Dedicated Subsystem WorkbenchPlatform Gen: 2017–2024
2019 KTM 390 Duke Oil Capacities, Coolant & Fluid Specifications
Verified fluid capacities for 2019 KTM 390 Duke: engine oil 1.60 L (1.69 US qt), viscosity Motorex Formula 4T 15W-50 JASO MA2, coolant 1.20 L (1.27 US qt), brake fluid, and fork oil levels.
Gen 2017–2024
Factory Platform Compatibility: All workshop fluid capacities, maintenance milestones, torque specifications, and consumables on this specification sheet are factory-identical across model years 2017 through 2024.
Engine
373cc
Drive
520
Cooling
Liquid-Cooled
Fluids & Service Capacities
Shop Fluids →Engine Oil (Drain & Filter Change)1.60 L (1.69 US qt)
Engine Oil (Drain Only)1.50 L (1.59 US qt)
Recommended Oil ViscosityMotorex Formula 4T 15W-50 JASO MA2
Coolant System Capacity1.20 L (1.27 US qt)
Brake Fluid StandardDOT 4
Drivetrain, Chain & Gearing
Shop Chains & Sprockets →Drive Chain Pitch520
Chain Link CountN/A
Front Sprocket TeethN/A
Rear Sprocket TeethN/A
Final Drive Configuration520 Pitch Chain
Ignition & Electrical Specifications
Shop Plugs & Batteries →OEM Spark Plug Part NumberBosch VR5NEU / NGK LKAR8A-9
Electrode Spark Plug Gap0.8 mm (0.031 in)
OEM Battery Reference CodeYTX9-BS
Battery Output & Rating12V 8Ah 135 CCA
Spark Plug Inspection Interval9,300 miles (15,000 km)
Wheels, Tires & Inflation Pressures
Shop Tires →Front Tire Dimensions110/70R17
Cold Front Inflation Pressure29 PSI (Cold)
Rear Tire Dimensions150/60R17
Cold Rear Inflation Pressure32 PSI (Cold)
OEM Wheel Rim Widths (F / R)3.50" / 5.50"
Factory Liquid Cooling Hydraulics
Engine Cooling System Hydraulics, Thermostat & Antifreeze Calibration
Fluid capacity, silicate-free chemistry, thermostat opening bench tolerances, and radiator cap relief pressure for the 2019 KTM 390 Duke.
Factory Hydraulic Capacities & Pressurization
Total Cooling Capacity
1.2 L
Radiator + Jacket + Reservoir
Radiator & Engine Jacket
1 L
Circulating loop volume
Expansion Reservoir
0.2 L
Cold fill to MIN line
Radiator Cap Relief Spec
1.4 bar
140 kPa valve release
OEM Chemical Mandate: 100% Silicate-Free Ethylene Glycol (OAT)
Recommended: Motorex Coolant M3.0 (OAT Silicate-Free Ethylene Glycol). Traditional automotive green coolants contain silicates that precipitate as microscopic sand crystals, scouring and destroying motorcycle ceramic water pump mechanical seals within 5,000 miles. Always dilute with pure distilled water; tap water minerals bond to hot aluminum cylinder liners and cause localized boiling hot spots.
Interactive Antifreeze Concentration & Protection Engine
Concentration: 50% Concentrate / 50% Distilled Water
Freeze Point Protection
-37°C
Coolant remains slush-free without expanding or cracking aluminum cylinder water jackets.
Boiling Point (Under 1.4 bar Cap)
128°C
Pressurized protection prevents localized steam pockets and head gasket blowout.
Workshop Batch Mixing Recipe
Concentrate: 0.6 L
Distilled Water: 0.6 L
Pre-mix together in clean container before pouring into radiator filler neck.
