KTM LC4 400-660LC42003 engine. Manual - part 2

2-5D

8

7

1

2

3

4

4

5

6

9

10

11

Oil circuit 660 SMC

The oil pump 

1

pumps the engine oil past the by-pass valve 

2

through the oil filter 

3

. After the oil filter, an oil lead branches

off to a jet 

4

which sprays engine oil onto the piston pin bearing and piston head. The second oil lead takes the main flow of oil

to the second jet 

4

and the microfilter 

5

, which filters out even the finest impurities. The cleaned engine oil is pumped through

the oil lead and the clutch cover into the crankshaft to the connecting rod bearing 

6

and drips into the crankcase. An additional

oil pump 

7

sucks the engine oil out of the crankcase and pumps it through the oil line 

8

to the gear wheels of the 4th and 5th

gear. Via the gear wheels, the engine oil reaches the oil sump. The timing chain 

9

runs through the oil sump and transports the

engine oil upwards to the cylinder head. Through the bore 

bk

the oil reaches the camshaft 

bl

and the valves.

2-6D

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

Changing the engine oil (models with frame oil)

NOTE: For improved cooling of the engine oil, the front tube of the
frame was integrated into the oil circuit.Thus, when you change the oil,
you also have to drain the engine oil from the front tube and bleed the
oil system.

If the oil system is not bled at all or bled insufficiently, the bearings of
the engine will not get enough lubrication, which in turn may result in
engine failure.

The engine oil change is to be carried out when the engine is still warm.

WARNING

A

N ENGINE HAVING BEEN RUN WARM

, 

AND THE ENGINE OIL IN IT ARE VERY HOT

-

DO NOT BURN YOURSELF

.

– Place the motorcycle on a horizontal surface. When working on a

motorcycle with engine guard, remove the latter before commencing
to change the engine oil.

– Remove the two plugs 

1

and 

2

, and drain oil into a container. 

! 

CAUTION

!

P

LUG

A

MUST NOT BE REMOVED

, 

THIS IS PART OF THE BY

-

PASS VALVE

.

Changing the fine screen filter 

Replace the fine screen 

3

filter when changing the engine oil.

– Loosen the three bolts and remove the cover. 
– Undo the spin-on filter 

3

with the corresponding special tool, twist

it off manually and let the engine oil out of the front pipe of the
frame.

– Unscrew plug 

4

at the lower end of the front pipe and drain oil (up

to model 2000).

– Clean sealing surfaces on the front pipe 

5

, fill new fine screen filter

with engine oil, and oil rubber gasket 

6

. Replace fine screen filter

and screw it back in place, your bare hand will do. 

! 

CAUTION

!

U

SE ONLY ORIGINAL

KTM 

FINE SCREEN FILTERS

. U

SING ANOTHER FILTER BRAND CAN

RESULT IN DAMAGE TO THE ENGINE

!

– From  model 2001 onwards the drain plug 

7

of the frame oil is

located in the oil filter flange, draining is only possible after removing
the oil filter.

– Clean all 3 plugs thoroughly with a fireproof solvent and compressed

air, in order to remove the metal abrasion. 

– After all the oil has drained through, clean sealing areas and install

plugs with gaskets. Tighten plug 

1

with 30 Nm (23 ft.lb), plug 

2

with 20 Nm and plug 

4

with 10 Nm (up to model 2000). Drain plug

of frame oil (model 2001 onwards) is to be mounted without a
gasket and tightened to 10 Nm (7 lb.ft).

1

1

A

A

2

up to Modell 2001

from Modell 2002 on

2

5

3

4

6

7

2-7D

Changing the oil filter

Replace the oil filter when changing the engine oil.
– Press the foot brake pedal and place a screwdriver or similar between

foot brake pedal and stopper roll so that the oil filter cover is more
accessible.

– Remove banjo bolt 

1

and the three bolts 

2

.

– Remove oil filter cover 

3 

and oil filter.

– Clean filter housing, oil filter cover and sealing surfaces. Check oil

duct in oil filter cover if clogged.

– Press the new O-ring 

4

into the groove of the filter cover (if

necessary fix with grease). Mount a new oil filter 

5

on the

connection piece of the oil filter cover an mount the whole unit.

