Aprilia Workshop Manual Minarelli MA 50 MY 50

Workshop manual

MA 50

MY 50

976 X

Introduction

This manual provides basic information on standardservicing procedures. The data and illustrations con-tained in the manual were up to date at the moment ofpublication.Owing to aprilia ’s constant commitment to improvingthe quality and performance of its products, vehicles aresubject to change without notice. Users of this publica-tion should consequently be aware that, for some mod-els, the information provided may not be entirely up todate.Updates of specifications and servicing procedures re-sulting from changes made to vehicles will be notified toall aprilia distributors, who will in turn make them avail-able to after-sales mechanics.Before performing any operation, ensure that the infor-mation contained in this manual is applicable to the ve-hicle to be serviced.This publication is meant for aprilia dealers and theirtrained and qualified mechanics. The description of manyservice and repair operations has been deliberatelyomitted in that it is assumed that users of this manualhave received a basic training in mechanics, that theyare aware of vehicle repairing techniques, and that theyhave at their disposal all the information published byaprilia on the vehicle. Should any of these three condi-tions not be fulfilled, repairs and/or servicing may proveinadequate and thereby result in danger or injury.This manual does not provide a detailed description ofall the procedures required to perform repairs and serv-icing operations. It is therefore essential to exercise ex-treme caution in order to prevent damage to the vehicleand its components as well as personal injury to me-chanics and the user.

In case of doubt as to the repairing or servicing proce-dures, please contact aprilia’s AFTER-SALES DEPART-MENT: aprilia ’s technicians will be pleased to provideall necessary support.

For further information, please refer to:– THE CYCLE PARTS WORKSHOP MANUAL– THE ENGINE SPARE PARTS CATALOGUE– THE CHASSIS SPARE PARTS CATALOGUE

aprilia reserves the right to make any changes at any moment to allits models.This manual is copyright worldwide. Any reproduction thereof in printedor electronic form is forbidden.The mention of third parties’ products is only made for informationpurposes, and constitutes no engagement.aprilia assumes no responsibility for the use of products it has notexpressly recommended or approved.

LIST OF SECTIONS

6Starting System - Clutch

3Power Plant

2General Specifications

1General Information

7Crankcase - Crankshaft

4Carburettor - Reed Valve Unit

5Oil Pump - Starter Motor

First release: January 2000

Designed and printed by:CLD s.r.l Technical Manuals DepartmentVia Dante Alighieri, 37/A - 56012 Fornacette (Pisa) - ItalyTel. +39 0587 422800Fax +39 0587 422801www.cld.itE-mail: [email protected]

for:aprilia S.p.A.Via G. Galilei, 1 – 30033 Noale (VE) – ItalyTel. +39 041 5829111Fax +39 041 441054www.aprilia.comwww.serviceaprilia.com

General Information MA50 - MY50

chap. 11-2 Release 00 2000-01

CONTENTS

Chapter 1Introduction ............................................................................................................................... 1-1CONTENTS ....................................................................................................................... 1-2, 1-3SAFETY PRECAUTIONS ......................................................................................................... 1-4RECOMMENDATIONS ON MAINTENANCE ........................................................................... 1-4GENERAL SAFETY RULES ..................................................................................................... 1-5CARBON MONOXIDE .............................................................................................................. 1-5FUEL ......................................................................................................................................... 1-5TRANSMISSION OIL ................................................................................................................ 1-6COOLANT ................................................................................................................................. 1-6

Chapter 2Tightening torques..................................................................................................................... 2-2Table of lubricants ..................................................................................................................... 2-2Tools .......................................................................................................................................... 2-3

Chapter 3Removing the cylinder head...................................................................................................... 3-2Removing the thermostat .......................................................................................................... 3-2Removing the cylinder ............................................................................................................... 3-3Removing the piston ................................................................................................................. 3-3Checking the cylinder head ....................................................................................................... 3-3Checking the cylinder ................................................................................................................ 3-4Checking the piston................................................................................................................... 3-5Refitting the power plant ........................................................................................................... 3-7

Chapter 4Removing the carburettor .......................................................................................................... 4-2Removing the reed valve unit .................................................................................................... 4-2Checking the reed valve unit ..................................................................................................... 4-2Fitting the reed valve unit .......................................................................................................... 4-3Installing the carburettor ............................................................................................................ 4-3

