2021 KTM 390 Duke Specifications

Name: 2021 KTM 390 Duke
Brand: KTM

Sport • Specs last verified 13 July 2026

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2021 KTM 390 Duke Overview

For 2021, KTM offers the 390 Duke as a sport motorcycle with 373 cc on tap. The 2021 KTM 390 Duke is built around a Four stroke, single cylinder, DOHC with finger followers, 4 valves engine, a compression ratio of 12.6:1. Out on the road, the 390 Duke delivers 43.5 hp @ 9500 rpm of peak power and 37 Nm @ 7000rpm of torque. In everyday use, the 2021 390 Duke tips the scales at 149 kg, carries a 13.4-litre fuel tank, offers a seat height of 830 mm and spans a 1357 mm wheelbase. That's roughly 53.7 kg lighter than the average sport motorcycle in our database. Every technical detail, from suspension travel to tyre sizes, is covered in the full 2021 KTM 390 Duke spec sheet below.

2021 390 Duke - Pros & Cons

Strengths

Strong power output: Peak output on the 390 Duke is 43.5 hp @ 9500 rpm and 37 Nm @ 7000rpm of torque - strong numbers for what it is.
Fuel injection: No choke, no jetting, no altitude compensation to think about - fuel injection just works across a wider range of conditions than carburetion.

Considerations

Tall seat height: A 830 mm seat puts flat-footing out of reach for a lot of riders - sit on it in person before committing.
Chain final drive upkeep: A chain drivetrain is the most common setup in its class, but it's also the one that demands the most regular hands-on maintenance.

Wear Points & Servicing Notes

Cooling system servicing

With Liquid Cooled, thermal management is largely automatic, but the coolant has a service life of its own - replace it on the manufacturer's interval to protect the water passages and thermostat.

Fuelling & injector care

Fuelling on the 390 Duke comes from Bosch Injection. Cold starts and throttle response stay consistent across altitude and temperature, the main practical edge over a carbureted equivalent.

Brake disc and pad wear

Single 320 mm disc, 4 piston radial fixed caliper up front provides the primary stopping power; inspect disc thickness and pad wear at each tyre change to catch scoring before it becomes a rotor replacement.

Suspension condition on used examples

Suspension duties are handled by 43mm WP APEX 43 up front and WP APEX - Monoshock at the rear. Weeping fork seals aren't a dealbreaker on a used bike, but they're a fair basis for negotiating price.

Final drive maintenance

Chain final drive on the 390 Duke means routine lubing and tension checks are part of ownership - skip them and sprocket wear accelerates noticeably.

Frame & chassis check

The Steel trellis frame, powder coated chassis holds up well with normal use; on a used bike it's still worth checking the head-stock and swingarm pivot area for impact damage or corrosion.

390 Duke - Buying & Maintenance Guide

What to check before buying

A pre-purchase check on the 2021 KTM 390 Duke should cover the same ground every time: service history, chain and sprocket condition, and any oil seepage around the casings. Start it from cold if you can - a well-kept 390 Duke settles to a smooth idle within seconds.

Oil and filter changes

Oil changes are the cheapest insurance you can buy for a 390 Duke's engine - keep to the manufacturer's interval rather than stretching it. Use the viscosity grade the manual specifies, not whatever's on sale.

Fuel system care

Injector systems like the 390 Duke's hold up well with basic care - decent fuel, an occasional cleaner additive, and draining old fuel before any layup longer than three months.

2021 KTM 390 Duke - Frequently Asked Questions

What engine does the 2021 KTM 390 Duke have?

The 2021 KTM 390 Duke uses a Four stroke, single cylinder, DOHC with finger followers, 4 valves engine with 373 cc of displacement. It is liquid cooled.

How much does the 2021 KTM 390 Duke weigh?

The 2021 KTM 390 Duke weighs 149 kg. This is the manufacturer's dry figure.

How much power does the 2021 KTM 390 Duke make?

The 2021 KTM 390 Duke produces 43.5 hp @ 9500 rpm of power and 37 Nm @ 7000rpm of torque. These are peak figures.

What is the fuel tank capacity of the 2021 KTM 390 Duke?

The 2021 KTM 390 Duke has a 13.4-litre fuel tank. At around 5-6 litres per 100 km, that is roughly 223-268 km between stops.

Is the 2021 KTM 390 Duke suitable for shorter riders?

The 2021 KTM 390 Duke has a seat height of 830 mm. This is towards the tall end of the spectrum and will require most riders under 175 cm to tiptoe at stops.

What brakes does the 2021 KTM 390 Duke have?

The 2021 KTM 390 Duke uses Single 320 mm disc, 4 piston radial fixed caliper at the front and Single 230 mm disc, 1 piston floating caliper at the rear.

What tyre sizes does the 2021 KTM 390 Duke use?

