There's a new kid on the block in the pavement arena of the motorcycle industry. And while he's not exactly a threat to the neighborhood bullies at the moment, taking a look at his past deeds might give them some cause for concern in the not-too-distant future.
Austrian manufacturer KTM has carved out a sizable chunk of market share in the off-road portion of motorcycling, and it's accomplished this with solid engineering, aggressive marketing and a fierce competitive instinct. As a possible precursor of things to come, the company entered the 125 Grand Prix Roadracing World Championship in 2003 after a long history of successful off-road racing exploits and then followed that up by officially entering the 250 GP World Championship in 2005. Behind-the-scenes snickering at the orange bikes soon fell silent when the KTMs rapidly established themselves as serious competitors with numerous race wins in both classes. After quickly adapting to the four-stroke movement in off-road motorcycle design, the company even developed a 990cc V-four pneumatic valve engine used by Kenny Roberts' Team KR machines in the premier MotoGP class in 2005, but the project was abruptly shelved midseason due to cost concerns.
The forthcoming RC8 V-twin sportbike we previewed in a previous issue ("Austrian Attack," June '08) is the latest road-going product from KTM and aptly demonstrates how serious the company really is about the pavement market sector. Prior to the RC8, however, KTM's street lineup was limited to mostly supermoto-style machines, along with the single-cylinder 690 Duke and 990cc V-twin Super Duke, the latter of which we last tested in our naked-bike group test ("Naked & Naughty," Sept. '07). We were impressed with-although not overly excited about-the Super Duke's combination of peppy engine and nimble handling, with most of our testers agreeing the KTM was the most fun to ride in that group.
So when the '08 Super Duke R rolled into our shop, a cursory look at the carbon-fiber bits and upgraded wheels and suspension had us thinking the R was basically a dressed-up standard Super Duke. How wrong we were. . . .
Much More Than Skin-Deep
The 999cc, 75-degree V-twin engine received numerous internal upgrades aimed at boosting top-end power without compromising the KTM's superb low- and midrange grunt. Up top, the cylinder head underwent a thorough revamp, starting with larger intake and reshaped exhaust ports to help improve flow. The bigger intake ports are a perfect fit to the 3mm-larger intake valves (now 41mm), now titanium instead of steel. The same NHK single-valve springs fitted to the RC8 are used in the Super Duke R, in conjunction with the lighter valves, allowing the rev limit to be increased from 9500 rpm to 10,250 rpm. Coolant passages inside the cylinder head were redesigned to work with the new water pump (using a more efficient curved impeller) for improved flow and cooling, especially around the exhaust-valve area.
Contributing to the higher rev limit are revised pistons and connecting rods that have been trimmed of an undisclosed amount of reciprocating weight. Each 101mm piston features a DLC-coated pin that permits a smaller diameter to be utilized, cutting weight from both the pin and the piston itself, because the surrounding material in the piston can be reduced. The rods have been slightly redesigned, with a reduction in big-end bearing size paring both weight and friction. The crankshaft counterweights and single counterbalancer have been somewhat reshaped to work with the lighter pistons and rods, although no weight reduction is claimed.
All of this inhales through a new Keihin EFI system with larger 52mm throttle bodies (up from the standard Super Duke's 48mm units) each using a single injector, identical to the setup fitted to the new RC8. Exhaled gases are handled by an exquisite tapered-diameter 2-into-1-into-2 stainless steel header system built by renowned exhaust manufacturer Akrapovic, the first time its handiwork has been made available as standard equipment on a production bike, according to KTM.
The chromoly-steel tube trellis frame and aluminum beam swingarm are basically unchanged from the standard Super Duke, although the 48mm inverted WP fork now has titanium nitride coating on the fork tubes for less stiction, and the WP rear shock has a slightly increased length that raises the rear ride height enough to sharpen the steering geometry's rake and trail from the standard Super Duke's 23.9 degree/103mm to the R model's 22.7-degree/93.9mm setup. An adjustable WP steering damper is included with the R to help keep the front end from getting nervous at higher speeds. For 2008 the 3.5 x 17-inch and 5.5 x 17-inch Marchesini aluminum wheels come shod with Pirelli's Diablo Corsa III rubber.
The first thing you notice when swinging a leg over the Super Duke R is that the KTM is definitely not for the inseam-challenged. The longer rear shock has raised the ride height enough that the seat is now more than half an inch higher (34 inches) than the standard Super Duke, which already had a tall saddle to begin with. The KTM's narrow midsection helps reduce the effect somewhat, but anyone under six feet tall will still be on their toes at a stop.
The next aspect of the Super Duke R that immediately becomes apparent is that the solo seat is probably the worst saddle in motorcycling. Not only is it thinly padded, but the padding itself is very stiff, and the seat's narrow width only accentuates its somewhat sharp edges on each side. To tell you the truth we've ridden racebikes with seats that basically comprised a half-inch-thick foam pad over the tailpiece that were more comfortable. Any riding on the KTM that doesn't involve a lot of movement on the seat will quickly have your butt screaming for mercy after 15 minutes.