Chapter 5Disassembling the water pump ................................................................................................. 5-2Removing the flywheel cover .................................................................................................... 5-2


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Checking the water pump ........................................................................................................ 5-2Reassembling the water pump................................................................................................. 5-3Removing the flywheel magneto .............................................................................................. 5-3Removing the stator ................................................................................................................. 5-3Checking the oil pump.............................................................................................................. 5-4Removing the oil pump ............................................................................................................ 5-4Checking the flywheel .............................................................................................................. 5-5Checking the stator .................................................................................................................. 5-5Fitting the oil pump ................................................................................................................... 5-6Fitting the stator ....................................................................................................................... 5-7Fitting the flywheel magneto .................................................................................................... 5-7Fitting the flywheel cover .......................................................................................................... 5-7Removing the starter motor ...................................................................................................... 5-8Fitting the starter motor ............................................................................................................ 5-8Fitting the water pump cover .................................................................................................... 5-8

Chapter 6Disassembling the starting system........................................................................................... 6-2Checking the starting shaft ....................................................................................................... 6-2Reassembling the starting system ........................................................................................... 6-3Removing the primary pulley.................................................................................................... 6-3Checking the primary pulley ..................................................................................................... 6-4Removing the starting clutch .................................................................................................... 6-5Checking the starting clutch ..................................................................................................... 6-6Removing the clutch and the secondary pulley........................................................................ 6-6Checking the clutch .................................................................................................................. 6-7Checking the secondary pulley ................................................................................................ 6-8Checking the belt ..................................................................................................................... 6-8Disassembling the transmission ............................................................................................... 6-9Checking the transmission ....................................................................................................... 6-9Reassembling the transmission ............................................................................................. 6-10Fitting the secondary pulley ................................................................................................... 6-11Fitting the clutch ..................................................................................................................... 6-11Fitting the starting clutch ........................................................................................................ 6-12Fitting the primary pulley ........................................................................................................ 6-13Reassembling the starting system ......................................................................................... 6-13

Chapter 7Removing the right-hand crankcase and the crankshaft .......................................................... 7-2Checking the crankcase, the crankshaft and the connecting rod............................................. 7-2Fitting the bearings ................................................................................................................... 7-3Fitting the crankshaft ................................................................................................................ 7-4Fitting the crankcase ................................................................................................................ 7-4Fitting the crankshaft oil seal .................................................................................................... 7-6


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SAFETY PRECAUTIONS

The following symbols are used in the manual to stress the importance of certain pieces of information:

: This symbol is used when special precautions are needed in dangerous situations that cancause death or serious injury to the operator and other exposed people, or result in serious and permanentdamage to the vehicle.

: This symbol denotes a potentially hazardous situation that may result in minor personalinjury or damage to the vehicle.

IMPORTANT: This term precedes important information or instructions that deserve special attention.

: Liquid cooling version only

RECOMMENDATIONS ON MAINTENANCE

IMPORTANT: Always observe the following precautions when repairing, fitting or removing engine compo-nents.

: All engine inspections and maintenance operations must be carried out while the engine isswitched off. Also ensure that no parts (such as the silencer, the brakes and other components that aresubject to heating) are hot after removing the engine from the vehicle. If necessary, wait for all parts to cooldown. Use suitable equipment to support the engine, taking care to place it on a level and solid workingsurface.

: Do not hold mechanical parts or engine components in the mouth, as some of them are madeof toxic materials.

: Avoid starting the engine in closed or poorly ventilated rooms.

: Keep away from heat sources. Do not use bright flames.

IMPORTANT: Operators servicing or repairing the engine must have all operating instructions to hand andfollow them scrupulously while observing the safety precautions prescribed for each part (e.g. tighteningtorques). When two or more operators are required to work on the same engine at the same time, all ofthem must observe the rules that ensure their own safety and that of others.

Only use GENUINE aprilia spares.Avoid using lubricants other than those shown in the table on page 2-2.

Always use the special tools that are prescribed in this manual. Never attempt to perform operations that requirethe use of special equipment with tools other than those specified in this manual.

: Failure to comply with the above instructions can result in serious personal injury, as is thecase when an unsuitable spanner slips off a fastening device, causing the operator’s hand to strike againstthe workbench.