Thermostat Stove-Top Bench Testing Simulator
Water Bath Temperature: 25°C (77°F)
Thermostat Valve Lift Height0.0 mm / 8.0 mm Min
VALVE SEALED COLD (25°C / 77°F) — NORMAL WARM-UP
Workshop Bench Technique: Suspend thermostat on a wire suspended in a beaker of water with a digital thermometer. Do NOT let thermostat touch the metal bottom of the pan. Heat slowly; valve must crack at 82°C and open at least 8 mm by 95°C. If it opens late or fails to reach 8 mm, replace thermostat immediately.
Radiator Cap Pressure Tester Diagnostic
Holding Spec: 1.4 bar (20.3 psi)
Motorcycle radiator caps feature a calibrated spring that holds hydraulic pressure inside the radiator. Every 1 psi of pressure elevates the coolant boiling point by 3°F.
Symptom: Mystery Boil-Over at Traffic Stops
If a bike runs cool at 60 MPH but immediately burps coolant into the reservoir and overflows onto the ground at stoplights, test the cap with a Stant pressure tester. An aged cap venting early at 0.7 bar (10 psi) lets coolant flash into steam at 115°C instead of 128°C.
Five-Step Workshop Air-Burp Protocol
Drain Plug: 10 N·m1
Drain & New Washer
Remove water pump drain bolt and cylinder jacket drain. Replace copper/aluminum crush washer; torque to 10 N·m.
2
Slow Gravity Fill
Pour pre-mixed coolant slowly into radiator filler neck so air bubbles have time to vent upward.
3
Hose Kneading
Firmly squeeze upper and lower radiator hoses by hand to dislodge air bubbles trapped in the water pump impeller and cylinder head.
4
Thermostat Cycle
Idle engine with radiator cap off. Wait for thermostat to crack open at 82°C. Level will burp and drop; immediately top off.
5
Reservoir Cold Fill
Fill expansion reservoir between MIN and MAX marks. Install pressure cap past first safety detent to full lock.
BRAKING SYSTEM HYDRAULICS, WEAR LIMITS & CALIPER REBUILD MATRIX
Rotor Discard Limits (Tmin) • Caliper Piston Architecture • Pad Compounds • Hydraulic Bleed Specs
FACTORY CERTIFIED SPECIFICATIONS
Front Rotor Discs
320 mm × 5 mm
Discard Limit: 4.5 mm Tmin
Rear Rotor Disc
230 mm × 4 mm
Discard Limit: 3.6 mm Tmin
Caliper Architecture
ByBre 4-Piston Radial Monobloc Caliper (Single 320mm)
Rear: ByBre 1-Piston Floating Pin-Slide Caliper
Hydraulic Fluid Standard
DOT 4 Synthetic Glycol
Dry BP ≥ 260°C • Wet BP ≥ 165°C
Caliper Bolt Torques (NM)
Mount: 40 N·m
Banjo: 25 N·m • Bleed: 6 N·m
Friction Material Lining
Sintered Metallic (Front)
Discard Pad at ≤ 1 mm
DIGITAL MICROMETER ROTOR WEAR DIAGNOSTIC GAUGE
Measure rotor friction ring with a pointed blade micrometer to verify safe thermal mass and discard limits
Enter Measured Disc Thickness (mm)
mm
Nominal New: 5.00 mm • Stamped Discard: 4.50 mm Tmin
Quick Benchmark Simulation Presets
Enter your micrometer rotor reading above or click a simulation preset to calculate remaining disc service life and discard safety status.
BRAKE PAD FRICTION COMPOUND & METALLURGY MATRIX
Compare OEM sintered metallic, organic carbon-ceramic, and racing compound friction dynamics
Compound Architecture
Double-H (HH) Sintered Metallic Compound
Friction Rating & Thermal Operating Envelope
HH Rated (μ ≥ 0.55 across cold and hot temperature zones)
0°C – 650°C (32°F – 1,200°F) • Exceptional High-Temp Fade Resistance
Lever Modulation & Initial Cold Bite
Sharp, aggressive initial bite with linear lever feel and minimal thermal hysteresis under repeated heavy slowdowns.