Although the Super Duke R engine is equipped with a counterbalancer, vibration at anything other than aggressive throttle inputs can become bothersome after extended periods, with the vibes tingling through the grips and footpegs. The rear view provided by the mirrors is good, but the images get fuzzed out by the vibration. Fuel consumption never dipped below the 35 mpg mark, even with lots of throttle twisting.
The standard Super Duke stood out among the other naked bikes in last year's group test with its peppy, responsive engine-but the R model takes that trait to a whole new level. The R's engine has a much more aggressive character with very little flywheel effect and a throttle response that is very crisp and immediate right off idle. Bottom-end torque has received a substantial boost, and when coupled with the shorter gearing (the R has a one-tooth-smaller countershaft sprocket), the R zips through city traffic with ease, literally leaping off the exits of slower turns. In fact, the KTM is so responsive at slower speeds and small throttle openings that you need to keep a light grip on the bars when riding at cruising speeds; the stiff suspension (more on that later) can inadvertently cause your throttle hand to move ever so slightly over bumps, resulting in small bursts of unintended acceleration that-combined with the heavy engine braking due to the lack of flywheel effect when backing off the throttle-can fast get annoying.
This is not to say the Super Duke R's off-idle throttle response is overly abrupt, however. The KTM is actually quite smooth when applying the throttle after transitioning off the brakes into the corner, and while the engine's acceleration is pretty responsive, it still has the relatively flat torque curve of a V-twin that doesn't threaten to spin the rear tire out from under you.
The internal tweaks on the R engine make their presence felt even more in the midrange and top-end portions of the powerband. The R will leave the standard Super Duke-and basically every other twin-cylinder naked bike-for dead past 5000 rpm, with a stout midrange pull swiftly transitioning into a hard-charging top end that has you gaining serious speed a lot quicker than you expect. We did notice the power tended to tail off a bit at 8000 rpm, but the KTM was still putting out good steam all the way to the rev limiter at 10,250 rpm (a look at the dyno chart confirmed our initial impressions; we'll be doing some experimenting to see if we can unleash the Super Duke R's full potential). The end result is a peak of 118.4 horsepower at 10,000 rpm, an astounding 16.3-horsepower increase over the standard Super Duke, without changing displacement, bore and stroke, or compression ratio-an impressive accomplishment by KTM engineers.
Luckily the same radial-mount four-piston Brembo calipers and 320mm discs from the standard Super Duke are found on the R model, allowing you to quickly and easily bleed off all that extra speed with plenty of feel, power and control. It's also a good thing the slipper clutch from the standard model is included, as the lack of flywheel causes a lot of engine braking that would easily chatter the rear wheel and upset the handling under aggressive stopping from high speeds. The clutch slip apparently is set up fairly tight, as the KTM's engine still bleeds off a lot of speed when you let off the throttle in the lower gears.
The previous version of the Super Duke R was released in Europe last year, and to help promote the new model KTM sanctioned a spec-class race series that ran in conjunction with the British Superbike Championship. We're thinking that KTM was influenced by that race series, because the spring rates on the new Super Duke R are stiff enough that only very hard riding on the street or track use can put enough force on them to work properly. Unless you weigh upwards of 200 pounds, anything less than an extralegal pace on the imperfect pavement usually found on public roads results in a ride harsh enough (combined with the hard seat) to pound you into submission after about 20 minutes.
Ratchet up the pace, however, and the Super Duke R finally comes into its own. The steeper steering geometry afforded by the longer rear shock has noticeably quickened the steering response over the standard Super Duke, providing an even more agile mount to carve corners with. Stability is never lacking with the race-oriented steering numbers, even while running hard and fast over rough pavement; you do need to exercise care in your steering inputs due to the extra leverage imparted by the wide handlebars to avoid upsetting the handling, though. The suspension spring rates that seemed overly stiff during normal street riding gain more compliance as speed increases yet keep the KTM's chassis well under control during aggressive acceleration and braking. Ground clearance is never lacking, and the Pirelli Diablo Corsa III rubber nearly always provides reassuring grip. On a tight canyon road, only an expert pilot aboard a conventional sportbike will be able to keep a well-ridden Super Duke R in sight.
It was only at extreme lean angles that we were left wishing for a bit more sidewall compliance from the Diablo Corsa III tires. Encountering bumps or irregular pavement while keeled over tended to get the Pirellis skittering around a bit, which sapped confidence; playing with tire pressures failed to solve the problem. We also felt that the lack of linkage in the rear suspension forced some compromises in rear-suspension setup. While the rear suspension absorbed most of the big hits at speed well, big dips would use up more suspension travel than we're used to, and attempting to counter this tendency with compression damping only hurt compliance on rough tarmac. These were really minor issues that only showed themselves at a seriously fast pace, however.