NOTE: From model 2001 onwards the gasket 

6

is mounted with a

changed filter cover 

3

. If the new gasket 

6

should be used on older

engines, the filter cover must be flat regrinded or renewed (see
Technical Info Nr. 0201/30/01).

– Mount three bolts and tighten with 5 Nm (4 ft.lb). 
– Mount banjo bolt with seal rings and tighten with 15 Nm

(11 ft.lb).

– Remove the oil dipstick at the clutch cover, pour in engine oil and

replace the oil dipstick.

Oil quantity (engine only) :  1.40 liter

! 

CAUTION

!

I

F THE ENGINE OIL HAS BEEN DRAINED FROM THE FRONT PIPE OF THE FRAME

, 

YOU

MUST BLEED THE OIL SYSTEM

!

– Remove the plug 

7

next to the steering head and use a lubricating

syringe 

8

(see special tools) to fill the front pipe with approx. 0.6 l

engine oil. Add oil until it begins to emerge at bore 

B

.

– Mount the plug, using a new seal ring.

! 

CAUTION

!

D

O NOT REV UP THE ENGINE IMMEDIATELY AFTER AN OIL CHANGE

. K

EEP IN MIND

THAT IT TAKES SOME TIME UNTIL ALL LUBRICATING POINTS ARE PROPERLY PROVIDED
WITH ENGINE OIL

.

– Allow the engine to run until warm. Then, turn off the engine, and

place the motorbike on a flat, level surface in an upright position
(center stand). Wait for 5 minutes. Unscrew and remove the oil 
dipstick, and wipe it clean with a cloth.

– Screw the dipstick in all the way and remove it again. The oil level

should be between the two marks on the oil dipstick, however, it
must never rise above the MAX mark. Otherwise, engine oil would
get into the air filter box by way of the engine venting system. Add
engine oil, if necessary.

– Finally, check oil system and engine for leaks.

! 

CAUTION

!

– O

NLY

USE

HIGH

-

QUALITY

OILS

MEETING

OR

SURPASSING

THE

QUALITY

REQUIREMENTS OF

JASO T903 MA (

FOR SPECIFICATIONS SEE CONTAINERS

).

– I

NSUFFICIENT OIL OR POOR QUALITY OIL RESULTS IN PREMATURE WEAR OF THE

ENGINE

.

– Y

OU MAY USE EITHER MINERAL OILS OR SYNTHETIC OILS FULFILLING THE ABOVE

CRITERIA

.

NOTE: Dispose of used oil properly !
Under no circumstances may used oil be disposed of in the sewage
system or in the open countryside !
1 liter oil contaminates 1.000.000 liter water !

B

1

2

3

4

5

6

3

1

2

7

8

2-8D

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

Oil circuit

The oil pump 

1

pumps the engine oil past the by-pass valve 

2

through the oil filter 

3

. After the oil filter, an oil line branches off

to a jet 

4

which sprays engine oil onto the piston pin bearing and piston head. The second oil line takes the main flow of oil into

the front pipe of the frame 

5

, where the engine oil is cooled down. Afterwards the engine oil runs through the fine screen filter

6

, which filters out even the finest impurities. The cleaned engine oil is pumped through the oil line and the clutch cover into the

crankshaft to the conrod bearing 

7

and drips into the crankcase. An additional oil pump 

8

sucks the engine oil out of the

crankcase and pumps it through the oil line 

9

to the gear wheels of the 4th and 5th gear. Via the gear wheels, the engine oil

reaches the oil sump. The timing chain 

bk

runs through the oil sump and transports the engine oil upwards to the cylinder head.

Through the bore hole 

bl

the oil reaches the camshaft 

bm

and the valves.

8

7

5

6

9

10

12

11

1

2

3

4

Drain plug - frame oil 
up to Model 2000

Drain plug - frame oil  
Model 2001 onwards

2-9D

Functional characteristics of the secondary air system (SLS)

When the exhaust valve is open, the hot exhaust gases flow through the exhaust port 

1

at a very high speed. As a consequence

of the flow conditions in the exhaust port and due to the  influence exerted by the entire exhaust system on the escaping gases,
the pressure in the exhaust port drops temporarily (underpressure).

