The KTM 640 Duke II stands as a bold and aggressive street machine, representing KTM’s unique approach to naked motorcycles. Built with Austrian precision, this bike blends supermoto agility with daily rider practicality. Whether you’re an enthusiast seeking a lightweight performance bike or a city commuter wanting something different, the KTM 640 Duke II delivers in style, speed, and substance.
A Brief History of the KTM 640 Duke Series
The Duke series first made headlines in the mid-1990s as KTM’s foray into road bikes. The KTM 640 Duke II, introduced in the early 2000s, quickly gained recognition for its unapologetically raw character and aggressive design.
Unlike traditional sport bikes, the 640 Duke II took inspiration from KTM’s off-road lineage. The result was a street-legal supermoto that could handle twisty backroads, city traffic, and even the occasional gravel path with equal enthusiasm.
KTM 640 Duke II Design & Styling
Aggressive, Minimalist Design
The KTM 640 Duke II sports a sharp, minimalist design with supermoto DNA written all over it. With its tall stance, high front fender, and angular tank shrouds, the Duke II looks more like a dirt bike outfitted for the road.
Its high seat position gives the rider a commanding view, while the minimalistic bodywork ensures low weight and easy maneuverability. The bike’s signature twin under-seat exhausts enhance its aggressive look and emit a throaty growl that turns heads on the street.
Build Quality & Finish
Austrian engineering shows in the build quality. The KTM 640 Duke II uses a lightweight chrome-molybdenum steel trellis frame that’s both strong and agile. High-end components like Brembo brakes and WP suspension come standard, giving the bike a premium feel despite its bare-bones aesthetic.
Engine and Performance
Engine Specifications
At the heart of the KTM 640 Duke II is a 625cc liquid-cooled, single-cylinder, 4-stroke engine, commonly referred to as the LC4. Here are the key specs:
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Engine Type: Single-cylinder, 4-stroke, SOHC
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Displacement: 625 cc
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Cooling: Liquid-cooled
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Horsepower: Approximately 55 hp
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Torque: Around 60 Nm
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Transmission: 5-speed manual
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Fuel System: Mikuni BST 40 carburetor
This engine is known for its torque-heavy performance and punchy mid-range power. Though not the smoothest powerplant due to its single-cylinder layout, it’s responsive and fun, especially for urban riders and twisty mountain roads.
Riding Experience
The KTM 640 Duke II is designed for thrill-seekers. It accelerates briskly, thanks to its light weight (around 149 kg dry) and torquey engine. It feels nimble and responsive, allowing for quick changes in direction—ideal for darting through traffic or carving up curvy roads.
The bike’s upright riding posture and wide handlebars give the rider excellent control. However, its tall seat height (approximately 865mm) may be intimidating for shorter riders. Also, due to the thumping nature of the LC4 engine, vibrations are noticeable, particularly at highway speeds.
Suspension & Handling
The KTM 640 Duke II excels in the handling department. It comes equipped with:
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Front Suspension: 43mm WP upside-down forks
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Rear Suspension: WP monoshock with adjustable preload and rebound
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Brakes: 320mm front disc with Brembo caliper, 220mm rear disc
These high-quality components translate into outstanding road feel and confidence-inspiring performance. The suspension is firm, tuned for sporty riding rather than long-distance comfort, which fits the Duke II’s supermoto character.
The brakes are powerful and provide excellent feedback, allowing for aggressive riding with plenty of stopping power.
Wheels and Tires
The Duke II rides on lightweight 17-inch alloy wheels wrapped in sportbike-grade tires, giving it excellent road grip. This setup, combined with its suspension and light chassis, makes the bike feel planted in corners and responsive in quick maneuvers.
Comfort and Practicality
While the KTM 640 Duke II is primarily designed for fun and agility, it isn’t the most comfortable option for long-distance touring. The seat is relatively hard, and the lack of wind protection means highway cruising can be fatiguing.
However, in an urban environment or on winding country roads, it’s hard to beat. Its lightweight and nimbleness make it a favorite for city dwellers who want a spirited ride without the bulk of a full-size sportbike.
Fuel Efficiency
Thanks to its single-cylinder engine, the KTM 640 Duke II is relatively fuel-efficient. Riders can expect an average of 45-55 mpg (5-6 L/100km) depending on riding style. The fuel tank holds approximately 11 liters, providing a decent range for commuting and weekend rides.
KTM 640 Duke II Price and Availability
When it was launched, the KTM 640 Duke II was priced competitively within the premium single-cylinder segment. Today, it is no longer in production, but it holds strong value in the used market.
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Original MSRP (varies by market): Around $7,000 – $8,000 USD
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Used Market Price: $3,000 to $5,500 USD (condition-dependent)
Finding a clean example can be challenging, but for enthusiasts, it’s worth the search. Always look for models with proper maintenance records, especially regarding the engine and suspension.
Pros and Cons
Pros
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Lightweight and agile
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High-quality WP suspension and Brembo brakes
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Strong low-end torque
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Unique supermoto styling
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Excellent for city and backroad fun
Cons
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Noticeable engine vibrations
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Tall seat height
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Not ideal for long-distance touring
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Limited wind protection
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Out of production (harder to find parts)
Maintenance and Reliability
The KTM 640 Duke II is generally reliable when properly maintained, but its high-strung engine demands regular attention. Oil changes, valve checks, and routine inspections are crucial.
Common issues to look for include:
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Camshaft wear
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Water pump seal failures
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Chain and sprocket wear
Having a trusted mechanic familiar with KTM bikes or a willingness to perform DIY maintenance is recommended for long-term ownership.
Who Should Buy the KTM 640 Duke II?
The KTM 640 Duke II is perfect for:
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Riders who want a lightweight, powerful street machine
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Supermoto enthusiasts
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Experienced riders looking for something different from typical sportbikes
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City commuters wanting agile performance with a bit of flair
However, it’s not ideal for those seeking a beginner-friendly bike, long-distance comfort, or minimal maintenance.
Conclusion
The KTM 640 Duke II remains one of the most exciting and distinctive motorcycles to come out of KTM’s lineup. With its supermoto roots, aggressive styling, and torquey engine, it offers a unique riding experience that few other bikes can match.
Though no longer in production, it continues to enjoy a cult following among motorcycling enthusiasts who appreciate its raw character and uncompromising performance. If you’re in the market for a used motorcycle with spirit and edge, the KTM 640 Duke II should definitely be on your radar.
