TABLE OF CONTENTS
www.betamotor.com
PREAMBLE 2
TECHNICAL FEATURES OF ENGINE 4
SPECIAL EQUIPMENT 5
1 REMOVAL OF MOTOR FROM VEHICLE 6
2 ENGINE DISASSEMBLY 13
2.1 CLUTCH/GEAR OIL DRAIN......................................................13
2.2 REMOVAL OF CLUTCH CONTROL ROD AND PINION
SPACER ......................................................................................13
2.3 REMOVAL OF PISTON, CYLINDER AND HEAD ...................14
2.4 REMOVAL OF IGNITION UNIT ...............................................17
2.4.1 Removal of flywheel coveR........................................................ 17
2.4.2 Removal of statoR ............................................................................. 17
2.4.4 Removal of pick-up............................................................................ 18
2.4.3 Removal of flywheel ....................................................................... 18
2.5 REMOVAL OF ELECTRIC IGNITION .......................................19
2.5.1 Removal of staRt motoR................................................................ 20
2.5.2 Removal of Bendix coupling ..................................................... 20
2.6 REMOVAL OF COOLANT LIQUID PUMP, CLUTCH UNIT,
MAIN GEAR, CENTRIFUGAL UNIT, GEARSHIFT ORGANS,
KICKSTART .................................................................................21
2.6.1 Removal of coolant liquid pump.......................................... 24
2.6.2 Removal of centRifugal unit and leveRage................... 25
2.6.3 Removal of main geaR and clutch unit ............................ 28
2.6.4 pedal kickstaRt..................................................................................... 31
2.6.5 exteRnal geaRshift unit................................................................ 33
2.7 INTAKE SYSTEM........................................................................34
2.8 CRANKSHAFT, GEARBOX UNIT AND INTERNAL
GEARSHIFT ................................................................................35
2.81 opening of cRankcase ................................................................... 35
2.8.2 motoR shaft........................................................................................... 36
2.8.3 inteRnal geaRshift unit and complete geaRBox ........ 36
2.9 DISASSEMBLY OF PARTS FROM CRANKCASES..................37
2.9.1 Right cRankcase half...................................................................... 37
2.9.2 left cRankcase half ......................................................................... 40
3 MOTOR CHECKS AND ASSEMBLY 41
3.1 CRANKCASE HALF ...................................................................41
3.1.1 application of Right cRankcase half paRts.................... 42
3.1.2 application of left cRankcase half paRts........................ 44
3.2 CHECK OF CONNECTING ROD AND MOTOR SHAFT.........45
3.3 ASSEMBLING OF COMPLETE CRANKSHAFT ......................46
3.4 GEAR UNIT: CHECKS AND REASSEMBLY ............................47
3.4.1 check of geaRBox unit................................................................... 47
3.4.2 assemBly of main unit .................................................................... 48
3.4.3 assemBly of secondaRy unit...................................................... 49
3.4.4 check of foRks, foRk pins and desmodRomic
device.......................................................................................................... 50
3.4.5 assemBly of geaRBox and inneR contRol........................ 52
3.5 CLOSING OF ENGINE CRANKCASE.......................................55
3.6 EXTERNAL GEARSHIFT............................................................56
3.6.1 check of complete dRive shaft ............................................... 56
3.6.2 assemBly of exteRnal geaRshift.............................................. 58
3.7 KICK STARTER DEVICE.............................................................58
3.7.1 check of kickstaRt shaft and assemBly ............................ 58
3.7.2 assemBly of kickstaRt device ..................................................... 60
3.8 MAIN GEAR AND CLUTCH UNIT............................................62
3.8.1 check of main geaR .......................................................................... 62
3.8.2 application of main geaR.............................................................. 62
3.8.3 check of clutch case, RolleR BeaRing and inteRnal
centRe BeaRing .................................................................................... 63
3.8.4 check of clutch discs.................................................................... 64
3.8.5 check of spRings .............................................................................. 65
3.8.6 check of clutch dRum................................................................... 65
3.8.7 check of thRust BeaRing device............................................. 66
3.8.8 assemBly of clutch unit............................................................... 66
3.9 COOLANT LIQUID PUMP AND CENTRIFUGAL UNIT ........68
3.9.1 check of pump unit and disassemBly, centRifugal
unit and idleR unit .......................................................................... 69
3.9.2 assemBly of centRifugal unit ................................................. 70
3.9.3 assemBly of pump unit................................................................... 73
3.9.4 assemBly of complete clutch coveR and pump
unit............................................................................................................... 73
3.10 ELECTRIC IGNITION UNIT ......................................................76
3.10.1 Bendix coupling checks .............................................................. 76
3.10.2 ignition unit coupling to motoR ......................................... 76
3.11 IGNITION SYSTEM ..................................................................77
3.11.1 check of ignition system ............................................................ 78
3.11.2 coupling of ignition system to cRankcase.................... 78
3.12 THERMAL UNIT ........................................................................81
3.12.1 checking piston and elastic Bands ..................................... 81
3.12.2 cylindeR check..................................................................................... 82
3.12.3 piston cylindeR coupling play................................................. 83
3.12.4 checks and exhaust valve unit disassemBly.................. 83
3.12.5 exhaust valve unit assemBly ...................................................... 85
3.12.6 piston, pin Bolt, elastic Bands and cylindeR
assemBly .................................................................................................. 87
3.12.7 check of cRankcase/cylindeR gasket thickness........ 89
3.12.8 head application................................................................................. 90
3.12.9 exhaust valve adjustment ........................................................... 91