Rotor Wear Index & Wet Weather Recovery
Moderate to high rotor abrasive index. Requires hardened stainless steel rotors; not compatible with cast iron discs. • Superior wet recovery. Metallic sintered composition cuts cleanly through surface water film without delaying pad response.
Application & Recommended Riding Profile
Recommended for modern high-performance street motorcycles, spirited canyon riding, two-up touring, and occasional trackdays.
Hydraulic Fluid Bleeding & Caliper Overhaul Protocol
Hygroscopic Moisture Curve
Glycol brake fluid absorbs 2%–3% atmospheric water annually. Over 24 months, boiling point collapses from 260°C (500°F) to below 165°C (329°F), risking sudden vapor-lock brake loss. Flush fluid every 2 years.
Piston Seal Rollback Function
Caliper square-profile rubber seals flex under pressure to retract pistons ~0.15 mm when pressure drops. Hardened or dirty seals prevent rollback, causing continuous pad drag, glazed rotors, and fuel mileage loss.
Bleeder Torque & Sequence
Bleed master cylinder first, then furthest caliper, then nearest caliper. Tighten bleeder nipples to strictly 6 N·m. Over-tightening permanently shears threads in aluminum calipers.
Direct-Fit Braking Components & Hydraulic Fluids
Authentic double-H sintered pads, replacement floating rotors, and high-temp racing brake fluid
1-Click Factory Service KitOEM Spec Fluid Capacities Matched
Workshop Maintenance Kit & Factory Fluids
Authentic factory-grade motor oil, oil filter, and high-temp brake fluid matched precisely to 2019 KTM 390 Duke capacities.
Full Kit Subtotal
$86.49
Matches factory 15W-50 spec (Oil spec: 1.60 L (1.69 US qt))
Item Price
$68.95
Premium OEM-spec replacement with 17mm hex nut
Item Price
$11.99
DOT 4 Synthetic Formula
EBC High-Performance DOT 4 Synthetic Brake Fluid
8.8 oz (250 ml) Workshop Bottle
Meets & exceeds factory DOT 4 specifications
Item Price
$5.55
Factory OEM Spark Plug Spec
Bosch VR5NEU / NGK LKAR8A-9
Gap: 0.8 mm (0.031 in)
Inspection milestone: 9,300 miles (15,000 km). Exact factory part specification.
Authentic OEM Reference
Search OEM Plugs →Explore Other Subsystems for this 2019 KTM 390 Duke
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Subsystem Guide/torques
Fastener Torques
Engine drain plug, axle spindles, caliper mounts, triple clamp pinch bolts & thread lubrication derating guide.
Open Dedicated Workbench →
Subsystem Guide/fuses-relays
Fuses & Relays
Main: 30A Blade / Starter Relay • Location: Under rider seat
Open Dedicated Workbench →
Subsystem Guide/compression
Compression & Leakdown
Ratio: 12.6:1 • Std: 165-205 PSI • Limit: 135 PSI
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Subsystem Guide/valves
Valve Clearances
Intake: N/A mm • Exhaust: N/A mm
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Subsystem Guide/fuel-delivery
Fuel Delivery & TB Sync
Idle: N/A • Rail Pressure: N/A • Vacuum: N/A
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Subsystem Guide/electrical
Charging & Battery
Battery: YTX9-BS (135 CCA) • Regulated: 14.2 - 14.8 V DC (at 5,000 RPM with High Beam)
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Subsystem Guide/tires
Tires & Gearing
Front: 110/70R17 (36 PSI) • Rear: 150/60R17 (42 PSI)
Open Dedicated Workbench →
Subsystem Guide/suspension
Suspension & Sag
Front Travel: 142 mm • Rear Travel: 150 mm
Open Dedicated Workbench →
Subsystem Guide/maintenance
Maintenance Schedule
Oil: Every 4,650 miles (7,500 km) mi • Valves: Every 26,600 mi • Spark Plugs: Every 9,300 miles (15,000 km) mi
Open Dedicated Workbench →
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