KTM 50 SX - Technical Data and Specifications; Engine Specifications; Engine Tightening Torques

19 TROUBLESHOOTING 74
Faults Possible cause Action
Engine turns but does not start Operating error – Go through the steps of starting the engine.
( p. 17)
Motorcycle was out of use for a long
time and there is old fuel in the float
chamber
–
Empty the carburetor float chamber. x
Fuel feed interrupted – Check the fuel tank breather.
– Clean the fuel tap.
(50 SX Mini)
–
Check/set the carburetor components. x
(50 SX)
–
Check/set the carburetor components. x
Spark plug oily or wet – Clean and dry the spark plug, or change it if
necessary.
Electrode distance (plug gap) of spark
plug too wide
– Adjust the plug gap.
Guideline
Spark plug electrode gap
0.60 mm (0.0236 in)
Fault in ignition system –
Check the ignition system. x
Short circuit cable in wiring harness
frayed, kill switch defective
–
Check the kill switch. x
The connector or ignition coil is loose
or oxidized
– Clean the plug-in connection and treat it with
contact spray.
Water in carburetor or jets blocked
(50 SX Mini)
–
Check/set the carburetor components. x
(50 SX)
–
Check/set the carburetor components. x
Engine has no idle Idling jet blocked
(50 SX Mini)
–
Check/set the carburetor components. x
(50 SX)
–
Check/set the carburetor components. x
Adjusting screws on carburetor dis-
torted
(50 SX Mini)
–
Carburetor - adjust the idle speed. x
( p. 64)
(50 SX)
–
Carburetor - adjust the idle speed. x
( p. 63)
Spark plug defective – Change spark plug.
Ignition system defective –
Check the ignition coil. x
–
Check the spark plug connector. x
Engine does not speed up Carburetor running over because float
needle dirty or worn
(50 SX Mini)
–
Check/set the carburetor components. x
(50 SX)
–
Check/set the carburetor components. x
Loose carburetor jets
(50 SX Mini)
–
Check/set the carburetor components. x
(50 SX)
–
Check/set the carburetor components. x
Fault in ignition system –
Check the ignition system. x
Engine has too little power Fuel feed interrupted – Check the fuel tank breather.
– Clean the fuel tap.
(50 SX Mini)
–
Check/set the carburetor components. x
(50 SX)
–
Check/set the carburetor components. x
Air filter very dirty –
Clean the air filter and air filter box. x
( p. 36)