When clamping fastening devices, always begin with the largest ones. Apply sufficient torque to tighteneach of the large-diameter fasteners, starting with the innermost device, and then proceeding diagonally.Following the same order, clamp the fastening devices with the prescribed torques, and then check thetorque value for each of the fasteners.

: Never use flammable solvents to clean the parts. Only use antifire detergents and solvents.Failure to observe this precaution may result in a fire breaking out and in serious or even fatal personalinjury.

DANGER

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CAUTION

CAUTION

Before fitting or assembling any components, always lubricate the metallic parts and the gaskets.

: Failure to observe the above prescription may result in seizure or early breakage of the parts.

: When fitting or assembling parts, be sure to perform the operation properly. Some of theparts can be fitted upside down or in the opposite direction, and the error will become evident only at theend of the assembly.

: Incorrect fitting or assembly can result in irreparable engine damage, seizure or malfunction.

Never reuse gaskets, seeger rings, snap rings, O-rings and cotter pins.

When fitting a new snap ring on a shaft, be sure not to part its ends more than necessary. Once it is inplace, ensure that it is firmly seated in its groove. Remember that snap rings do have a fitting direction, asthe rounded rim of the ring is designed to bear the thrust load (sharp edge “on the outside”).

Generously lubricate the bearings before fitting them.

IMPORTANT: Bearings must rotate freely, smoothly and noiselessly, otherwise they need to be replaced.

Apply distinctive marks to the positions of all connections (pipes, wires, etc.) before removing the compo-nents. Each part must be clearly identifiable to allow it to be properly reinstalled.

Before fitting new gaskets, thoroughly clean all their surfaces. Take care to remove any fragments of theold gaskets and any residues of the gasket adhesive.

IMPORTANT: Failure to observe this prescription will result in leakage from the engine.

Never reuse oil seals and gaskets. Before fitting oil seals and gaskets, apply a film of grease to the rims ofthe oil seals, and a film of grease or adhesive to the gaskets. Unless otherwise directed in this manual,install the oil seals and the bearings so that their marks or identification numbers are clearly visible whenthe parts have been fitted.

IMPORTANT: Unless otherwise directed, reassembling operations are to be performed in reverse order tothe disassembly.

: Failure to observe the above directions may result in serious and dangerous engine malfunc-tions such as seizure and breakage. Should such breakdowns occur during driving, the vehicle may over-turn and cause serious or even fatal personal injury. If you are unsure about your ability to properly per-form the operations described in this manual, please contact your local Aprilia dealer, or Aprilia’s Cus-tomer Care. Never attempt to perform any of the operations described in this manual if you do not have thespecific knowledge and special equipment required, as well as a clean, well-lit and well-ventilated workingarea.

GENERAL SAFETY RULES

CARBON MONOXIDEIf any operations are to be performed while the engine is running, it is essential that they should be carried out inthe open air or in a well-ventilated room.

: Avoid operating in indoor spaces that are not provided with an exhaust-gas venting system.Exhaust gases contain carbon monoxide, a toxic gas that may cause fainting or even death.

FUELFor information on the type of fuel to be used, please refer to the operation and maintenance manual provided withthe vehicle.

DANGER

DANGER

CAUTION


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: Fuel is highly flammable, and in certain conditions can even become explosive. Alwayshandle it with great care.

: Avoid inhaling fuel fumes as they are toxic. Fuel should be handled in a closed environmentonly if an adequate air change is ensured.

: Never smoke near fuel stores or where fuel fumes may be present. Also avoid sparks, openflames and whatever may cause the ignition or explosion of the fumes.

: Avoid spilling fuel on the skin. Wear protective gloves when pouring it. To avoid ingestingfuel or inhaling its fumes, use a length of tube without sucking with the mouth.

: Do not dispose of fuel in the environment.

KEEP OUT OF REACH OF CHILDREN

TRANSMISSION OIL

U s e FC SAE 75W-90 oil or GEAR SYNTH. Alternatively, use brand name oil complying with orexceeding the API GL-4 specifications.

: Insufficient lubrication or the use of unsuitable lubricants may result in irreparable damagedue to increased wear and tear of the moving parts.

: Do not overtighten the oil drain plug. Excessive tightening may damage the crankcase.

: Used oil contains substances that are harmful to the environment. Even small quantitiesmust be disposed of in compliance with the regulations in force.

