Engine architecture
Single → V-twin → Single → Twin
KTM has tried every middleweight engine layout under the Duke name. 620 Duke single, 990 Super Duke V-twin, 690 Duke single again, then 790/890 Duke parallel twin. Each generation chose a different answer to the question of what makes a Duke.
Power gain
+73bhp
50bhp 620 Duke → 123bhp 990 Duke. Nearly two and a half times. The category KTM essentially invented (supermoto-naked) has gone from quirky single-cylinder to mainstream parallel twin in 30 years.
What stays the same
Light, sharp, aggressive
Every Duke is light for its class. Every Duke has aggressive geometry. Every Duke has WP suspension and Brembo brakes. KTM brand identity (Ready To Race) shapes the bike more than any single engine choice.
Real cost change
+£1.0k
620 Duke was about £5,000 in 1996 (£10,000 today). The 2026 990 Duke (which replaced the 890 Duke for 2024) is £10,999 — about 10% more in real terms. KTM premium has stayed roughly constant. Note: the 890 Duke standard was discontinued; KTM now sells the 947cc LC8c-powered 990 Duke as its mid-naked, with the 790 Duke revived as the entry-level twin.
Why the twin won
Right balance
The LC8c parallel twin makes V-twin character with parallel-twin packaging benefits. Light enough to keep the Duke geometry sharp, powerful enough to compete with the Yamaha and Triumph triples. The 947cc 990 Duke version pushes well beyond A2 limits — KTM offers the 790 Duke (also LC8c, smaller) for A2 riders.
Rider aids count
0 → 9
1996: nothing. 2026: cornering ABS, MSC, traction control, slide control, wheelie control, ride modes (4 inc Track), quickshifter, IMU electronics, smartphone connectivity. KTM electronics are class-leading.
Cheapest way in
£2k
A clean KTM 620 Duke from the mid-90s. The bike that started a category. Single-cylinder thumper with WP suspension, light, simple, characterful. Becoming sought-after as the supermoto-naked category continues to grow.
