KTM 400 – 660 LC4 1998 1999 2000 2001 2002 2003 FACTORY SERVICE REPAIR MANUAL + WIRINGS

KTM 400 – 660 LC4 1998 1999 2000 2001 2002 2003 FACTORY SERVICE REPAIR MANUAL + WIRINGS

 

Loaded with Hi Resolution illustrations, instructions, photos, and diagrams, complete to service and repair your motorbike.  

387 PAGES

 

 

TABLE OF CONTENTS:

1 SERVICE INFORMATIONS

2 GENERAL INFORMATION

3 REMOVING AND REFITTING ENGINE

4 DISASSEMBLING THE ENGINE

5 SERVICING ON INDIVIDUAL COMPONENTS

6 ASSEMBLING THE ENGINE

7 ELECTRICAL

8 FUEL SYSTEM

9 TROUBLE SHOOTING

10 TECHNICAL SPECIFICATIONS

11 PERIODIC MAINTENANCE SCHEDULE

12 WIRING DIAGRAMS

13 Owner’s Manuals

 

MANUALS COVER:

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

REMOVING THE ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

REFITTING THE ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-4

DRAIN ENGINE OIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2

REMOVING THE ELECTRIC STARTER MOTOR . . . . . . . . . . . . . . . . . . . . .4-2

REMOVING THE CLUTCH RELEASE LEVER AND THE OIL HOSES . . . . . . .4-3

REMOVING THE OIL FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3

REMOVING THE EPC WIRING HARNESS . . . . . . . . . . . . . . . . . . . . . . . . . .4-3

REMOVING THE IGNITION (KOKUSAN 4K-2) . . . . . . . . . . . . . . . . . . . . . .4-3

REMOVING THE IGNITION (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5

REMOVING THE IGNITION (KOKUSAN 4K-3) . . . . . . . . . . . . . . . . . . . . . .4-5

REMOVING THE ELECTRIC STARTER DRIVE . . . . . . . . . . . . . . . . . . . . . . .4-6

REMOVING THE CYLINDER HEAD TOP SECTION . . . . . . . . . . . . . . . . . . .4-7

BLOCKING THE CRANKSHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8

REMOVING THE CAMSHAFT AND THE AUTOMATIC TENSIONER . . . . . .4-8

REMOVING CYLINDER HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10

REMOVING CYLINDER AND PISTON . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10

REMOVING ENGINE SPROCKET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11

REMOVING CLUTCH AND PRIMARY DRIVE . . . . . . . . . . . . . . . . . . . . . .4-11

REMOVING THE OIL PUMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-13

REMOVING THE TIMING CHAIN AND THE TIMING GEAR . . . . . . . . . . .4-14

REMOVING THE CLUTCH RELEASE SHAFT . . . . . . . . . . . . . . . . . . . . . . .4-14

PARTING OF ENGINE HOUSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-15

REMOVING THE SHIFT MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . .4-15

REMOVING THE TRANSMISSION SHAFTS . . . . . . . . . . . . . . . . . . . . . . .4-17

REMOVING THE KICKSTARTER SHAFT . . . . . . . . . . . . . . . . . . . . . . . . . .4-17

WORKING ON THE RIGHT HOUSING HALF . . . . . . . . . . . . . . . . . . . . . . .5-3

WORKING ON THE LEFT HOUSING HALF . . . . . . . . . . . . . . . . . . . . . . . .5-5

CRANKSHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-6

MEASURING AND ADJUSTING OF CRANKSHAFT AXIAL PLAY . . . . . . . . .5-7

CHECKING THE PISTON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7

MOUNTING INSTRUCTIONS FOR PISTON RINGS . . . . . . . . . . . . . . . . . . .5-8

PISTON RING END GAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-8

MEASURING PISTON AND CYLINDER, DETERMINING

THE PISTON FITTING CLEARANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-8

CYLINDER – NIKASIL COATING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-9

