging from 48mm to 52mm in diameter (final size has yet to be chosen) and a single injector per cylinder. In this first tarmac application, power from the 942cc engine will rise to around 120 hp at the crankshaft, says Felber, compared to the current output of the carburetted off-road engine of 102 hp at 7800 rpm. STRESSING Though the engine has the swingarm pivoting in the crankcases (as well as in the frame) for extra rigidity, it's not a stressed chassis member. "We didn't want to have this because, in off-road use, we have controlled deformation of the frame in order to reduce rider fatigue," explains Felber, "and if you use the engine as part of the chassis in such a situation, it risks problems with the base gaskets and cylinderhead gaskets, and so on." The LC8's compact design not only permits greater freedom of choice in positioning the engine in the frame, it also allows a very long swingarm, for improved traction and grip on the V2 Duke, while the 25mm even longer one on the 950 Adventure delivers crucial high-speed stability on loose surfaces. "I see a motorcycle as a total package," says Felber. "Here at KTM, we always make sure our engine designers and the frame builders work together all the way through the project, not just have occasional meetings to let each other know what's going on." After seeing the fruits of KTM's efforts so far to build a better twin, and the success of its engineers in making a proven, effective package for off-road use, it's hard not to believe that this is a Superbike engine in the making. The LC8 motor has all the attributes in terms of architecture, weight and potential performance to allow the Austrian firm to produce a 250cc GP-sized sportbike weighing well under 400 Ibs., but with more than 130 hp available in street guise. Might KTM perhaps go Superbike racing, while working all the time on its future 75-degree V4 MotoGP contender, and prototype four-cylinder sportbike? Don't bet against it... U ... - n __ s: • JULY 24,2002 47

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