Malaguti Centro 160 Workshop Manual

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 retting of transmission cover bearings

and oil seal.......................................................................................94

Removal and retting 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

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125 - 160 cc

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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

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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).

8

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).

9

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

11

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%

12

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.

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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

16

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

18

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

19

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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Malaguti Centro 160 Workshop Manual

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Malaguti Centro 160 Workshop Manual

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