Faults:

The bike stalls, shuts off intermittently, or is difficult to start when cold.

Loss of pressure in the lever, difficulty engaging gears, or hydraulic fluid leaks.

The temperature rises rapidly when driving in the city or in heavy traffic. The single-cylinder engine generates a lot of heat, and the standard ventilation system may be insufficient under those conditions.

Gear indicator or neutral indicator that fails on the dashboard, or unexpected battery discharge.

The engine requires rigorous maintenance. It's normal for it to consume some oil between changes, so you should check the level frequently to avoid severe internal damage.

General Comments:

The Duke 690 is like a toy, a BMX with a motor. It turns with very little effort and leans easily until it almost touches the ground. There's no need for tricks or sudden maneuvers; just look where you want to go and you're there.

At just 148.5 kg, it's incredibly light. The moment you lift the Duke off its side stand, you'll instantly notice its lightness. This makes city riding much easier and allows the Duke to corner with astonishing agility.

The Duke's lightness also has its fun side: less weight means better handling and more enjoyment. It turns with very little effort and leans easily until the footpegs are almost touching the ground. You don't need to lean too far or countersteer; just look where you want to go and you're already there. The non-adjustable WP suspension is impressive as standard, even on the track.

Track package includes the MSR (engine slip regulation) system, which prevents the rear wheel from locking up during hard downshifts by increasing engine revs. It also features the optional Supermoto braking system; while the ABS only operates on the front wheel, the rider controls the rear.

The engine is a redesign of the old 690; in fact, very little of the original engine remains. The cylinder bore has increased by 3 mm, but the stroke has been reduced proportionally, maintaining the same displacement. The cylinder head has been significantly improved, resulting in a 7% increase in power, to 73 hp, and a 6% increase in torque, to 54.48 lb-ft. The new engine also revs 1,000 rpm higher, to 9,000 rpm; peak power is delivered at 8,500 rpm, which is astonishing for a single-cylinder engine, as is its smoothness and refinement.

Engine quality is truly impressive, as is the technology behind it. The WP engine doesn't feel cheap; the components used are high-quality, but this is reflected in its price.

The full-color gauges are an elegant detail that gives the 690 a premium feel. The gauges change color depending on the light, automatically switching to a night mode for easier reading.

When the engine is cold, the digital tachometer displays blue, orange by default, and turns red when it reaches the redline. ABS comes standard, as do the WP suspension and Brembo brakes.

In short, the KTM 690 Duke is truly impressive: it would undoubtedly be a must-have motorcycle in any garage. Its engine is versatile, smooth, easy to handle, and responds well at high revs. Its light weight makes it a very maneuverable, fun, and enjoyable motorcycle, perfect for climbing mountain hills or navigating city traffic with agility.