RECOATED CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-9

DISASSEMBLING THE CYLINDER HEAD AND CHECKING

THE COMPONENTS FOR WEAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-10

DISASSEMBLING THE CYLINDER HEAD TOP SECTION AND

CHECKING COMPONENTS FOR WEAR . . . . . . . . . . . . . . . . . . . . . . . . .5-11

PRE-ASSEMBLING THE CYLINDER HEAD TOP SECTION . . . . . . . . . . . . .5-11

CHECKING THE COMPONENTS OF THE TIMING MECHANISM FOR WEAR . . .5-12

DISASSEMBLING THE CAMSHAFT AND CHECKING THE

COMPONENTS FOR WEAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-12

PRE-ASSEMBLING THE CAMSHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-12

AUTOMATIC TENSIONER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-13

PREASSEMBLY OF AUTOMATIC TENSIONER . . . . . . . . . . . . . . . . . . . . .5-13

DISASSEMBLING THE OIL PUMPS AND CHECKING THE

COMPONENTS FOR WEAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-13

OIL LINES (SX, SXC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-14

OIL LINES (SC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-14

OIL LINES (660 SMC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-15

OIL LINES (MODELS WITH FRAME OIL) . . . . . . . . . . . . . . . . . . . . . . . . .5-15

CHECKING THE KICKSTARTER COMPONENTS FOR WEAR . . . . . . . . . . .5-16

PREASSEMBLY OF KICKSTARTER SHAFT . . . . . . . . . . . . . . . . . . . . . . . . .5-16

CLUTCH COVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-16

REPLACING ABSORBING ELEMENTS OF THE OUTER CLUTCH HUB . . . .5-16

CHECKING THE CLUTCH COMPONENTS FOR WEAR . . . . . . . . . . . .5-17

CHECKING THE SHIFT MECHANISM COMPONENTS FOR WEAR . . . .5-18

PREASSEMBLY OF SHIFT SHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . .5-18

SHIFT MECHANISM SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-19

BALANCER SHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-19

DISASSEMBLING AND REASSEMBLING THE WATER PUMP . . . . . . . .5-19

IMPORTANT NOTE REGARDS WORKING ON TRANSMISSION . . . . .5-20

ASSEMBLING THE MAIN SHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . .5-20

ASSEMBLING THE COUNTER SHAFT . . . . . . . . . . . . . . . . . . . . . . . .5-21

REMOVING THE INTERMEDIATE GEAR . . . . . . . . . . . . . . . . . . . . . .5-22

CHECKING THE FREEWHEEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-22

REPLACING THE FREEWHEEL HUB . . . . . . . . . . . . . . . . . . . . . . . . .5-22

ELECTRIC STARTER MOTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-22

IGNITION (KOKUSAN 4K-2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-23

CHECKING THE STATOR AND THE PULSE GENERATOR (KOKUSAN 4K-2) . . .5-23

REPLACING THE STATOR (KOKUSAN 4K-2) . . . . . . . . . . . . . . . . . . .5-23

IGNITION (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-24

CHECKING THE STATOR (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-24

REPLACING THE STATOR (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . .5-24

CHECKING THE STATOR (KOKUSAN 4K-3) . . . . . . . . . . . . . . . . . . .5-25

REPLACING THE STATOR (KOKUSAN 4K-3) . . . . . . . . . . . . . . . . . . .5-25

MOUNTING THE KICKSTARTER UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2

MOUNTING TRANSMISSION AND SHIFT MECHANISM . . . . . . . . . . . . . .6-2

ADJUSTMENT OF RETURN SPRING . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-4

PRETENSIONING OF THE STARTER SPRING . . . . . . . . . . . . . . . . . . . . . . .6-4

MOUNTING CRANKSHAFT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-4

ASSEMBLY OF ENGINE HOUSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-5

MOUNTING OIL FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-6

MOUNTING THE ENGINE SPROCKET . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-6

MOUNTING THE TIMING GEAR AND THE TIMING CHAIN . . . . . . . . . . . .6-7

MOUNTING THE OIL PUMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-7

MOUNTING THE BALANCER SHAFT AND THE PRIMARY PINION . . . . . . .6-8

MOUNTING THE CLUTCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-8

MOUNTING THE CLUTCH DISCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-9

INSTALLING THE CLUTCH RELEASE SHAFT . . . . . . . . . . . . . . . . . . . . . . . .6-9

ADJUSTING THE CLUTCH RELEASE . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-10

MEASURE DIMENSION „Y“ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-10

MOUNTING PISTON AND CYLINDER . . . . . . . . . . . . . . . . . . . . . . . . . . .6-10

MOUNTING THE CYLINDER HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-11

MOUNTING THE CAMSHAFT, TIMING MARKS . . . . . . . . . . . . . . . . . . . .6-12

MOUNTING THE WATER PUMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-13

MOUNTING THE CYLINDER HEAD TOP SECTION . . . . . . . . . . . . . . . . .6-14

MOUNTING THE AUTOMATIC TENSIONER . . . . . . . . . . . . . . . . . . . . . .6-14

AUTOMATIC DECOMPRESSION TESTING . . . . . . . . . . . . . . . . . . . . . . . .6-14

ADJUSTMENT OF VALVE CLEARANCE . . . . . . . . . . . . . . . . . . . . . . . . . .6-15

MOUNTING THE CLUTCH COVER . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-15

MOUNTING THE ELECTRIC STARTER DRIVE . . . . . . . . . . . . . . . . . . . . . .6-16

MOUNTING THE IGNITION (KOKUSAN) . . . . . . . . . . . . . . . . . . . . . . . .6-16

ADJUSTING THE PULSE GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . .6-17

