KTM 150 SX 2021 User Manual (English)

Other manuals for KTM 150 SX 2021

Questions and Answers:

G
Gregory HunterAug 18, 2025
What to do if my KTM Motorcycle engine has too little power?
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  Marilyn WagnerAug 18, 2025
  If your KTM Motorcycle engine has insufficient power, begin by checking for any interruptions in the fuel feed, such as a blocked fuel tank breather or a dirty fuel tap. Make sure to check the carburetor components. A very dirty air filter can also cause this issue, so clean the air filter and air filter box. Inspect the exhaust system for leaks or deformation, and replace the glass fiber yarn filling in the main silencer if it's insufficient. Additionally, a fault in the ignition system or damage to the diaphragm or reed valve housing could be responsible, so check these components as well.
K
Karina GomezAug 21, 2025
What causes a KTM 150 SX 2021 Motorcycle engine not to speed up?
- N
  Noah ThomasAug 21, 2025
  If your KTM Motorcycle engine does not speed up, it could be due to the carburetor running over because the float needle is dirty or worn, or the carburetor jets are loose. In both cases, check and set the carburetor components. Also, a fault in the ignition system can cause this issue, so inspect the ignition system.
F
Frank BaileyAug 25, 2025
What to do if my KTM 150 SX 2021 engine cannot be cranked?
- C
  Christopher Pollard IVAug 25, 2025
  If the engine of your KTM Motorcycle fails to crank, several factors could be at play. First, ensure the start procedure is correctly followed. If that's not the issue, check the 12-V battery to see if it's discharged and charge it if necessary. Also, inspect the main fuse and replace it if blown. The starter relay or the starter motor itself could be faulty, so these should be checked as well.
D
Deborah YoderAug 27, 2025
What to do if my KTM Motorcycle engine overheats?
- J
  Jessica JohnsonAug 27, 2025
  If your KTM Motorcycle engine is overheating, check the coolant level and look for leaks in the cooling system. Ensure there's sufficient air stream and switch off the engine when stationary. Clean the radiator fins if they are very dirty. If there's foam formation in the cooling system, drain and refill the coolant. Also, inspect the cylinder head and cylinder head gasket for damage and replace any bent radiator hoses.
C
Catherine MoraAug 30, 2025
Why KTM 150 SX 2021 Motorcycle engine stalls or is popping into the carburetor?
- H
  Howard RamosAug 30, 2025
  If your KTM Motorcycle engine stalls or pops into the carburetor, it might be due to a lack of fuel. For all SX models and 125 XC US, ensure the fuel tap is in the ON position, or RES position if needed, and refuel if necessary. Another cause could be the engine taking in bad air; check the intake flange and carburetor for tightness. Also, inspect the connector or ignition coil for looseness or oxidation, and clean the connector with contact spray.
V
Vincent ReedSep 2, 2025
How to fix KTM Motorcycle engine with no idle speed?
- B
  brettprattSep 3, 2025
  If your KTM Motorcycle engine has no idle speed, the idling jet might be blocked, so check the carburetor components. The adjusting screws on the carburetor could be distorted, so adjust the idle speed. A defective spark plug can also cause this, so replace the spark plug. Finally, a defective ignition system could be the problem, so check the ignition coil and spark plug connector.
C
Charles DuncanSep 5, 2025
Why is there white smoke emission (steam in exhaust gas) from my KTM 150 SX 2021 Motorcycle?
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  bwilliamsSep 6, 2025
  White smoke emission (steam in exhaust gas) from your KTM Motorcycle could be due to a damaged cylinder head or cylinder head gasket. In this case, check the cylinder head and cylinder head gasket.
E
emily90Sep 8, 2025
Why is gear oil exiting at the vent hose of my KTM 150 SX 2021 Motorcycle?
- C
  Cory StewartSep 8, 2025
  Gear oil exiting at the vent hose of your KTM Motorcycle is likely because too much gear oil was added. Check the gear oil level.
B
Brenda FernandezSep 12, 2025
Why is there water in the gear oil of my KTM 150 SX 2021 Motorcycle?
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  Michael MooreSep 12, 2025
  Water in the gear oil of your KTM Motorcycle might be due to a damaged radial shaft seal ring or water pump. Check the radial shaft seal ring and the water pump.

KTM 150 SX 2021 Specifications

General

Bore x Stroke	58 mm x 54.5 mm
Transmission	6-speed
Seat Height	950 mm
Starter	Kickstarter
Front Suspension	WP XACT-USD, Ø 48 mm
Rear Suspension	WP XACT Monoshock
Ground Clearance	375 mm
Engine Type	2-stroke
Displacement	143.99 cc
Fuel Tank Capacity	7.5 liters
Cooling	Liquid cooled
Front Brake	Disc brake
Rear Brake	220 mm disc