RIEJU Century 125 Workshop Manual Download Page 53

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ENGLISH

Engine

- top ring: +0.03 / 0.062 mm (0.0012 / 0.0024 in

- middle ring: +0.02 / 0.052 mm (0.0008 / 0.0020 in

- oil scraper: +0.01 / 0.19 mm (0.0004 / 0.007480 in

cylinder check

•

Using a bore meter, measure the cyl-
inder inside diameter at three different
points according to the directions
shown in the figure.

•

Check that the coupling surface with
the head is not worn or misshapen.

CAUTION

THE MARKING IS LOCATED ON THE PISTON CROWN.

Characteristic

Maximum run-out allowed:

0.05 mm

YLINDER

PISTON

COUPLING

CLEARANCE

125

Coupling categories with cast-iron cylinder

NAME

ABBREVIA

TION

CYLINDER

PISTON

FITTING

CLEARANCE

min

max

min

max

min

max

Cylinder/Piston

58.010

58.017

57.963

57.970

0.040

0.054

Cylinder/Piston

58.017

58.024

57.970

57.977

0.040

0.054

Cylinder/Piston

58.024

58.031

57.977

57.984

0.040

0.054

Cylinder/Piston

58.031

58.038

57.984

57.991

0.040

0.054

Inspecting the wrist pin

•

Check the pin outside diameter.

Characteristic

Pin

Minimum diameter: 14.995 mm (0.590 in)

Standard diameter: 15.0000 +0/-0.0030 mm (0.00012 in)

Inspecting the piston rings

ANELLI DI TENUTA

Specification

Desc./Quantity

Compression ring (top)

0.2 / 0.35 mm (0.0079 / 0.014 in)

Compression ring (middle)

0.2 / 0.35 mm (0.0079 / 0.014 in)

Summary of Contents for Century 125

Page 1: ...CENTURY 125 i e E4 En g i n e Wo rksh o p Ma n u a l ...

Page 2: ...cation beforehand to make any changes to components parts or accessories which it considers necessary to improve the product or which are required for manufacturing or construction reasons Not all versions models shown in this publication are available in all countries The availability of each model should be checked at the official RIEJU sales network Copyright 2014 Rieju S A All rights reserved ...

Page 3: ... B Provides key information to make the procedure easier to understand and carry out CAUTION Refers to specific procedures to carry out for preventing damages to the vehicle WARNING Refers to specific procedures to carry out to prevent injuries to the repairer Personal safety Failure to completely observe these instructions will result in serious risk of personal injury Safeguarding the environmen...

Page 4: ...clutch b Cheecking the springs 5 CRANKCASE a Bushing slection 6 HEAD AND TIMING a Checking the overhead camshaft 6 9 ENGLISH Index 43 46 52 54 59 9 LUBRICATION c Valve clerance b Valve check d e Checking the connecting rod small end b Valve check c Valve clerance b Valve check c Checking the piston ...

Page 5: ...Engine ENGLISH 5 ...

Page 6: ... primary shaft COUPLING CLASSES The gears of the primary drive are classified according to the coupling with the gear of the clutch housing and with the gear of the balancing countershaft and follow the logic shown in the tables listed below COUPLING CLASSES CLUTCH HOUSING FIRST GEAR SHAFT Coupling classes on Crankcase Clutch housing gear Transmission gear X X X Y Y Y COUPLING CLASSES FIRST GEAR S...

Page 7: ...e freely and check if there are signs of corrosion Check the eccentricity of the transmis sion shafts Check the condition of the two springs 5 and 6 of the selector 7 Check the condition of the gears re place them if they are blue if they have cracks or are worn Assembling the gearbox Place the specific tool on the secon dary shaft to avoid damaging the oil seal Heat up the engine crankcase Apply ...

Page 8: ... the crankshaft Starter motor STARTER MOTOR pos Description Type Quantity Torque Notes 1 Starter motor fixing screw M6x25 2 11 13 Nm 8 11 9 58 lbf ft STARTER MOTOR Make sure that the toothing 1 is not deformed or worn Make sure that the O ring 2 is not damaged or worn The electric starter motor is not fitted for repair If necessary replace the whole motor ...