MOUNTING THE IGNITION (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-17

ADJUSTMENT OF IGNITION POINT (SEM) . . . . . . . . . . . . . . . . . . . . . . .6-18

MOUNTING THE EPC WIRING HARNESS . . . . . . . . . . . . . . . . . . . . . . . .6-18

MOUNTING THE IGNITION (KOKUSAN 4K-3) . . . . . . . . . . . . . . . . . . . .6-19

ADJUSTMENT OF IGNITION POINT (KOKUSAN 4K-3) . . . . . . . . . . . . . .6-19

MOUNTING THE OIL HOSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-20

MOUNTING THE CLUTCH RELEASE LEVER . . . . . . . . . . . . . . . . . . . . . . .6-20

MOUNTING THE ELECTRIC STARTER MOTOR . . . . . . . . . . . . . . . . . . . .6-20

MOUNTING THE WATER HOSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-20

POURING IN ENGINE OIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-21

MOUNTING THE KICKSTARTER AND THE SHIFT LEVER . . . . . . . . . . . . .6-21

ELECTRICAL – SUPER COMPETITION . . . . . . . . . . . . . . . . . . . . . . . . .7-4

CHECKING THE VOLTAGE REGULATOR-RECTIFIER . . . . . . . . . . . . . . . . . .7-4

CHECKING THE VOLTAGE REGULATOR . . . . . . . . . . . . . . . . . . . . . . . . . .7-4

CHECKING THE CAPACITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-4

ELECTRICAL – LC4 COMPETITION . . . . . . . . . . . . . . . . . . . . . . . . . . .7-5

CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-5

LEAKAGE INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-5

REMOVING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-6

CHARGING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-6

CHARGING VOLTAGE / CHECKING THE VOLTAGE REGULATOR . . . . . . . .7-6

CHECKING THE CAPACITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-7

CHECKING THE NEUTRAL SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-7

ELECTRICAL – LC4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-8

CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-8

LEAKAGE INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-8

REMOVING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-9

CHARGING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-9

CHARGING VOLTAGE / CHECKING THE VOLTAGE REGULATOR . . . . . . . .7-9

CHECKING THE CAPACITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-10

ELECTRIC STARTER SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-11

CHECKING THE START AUXILIARY RELAY . . . . . . . . . . . . . . . . . . . . . . . .7-12

CHECKING THE AUXILIARY STARTING RELAY FOR FAULTLESS OPERATION . .7-12

CHECKING THE DIODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-12

CHECKING THE STARTER RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-13

CHECKING THE ELECTRIC STARTER MOTOR . . . . . . . . . . . . . . . . . . . . .7-13

CHECKING THE CLUTCH SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-14

CHECKING THE EMERGENCY OFF SWITCH . . . . . . . . . . . . . . . . . . . . . .7-14

TROUBLE SHOOTING IN THE ELECTRIC STARTER SYTEM . . . . . . . . . . . .7-14

IGNITION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-15

CDI UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-16

CHECKING THE IGNITION COIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-16

TROUBLE SHOOTING IN THE IGNITION SYSTEM . . . . . . . . . . . . . . . . . .7-16

EPC SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-17

DISMOUNT / RENEW SOLENOID VALVE FOR EPC . . . . . . . . . . . . . . . . .7-18

CHECK OF SOLENOID VALVE FOR EPC . . . . . . . . . . . . . . . . . . . . . . . . .7-18

CONTROLLER OF THE EPC SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-18

CHECK OF EPC SYSTEM MICROSWITCH . . . . . . . . . . . . . . . . . . . . . . . .7-19

REPLACING THE EPC SYSTEM MICROSWITCH . . . . . . . . . . . . . . . . . . . .7-19

CHECK OF IDLE SWITCH / CONTACT SCREWS . . . . . . . . . . . . . . . . . . .7-19

ELECTRICAL – DUKE-E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-20

CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-20

LEAKAGE INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-20

CHARGING VOLTAGE / CHECKING THE VOLTAGE REGULATOR . . . . . . .7-21

REMOVING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-21

CHARGING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-21

CHECKING THE CAPACITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-22

ELECTRIC STARTER SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-23

CHECKING THE START AUXILIARY RELAY . . . . . . . . . . . . . . . . . . . . . . . .7-24

CHECKING THE AUXILIARY STARTING RELAY FOR FAULTLESS OPERATION . . .7-24

CHECKING THE DIODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-25

CHECKING THE CLUTCH SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-25

CHECKING THE EMERGENCY OFF SWITCH . . . . . . . . . . . . . . . . . . . . . .7-25

CHECKING THE STARTER RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-26

CHECKING THE ELECTRIC STARTER MOTOR . . . . . . . . . . . . . . . . . . . . .7-26

TROUBLE SHOOTING IN THE ELECTRIC STARTER SYTEM . . . . . . . . . . . .7-26

IDLE SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-26

IGNITION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-27

CDI UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-28

CHECKING THE IGNITION COIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-28

