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125 - 160cc 4T
Workshop Manual Engine
1
125 - 160 cc
C
WORKSHOP MANUAL
GENERAL INDEX
Assembling the piston ...................................................................37
Stripping down the cylinder head .................................................38
Checking valve springs ..................................................................................40
Checking valves ............................................................................................. 40
Checking and adjusting valve seating ..........................................42
Inspection ....................................................................................................... 42
Change ........................................................................................................... 42
Lapping .......................................................................................................... 44
Installing the cylinder .....................................................................50
Installing the cylinder head ............................................................52
Installing the camshaft support .....................................................53
Checking engine timing .................................................................57
Fitting the valves cover ..................................................................58
SPEED VARIATOR-CLUTCH UNIT
..................................60
Trouble shooting .............................................................................
61
Variator unit exploded view ..........................................................
62
Clutch unit exploded view .............................................................63
Clutch pulley exploded view .........................................................64
Clutch shoes assy exploded view ................................................65
Removing the clutch cover ............................................................66
Assembly ........................................................................................................ 67
Primary pulley .................................................................................67
Disassembly ................................................................................................... 67
Checks .............................................................................................70
Drive belt ........................................................................................................ 70
Roller weights ................................................................................................. 71
Mobile primary pulley ..................................................................................... 71
OIL PUMP ASSY
...........................................................................3
Trouble shooting ...............................................................................................4
Exploded view of oil pump ...............................................................5
Disassembly ......................................................................................6
Removing the oil pump .................................................................................... 8
Oil pump body tolerances ................................................................................ 9
Clearance between oil pump inner and outer rotors ...................10
Clearance between front surfaces ................................................10
Assembly ......................................................................................... 11
CYLINDER HEAD, VALVES, CYLINDER, PISTON
.....15
Working precautions ......................................................................
15
Trouble shooting .............................................................................
18
Cylinder head exploded view .........................................................19
Cylinder compression pressure ...................................................20
Valve clearance adjustment ...........................................................
21
Removing camshaft support .........................................................23
Removing the camshaft .................................................................26
Checks .............................................................................................27
Camshaft ....................................................................................................... 27
Rocker arms and rocker arm spindles ........................................................... 28
Removing the cylinder head ..........................................................29
Removing the cylinder ...................................................................31
Removing the piston ......................................................................32
Cylinder / piston checks .................................................................34
Checking the cylinder ..................................................................................... 34
Checking the piston ........................................................................................ 34
2
125 - 160 cc
C
WORKSHOP MANUAL
GENERAL INDEX
Installing the primary pulley ..........................................................73
Disassembling the clutch ...............................................................
76
Disassembling the clutch unit .......................................................
77
Removing the secondary pulley ...................................................
78
Checks .............................................................................................80
Clutch bell ...................................................................................................... 80
Clutch linings .................................................................................................. 80
Variator contrast spring ................................................................................. 81
Fixed secondary pulley .................................................................................. 81
Mobile secondary pulley ................................................................................. 82
Assembling the clutch ....................................................................83
Installing the clutch bell .................................................................
87
FINAL DRIVE GEARS
.............................................................88
Final drive exploded view...............................................................89
Removing the transmission cover ................................................
90
Remove pulley shaft .......................................................................
92
Transmission cover checks ...........................................................92
Removal and retting of transmission cover bearings
and oil seal.......................................................................................94
Removal and retting of clutch side engine casing bearings
and oil seals.....................................................................................96
Installing the transmission gears ..................................................
97
Installing the transmission cover ..................................................
98
FLYWHEEL COVER, FLYWHEEL MAGNETO,
WATER PUMP
............................................................................100
Exploded view of water pump
......................................................101
Exploded view of ywheel cover .................................................102
Removing the ywheel cover.......................................................103
Removing the ywheel magneto .................................................................. 104
Removing the freewheel gear ...................................................................... 105
Removing the stator/pick-up assy ................................................................ 106
Removing the water pump impeller .............................................................. 106
Installing the water pump .............................................................107
Assembly procedure .................................................................................... 107
Installing the stator/pick-up assy ................................................108
Installing the freewheel gear and rotor .......................................
109
Installing the ywheel cover ........................................................ 111
ENGINE CASING, CRANKSHAFT
.................................113
Removing the engine casings ..................................................... 114
Crankshaft checks ........................................................................ 115
Installing the engine casing .........................................................
117
3
125 - 160 cc
C
WORKSHOP MANUAL
• The oil pump must be serviced after having removed the flywheel cover.
• When the values measured are outside the service limits, renew the oil pump.
• Ensure that no foreign material enters the engine when the oil pump is removed.
• Check for oil leaks once the pump has been installed.