Page 9: ...TER MOTOR CAN ALSO BE REMOVED IF THE ENGINE IS FITTED TO THE VEHICLE Installing the starter motor Place the electric starter motor Apply LOCTITE 221 Tighten the starter motor fixing screws Generator side FLYWHEEL COVER pos Description Type Quantity Torque Notes 1 Flywheel cover fastener screw M6 10 11 13 Nm 8 11 9 58 lbf ft ...

Page 10: ... IGNITION UNIT pos Description Type Quantity Torque Notes 1 Flywheel rotor fixing screw M14x1 5 1 83 90 Nm 61 21 66 38 lb ft Removing the flywheel cover Unscrew and remove the two adjust ment plugs 1 Unscrew and remove the engine oil pre filter plug 2 Remove the engine oil pre filter Undo and remove the ten screws fixing the flywheel cover Remove the flywheel cover ...

Page 11: ...H Engine 11 Magneto flywheel removal Remove the starter motor gear Position the locking tool Unscrew and remove the hex head screw and retrieve the washer Position the tool Remove the flywheel and its spline ...

Page 12: ...Engine 12 ENGLISH Remove the oil filter ...

Page 13: ...e 13 Freewheel removal Undo and remove the screw from the lock Remove the freewheel Installing the flywheel For refitting follow the operations described previously in reverse order See also Magneto flywheel removal ...

Page 14: ... CLUTCH COVER pos Description Type Quantity Torque Notes 1 Clutch cover fixing screw M6x35 10 11 13 Nm 8 11 9 58 lbf ft 2 Oil filter cover M56x1 5 1 24 26 Nm 17 70 19 17lbf ft 3 Oil pressure sensor M10 1 12 14 Nm 8 85 10 32 lbf ft ...

Page 15: ...h spring screw M5 5 3 5 4 5 Nm 2 58 3 31 lbf ft 2 Clutch housing retainer nut M12 1 35 45 Nm 25 81 33 19 lbf ft Removing the clutch cover Unscrew and remove the three water pump cover screws Remove the water pump cover Unscrew and remove the rotor fixing screw Remove the rotor ...

Page 16: ...Engine 16 ENGLISH Unscrew and remove the oil filter plug Remove the spring and oil filter ...

Page 17: ...s ket Collect the dowel pins WARNING REPLACE THE GASKET DURING REFITTING Remove the lubrication circuit by pass spring Disassembling the clutch Unscrew and remove the six screws by loosening them 1 4 of a turn at a time operate in stages and diagonally and retrieve the washers and the clutch springs ...

Page 18: ...rust bearing Remove the discs Release the screw by lowering the lock tab Block clutch bell rotation using the spe cific tool Unscrew and remove the clutch bell fixing nut Remove the clutch hub Remove the shim and the clutch hous ing ...

Page 19: ...ing plates 5 Driven plates thickness 1 46 1 53 mm 0 057 0 06 in Number of driven plates 4 Checking the clutch housing COUPLING CLASSES The gears that are coupled to each other clutch housing first gear shaft and balancing countershaft indicate the coupling classes in this regard see section Checking the primary shaft within the topic Gearshift ...

Page 20: ...he clutch bell all together Check the worn guiding grooves of the clutch bell 1 max insertion depth A 0 5 mm 0 020 in Checking the clutch hub When the clutch hub is worn it can cre ate problems with sliding of the hous ing The hub should be replaced if the surface of the spring has exceeded the wear limits Max wear limit A 0 3 mm 0 012 in Check the clutch hub for damage and wear that may result in...

Page 21: ...them all togeth er Measure the clutch spring length when unloaded if necessary replace the springs all together Characteristic Minimum wear limit in the release position of the individual clutch springs 31 6 mm 1 24 in Assembling the clutch Insert the shim Fit the clutch housing Fit the shim washer ...

Page 22: ...de of the lock tab Insert the disc covered with the friction material into the bell Continue inserting alternating a metal disc with one with friction material fin ishing with a friction material disc with a black tooth Place the thrust plate Fit the clutch springs Fit the screw washers Tighten the six screws operating in stages and diagonally ...

Page 23: ...htening di agonally and in stages Refit the water pump Refit the oil filter Add engine oil up to the correct level WARNING TO FACILITATE INSERTION OF THE COVER ROTATE WA TER PUMP THE ROTOR UNTIL THE GEARS ENGAGE Crankcase ENGINE CRANKCASE pos Description Type Quantity Torque Notes 1 Crankcase halves union M6 12 11 13 Nm 8 11 9 58 lbf ft ...