SPARK PLUG CONNECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-28

CHECKING THE SIDE STAND RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-28

CHECKING THE SIDE STAND SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . .7-29

TROUBLE SHOOTING IN THE IGNITION SYSTEM . . . . . . . . . . . . . . . . . .7-29

ELECTRICAL – SXC ‘99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-30

CHECKING THE VOLTAGE REGULATOR . . . . . . . . . . . . . . . . . . . . . . . . .7-30

CHECKING THE CAPACITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-30

ELECTRICAL – SC ‘99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-31

CHECKING THE VOLTAGE REGULATOR . . . . . . . . . . . . . . . . . . . . . . . . .7-31

CHECKING THE CAPACITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-31

CHECKING THE IGNITION COIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-31

ELECTRICAL – DUKE ‘99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-32

CHARGING SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-32

LEAKAGE INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-32

CHARGING VOLTAGE / CHECKING THE VOLTAGE REGULATOR . . . . . . .7-33

REMOVING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-33

CHARGING THE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-33

CHECKING THE CAPACITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-34

ELECTRIC STARTER SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-35

CHECKING THE START AUXILIARY RELAY . . . . . . . . . . . . . . . . . . . . . . . .7-36

CHECKING THE AUXILIARY STARTING RELAY FOR FAULTLESS OPERATION . . .7-36

CHECKING THE DIODES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-37

CHECKING THE CLUTCH SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-37

CHECKING THE EMERGENCY OFF SWITCH . . . . . . . . . . . . . . . . . . . . . .7-37

CHECKING THE STARTER RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-38

CHECKING THE ELECTRIC STARTER MOTOR . . . . . . . . . . . . . . . . . . . . .7-38

TROUBLE SHOOTING IN THE ELECTRIC STARTER SYTEM . . . . . . . . . . . .7-38

CHECKING THE IDLE SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-38

IGNITION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-39

CDI UNIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-40

CHECKING THE IGNITION COIL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-40

SPARK PLUG CONNECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-40

CHECKING THE SIDE STAND RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-40

CHECKING THE SIDE STAND SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . .7-41

TROUBLE SHOOTING IN THE IGNITION SYSTEM . . . . . . . . . . . . . . . . . .7-41

MEASUREMENTS WITH PEAK VOLTAGE ADAPTER

(FROM MODEL 2000 ON)

DYNAMIC GENERATOR VALUES 400/640 LC4-E, 625 SXC, DUKE, ADVENTURE . . .7-42

STATIC IGNITION VALUES 400/640 LC4-E, 625 SXC, DUKE, ADVENTURE . . .7-43

STATIC GENERATOR VALUES 400/640 LC4-E, 625 SXC, DUKE, ADVENTURE . . .7-45

STATIC IGNITION VALUES 400/620/625 SC, 660 SMC . . . . . . . . . . . . . . . .7-47

STATIC GENERATOR VALUES 400/620/625 SC, 660 SMC . . . . . . . . . . . . . .7-49

CHECKING SPEEDOMETER AND SPEEDOMETER SENSOR . . . . . . . . . . . .7-51

MIKUNI BST 40

PART-LOAD SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-4

FULL-LOAD SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-5

DISASSEMBLING THE CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-6

ASSEMBLING THE CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-8

CHECKING/ADJUSTING THE THROTTLE SENSOR . . . . . . . . . . . . . . . . . . .8-9

ADJUST IDLING SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-10

ADJUSTING THE THROTTLE CABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-10

CHECK FLOAT LEVEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-10

DELL’ORTO

DISASSEMBLING THE CARBURETOR (DELL’ORTO PHM 40 SD) . . . . . . .8-12

ASSEMBLING THE CARBURETOR (DELL’ORTO PHM 40 SD) . . . . . . . . . .8-13

DISASSEMBLING THE CARBURETOR (DELL’ORTO PHM 38 ND) . . . . . . .8-16

ASSEMBLING THE CARBURETOR (DELL’ORTO PHM 38 ND) . . . . . . . . . .8-18

DISASSEMBLING THE CARBURETOR (DELL’ORTO VHSB 38 QS) . . . . . . .8-21

ASSEMBLING THE CARBURETOR (DELL’ORTO VHSB 38 QS) . . . . . . . . .8-22

CHECK FLOAT LEVEL (DELL’ORTO 38 ND / 40 SD) . . . . . . . . . . . . . . . . .8-25

CHECKING AXIAL CLEARANCE OF FLOAT (DELL’ORTO 38 ND / 40 SD) . .8-25

ADJUST HOT START DEVICE (DELL’ORTO 40 SD) . . . . . . . . . . . . . . . . . .8-25

ADJUSTING THE THROTTLE CABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-26

