TECHNICAL SPECIFICATIONS

KTM 125 SX 2026 (EE. UU.)

2026–2026 125 SX (2026) US

125 cc 2T

MotorDataBook

Key specifications

The essentials of this version at a glance.

80/100 - 21 TT
Front tyre size
✓
100/90 - 19 TT
Rear tyre size
✓
2 Ah
Battery capacity
✓
Protección anticongelante como mínimo hasta −25 °C
Coolant specification
✓
1.27 US qt
Coolant capacity
✓
Batería de iones de litio
Battery technology
✓
DOT 4 / DOT 5.1
Brake fluid specification
✓
JASO T903 MA2
Transmission fluid specification
✓
2 items

Transmission & Drivetrain

Transmission fluid specification
JASO T903 MA2 ✓
Aceite del cambio (motor de 2 tiempos).
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 167 Verification: Verified Open document
Transmission fluid total capacity
0.85 US qt ✓
Aceite del cambio (motor de 2 tiempos): cantidad de llenado del aceite que se cambia.
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 151 Verification: Verified Open document
7 items

Brakes

Brake fluid specification
DOT 4 / DOT 5.1 ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 168 Verification: Verified Open document
Front brake disc diameter
10.24 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 151 Verification: Verified Open document
Front brake disc minimum thickness
0.1 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 151 Verification: Verified Open document
Rear brake disc diameter
8.66 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 151 Verification: Verified Open document
Rear brake disc minimum thickness
0.14 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 151 Verification: Verified Open document
Front brake pad minimum thickness
0.04 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 99 Verification: Verified Open document
Rear brake pad minimum thickness
0.04 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 106 Verification: Verified Open document
2 items

Wheels and tyres

Front tyre size
80/100 - 21 TT ✓
El manual da el tamaño según la versión; se toma la fila «Todos los modelos SX».
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 152 Verification: Verified Open document
Rear tyre size
100/90 - 19 TT ✓
El manual da el tamaño según la versión; se toma la fila «Todos los modelos SX».
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 152 Verification: Verified Open document
5 items

Motorcycle Specific

Drive chain size
5/8 x 1/4" ✓
Paso y ancho interior de la cadena en pulgadas, tal como los da el manual.
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 152 Verification: Verified Open document
Drive chain slack minimum
2.28 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 87 Verification: Verified Open document
Drive chain slack maximum
2.4 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 87 Verification: Verified Open document
Front axle torque
25.81 lb-ft ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 163 Verification: Verified Open document
Rear axle torque
59 lb-ft ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 163 Verification: Verified Open document
2 items

Engine & Fluids

Coolant specification
Protección anticongelante como mínimo hasta −25 °C ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 168 Verification: Verified Open document
Coolant capacity
1.27 US qt ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 151 Verification: Verified Open document
2 items

Filters & Service Parts

OEM spark plug reference
NGK BR10 ECMVX ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 150 Verification: Verified Open document
Spark plug gap
0.03 in ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 150 Verification: Verified Open document
3 items

Electrical & Battery

12 V battery nominal voltage
12 V ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 153 Verification: Verified Open document
Battery capacity
2 Ah ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 153 Verification: Verified Open document
Battery technology
Batería de iones de litio ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 153 Verification: Verified Open document
3 items

Torque Specifications

Spark plug torque
18.44 lb-ft ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 158 Verification: Verified Open document
Front brake caliper torque
18.44 lb-ft ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 161 Verification: Verified Open document
Transmission drain plug torque
14.75 lb-ft ✓
Sources and verification (1)
Primary source ✓ Official Publisher: KTM Sportmotorcycle GmbH (buscador oficial de manuales) Document: 125 SX 2026 – Manual de instrucciones, EE. UU. en español (26_3240232_es_BA) Reference: 158 Verification: Verified Open document

How we handle technical data

MotorDataBook prioritises official documentation and shows conditions, notes and traceability whenever a figure needs context. Unconfirmed values should not be presented as facts.