Page 24: ...t gear retainer nut M10 1 35 45 Nm 25 81 33 19 lbf ft Balancing countershaft removal Before taking out the balancing coun tershaft the clutch cover and flywheel cover must be removed Lock the countershaft with the specific tool Unscrew and remove the nut and col lect the washer See also ...

Page 25: ... countershaft gear Remove the countershaft from the al ternator side Balancing countershaft fitting Insert the countershaft from the alter nator side Insert the gear aligning its reference to the primary gear Using the specific tool tighten the nut remember first to place the washer ...

Page 26: ...d the clutch Remove the gear selector Install the countershaft blocking tool Remove the primary gear unscrewing and removing the nut Collect the washer Remove the countershaft gear Remove the primary remaining gears Remove the head and cylinder See also Removing the cylinder ...

Page 27: ... the chain guide slider un screwing and removing the fixing screw Remove the timing chain gear Remove the pump drive gear remov ing the seeger and recovering the washer Remove the base gear of the main shaft Remove the cotter ...

Page 28: ...he gear spider screw un screwing and removing the fixing screw Moving from the left side of the engine remove the flywheel and all of its com ponents beforehand Unscrew and remove the six screws on the outside of the crankcase 1 See also Magneto flywheel removal Unscrew and remove the longest screw 2 ...

Page 29: ...k There are two classes of couplings highlighted on the crankcases X Y and S T The coupling between the gears of the crankshaft and the first gear shaft has been classified into two classes These classes are defined according to the interaxial distance that exists between two ele ments COUPLING CLASS INTERVALS CRANKSHAFT FIRST GEAR SHAFT Specification Desc Quantity X 86 00 86 04 mm 3 386 3 388 in ...

Page 30: ...aft has been classified into two classes These classes are defined according to the interaxial distance that exists between two elements COUPLING CLASS INVERVALS FIRST GEAR SHAFT BALANCING COUNTERSHAFT Specification Desc Quantity S 64 00 64 03 mm 2 520 2 521 in T 63 97 64 00 mm 2 519 2 520 in Therefore the couplings will be COUPLING CLASSES FIRST GEAR SHAFT BALANCING COUNTERSHAFT Coupling classes ...

Page 31: ...ent ball Check that the surfaces are free from dents or deformations with special attention to both the crankcase coupling and the cylinder crankcase surfaces Defects in the crankcase coupling gasket or the surfaces indicated in the figure can cause a drop in the oil pressure and affect the lubrication pressure for the main bushings and the connecting rod Check that the surfaces that limit cranksh...

Page 32: ...10 mm 0 0791 in Blue MIN 2 010 mm 0 0791 in MAX 2 015 mm 0 0793 in CRANKSHAFT COUPLING BUSHING SEAT DIAMETER Specification Desc Quantity Crankshaft type 2 Type 1 crankcase diameter RED RED Type 2 crankcase diameter RED BLUE Crankshaft type 1 Type 1 crankcase diameter RED BLUE Type 2 crankcase diameter BLUE BLUE Bearing fitting Heat up the crankcase using the thermal gun Fit the bearing in the seat...

Page 33: ... screws 3 See also Assembling the gearbox Position and screw the long screw 2 Moving from the left side of the crank case position and screw the six screws 1 Fit the countershaft Position the selection spider screw Position and screw the screw See also Balancing countershaft fitting ...

Page 34: ...ket Fit the oil pump screwing the three screws Insert the countershaft gear and posi tion the washer Use the specific tool to tighten the nut Apply the cotter to the main shaft Position the base gear of the primary aligning the two references ...

Page 35: ... seeger Insert the timing chain gear paying at tention to the direction The engraving must face upward Fit the timing chain Position the chain guide slider Position and screw the fixing screw Fit the rest of the primary gears Tighten the fixing nut Remove the countershaft locking tool ...

Page 36: ...e 36 ENGLISH Fit the gear selector Head and timing HEAD COVER pos Description Type Quantity Torque Notes 1 Spark plug M10 1 12 14 Nm 8 85 10 32 lbf ft 2 Head cover fixing screw M6 4 10 12 Nm 7 38 8 85 lbf ft ...