ADJUSTING THE CHOKE CABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-26

KEIHIN FCR 41

DISASSEMBLING THE CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . .8-28

CHECKING THE CHOKE SLIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-31

CHECKING THE ACCELERATOR PUMP . . . . . . . . . . . . . . . . . . . . . . . . . .8-31

CHECKING THE JET NEEDLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-31

CHECKING THE FLOAT NEEDLE VALVE . . . . . . . . . . . . . . . . . . . . . . . . . .8-31

CHECKING THE THROTTLE VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-31

ASSEMBLING THE CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-32

ADJUSTING THE POSITION OF THE THROTTLE VALVE SENSOR . . . . . . .8-35

CHECKING THE THROTTLE VALVE SENSOR . . . . . . . . . . . . . . . . . . . . . .8-36

DISMOUNTING AND INSTALLING THE THROTTLE VALVE SENSOR . . . . .8-36

ADJUST IDLING SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-37

CHECKING/ADJUSTING THE FLOAT HEIGHT . . . . . . . . . . . . . . . . . . . . .8-38

KEIHIN FCR-MX 41

DISASSEMBLING THE CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . .8-40

CHECKING THE CHOKE SLIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-43

CHECKING THE ACCELERATOR PUMP . . . . . . . . . . . . . . . . . . . . . . . . . .8-43

CHECKING THE JET NEEDLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-43

CHECKING THE FLOAT NEEDLE VALVE . . . . . . . . . . . . . . . . . . . . . . . . . .8-43

CHECKING THE THROTTLE VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-43

ASSEMBLING THE CARBURETOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-44

ADJUSTING THE POSITION OF THE THROTTLE VALVE SENSOR . . . . . . .8-47

CHECKING THE THROTTLE VALVE SENSOR . . . . . . . . . . . . . . . . . . . . . .8-48

DISMOUNTING AND INSTALLING THE THROTTLE VALVE SENSOR . . . . .8-48

ADJUST IDLING SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-49

CHECKING/ADJUSTING THE FLOAT HEIGHT . . . . . . . . . . . . . . . . . . . . .8-49

TROUBLE SHOOTING (SX, SXC, SC, SMC) . . . . . . . . . . . . . . . . . . . .9-2

TROUBLE SHOOTING (LC4 COMPETITION) . . . . . . . . . . . . . . . . . . .9-4

TROUBLE SHOOTING (LC4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-7

 

TECHNICAL SPECIFICATIONS:

MODEL 1998

TECHNICAL SPECIFICATIONS – ENGINE 400/540 SXC . . . . . . . . . . . . . .10-3

TECHNICAL SPECIFICATIONS – CHASSIS 400/540 SXC . . . . . . . . . . . . . .10-5

TECHNICAL SPECIFICATIONS – ENGINE 400/620 SX, SC . . . . . . . . . . . . .10-6

TECHNICAL SPECIFICATIONS – CHASSIS 400/620 SX, SC . . . . . . . . . . . .10-8

TECHNICAL SPECIFICATIONS – ENGINE 620 LC4 COMPETITION . . . . . .10-9

TECHNICAL SPECIFICATIONS – CHASSIS 620 LC4 COMPETITION . . . . .10-11

TECHNICAL SPECIFICATIONS – ENGINE 400/540 SXC . . . . . . . . . . . . . .10-12

TECHNICAL SPECIFICATIONS – CHASSIS 400/640 LC4 . . . . . . . . . . . . .10-15

TECHNICAL SPECIFICATIONS – CHASSIS 640 ADVENTURE-R . . . . . . . .10-16

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE-E . . . . . . . . . . . . . .10-17

 

MODEL 1999

TECHNICAL SPECIFICATIONS – ENGINE 400/540 SXC, 620 SX . . . . . . . 10-18

TECHNICAL SPECIFICATIONS – CHASSIS 400/540 SXC, 620 SX . . . . . . 10-20

TECHNICAL SPECIFICATIONS – ENGINE 400/620 SC . . . . . . . . . . . . . . 10-21

TECHNICAL SPECIFICATIONS – CHASSIS 400/620 SC . . . . . . . . . . . . . 10-23

TECHNICAL SPECIFICATIONS – ENGINE 620 LC4 COMPETITION . . . . . 10-24

TECHNICAL SPECIFICATIONS – CHASSIS 620 LC4 COMPETITION . . . . 10-26

TECHNICAL SPECIFICATIONS – ENGINE 400/640 LC4 . . . . . . . . . . . . . .10-27

TECHNICAL SPECIFICATIONS – CHASSIS 400/640 LC4 . . . . . . . . . . . . .10-29

TECHNICAL SPECIFICATIONS – ENGINE 640 ADVENTURE-R . . . . . . . . .10-30

TECHNICAL SPECIFICATIONS – CHASSIS 640 ADVENTURE-R . . . . . . . .10-32

TECHNICAL SPECIFICATIONS – ENGINE 640 DUKE . . . . . . . . . . . . . . . .10-33

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE . . . . . . . . . . . . . . .10-35

 

MODEL 2000

TECHNICAL SPECIFICATIONS – ENGINE SC, SUPERMOTO . . . . . . . . . . 10-36

TECHNICAL SPECIFICATIONS – CHASSIS SC, SUPERMOTO . . . . . . . . . 10-38

TECHNICAL SPECIFICATIONS – ENGINE LC4-E, ADVENTURE, DUKE . . .10-39

TECHNICAL SPECIFICATIONS – CHASSIS LC4-E SUPERMOTO . . . . . . . .10-41

TECHNICAL SPECIFICATIONS – CHASSIS 640 ADVENTURE-R . . . . . . . .10-42

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE . . . . . . . . . . . . . . .10-43

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE AUS . . . . . . . . . . .10-44

TECHNICAL SPECIFICATIONS – ENGINE 400 SXC . . . . . . . . . . . . . . . . . 10-45

TECHNICAL SPECIFICATIONS – CHASSIS 400/540 SXC . . . . . . . . . . . . .10-46

MODEL 2001

TECHNICAL SPECIFICATIONS – ENGINE 620 SC, SUPERMOTO . . . . . . 10-47

TECHNICAL SPECIFICATIONS – CHASSIS 620 SC, SUPERMOTO . . . . . . 10-49

TECHNICAL SPECIFICATIONS – ENGINE LC4-E, ADVENTURE, DUKE . . .10-50

TECHNICAL SPECIFICATIONS – CHASSIS LC4-E, SUPERMOTO . . . . . . .10-52

TECHNICAL SPECIFICATIONS – CHASSIS 640 LC4 ADVENTURE . . . . . .10-53

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE . . . . . . . . . . . . . . .10-54

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE USA, AUS . . . . . . .10-55

 

MODELL 2002

TECHNICAL SPECIFICATIONS – ENGINE 625 SC, SUPERMOTO . . . . . . 10-56

TECHNICAL SPECIFICATIONS – CHASSIS 625 SC, SUPERMOTO . . . . . . 10-57

TECHNICAL SPECIFICATIONS – ENGINE 640 LC4, ADVENTURE, DUKE . . . 10-58

TECHNICAL SPECIFICATIONS – CHASSIS 640 LC4, SUPERMOTO . . . . . 10-59

TECHNICAL SPECIFICATIONS – CHASSIS 640 ADVENTURE . . . . . . . . . 10-60

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE . . . . . . . . . . . . . . . 10-61

 

MODELL 2003

TECHNICAL SPECIFICATIONS – ENGINE 625 SXC . . . . . . . . . . . . . . . . . 10-62

TECHNICAL SPECIFICATIONS – CHASSIS 625 SXC . . . . . . . . . . . . . . . . 10-63

TECHNICAL SPECIFICATIONS – ENGINE 640 LC4, ADVENTURE, DUKE . . . 10-64

TECHNICAL SPECIFICATIONS – CHASSIS 640 LC4, SUPERMOTO . . . . . 10-65

TECHNICAL SPECIFICATIONS – CHASSIS 640 LC4 ADVENTURE . . . . . . 10-66

TECHNICAL SPECIFICATIONS – CHASSIS 640 DUKE . . . . . . . . . . . . . . . 10-67

TECHNICAL SPECIFICATIONS – ENGINE 660 SMC . . . . . . . . . . . . . . . . 10-68

TECHNICAL SPECIFICATIONS – CHASSIS 660 SMC . . . . . . . . . . . . . . . 10-69

TIGHTENING TORQUES

ENGINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-70

CHASSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-71

ASSEMBLY CLEARANCE, WEAR LIMIT . . . . . . . . . . . . . . . . . . . . . . . . .10-72

 

PERIODIC MAINTENANCE SCHEDULE:

MODEL 1998

PERIODIC MAINTENANCE SCHEDULE SX, SXC, SC . . . . . . . . . . . . . . .11-2

PERIODIC MAINTENANCE SCHEDULE LC4 COMPETITION, LC4 . . . . .11-3

PERIODIC MAINTENANCE SCHEDULE ADVENTURE-R . . . . . . . . . . . .11-4

PERIODIC MAINTENANCE SCHEDULE DUKE . . . . . . . . . . . . . . . . . . . .11-5

 