: To avoid serious skin damage due to prolonged contact with oil, accurately wash the handsafter handling the lubricant.


COOLANTThe coolant contains 50% of distilled water and 50% of antifreeze, and is ideal at all operating temperatures. It alsoprovides adequate protection against corrosion.Using the same mixture during the hot season will reduce evaporation and the necessity to top up. This will in turnslow the formation of deposits of mineral salts and keep the cooling system in working order.At temperatures below 0° C, check the cooling circuit at short intervals and if necessary add antifreeze to a maxi-mum concentration of 60%.Only use nitrite-free antifreeze and anticorrosive products ensuring protection down to -35° C.

: Never remove the filler cap while the engine is hot: the coolant is under pressure, and mayspurt out and cause burns.

: Some of the coolant components are flammable and burn with an invisible flame that mayeasily cause burns.

: Contact with the coolant may cause skin burns or irritation. In case of contact with the eyes,rinse abundantly with clean water and immediately seek medical attention.

: Should the coolant be accidentally ingested, cause vomiting and immediately seek medicalattention. Despite its toxicity, the coolant is particularly attractive to animals: be sure to seal the containerto stop them from drinking it.


DANGER

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General Specifications

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12

3

4

5

67

8

9

10

11

1314

12

1615

1718

19

General Specifications MA50 - MY50

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Pos. Description Qty Type Tighteningtorque Nm

1 Water pump cover screw 3 M5 x 0.8 72 Right-hand crankcase cover screw 5 M6 x 1 73 Stator nut 1 M10 x 1.25 384 Stator screw 3 M6 x 1 95 Oil pump screw 2 M5 x 0.8 46 Oil seal support screw 1 M6 x 1 107 Crankcase screw, flywheel side 6 M6 x 1 98 Carburettor sleeve screw 4 M6 x 1 89 Starter motor screw 2 M6 x 1 1310 Oil drain screw 1 M8 x 1.25 1811 Starting gear screw 2 M6 x 1 912 Transmission cover screw 6 M6 x 1 1213 Clutch holding nut 1 M28 x 1 5014 Secondary pulley nut 1 M10 x 1 5015 Transmission casing cover screw 12 M6 x 1 1216 Primary pulley nut 1 M10 x 1.25 3317 Cylinder head nut 4 M7 x 1 1018 Spark plug 1 M14 x 1.25 2019 Thermostat screw 2 M4 x 0.7 35

* Alternatively, use brand name oil complying with or exceeding the specifications shown in the table.** Alternatively, use brand name grease for rolling-contact bearings having the following characteristics: useful temperature -

30° C to +140° C, dropping point 150° C to 230° C, excellent anticorrosive protection, resistance to water and oxidation.*** Only use nitrite-free antifreeze and anticorrosive products ensuring protection down to -35° C.

Tightening torques

TABLE OF LUBRICANTS

USE SPECIFICATIONS PRODUCTS SYMBOLS

Mixer oil * ISO-L-ETC++, A.P.I. TC++ GREEN HIT 2

CITY 2T

Transmission oil * A.P.I. GL-4 F.C. SAE 75W – 90

GEAR SYNTH

Grease for joints,

pins and bearings ** AUTOGREASE MP

GREASE 30

Coolant *** ECOBLU –40°C

COOL

Thread-braking Loctite LOCTITE 243

Liquid seal Loctite LOCTITE 580

C

F

B

M

T

General Specifications

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Ducati flywheelextractor

8140208

Crankshaft bearingextractor

8140152

Crankcase separator

8106698

8140234

8106702

8106703

8106707

8140259

8140207

Crankshaft assemblymounting tool

Flywheel retainer

Clutch removingspanner

Pulley spanner

Tool for clutch springs

Moryama flywheelextractor

Tools - Tool kit no. 8201821

General Specifications MA50 - MY50

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NOTES

Power Plant

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B

M

M

Power Plant MA50 - MY50

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Removing the cylinder head

: The manufacturer assumes noresponsibility for damage resulting from the useof unsuitable tools for the removal and refitting ofthe engine or any part of it.

When the engine is in place, the cylinder head, thecylinder, the piston and the reed valve can beexposed by removing the following parts: exhaustpipe, air filter casing, carburettor.