Standard
Oil quantity For oil change 1.1 L
Total capacity
1.15 L
Recommended oil
temperature and viscosity
(temperature)
- 10° 0° 10° 20° 30° 40°C
SAE 20W /40
SAE 10W / 50
SAE 10W / 40
SAE 10W / 30
SAE 10W-40 20W-50 Special
for 4-stroke engines
When using alternative oils, select from the following range
API: type SE or SF engine oil
SAE: select from the table alongside on the basis of the outdoor
temperature.
cont’d
OIL PUMP ASSY
07028005
4
125 - 160 cc
C
WORKSHOP MANUAL
OIL PUMP ASSY
Standard Service limit
Oil pump rotor Radial clearance between
inner and outer rotors
0.15 mm 0.20 mm
Pump body radial clearance 0.15 - 0.23 mm 0.25 mm
Front clearance between
surfaces
0.05 - 0.10 mm 0.12 mm
Tightening torques
Pump body screws 10 N*m ± 15%
Pump cover screws 2 N*m ± 15%
Protection plate A assy
10 N*m ± 15%
Protection plate B 10 N*m ± 15%
Trouble shooting
Low oil level; possible causes:
1) Normal consumption (check scheduled service has been performed).
2) Oil leaks.
3) Wear or incorrect fitting of piston rings.
4) Wear of valve guide or valve stem.
5) Valve seat rings damaged.
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125 - 160 cc
C
07028001
7
1
6
3
4
5 2
WORKSHOP MANUAL
OIL PUMP ASSY
Exploded view of oil pump
1) Pump cover
2) Pump shaft
3) Inner rotor
4) Outer rotor
5) Pump body
6) Locating dowel
7) Screw
6
125 - 160 cc
C
A
C
07028101
07028102
WORKSHOP MANUAL
Ensure that no foreign material enters the engine when the
oil pump is removed and refitted.
Disassembly
Remove:
• flywheel cover.
• rotor and freewheel gear.
• chain guard (A) and oil pump assembly.
Remove circlip (C) from shaft.
OIL PUMP ASSY
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125 - 160 cc
C
D
E
B
07028103
07028104
WORKSHOP MANUAL
OIL PUMP ASSY
Remove chain ring (D) and chain (E).
Check chain for damage or excessive wear.
Remove chain guard (B).
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125 - 160 cc
C
G
F
C V
07028100
DSCN8392
WORKSHOP MANUAL
OIL PUMP ASSY
Remove pump assy (F) and pump shaft (G).
Check pump for possible damage or excessive wear.
Removing the oil pump
Undo screw (V) and remove pump cover (C).
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125 - 160 cc
C
Q M
L N
M N
07028105
07028106
WORKSHOP MANUAL
OIL PUMP ASSY
Remove inner rotor (L) and outer rotor (M) from pump body (N), paying
attention to locating dowel (Q).
Oil pump body tolerances
Measure outside diameter of outer rotor (M) and inside diameter of pump
body (N) with callipers and inside micrometer; the difference between the
two values is the “radial clearance” of the pump body.
Service limit: 0.25 mm
10
125 - 160 cc
C
N
M
L
07028107
N
L
M
07028108
WORKSHOP MANUAL
OIL PUMP ASSY
Clearance between oil pump inner
and outer rotors
Install inner rotor (L) and outer rotor (M) in pump body (N); measure
clearance between inner and outer rotors with feeler gauge.
Service limit: 0.20 mm
Clearance between front surfaces
Fit inner rotor (L) and outer rotor (M) in pump body (N) and use a feeler
gauge to measure axial clearance between rotors and pump body.
Service limit: 0.12 mm
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125 - 160 cc
C
Q M
L
N
C V
07028109
DSCN8392
WORKSHOP MANUAL
OIL PUMP ASSY
Assembly
Wash all parts in clean diesel fuel before refitting.
Fit inner rotor (L) and outer rotor (M) in pump body (N), paying attention
to locating dowel (Q)
Fit pump cover (C) and tighten screw (V) to prescribed torque.
V
Cs-N
*
m
2 ± 15%
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125 - 160 cc
C
P
N
V
2
B
07028110
07028111
WORKSHOP MANUAL
Ensure fixing holes (P) of pump body (N) are aligned with holes in flywheel
cover.
If holes are not aligned, screws (V
2
) cannot be tightened.
Fit and tighten two screws (V
2
) of pump body and chain guard (B); tighten
screws to prescribed torque.
V
2
Cs-N
*
m
10 ± 15%
OIL PUMP ASSY
13
125 - 160 cc
C
E
D
C
07028112
07028113
WORKSHOP MANUAL
OIL PUMP ASSY
Fit chain ring (D) and chain (E).
Fit circlip (C) in shaft groove.
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125 - 160 cc
C
B
A
V
07028114
WORKSHOP MANUAL
OIL PUMP ASSY
Couple chain guard (A) to chain guard (B) and tighten screw (V).
Fit rotor assembly and freewheel gear.
Fit flywheel cover.
15
125 - 160 cc
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WORKSHOP MANUAL
Working precautions
• Valves cover, camshaft, camshaft support, rocker arm, cylinder head and cylinder can be removed without
dropping engine from frame.
• Take care not to damage mating surfaces when removing valves cover, cylinder head and cylinder.
• Mark disassembled parts so they can be refit in exactly the same position.
• After disassembly, wash parts and dry with compressed air before checking and measuring them.
