KTM 990 Super Duke – the original Austrian wild child

The original Austrian wild child – KTM’s barking 990 Super Duke…

Words: Jon Urry  Pics: Mortons Archive

Nowadays it seems hard to comprehend, but the 990 Super Duke was launched at a time when KTM was a name that most road riders hadn’t really heard of, let alone considered owning one of its products. In the off-road world, the Austrian brand was an established force, but to your average tarmac rider, it was something of an anomaly as it had only just launched its first big-capacity road bike, the 950 Adventure. But with the Super Duke, KTM aimed to make a big impression – and fast…

Hitting dealerships on the back of a controversial marketing video (which was actually banned, look it up on YouTube), the 990 Super Duke was KTM’s first big-capacity purely road-focused motorcycle. Brimming with attitude and targeted directly at the rapidly expanding super naked class, the 990 Super Duke’s job was to attract the attention of road riders and put KTM firmly on their radar, a task it certainly succeeded in doing.

Not only did this Austrian-built V-twin impress in group comparison tests alongside the likes of far more established rivals like the Aprilia Tuono, Triumph Speed Triple and Ducati Streetfighter, it also proved its worth on track in the BSB paddock as KTM ran a one-make Super Duke Battle at selected BSB rounds, thrilling the crowds with bar-to-bar naked bike racing madness. But that was then – how does the original Super Duke stand up in the used market? Has this pioneer of KTM’s aggressive attitude mellowed with age? Or does it still have enough in its locker to excite?

Even parked up, you have to say the Duke’s wild insectoid look is still impressive. At a time when the Japanese were struggling to stand out (aside from the Z1000), KTM absolutely nailed the Duke’s look, and its hunched-up, forward-biased stance remains a head-turner. Add in the trademark orange colour (or even black with orange flashes) and it is both instantly recognisable and somehow cool. And the great thing is that, as well as the look standing the test of time, the Duke’s ride has as well. Fire it up (after waiting for the diagnostic sweep on an older model…) and although the 75-degree V-twin initially sounds a little bit rough and ready, once on the go it soon quietens up and smooths off. A thoroughly engaging engine with bags of poke and a quick-revving nature, it may only make about 110bhp, but it does so with a good dollop of torque backing it up – and that’s where the fun is found.

A great engine for twisty B-roads when you are banging through the gears (it has to be said, the gearbox is a touch sloppy) and zapping out of bends, the Duke is entertaining to ride but not over-the-top, meaning you get lots of grins and very little intimidation, always a good combination. And that’s before you add in its chassis…

It is remarkable that a company so off-road focused as KTM (at the time) managed to nail the Duke’s chassis so well but, hands up, it is a joy. Hitting a pleasant balance of sporting ability and stability, with its wide-bar off-road-style stance, the Duke is an absolute riot to muscle around and feels perfectly suited to the UK’s roads. Like the motor, the chassis manages to hit a great middle ground where it has all the agility you need, as well as cracking Brembo brakes, but never feels like it has overstepped the mark.

And it can be made even better through simple upgrades such as overhauling the suspension and fitting sticky tyres; a major consideration when it comes to buying the Duke, because while undeniably impressive, it isn’t quite the finished article and has its quirks.

The key to happy KTM ownership, as with so many of the less mainstream brands, is getting the bike to an expert. You can’t expect to just buy a Super Duke and thrash it in the same kind of way you can a Japanese-built sportsbike. It has a few foibles, both mechanically and handling-wise, that will probably leave you frustrated.

After the right person has given it a proper service and check-over, and has tweaked the areas that need tweaking, the final result is a really cracking naked bike that has bags of kerb appeal, a top-rate chassis, and a thoroughly enjoyable V-twin motor. It’s far from refined, but it’s an old-school KTM product built at a time when the company was still finding its feet in the tarmac world, so what do you expect? Pick a good one up for £4000 to £4500, spend about £500 on getting it fettled, and the final result will leave you grinning from ear to ear.

Oil level

The Duke has a dry sump design, which often catches out owners more used to a conventional wet sump. When checking the oil level, get the bike hot and then top it up to just shy of the maximum oil level on the indicator, with the bike upright on a level surface. The oil level will drop once the bike is cool. Check what the oil level is at because it is easy to accidentally over or under-fill a Duke.