MODEL1999

PERIODIC MAINTENANCE SCHEDULE SX, SXC, SC . . . . . . . . . . . . . . .11-6

PERIODIC MAINTENANCE SCHEDULE LC4 COMPETITION, LC4 . . . . .11-7

PERIODIC MAINTENANCE SCHEDULE ADVENTURE-R . . . . . . . . . . . .11-8

PERIODIC MAINTENANCE SCHEDULE DUKE . . . . . . . . . . . . . . . . . . . .11-9

 

MODEL 2001

PERIODIC MAINTENANCE SCHEDULE 620 SC . . . . . . . . . . . . . . . . . .11-10

PERIODIC MAINTENANCE SCHEDULE LC4-E, ADVENTURE . . . . . . . .11-12

PERIODIC MAINTENANCE SCHEDULE DUKE . . . . . . . . . . . . . . . . . . .11-14

 

MODEL 2002

PERIODIC MAINTENANCE SCHEDULE 625 SC . . . . . . . . . . . . . . . . . .11-16

PERIODIC MAINTENANCE SCHEDULE LC4, ADVENTURE . . . . . . . . . .11-18

PERIODIC MAINTENANCE SCHEDULE DUKE . . . . . . . . . . . . . . . . . . .11-20

 

MODEL 2003

PERIODIC MAINTENANCE SCHEDULE 625 SXC, 660 SMC . . . . . . . . .11-22

PERIODIC MAINTENANCE SCHEDULE 640 LC4, 640 LC4 ADVENTURE . . .11-24

PERIODIC MAINTENANCE SCHEDULE DUKE . . . . . . . . . . . . . . . . . . .11-26

 

WIRING DIAGRAMS:

MODEL1998

WIRING DIAGRAM 400 / 540 SXC . . . . . . . . . . . . . . . . . . . . . .12-3

WIRING DIAGRAM 400 / 620 SC (For Competition) . . . . . . . . .12-5

WIRING DIAGRAM 400 / 620 SC (For Australia) . . . . . . . . . . . .12-7

WIRING DIAGRAM 400 / 620 SC (For Germany) . . . . . . . . . . . .12-9

WIRING DIAGRAM 640 LC4 (For USA) . . . . . . . . . . . . . . . . . . .1211

WIRING DIAGRAM 640 ADVENTURE-R (Dell Orto) . . . . . . . . .12-13

WIRING DIAGRAM 640 DUKE-E . . . . . . . . . . . . . . . . . . . . . . .12-15

WIRING DIAGRAM 620 LC4 COMPETITION . . . . . . . . . . . . . .12-17

WIRING DIAGRAM 400 LC4 . . . . . . . . . . . . . . . . . . . . . . . . .12-19

WIRING DIAGRAM 640 LC4 . . . . . . . . . . . . . . . . . . . . . . . . .12-21

 

MODEL 1999

WIRING DIAGRAM 400 / 540 SXC . . . . . . . . . . . . . . . . . . . . .12-23

WIRING DIAGRAM 400 / 540 SXC (Australia) . . . . . . . . . . . . .12-25

WIRING DIAGRAM 400 / 620 SC . . . . . . . . . . . . . . . . . . . . .12-27

WIRING DIAGRAM 400 / 620 SC (Australia) . . . . . . . . . . . . . .12-29

WIRING DIAGRAM 640 ADVENTURE-R (Dell Orto) . . . . . . . . .12-13

WIRING DIAGRAM 640 ADVENTURE-R (Mikuni) . . . . . . . . . . .12-31

WIRING DIAGRAM 640 DUKE . . . . . . . . . . . . . . . . . . . . . . . .12-33

WIRING DIAGRAM 620 LC4 COMPETITION . . . . . . . . . . . . . .12-17

WIRING DIAGRAM 400 LC4 . . . . . . . . . . . . . . . . . . . . . . . . .12-19

WIRING DIAGRAM 640 LC4, SUPERMOTO . . . . . . . . . . . . . . .12-21

WIRING DIAGRAM 640 LC4 (USA) . . . . . . . . . . . . . . . . . . . . .12-11

 

MODEL 2000

WIRING DIAGRAM 400 / 620 SC / 620 SC SUPERMOTO . . . . .12-27

WIRING DIAGRAM 640 ADVENTURE-R . . . . . . . . . . . . . . . . .12-31

WIRING DIAGRAM 640 DUKE . . . . . . . . . . . . . . . . . . . . . . . .12-33

WIRING DIAGRAM 400 LC4-E . . . . . . . . . . . . . . . . . . . . . . . .12-19

WIRING DIAGRAM 640 LC4-E, SUPERMOTO . . . . . . . . . . . . .12-21

WIRING DIAGRAM 400 / 640 LC4-E (USA) . . . . . . . . . . . . . . .12-35

MODEL 2001

WIRING DIAGRAM 620 SC / 620 SC SUPERMOTO . . . . . . . . .12-37

WIRING DIAGRAM 640 LC4 ADVENTURE . . . . . . . . . . . . . . .12-39

WIRING DIAGRAM 640 DUKE . . . . . . . . . . . . . . . . . . . . . . . .12-41

WIRING DIAGRAM 400 LC4-E, 400 / 640 LC4-E USA . . . . . . .12-43

WIRING DIAGRAM 640 LC4-E, SUPERMOTO . . . . . . . . . . . . .12-45

 

