KTM 640 Duke II


Make Model

KTM 640 Duke II 


1998 - 00


Four stroke, single Cylinder. SOHC, 4 valves, engine balancer


624.6 cc / 38.1 cu in
Bore x Stroke 101 x 78 mm
Compression Ratio 11.5:1
Cooling System Liquid cooled
Lubrication 2 x Eaten oil pumps


Mikuni BST 40 carburetor


Kokusan contactless DC-CDI ignition with advanced system


Electric & kick

Spark Plug



12V 8Ah, maintenance free

Max Power

40.1 kW / 55 hp @ 7000 rpm

Max Torque

60 Nm / 6.1 kgf-m / 44.3 lb-ft @ 5500 rpm


Multi-disc in oil bath


5 Speed

Primary Drive Ratio

30:81, straight cut gears

Gear Ratios

1st 14:35 / 2nd 15:24 / 3rd 18:21 / 4th 20:19 / 5th 22:18

Final Drive Ratio


Final Drive

Chain, O-ring 5/8 x 1/4"


Central chrome-moly steel frame

Front Suspension

WP - 4054 Roma Top adjuster, preload, compression and rebound adjustable

Front Wheel Travel

140 mm / 5.5 in

Rear Suspension

Central shock absorber WP IBS with PRO-LEVER linkage to rear- swing-arm with needle bearing

Rear Wheel Travel

170 mm / 6.7 in

Front Brakes

Single 320 mm disc, 4 piston caliper

Rear Brakes

Single 220 mm disc, 1 piston caliper

Front Tyre

120/70 - ZR17 58H

Rear Tyre

160/60 - ZR17 69H

Steering Head Angle



1460 mm / 57.5 in

Ground Clearance

250 mm / 9.9 in

Seat Height

860 mm / 33.9 in

Dry Weight

145 kg / 320lbs


350 kg / 773 lbs

Engine Oil Capacity 

2.2 L / 2.3 US qt / 1.9 Imp qt

Fuel Capacity 

11.3 L / 3.0 US gal / 2.4 Imp gal

Standing ¼ Mile  

12.5 sec

Top Speed

162 km/h / 101 mph

AN ANGUISHED HOWL OF RUBBER AGAINST PAVEMENT ECHOES off the surrounding buildings as the peculiar machine slows for a comer. Tail hung well out in a controlled brake slide as the fat rear tire scribes a dark arc deep into the apex. Confident in the bike's capability, the rider dials on the power and completes the corner in a crossed-up wheelie. A few more hot laps around the curbed islands and li, poles, and it's time to get out of Dodge before the sheriff arrives...

Okay, so an occasional late-night romp through a vacant shopping-center parking lot may not be the most responsible two-wheeled behavior, but are we to blame for the company we keep? It's a classic case of guilt by association when a KTM Duke II is your accomplice. "Tlie bike made me do it, officer, honest."'

Since its 1994 release, KTM's street-legal supermotard bike has amassed a reputation for pavement play. Talk to any sport rider who has crossed paths with one of these "Dukes of Hazard," and you'll likely hear tales of wild wheelies, eye-popping stoppies and an uncanny ability to gun down bikes twice its size in the twisties.

Over the years, the Duke has grown increasingly popular, and has received minor updates, including an electric starter in '96, and 16cc of added displacement two years ago. With the Duke II comes further street refinement and new wrappings that keep step with the current styling of KTM's LC4 off-road models. Sharper-edged lines have replaced the rounded body contours of its predecessor, giving the Duke II a more compact and aggressive appearance. Viewed from the front, the vertically stacked projector-beam headlight array commands attention, resembling that of the Suzuki Hayabusa and Italian exotics such as the MV Agusta F4 and Benelli Tornado Tre.

Other updated bits include Italian-made BBS cast-alloy wheels in place of the previous wire-spoked Akronts. The front rim still measures 3.5 x 17 inches^, while the rear has grown .25-inch wider to 4.5 x 17 inches. Apart from their stylish looks-closely resembling BBS's race-car rims-the new wheels are tubeless. A stout, new 43mm WP inverted fork replaces the old Duke's 40mm legs, and there's a stiffer swingarm, too.

A tush tuck has cleaned-up the Duke's tail, as the bike now shoots from both hips with dual muffler cans positioned, Ducati 996-style, beneath its seat. The double-barreled arrangement recalls the Vickers machine guns mounted on the business end of a Sopwith Camel. Backroad dogfighters beware!

It may sound like tall talk coming from a rider astride a humble 626cc Single, but the Duke's off-road-bred chassis makes it a fierce scrapper on its home turf. Loads of cornering clearance, grippy Bridgestone BT93 Battlax radials, tractable power delivery and no small helping of attitude are the ingredients for setting a blistering pace through any tight series of switchbacks. And if the road surface suddenly rums bad, no problem-the Duke's suspension eats up bumps and potholes like few streetbikes can.

Unlike a conventional long-travel dual-sport machine, the Duke II makes do with just 5.5 inches of front-wheel movement and 6.7 inches at the rear. With its spring and damping rates calibrated for road work, fore-and-aft chassis pitching is minimal. The only handling quirk we encountered was fair bit of fork dive when the front brake was suddenly applied while leaned over in a corner-not a recommended riding practice by any means.

But when it comes to dealing with a dicy situation, the Duke II has the instincts of a cat. The wide Magura tapered-aluminum handlebar and dirtbike-inspired riding position instill an uncanny sense of control when ridden to the limit, even over the roughest pavement. And wet road conditions? Pour it on!

As for negotiating urban traffic, riding the KTM is like having the keys to the city. Its 35-inch-high seat provides a clear line of sight over the tops of cars, yet it's low enough for riders of average inseam to find a firm footing at stops. And the bike's light weight, coupled with torque-rich power delivery right off the bottom, gets the drop on the rush-hour rat race every time.

Ride a Duke about town for long, and you begin to perceive your environment differently. A raised manhole cover is no longer an obstacle to avoid, but a chance to catch some free air! Ditto for speed bumps or sudden elevation changes. Low-traction surfaces add another fun element to any urban hard-cross course.

Pulling wheelies is simply a matter of rolling on the gas in low gear or snapping the throttle open along with a light tug on the bar in second. True, the KTM is no match for multi-cylinder sportbikes in straight-line acceleration, but among its one-lunged peers, the Duke makes no apologies. Its liquid-cooled, four-valve, four-stroke engine churned out 49 horsepower and 42 foot-pounds of torque on CfFs rear-wheel dyno. Accelerating through the slick-shifting five-speed gearbox is swift and effortless, evidenced by its 99-mph quarter-mile trap speed and gearing-limited, 108-mph top speed. At freeway speeds, there is more than enough juice in reserve to cleanly pull roll-on passes without kicking it down a gear.

A gear-driven counterbalancer helps keep engine vibes at an acceptable level. At lower revs, the power pulses are soul-stirring, but as engine speeds exceed 5000 rpm-an indicated 75 mph in top gear-a high-pitched buzz develops, making long freeway hauls taxing. The stylish mirrors provide very good views to the rear, but are inflicted with a healthy buzz. A good practice is to periodically pull in the clutch and let the revs fall to idle, and then check your mirrors for the fuzz.

In fact, hanging onto your driver's license is quite probably the greatest challenge you'll face as a Duke II owner. While speeding citations are the bane of any sport rider's existence, Duke riders are just as likely to rack up "exhibition of speed" or "reckless driving" charges.

Best of luck with the-Duke-made-me-do-it defense. If all else fails, plead insanity. S

Source Cycle World 1999