2005–2007 · Naked Bike · Buyer's Guide
One Thumper, Zero Apologies
The 640 Duke 2 is KTM's big single dressed for the street, and it is honest about it. The 625 cc liquid-cooled single makes 57 hp and 42 lb-ft. Those numbers look modest until you feel the torque arrive in fat, distinct pulses. It sits in a steel double-cradle frame with an upside-down fork, a single 320 mm (12.6 in) front disc and 17-inch wheels, so it steers like something far lighter than its stance suggests. The insect-faced styling and twin under-seat exhausts make it one of the most recognizable nakeds of its time. Nothing electronic sits between you and the engine: no ABS, no traction control, no ride modes.
On a tight back road it is a joy. The steering is light, the lean clearance is deep and the front end talks to you clearly, so you carry speed with very little drama. In town it threads through traffic just as easily. It is cheap to run, and routine work is simple enough to do yourself. The caveat is real, though. The tank holds only 3.0 gal (11.2 L), and the single never lets you forget what it is. This bike is for a confident rider who wants sharpness and doesn't need comfort.
Spec sheets don't ride bikes, but they set the baseline.
| Power | 57 hp (42 kW) @ 7,000 rpm |
|---|---|
| Torque | 42 lb-ft (57 Nm) @ 5,500 rpm |
| Displacement | 625 cc |
| Engine | Single-cylinder |
| Cooling | Liquid-cooled |
| Gearbox | 5-speed |
| Final drive | Chain |
| Fork | Upside-down (USD) |
| Front brake | 320 mm |
| Front tire | 120/70-17 |
| Rear tire | 160/60-17 |
| Wheelbase | 57.5 in (1460 mm) |
| Seat height | 35.4 in (900 mm) |
| Fuel capacity | 3.0 gal (11.2 L) |
| Fuel economy | 34 mpg (US) |
Much of what I know about how the Duke II lives with its owners comes from years of listening: talk in the paddock, club nights, owners chatting over coffee, and the emails riders send me. The pattern for this bike is consistent. People love the engine and the chassis, and they accept that the bike asks a lot of their body in return.
The engine comes up more than anything else in owner talk. Riders describe a punchy midrange followed by a real rush near the top, and many admit it pushes them to ride harder than they planned. The chassis gets almost as much praise. Owners say that once the bike is committed to a corner it holds its line with real precision, and they credit the stiff frame and WP suspension for how sharp it feels.
Buzz is the complaint riders raise most often. Owners feel it through the bars, the pegs and the tank, and on longer stints it ends in numb hands and feet. Taller riders say they feel perched on the thin, firm seat, and there is barely any room for a passenger. A smaller group mentions the engine's thirst. Real-world range of around 100 miles (160 km) is fine for a play ride but not for touring.
Where this KTM 640 Duke 2 pulls ahead of — or falls behind — its rivals on the numbers, and the typical bike in its class on character.
Power
Torque
Displacement
Seat height
Forget spec-sheet bragging. Here's who the 640 Duke 2 is actually built for.
For the canyon roads above LA, this fits. It's light, talkative and happiest in the tight stuff. Just don't expect it to pull hard on the long straights, because it rewards precision, not horsepower.
Made for Angeles Crest Highway · Coronado Trail / US 191 · Highway 1 / Big Sur
It makes Hill Country back roads a blast, but it's no road-trip bike. The small tank and buzzy single suit shorter loops with plenty of stops, not long highway hauls.
Made for Austin / Texas Hill Country · Twisted Sisters · Austin / Handbuilt Motorcycle Show
If you ride the Dragon to sharpen your technique rather than chase top speed, this is your kind of bike. Light steering and deep lean clearance let you work on your lines all day.
Made for Back of the Dragon · Blue Ridge Parkway · Cherohala Skyway
If this one isn't quite the fit, these are the bikes worth riding back-to-back against it.