MODEL 2002

WIRING DIAGRAM 625 SC / 625 SC SUPERMOTO . . . . . . . . .12-47

WIRING DIAGRAM 640 LC4 ADVENTURE . . . . . . . . . . . . . . .12-49

WIRING DIAGRAM 640 DUKE . . . . . . . . . . . . . . . . . . . . . . . .12-51

WIRING DIAGRAM 640 LC4, 640 LC4 SUPERMOTO . . . . . . . .12-53

WIRING DIAGRAM 640 LC4, 640 LC4 SUPERMOTO USA . . . .12-55

 

MODEL 2003

WIRING DIAGRAM 625 SXC . . . . . . . . . . . . . . . . . . . . . . . . .12-57

WIRING DIAGRAM 640 LC4, 640 LC4 SUPERMOTO . . . . . . . .12-59

WIRING DIAGRAM 640 LC4 ADVENTURE . . . . . . . . . . . . . . .12-61

WIRING DIAGRAM 640 DUKE . . . . . . . . . . . . . . . . . . . . . . . .12-63

WIRING DIAGRAM 660 SMC . . . . . . . . . . . . . . . . . . . . . . . . .12-64

Owner’s Manuals

 

 

This manual is the same as the manual used by workshops. Service Manual contains detailed instructions and step by step diagrams for all workshop procedures.

 Language: English 
Format: PDF – Indexed and Searchable

COMPATIBLE WITH ALL WINDOWS & MAC COMPUTERS 
(WINDOWS 11, WINDOWS 10, WINDOWS 8 ETC.) 

Windows/Mac/Tablet/Phone Friendly

 

 

 

• LC4 400: A 398cc single-cylinder engine with a more controllable power delivery and less vibration than the larger versions.
• LC4 640 Adventure: This dual-sport Paris/Dakar replica featured an updated 625cc engine for the 1998 model year and was known for its long-range capabilities.
• LC4 640 Supermoto: A street-focused model with a 625cc engine, 17-inch road tires, and adjustable WP suspension.
• LC4 660: The competition-focused 660cc engine was found on Rally Factory Replica and Supermoto models, typically with a kickstart-only design and a Keihin FCR41 carburetor. 

• Engine vibration: The big single-cylinder engine in the larger displacement LC4s is infamous for its heavy vibration. Riders can get used to it, but it can be tiring on long rides.
• Clutch bearing failure: In models until 2003, the clutch basket featured a ball bearing that was known to fail. This was later replaced with a more reliable roller bearing.
• Electrical issues: Older LC4s, especially the 640 Adventure, are known to have wiring harness and electrical component problems due to corrosion and degradation.
• Rocker arm wear: Some engines experience premature wear on the rocker arms or roller bearings, which requires routine inspection during valve adjustments.
• Water pump seal leak: A relatively common and straightforward issue is the failure of the water pump’s inner seals, which can be fixed with a simple rebuild.
• Head gasket oil leaks: An oil leak from the gasket between the upper and lower halves of the cylinder head is common and can be fixed with fresh sealant.
• Starter motor issues: While kickstarting was available, the electric starter motor was a known weak point on some models, requiring replacement. 

• 1998: The 620 Adventure became the 640 Adventure-R with a 625cc engine and a different exhaust system.
• 1999: The 640 LC4 Adventure saw significant cosmetic and suspension upgrades, including new plastic bodywork, a new tank, and WP Extreme forks.
• 2001: The 640 Adventure switched to a silver color scheme and gained a new fairing and updated 43mm WP forks.
• 2003: The engine was upgraded to the “High Flow” design, which was the final evolution of the early LC4 engine. It brought better performance and reliability

• Regular maintenance is critical: These engines were built for performance and require consistent, hands-on maintenance, including frequent oil and filter changes.
• Prepare for vibration: Be aware that the vibration can make long trips uncomfortable, especially on the larger displacement engines.
• Check service records: A complete service history is invaluable when purchasing a used LC4 from this era.
• Parts hunting: Some parts, particularly electrical components for older models, may be difficult to find in certain regions, so anticipate sourcing parts from abroad.
• Rust protection: To avoid corrosion, especially on adventure models, keep the bike clean and dry after riding in saltier conditions.