During these cyclic underpressure phases, the secondary air valve 

2

opens, thus adding oxygen of the air to the hot exhaust

gases through pipe 

3

.

At higher engine speeds, the secondary air valve interrupts the oxygen supply to prevent overheating of the catalytic converter.
Additionally, the secondary air valve prevents the exhaust gases from flowing back into the air filter box 

4

.

When the motorcycle is pushed (high underpressure in the intake port) the control valve (ASV) 

5

interrupts the air flow into the

exhaust port to prevent exhaust detonations.

The control valve is controlled via a control pipe 

6

. This control pipe transmits the underpressure from the intake port 

7

to the

control valve.
During normal operation (slight underpressure in the intake port), the  control valve is open.

The reaction between the oxygen of the air and the harmful components of the exhaust gases (CO - carbon monoxide, HC -
hydrocarbon) reduces the content of harmful substances by approximately 50%. The use of a catalytic converter, in combination
with the SLS, allows an additional significant reduction of pollutant emissions.

6

5

7

3

2

1

4

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

2-10D

Electronic Power Control System (EPC)

Main components of the EPC system:

–  Constant-pressure carburetor
–  Control device
–  Solenoid valve
–  2 contact screws at the engine
–  Micro-switch (at carburetor)

FUNCTIONAL CHARACTERISTICS:
The EPC system is not activated during normal operation of the motorcycle.
It is, however, activated as soon as the throttle is fully opened at a speed of 45 - 55 km/h while the second or third gear are
engaged. 
The EPC control device opens the solenoid valve, directing an appropriate flow of fresh air onto the upper side of the slide 
membrane of the constant-pressure carburetor, thus reducing the opening speed of the slide. This mechanism significantly reduces
the exhaust gas emissions of the vehicle.

SOLENOID VALVE

2-11D

SPECIAL TOOLS

130

35

65

150

5

70

27

16

6

4

3

26

12

20

7

15

23

2

11

1

39

ThreeBond

1215

Silicone Liquid Gasket

Silicone Flüssige Dichtung

18

17

648

4#

5#

5

22

48

19

8#

8

10

9

14

49

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

2-12D

FIG.

PART NO.

DESCRIPTION

1

560.12.001.000

Universal engine work stand

2

583.29.003.000

Clutch holder

3

580.12.005.025

Mounting sleeve for crankshaft seal ring Ø 25 mm

4

584.29.009.000

Magneto extractor (Kokusan)

4#

580.12.009.000

Magneto extractor  (SEM)

5

510.12.016.000

Protection cover for crankshaft (SEM)

5#

584.29.031.000

Protection cover for crankshaft (Kokusan)

6

580.12.015.089

Piston ringspanner  Ø 89 mm

580.12.015.095

Piston ringspanner  Ø 95 mm

580.12.015.100

Piston ringspanner  Ø 100 mm

580.12.015.101

Piston ringspanner  Ø 101 mm

585.29.015.102

Piston ringspanner  Ø 102 mm

7

590.29.021.044

Extractor for primary gear and clutch hub

8

580.12.019.000

Valve mounting set

8#

590.29.019.000

Valve mounting set

9

6.276.470

Valve spring-push insert

10

590.29.041.000

Feeler gauge for valve clearance

11

6.899.785

Loctite 243 blue   6 ml

12

584.29.059.000

Loctite 648 red   20 ml

14

590.29.034.000

Wrench for mixture regulating screw

15

151.12.017.000

Gear puller

16

151.12.018.000

Internal bearing puller  12 - 16 mm

16

151.12.018.100

Internal bearing puller  18 - 23 mm

17

584.29.012.000

Flywheel holding spanner (Kokusan)

18

3090.98

Seal (Three-Bond)

19

584.29.037.040

Mounting tool inner ring NJ207 (all versions of LC4)

19

584.29.037.043

Mounting tool inner ring NJ306 (LC4-E)

20

580.30.080.000

Crankshaft locking bolt

22

510.12.012.000

Chain sprocket holder

23

546.29.027.000

Clutch rivetting tool

26

580.29.026.007

Limit plug gauge Ø 7,05 mm

39

583.29.039.000

Oil filter wrench

48

584.29.048.000

Syringe for pipe oil

49

503.29.050.000

Bleeding syringe for hydraulic clutch