Drain all the coolant. (This operation must beperformed before removing the engine fromthe chassis.)

: The coolant must not be disposed ofin the environment.The disposal must be carried out in compliancewith the regulations in force.

Remove the spark plug and the two pipes of thecarburettor heating system with the four clamps.Loosen the four cylinder-head flanged locknuts (1) byunscrewing them a half turn at a time. Remove thecylinder head.

IMPORTANT: Remove the cylinder headwith the two sealing rings (inner and

outer). Before removing the two pipes of thecarburettor heating system, pay special attentionto the way they are connected so as to ensureproper refitting.

Removing the thermostat

Loosen the two screws (1) shown in the figure, re-move the thermostat and check its mechanical condi-tion.

IMPORTANT: Before removing the two thermostatfixing screws, ensure that they are not excessivelyencrusted with coolant residues. On account oftheir small size, the screws may break ifoverstressed. If necessary use a release agent.

CAUTION

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1

1

1

1

Power Plant

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Removing the cylinder

Remove the cylinder water connection (1).

Remove the cover (3) from its seat after loosening thetwo fixing screws (2).Remove the cylinder while keeping the piston in place.Remove the cylinder base gasket.

Removing the piston

: Before removing the piston pinretaining ring, cover the crankcase opening with aclean cloth so as to prevent the ring from fallinginto the crankcase. Before removing the pistonpin, carefully deburr the retaining ring groove andthe adjoining part of the pin insertion hole. If thepin is still difficult to extract, use the speciallydesigned extractor.

Do not use a hammer to eject the piston pin.

Remove the two retaining rings and extract the pistonpin. Remove the piston and the roller cage from itshousing in the connecting rod.

Checking the cylinder head

Check the condition of the inner (1) and outer(2) O-rings fitted on the cylinder head.

Decoke the head using a rounded scraper, and takingcare not to damage the spark plug thread or scrapethe aluminium.Inspect and decoke the cylinder head combustionchamber.

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2

3

1

2

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Check and if necessary restore the planarity of thehead to the limit of 0.03 mm. To do so, rest a straightedge on the cylinder head and check its planarityusing a thickness gauge.

If the planarity is outside the tolerance range, restoreit by rubbing the head with wetted 400-600 abrasivepaper in a figure-of-eight pattern.

Checking the cylinder

Decoke the exhaust manifold using a roundedscraper.

Check the cylinder sleeve and remove any carbonformation and residues.Check that the cylinder barrel shows no signs ofseizing, wear or scoring.

Power Plant

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Using a bore meter, check the diameter of the cylinderagainst the values shown in the table. Should themeasurement fall outside the tolerance range, replacethe cylinder, the piston and the piston rings (refer tothe mating chart).

Checking the piston

Remove the piston rings taking care not to part theirends more than necessary.To decoke the piston top,use a scraper with a slightly rounded edge. Clean thepiston grooves using a discarded piston ring as shownin the figure. Avoid using silicon-carbide abrasivepaper to clean the piston top or grooves, as an exces-sive amount of metal would be removed and siliconcarbide particles would settle in the piston and quicklydamage the cylinder bore and corrode the pistonitself.

* “T” being the difference between T1 and T2.** “R” being the difference between the two orthogonal measure-

ments.

Standard mm Wear limit (mm)

Cylinderdiameter “C”

Taper “T“ * -- 0.05

Ovalization “R” ** -- 0.01

40.139.99 ÷ 40.01

CAUTION

DANGER

Carefully check the piston skirt. Remove any hard-ened carbon formations by immersing the wholepiston in a suitable liquid such as the type used forcleaning carburettors.

: The use of detergents capable ofremoving hardened carbon formations is verydangerous. The fumes released by these chemi-cals can cause serious illnesses and any contactwith the skin or the eyes immediately producessevere lesions. It is therefore essential to wearsuitable protections such as goggles and gloves,and to scrupulously follow the instructions pro-vided on the package and the container of thedetergent.

After the cleaning, remove any superficial scoringfrom the piston skirt using an abrasive stone with avery fine grain.

: When removing the superficialscoring, take care not to overgrind the piston andmake it unusable. Remember that a minimumrubbing force always ensures proper removal ofsuperficial scratches. When working on the pistonskirt, never use files, silicon-carbide abrasives, orany other abrasive having a grain in excess of800.