With a suggested retail price of $15,598, the KTM Super Duke R definitely isn't for the average naked-bike consumer. As with any thoroughbred, living with the Super Duke R on a day-to-day basis requires some compromise in order to have such serious outright performance at your fingertips. Although there are some four-cylinder naked bikes with more power, the majority of them are much more cumbersome to ride than the agile KTM, and there's no twin-cylinder bike in the naked category that can outrun it. Yes, owning the Super Duke R would be a commitment-but it's one that has some just rewards.
'08 KTM Super Duke R
MSRP: $15, 598
Type: Liquid-cooled, 4-stroke, 75-deg. V-twin
Valve arrangement: DOHC, 4 valves/cyl.; shim-under-bucket adjustmentDisplacement: 999cc
Bore x stroke: 101 x 62.4mm
Compression ratio: 11.5:1
Induction: Keihin EFI, 52mm throttle bodies, single injector/cyl.
Front suspension: WP 48mm inverted cartridge fork, 5.3 in. travel; adjustments for spring preload, rebound and compression damping
Rear suspension: WP single shock, 5.9 in. travel; adjustments for spring preload, rebound damping, high- and low-speed compression damping
Front brake: 2 radial-mount/4-piston calipers, 320mm discs
Rear brake: Single-piston floating caliper, 240mm disc
Front wheel: 3.50 x 17 in.; forged aluminum alloy
Rear wheel: 5.50 x 17 in.; forged aluminum alloy
Front tire: 120/70ZR-17 Pirelli Diablo Corsa III
Rear tire: 180/55ZR-17 Pirelli Diablo Corsa III
Rake/trail: 22.7 deg./3.7 in. (94mm)
Wheelbase: 57.0 in. (1450mm)
Seat height: 34.0 in. (865mm)
Fuel capacity: 4.9 gal. (18.5L)
Weight: 448 lb. (203kg) wet, 420 lb. (191kg) dry
Instruments: Analog tachometer, LCD panel for digital speedometer, digital coolant temperature, odometer, tripmeter, low-fuel tripmeter, clock, engine maintenance reminder; warning lights for neutral, high beam, turn signal, oil pressure, fuel reserve
Roll-ons: 60-80 mph/3.48 sec.; 80-100 mph/ 4.23 sec.
Quarter-mile (corrected): 10.43 sec. @ 130.3 mph
Top speed: 158.0 mph
Fuel consumption: 41-35 mpg, 36 mpg average
The KTM Super Duke R is a cool bike. Really, it is. I mean, look at it-it just oozes character. But it needs some refinement. For starters, that seat feels like it's nothing more than a board from the local hardware store wrapped in vinyl. That you're sitting on the edge of it doesn't help in the comfort department, either. Next, the throttle is extremely sensitive-like it has a feather-light flywheel. With the slightest twitch of the wrist the bike lunges forward, a trait of the standard Super Duke as well. On the street this makes for a really difficult bike to ride smoothly. Further, the suspension is really stiff, especially in the rear. Even with the clickers set most of the way out this is not a bike you'd want to take over a bumpy road. Find some smooth and twisty piece of asphalt, and it comes alive. You'll first have to figure out whether to go foot-out or knee-down, but it has the potential to rip either way. It's an agile and quick little bike, but its usability is so limited that I'd only own it if my driveway led directly to the Alps or the racetrack.
For a standard bike the Super Duke R is pretty hard-edged, but there is no question it rips down a tight canyon road. My first thoughts after riding it were that the seat is too hard and the suspension too stiff for what I'd want in even a sporting standard-to me these bikes should be just as capable zipping down to the store or across the state as they are in the twisties. To that end, I'd almost prefer the standard Super Duke over the R model because it's so much more user-friendly and as much fun to ride. I say "almost" because the R costs not much more, and the increased performance is easily worth the price. For sure I'd spring for the R model and try to make it more comfortable-or just put up with it-rather than trying to up the performance of a standard version to match.
Although the standard Super Duke was probably the most enjoyable bike to ride in the naked-bike group test we did last year, it never really struck a chord with me for some reason. Sure, the engine was peppy, and there weren't any complaints with its overall handling. But there just wasn't anything that really made the KTM stand out from the rest.
The Super Duke R takes care of that missing aspect. There is literally no comparison in engine performance between the standard Super Duke and the R model; the R basically stomps on the standard version literally from idle on up and pretty much puts the hurt on any other V-twin naked bike. The KTM's quick-revving powerplant is fun to use, but it also requires some deft throttle and clutch work in dense traffic or slow going due to the lack of flywheel. And while the chassis is more than up to the task of handling the speed dished out by the engine, the R's suspension spring rates are more suited to racetrack scratching than everyday riding (as is the upholstered plank of a seat).
Nonetheless, if I were looking for one of the best-performing naked bikes out there, I'd seriously consider the KTM if it were within my means-and look into fixing the slight top-end flat spot, as well as the seat.