Page 37: ...rew M6x40 8 10 Nm 7 38 lbf ft 4 Head fixing screw M8x166 4 25 Nm 90 18 44 lbf ft 90 5 Thermostat cover fixing screw M6x20 2 10 Nm 7 38 lbf ft TIMING SYSTEM pos Description Type Quantity Torque Notes 1 Chain tensioner slider fulcrum fixing screw M6x16 1 10 Nm 7 38 lbf ft Loctite 243 2 Transmission timing gear fixing screw M8x40 1 27 Nm 19 91 lbf ft Loctite 243 Removing the head cover Remove the adj...

Page 38: ...Engine 38 ENGLISH Unscrew and remove the four cylinder head screws 2 Remove the cylinder head 3 Remove the gasket 4 Remove the spark plug ...

Page 39: ...ton to TDC The sign 2 must be aligned with the sign 3 Insert the specific pins 4 on the valves cam tower Remove the starter motor beforehand Loosen and remove the tensioner screw 5 Remove the spring Unscrew and remove the two screws 6 6 and remove the entire tensio control See also Removing the starter motor ...

Page 40: ...Lock the timing gear using the tool Unscrew and remove the gear Repeat the operation with the other gear Cylinder head Removing the overhead camshaft 1 1 Unscrew and remove the six screws 1 1 a Remove the cylinder head 3 ...

Page 41: ...ENGLISH Engine 41 Remove the cylinder head 3 Remove the two pins from the valves cam tower Remove the eight screws 1 Remove the valve cam tower 2 Remove the two camshafts intake and exhaust side ...

Page 42: ...move the head Place the head on supporting surface Number the valves and their bucket tappets in order to position them cor rectly upon refitting Remove the valve bucket tappets Compress the valve spring using the tool Remove both cotter pins ...

Page 43: ...their shoulders are not worn If values measured are not within the specified limits or there are signs of wear replace the defective components with new ones Characteristic Maximum axial clearance allowed 0 4 mm 0 0157 in Valve check Measure the width of the sealing surface on the valve seats and on the valves themselves If the sealing surface on the valve is wider than the specified limit damaged...

Page 44: ...0016 in Standard clearance Exhaust 0 025 0 052 mm 0 00098 0 00204 in Maximum clearance admitted Intake 0 060 mm 0 0023 in Maximum clearance admitted Exhaust 0 070 mm 0 0027 in Remove the head cover Bring the engine to reach the top dead centre and lock it at that position using the tool 4 ...

Page 45: ...es measured differ from the values specified record the difference between MAXIMUM ALLOWED CLEARANCE e CLEARANCE MEAS URED Remove the chain tensioner Undo and remove the eight screws and remove the cam tower Remove the timing chain and the gears of the camshaft of the valves in ques tion ...

Page 46: ...in Fit the camshaft the gears and the chain in their correct positions using the references located on the flywheel side of the crankcase Fit the cam tower and tighten the eight screws to the prescribed torque Fit the chain tensioner Check for correct valve clearance Fit the head cover Inspecting the valve sealings Fit the valves into the cylinder head Alternatively test the intake and exhaust val...

Page 47: ... valve guide Measure according to the thrust direction at three different heights Characteristic Intake guide standard diameter 4 012 mm 0 1579 in Intake guide Wear limit 4 020 mm 0 1582 in Discharge guide standard diameter 4 012 mm 0 1579 in Discharge guide Wear limit 4 020 mm 0 1582 in Replace the head if the values corre sponding to the width of the mark on the valve seat or the valve guide dia...

Page 48: ...he cylinder head Using a trued bar check that the head surface is not worn or distorted Check that the camshaft bushings are not worn Check that the head cover surface the intake manifold and the exhaust manifold are not worn Installing the valves Lubricate the valve guides with engine oil Position the two oil seals on the cylinder head Fit the valves the springs and the caps Usin the specific too...

Page 49: ...not worn Check the condition of the tensioner spring If signs of wear are found replace the whole assembly Checking the chain Check that the guide slider and the ten sioner pad are not excessively worn Check that the chain assembly the camshaft driving pulleys and the sprocket wheel are not worn Replace the parts if signs of wear are found Cylinder piston assembly ...

Page 50: ... PISTON pos Description Type Quantity Torque Notes 1 Chain tensioner screw M8 1 6 Nm 4 43 lbf ft Removing the cylinder CYLINDER REMOVAL Remove the cylinder head gasket 1 Remove the guide slider 2 Remove the water sleeve clamp 3 ...