The 2021 KTM 390 Duke runs 110/70 -17 front and 150/60-17 rear tyres. A good selection of sport, touring and all-weather rubber is available in these sizes.

What gearbox does the 2021 KTM 390 Duke have?

The 2021 KTM 390 Duke is fitted with a 6 Speed transmission.

KTM 390 Duke Spec Evolution

The KTM 390 Duke was produced across 6 model years (2014-2024). The table below highlights the key specifications that changed across the production run - useful whether you are comparing years or tracking down a specific variant.

Specification	2014	2016	2018	2020	2021	2024
Max Power	32 kW / 43.5 hp @ 9500 rpm	32 kW / 43.5 hp @ 9500 rpm	43.5 hp / 32 kW @ 9500 rpm	43.5 hp / 32 kW @ 9500 rpm	43.5 hp / 32 kW @ 9500 rpm	33 kW / 44.3 hp @ 8500 rpm
Dry Weight	139 kg / 306 lbs	139 kg / 306 lbs	149 kg / 328 lbs	149 kg / 328 lbs	149 kg / 328 lbs	-
Engine Detail	Four stroke, single cylinder, DOHC with finger followers, 4 valves per cylinder	Four stroke, single cylinder, DOHC with finger followers, 4 valves per cylinder	Four stroke, single cylinder. DOHC with finger followers, 4 valves	Four stroke, single cylinder. DOHC with finger followers, 4 valves	Four stroke, single cylinder, DOHC with finger followers, 4 valves	Four stroke, single cylinder, DOHC with finger followers, 4 valves
Seat Height	800 mm / 31.4 in	800 mm / 31.4 in	830 mm / 32.7 in	830 mm / 32.7 in	830 mm / 32.7 in	-
Fuel Capacity	11 L / 2.9 US gal / 2.4 Imp gal	11 L / 2.9 US gal / 2.4 Imp gal	13.4 L / 3.5 US gal / 2.9 Imp gal	13.4 L / 3.5 US gal / 2.9 Imp gal	13.4 Litres / 3.5 US gal	15 L / 4.0 US gal
Frame Type	Steel trellis	Steel trellis	Steel trellis frame, powder coated	Steel trellis frame, powder coated	Steel trellis frame, powder coated	Steel trellis frame, powder coated
Displacement	373.4 cc / 22.7 cu-in	373.4 cc / 22.7 cu-in	373 cc / 22.7 cu-in	373 cc / 22.7 cu-in	373 cc / 22.7 cu-in	398.7 cc / 24.3 cu-in
Wheelbase	1367 mm / 53.8 in	1367 mm / 53.8 in	1357 mm / 53.4 in	1357 mm / 53.4 in	1357 mm / 53.4 in	1357 mm / 53.4 in

Key Specifications

Engine

Four stroke, single cylinder, DOHC with finger followers, 4 valves

Power

43.5 hp / 32 kW @ 9500 rpm

Torque

37 Nm / 27.2 lb-ft @ 7000rpm

Top Speed

Not published by manufacturer

Weight

149 kg / 328 lbs

Fuel Capacity

13.4 Litres / 3.5 US gal

Full 2021 KTM 390 Duke Specifications

Year 2021

Make Model KTM 390 Duke

Seat Height 830 mm / 32.7 in

Wheelbase 1357 mm / 53.4 in

Ground Clearance 175 mm / 6.8 in

Dry Weight 149 kg / 328 lbs

Fuel Capacity 13.4 Litres / 3.5 US gal

Max Power 43.5 hp / 32 kW @ 9500 rpm

Max Torque 37 Nm / 27.2 lb-ft @ 7000rpm

Displacement 373 cc / 22.7 cu-in

Engine Detail Four stroke, single cylinder, DOHC with finger followers, 4 valves

Bore x Stroke 89 x 60 mm

Compression Ratio 12.6:1

Cooling System Liquid Cooled

Emissions EURO5

Fuel Induction Bosch Injection

Ignition Bosch EMS with RBW

Lubrication Wet sump

Starter Electric

Clutch Wet multi-disc clutch, hydraulically actuated

Final Drive Chain 520-X Ring

Transmission / Drive 6 Speed

Frame Type Steel trellis frame, powder coated

Suspension - Front 43mm WP APEX 43

Suspension - Rear WP APEX - Monoshock

Steering Head Angle 65°

Wheel Travel - Front 142 mm / 5.6 in

Wheel Travel - Rear 150 mm / 5.9 in

Brakes - Front Single 320 mm disc, 4 piston radial fixed caliper

Brakes - Rear Single 230 mm disc, 1 piston floating caliper

ABS Bosch 9.1MP Two Channel ABS (Supermoto ABS)

Tyres - Front 110/70 -17

Tyres - Rear 150/60-17

Specifications are compiled from manufacturer documentation and cross-referenced technical sources, and corrected on an ongoing basis. Spot an error? Let us know.