• Lubricate cam surfaces, shaft and internal hole of rocker arms before reassembling.
• Camshaft assy lubricating oil is fed through oil passages in the cylinder.
• Valve cover, cylinder head, and cylinder oilways must be perfectly clean prior to assembly.
Standard Service limit
125 cc 160 cc
Cylinder compression pressure 700 kPa (7 kgf/cm
2
) @ 260 RPM —
Valves
clearance
IN 0.05 mm —
EX 0.20 mm —
Flatness of cylinder head — 0.05 mm
Camshaft Cam height IN 30.74-30.86 mm 30.69 mm
EX 30.33-30.45 mm 30.28 mm
Rocker arm Rocker arm shaft bore
diameter
IN/EX 10.000-10.015 mm 10.10 mm
Rocker arm shaft diameter IN/EX 9.978-9.987 mm 9.91 mm
cont’d.
CYLINDER HEAD, VALVES, CYLINDER, PISTON
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125 - 160 cc
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WORKSHOP MANUAL
CYLINDER HEAD, VALVES, CYLINDER, PISTON
Standard Service limit
125 cc 160 cc
Valve guide Valve stem outside diameter
IN 4.975-4.990 mm 4.965 mm
EX 4.955-4.970 mm 4.945 mm
Valve guide inside diameter
IN 5.000-5.012 mm 5.040 mm
EX 5.000-5.012 mm 5.040 mm
Valve stem to guide
clearance
IN 0.100-0.037 mm 0.075 mm
EX 0.030-0.057 mm 0.095 mm
Valve guide height
IN/EX 11.9-12.1 mm —
Valve seating line height
IN/EX 0.9-1.1 mm 1.8 mm
Valve springs
Length
(Outer spring/inner spring)
IN/EX 35.0-32.3 mm 33.5-30.8 mm
Cylinder Internal diameter 52.400-52.419 mm 58.00-58.019 mm 52.449 mm 58.049 mm
Top face flatness
— 0.05 mm
Taper
— 0.05 mm
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125 - 160 cc
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WORKSHOP MANUAL
Standard Service limit
125 cc 160 cc
Piston Piston assembly direction “IN” on intake side —
Piston outside diameter 52.37-52.39 mm 57.97-57.99 mm 52.32/57.92 mm
Piston pin bore diameter 15.002-15.008 mm 15.04 mm
Piston pin diameter 14.994-15.000 mm 14.980 mm
Connecting rod small end diameter 15.016-15.034 mm 15.050 mm
Cylinder / piston tolerance 0.02-0.04 mm 15.05 mm
Piston / piston pin tolerance 0.002-0.014 mm 0.080 mm
Piston pin / small end tolerance 0.016-0.040 mm 0.040 mm
Piston rings / grooves
tolerance
Ring (1) 0.020-0.044 mm 0.070 mm
Ring (2) 0.020-0.044 mm 0.070 mm
Ring gap Ring (1) 0.15-0.30 mm 0.45 mm
Ring (2) 0.10-0.25 mm 0.45 mm
Scraper ring 0.2-0.7 mm 0.9 mm
Piston ring assembly direction punch marking at top —
Tightening torques
Cylinder head screw 10 N*m ± 15%
Tensioner screw
35 N*m ± 15%
Cylinder screws 9 N*m ± 15%
Valves cover screw
10 N*m ± 15%
Cylinder head nut 10 N*m ± 15%
Timing sprocket screw
10 N*m ± 15%
Chain tensioner screw 10 N*m ± 15%
CYLINDER HEAD, VALVES, CYLINDER, PISTON
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125 - 160 cc
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WORKSHOP MANUAL
Trouble shooting
Compression loss can be identified by measuring pressure directly.
If engine fails to start or idles unevenly, check for smoke in engine casing voids.
Presence of smoke means damaged, broken or worn piston rings.
Irregular full speed Low compression
Air infiltrating through carburettor couplings
Poor fuel feed
Low compression Incorrect valves clearance
Valve burnt or damaged
Incorrect timing
Weak valve spring
Poor valve seal
Pressure loss from head gasket
Head warped or cracked
Incorrect fitting of spark plug
High combustion pressure Carbon deposits on piston or in combustion chamber
Blue smoke from exhaust Damaged valve guide or valve stem
Damaged or worn seat ring
Anomalous noise Damage or wear of camshaft assy components
Incorrect valves clearance
Burnt valve or damaged valve spring
Rocker arm or rocker arm shaft damaged
Chain stretched
Chain tensioner malfunction
CYLINDER HEAD, VALVES, CYLINDER, PISTON
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125 - 160 cc
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WORKSHOP MANUAL
CYLINDER HEAD, VALVES, CYLINDER, PISTON
Cylinder head exploded view
1) Valve cotter
2) Valve upper spring retainer
3) Inner valve spring
4) Outer valve spring
5) Valve oil seal
6) Valve lower spring retainer
7) Cylinder head
8) Intake valve
9) Exhaust valve
10) Spark plug
9
7
6
4
3
1
2
5
2
1
3
4
5
6
10
8
07028109
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