KTM 400-660 LC4 1998-2005 Repair Manual page 223

TROUBLE
Engine fails to idle
Engine does not rev high
Engine will not reach full
power
Engine overheats
High oil consumption
CAUSE
Glogged idling jet
Uncorrect adjustment of adjusting
screws on carburetor
Defective spark plug
Defective ignition system
Carburetor fuel level too high
because
Float needle is dirty or worn out
Float leaks
The cold starting system
permanently activated due to a
lack of play in the choke cable.
Defective membrane of slide (640)
Loose carburettor jets
Electronic ignition timing faulty
Fuel supply partically interrupted or
carburetor dirty
Float leaks
Defective membrane of slide (640)
Air filter very dirty
Valve clearance to small
Loss of compression because hand
decompressor has no play
Electronic ignition timing faulty
Insufficient cooling liquid
Radiator fins are extremely dirty
Foam forms in cooling system
Bent cooling hose
Thermostat defective
Blown fan fuse
Defect thermo switch
Fan defective
Buckling gear ventilation hose
Engine oil level too high
Engine oil too thin (viscosity)
Disassemble carburetor and clean jets
Adjust carburetor
Replace spark plug
Check ignition system
Dismount carburetor and check if worn out
Replace float needle
Replace float
is Adjust choke cable.
Replace membrane
Tighten jets
Check pulse generator and ignition system
Clean and check fuel system as well as carburetor
Replace the float
Replace membrane
Clean or replace air filter
Adjust valve clearance
Check setting of the hand decompression cable
Check pulse generator and ignition system
Refill cooling liquid (see maintenace work), check cooling
system for leaks
Clean radiator with water jet
Replace cooling liquid, use antifreezer with brand name
Shorten or replace cooling hose
Remove and check thermostat (opening temperature 70°C
(158°F) or replace it.
Replace fuse and check if fan operates properly (see below)
Replace thermo switch
Check if fan operates properly. To do this, start the engine,
then bypass the connections to the thermo switch (bottom
right radiator).
Readjust or replace ventilation hose
Check engine oil level when the engine is warm; correct if
necessary
Use thicker engine oil; see chapter „Engine oil"
REMEDY
9-8E