KTM LC4 400-660LC42003 engine. Manual - part 1

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

E

X P L A N AT I O N

- U

P D AT I N G

Edition 4/2003

3.205.49-E

Repair Manual LC4

6/1998

Basicversion Modelyear 1998
(Engine number with first digit „8“)

3.205.73-E

Updating of Rep.Manual LC4

7/1999

Modelyear 1999
(Engine number with first digit „9“)

3.205.89-E

Updating of Rep.Manual LC4

9/2000

Modelyear 2000/2001
(Engine number with first digit „0“ and „1“)

3.210.30-E

Updating of Rep.Manual LC4

12/2001

Modelljahr 2002
(Engine number with first digit „2“)

3.206.006-E Updating of Rep.Manual LC4

4/2003

Modelljahr 2003
(Engine number with first digit „3“)

Modification / Updating:
Special tools, hydraulic clutch, Keihin carburator,
technical details model 2003, technical specification, 
Maintenance schedule and wiring diagrams for modell 2003 

INTRODUCTION

This repair manual offers extensiv repair-instructions and is an up-to-date version that describes the
latest models of the series. However, the right to modifications in the interest of technical 
improvement is reserved without updating the current issue of this manual.

A description of general working modes common in work shops has not been included. Safety rules
common in the work shop have also not been listed. We take it for granted that the repairs are
made by qualified profesionally trained mechanics.

Read through the repair manual before beginning with the repair work.

WARNING

STRICT COMPLIANCE WITH THESE INSTRUCTIONS IS 
ESSENTIAL TO AVOID DANGER TO LIFE AND LIMB.

!

CAUTION

!

NON-COMPLIANCE WITH THESE INSTRUCTIONS CAN LEAD
TO DAMAGE OF MOTORCYCLE COMPONENTS OR RENDER
MOTORCYCLES UNFIT FOR TRAFFIC !

„NOTE” POINTS OUT USEFUL TIPS.

Use only ORIGINAL KTM SPARE PARTS when replacing parts.

The KTM high performance engine is only able to meet user expectations if the maintenance work
is performed regularly and professionally.

KTM Austria’s certificate of achievement for its quality system ISO 9001 is the beginning of an 
ongoing total reengineered quality plan for a brighter tomorrow.

KTM Sportmotorcycle AG

5230 Mattighofen, Austria

All design and assembly modification rights reserved.

C

by KTM SPORTMOTORCYCLE AG, AUSTRIA         All rights reserved

REPLY FAX FOR REPAIR MANUALS

We have made every effort to make our repair manuals as accurate as possible but it is always possible for
a mistake or two to creep in.

To keep improving the quality of our repair manuals, we request mechanics and shop foremen to assist us
as follows:

If you find any errors or inaccuracies in one of our repair manual – whether these are technical errors, 
incorrect or unclear repair procedures, tool problems, missing technical data or torques, inaccurate or 
incorrect translations or wording, etc. – please enter the error(s) in the table below and fax the completed
form to us at 0043/7742/6000/5349.

NOTE to table:

–

Enter the complete item no. for the repair manual in column 1 (e.g.:  3.210.66-E).
You will find the number on the cover page or in the left margin on each right page of the manual.

–

Enter the corresponding page number in the repair manual (e.g.:  5-7c) in column 2.

–

Enter the current text (inaccurate or incomplete) in column 3 by quoting or describing the respective 
passage of the text.  If your text deviates from the text contained in the repair manual, please write
your text in German or English if possible.

–

Enter the correct text in column 4.

Your corrections will be reviewed and incorporated in the next issue of our repair manual.

Item no. of repair manual

Page

Current text

Correct text

Additional suggestions, requests or comments on our Repair Manuals (in German or English):

Name mechanic/shop foreman

Company/work shop

MODELS WITHOUT FRAME OIL
CHANGING THE ENGINE OIL  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

CHANGING THE OIL FILTER  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

CHANGING THE MICROFILTER  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3

OIL CIRCUIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

OIL CIRCUIT 660 SMC  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

MODELS WITH FRAME OIL
CHANGING THE ENGINE OIL  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6

CHANGING THE FINE SCREEN FILTER  . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-6

CHANGING THE OIL FILTER  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-7

OIL CIRCUIT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8

SECONDARY AIR SYSTEM  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9

EPC-SYSTEM  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-10

SPECIAL TOOLS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-11

BLEEDING OF THE HYDRAULIC CLUTCH  . . . . . . . . . . . . . . . . . . . . . . . .2-13

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

GENERAL INFORMATION

INDEX

2-1D

2

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

2-2D

Changing the engine oil (models without frame oil)

NOTE: 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 motorbike on a horizontal surface. Remove the two plugs 

(

1

and 

2

), and drain oil into a container.

NOTE: A third plug was installed in the 660 SMC model. Tightening
torque: 20 Nm

! 

CAUTION

!

T

HE SCREW PLUG

A

MUST NOT BE REMOVED

, 

THIS IS PART OF THE BY

-

PASS VALVE

.

– Clean the plugs thoroughly with a fireproof solvent and compressed

air, in order to remove the metal abrasion. 

– After all the oil has drained through, clean raised and flat faces and

install plugs with seals. Tighten plug 

1

with 30 Nm (22 ft.lb) and

plug 

2

with 20 Nm (15ft.lb).

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

replace the oil dipstick.

Oil capacity (up to model 2002) :  1.40 l

Oil capacity (from model 2003 on) :  1.50 l

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 

3

and the three bolts 

4

.

– Remove oil filter cover 

5 

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 

6

into the groove of the filter cover (if 

necessary fix with grease). Mount a new oil filter 

7

on the

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

NOTE: From model 2001 onwards the gasket 

8

is mounted with a

changed filter cover 

5

. If the new gasket 

8

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 hollow bolt with seal rings and tighten with 15 Nm

(11 ft.lb).

1

1

A

A

2

up to Modell 2001

from Modell 2002 on

2

3

4

5

6

7

8

3

4

5

2-3D

Changing the microfilter

Replace the microfilter while changing the engine oil. 
– To do so, remove bolts 

1

and take off the microfilter cover 

2

.

– Remove the microfilter, clean its parts and check the O-ring on the

microfilter cover for signs of damage.

– Insert a new microfilter into the filter housing, tilt the motorcycle

sideways and fill the microfilter housing with engine oil.

– Slightly grease the O-ring and mount the microfilter cover. Then put

the motorcycle back on its stand.

– It is necessary to bleed the microfilter so that all lubricating points

can be quickly supplied with engine oil. 

– To do this, fill with oil and remove the jet screw from the oil line on

the clutch cover. 

– Start the engine and close off the bore on the clutch cover with a

rag.

– Allow the engine to run at idle until oil runs out of the oil line 

3

. 

– Turn off the engine. Mount the jet screw, using two new seal rings.
– Torque the jet screw to 10 Nm and check for leaks.

– Start the engine and let it idle for 1 - 2 minutes.

! 

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.

3

1

1

2

0°C

32°F

10W/50

5W/40

JASO T903 MA

TEMPERATURE

2-4D

Repair manual  KTM LC4 

Art.-Nr

.  3.206.006 -E

8

7

1

2

3

4

5

6

9

10

11

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 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 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.