Page 51: ...ve the cylinder 4 Remove the gasket 5 Disassembling the piston Apply the tool under the piston 1 Cover the base of the cylinder with a cloth Remove the retainer ring which locks the pin 2 Remove the pin 3 Remove the piston 4 ...

Page 52: ...ooves coupling clearance using suitable sen sors as shown in the diagram If clearances measured exceed the limits specified in the table the piston should be replaced by a new one NOTE MEASURE CLEARANCE BY INSERTING THE BLADE OF THE FEELER GAUGE FROM THE 2nd SEALING RING SIDE Characteristic Piston cylinder Piston pin hole standard 15 003 15 008 mm 0 5907 0 5908 in Maximum piston cylinder coupling ...

Page 53: ...E 125 CM Coupling categories with cast iron cylinder NAME ABBREVIA TION CYLINDER PISTON FITTING CLEARANCE min max min max min max Cylinder Piston M 58 010 58 017 57 963 57 970 0 040 0 054 Cylinder Piston N 58 017 58 024 57 970 57 977 0 040 0 054 Cylinder Piston O 58 024 58 031 57 977 57 984 0 040 0 054 Cylinder Piston P 58 031 58 038 57 984 57 991 0 040 0 054 Inspecting the wrist pin Check the pin...

Page 54: ... cific micrometer NOTE IF THE CONNECTING ROD SMALL END DIAMETER EX CEEDS THE MAXIMUM DIAMETER ALLOWED SHOWS SIGNS OF WEAR OR OVERHEATING REPLACE THE CRANKSHAFT AS DESCRIBED IN THE CRANKCASE AND CRANKSHAFT CHAPTER Characteristic Rod small end Maximum diameter 15 023 mm 0 591 in Standard diameter 15 010 15 018 mm 0 5910 0 5912 in Fitting the piston Install piston and pin onto the connect ing rod ali...

Page 55: ...Move the dial gauge diagonally and measure the piston protrusion in rela tion to the reference surface Calculate the necessary thickness of the gasket selecting it based on the values shown in the table below Installing the cylinder Fit a new cylinder base gasket of the chosen thickness Refit the cylinder as indicated in the figure using the specific clamp tighten er tool NOTE BEFORE FITTING THE C...

Page 56: ... 5 0 05 mm 0 019 0 001 in Installing the cylinder head Fit the chain guide slider onto the cyl inder Fit the head gasket and the alignment dowels Fit the head Screw but do not tighten both central long screws 3 and position the wash ers Screw but do not tighten both central long screws 2 and position the wash ers Screw but do not tighten the two side short screws 1 NOTE BEFORE INSTALLING THE HEAD ...

Page 57: ...afts in their seats on the head remember to position the camshaft marked with the letter A on the intake side and the camshaft marked with the letter S on the ex haust side WARNING POSITION THE CAMS OF BOTH SHAFTS FACING OUT WARDS Position the cam tower cap Screw but do not and tighten the eight screws Place the pins in their positions on the overhead camshafts ...

Page 58: ...sioner on the cylinder using a new gasket and tighten the two screws 1 to the prescribed torque Insert the spring with the central screw 2 2 and o ring and tighten the cap the prescribed torque Tighten the screws fixing the camshaft gears to the prescribed torque Remove the pins on the camshafts Remove the specific crankshaft locking tool Tighten the screw on the crankcase Check the valve clearanc...

Page 59: ...ENGLISH 59 Engine Lubrication OIL PUMP pos Description Type Quantity Torque Notes 1 Oil pump fixing screw M6x25 3 10 Nm 7 38 lbf ft Loctite 243 Conceptual diagrams ...

Page 60: ...Engine 60 ENGLISH Removing Remove the Seeger ring Remove the pump gear Remove the pump gear Separate the components to inspect them ...

Page 61: ...clearance 1 between points of the rotor 0 04 mm 0 0015 in Radial clearance 2 between points of the rotor 0 08 mm 0 003 in Radial clearance 3 between rotor 1 and the pump body 0 04 mm 0 0015 in Radial clearance 3 between rotor 2 and the pump body 0 05 mm 0 0019 in Installing Refit the oil pump proceeding in re verse order of disassembly Pay atten tion to the direction of the rotor the dot should st...

Page 62: ......

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