Tank size

The first generation of Dukes have a small 15-litre tank, which grew in capacity to 18.5 litres from the 2007 update onwards. Ideally, you want a bigger tank model as the Duke is quite thirsty.

Diagnostic sweep

All pre-2009 Dukes run a diagnostic sweep when the ignition is turned on, which you can see happening as the rev counter flicks to the redline and then back again. If you try and start the bike before it has completed the sweep, it can throw out the calibration, making the bike run poorly. To ‘re-initialise’ the bike, let it do its sweep, start the motor without touching the throttle, and then leave it to idle uninterrupted for 10-15 minutes.

Evolution

The Duke arrived in 2005 and was first upgraded in 2007 through a new fuel injection system (increasing power by 2bhp) and a bigger tank. The R model was also launched this year and features upgraded WP suspension, an orange frame with sharper geometry, and radial brakes. In 2009 the stock Duke was dropped from the range and the R gained a more powerful (up 12bhp) engine. It was replaced by the 1290 Super Duke R in 2014.

TIs

KTM continually releases TIs (technical improvements) for its bikes; small modifications that are recommended by the factory. Only authorised KTM technicians gain access to these TIs, so it is worth getting the bike serviced by an official KTM dealer to ensure they are up-to-date.

Throttle response

If the bike is quite jerky on its throttle, it either needs its throttle bodies balanced or a new ECU map. Get it to a dyno house that knows KTMs and it will alter the ignition curve, removing some advance and giving it a beautiful feel.

More power!

KTM experts agree that adding a free-flowing air filter (don’t remove the airbox as some owners try), junking the cats through a set of end cans (the headers are good) and then remapping the ECU should gain you about 10-15bhp. Result!

Suspension

The great news about the KTM’s WP suspension is that it is fully rebuildable, meaning both the shock and forks can be serviced by a professional. The bad news is that the quality of the OE damping is a bit suspect. Ideally, get it refreshed and set up by someone who knows their stuff.

Leaks

The clutch slave cylinder and water-pump shaft seal are known weak points on the LC8 motor. Look for any weeps from the clutch and also inspect the oil level indicator for any signs of moisture that might indicate the shaft seal is on its way out.

Verdict: 7/10

About £4500 will get you a good 990 Super Duke, possibly even an R, and at that price it makes a lot of sense. Get it to an expert for a once-over and then enjoy.

+ Engaging engine, great chassis mad looks

– Reliability can be an issue

Tech Data

2005-2013 KTM 990 Super Duke

Engine

Type: 999cc, liquid-cooled, 8v, 75-degree V-twin
Bore x stroke: 101 x 62.4mm
Compression: 11.5:1
Fuelling: EFI
Tested power: 109bhp @ 9600rpm
Tested Torque: 93Nm @ 6600rpm

Chassis

Frame: Steel trellis
F suspension: 48mm WP inverted forks, fully adjustable
R suspension: WP monoshock, fully adjustable, twin speed
Front brakes: Four-piston calipers, 320m discs
Rear brakes: One-piston caliper, 240mm disc

Dimensions

Wheelbase: 1450mm
Seat height: 850mm
Dry weight: 186kg
Fuel capacity: 18.5 litres

SPEED

0-60: 3.13s
0-100: 6.71s
0-150: N/A
Stg ¼ mile: 11.26s @ 122.85mph
Standing mile: 30.68s @ 146.91mph
Top speed: 149mph

Also consider these

2007 Triumph Speed Triple 1050

Private: £4000 Dealer: £4500

A great sporty naked with a superb triple motor. The Triumph isn’t as agile as the Duke, but it has bags of character and is much easier-going.

Engine: 1050cc, liquid-cooled, 12v, triple
Power: 116bhp @ 9100rpm
Torque: 103Nm @ 8700rpm

2007 Aprilia Tuono Factory

Private: £3800 Dealer: £4300

The ‘twin pipe’ second generation of Tuono is a bit top-heavy, but with the R version you get all the kit – and it is still remarkably cheap.

Power: 119bhp @ 9300rpm
Torque: 96Nm @ 8300rpm

2009 Ducati Streetfighter

Private: £6300 Dealer: £7000

Powered by a 1098 engine, the Streetfighter is a fairly serious bit of kit and feels much more advanced than the Duke. Classy but expensive, especially the S model.

Engine: 1099cc, l/c, 8v, desmo, V-twin
Power: 140bhp @ 10,000rpm
Torque: 104Nm @ 9500rpm