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Check the piston-cylinder clearance against thevalues shown in the following table.

Measure the side clearance of the piston rings using athickness gauge.Side clearance: 0.03 ÷ 0.05 mm

Check that the piston rings show no signs of anomaly,and that the gap between the ring ends is as shown inthe table below. Take the measurement with a thick-ness gauge. Fit the segment into the cylinder, takingcare to position it horizontally. To do so, position thepiston rings in the cylinder using the lower part of thepiston.

The measurement must be in the following range:

0.15 ÷ 0.35 mm

If the scoring is too deep, replace the piston (refer tothe mating chart).Measure the diameter of the piston (D) using a mi-crometer. Take the measurement 5 mm from the lowerrim of the piston as shown in the figure.

5 m

m

MATING CHART (mm)

ENGINE TYPE CLEARANCE MIN/MAX

SCOOTERMA

(CAST-IRON CYLINDER)

0.29

0.042

Power Plant

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Measure the outside diameter (D) of the piston pin. Ifit falls outside the tolerance range, replace it.Piston pin outside diameter: 9.996 ÷ 10.000 mm.

Check the diameter of the piston pin seat. If it isoutside the tolerance range, replace the piston.Piston pin seat diameter: 10.004 ÷ 10.015 mm

Also check that the roller cage is not damaged, and ifnecessary replace it.

Refitting the power plant

Fit the new upper ring (1) and lower ring (2) on thepiston with the tapered side facing upwards. Refer topins (3).

: Failure to observe this procedurewill make it virtually impossible to fit the cylinderon the piston, and will result in breakage of thepiston rings, and possibly more serious damageduring engine assembly.

Check the piston pin for any scoring, scratches oraltered colour resulting from high temperatures. Thepiston pin needs replacing whenever it feels scored orscratched to the touch, or if it shows any blue-greyareas. Since such damage can be due to a lubricatingmalfunction, be sure to check the operation of thelubrication system before restarting the engine. If, onthe other hand, the piston pin has become slightlybrownish, there is no need to replace it.

CAUTION


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:Before fitting the cylinder, apply oilfor two-stroke engines to the piston rings.

Fit a new cylinder base gasket.Fit the cylinder.

Replace the two cylinder head O-rings,

then refit the head and fix it by tightening the four nutsin a crosswise pattern in numerical order. Fit the sparkplug.

Reconnect the pipe from the water pump toits fitting. Reconnect the pipes of the carbu-

rettor heating system by following these steps (asviewed from above the vehicle, in the direction ofmotion): join the left-hand head connection to theupper carburettor connection, and the right-hand headconnection to the lower carburettor connection.Fasten the pipes with new clamps.Refit the cover.Cylinder head nut tightening torque: 10 NmSpark plug tightening torque: 20 Nm

CAUTION

CAUTION

Lubricate the following parts with oil for two-strokeengines (see Table of Lubricants): roller cage, pistonpin, piston pin retainer seats, cylinder surface.

: Always use new retaining rings.

IMPORTANT: Remember that the piston rings mustbe fitted with the rounded edge facing the pistonpin.

: The arrow on the piston must pointto the lower part of the engine. Before fitting thepiston pin ring, cover the crankcase with a cleancloth so as to prevent any object from falling intothe crankcase.

DANGER

Carburettor - Reed Valve Unit

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Carburettor - Reed Valve Unit MA50 - MY50

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Removing the carburettor

Detach the connections on the carburettor, (oil deliv-ery and petrol delivery).

Disconnect the pipes of the water heatingdevice. Loosen the screw fixing the carburet-

tor to the reed valve unit and remove the carburettor.

IMPORTANT: Before removing the twopipes of the carburettor heating system,

pay special attention to the way they are con-nected in order to ensure proper refitting.

Removing the reed valve unit

Remove the four fixing screws shown in the figure.

Checking the reed valve unit

Check for any damage or breakage of the reed valvestops and if necessary replace them.

Measure the bending limit (A) of the reed valve. If itfalls outside the tolerance range, replace the valve.Bending limit: 0.2 mm.

Remove, in the following order, the intake manifold(1), the reed valve (2) and the related gasket (3),taking care to insert a cloth in the intake slot so as toprevent dirt from entering and hindering the operationof the mechanisms.

1

2

3


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Measure the height of the reed valve stops (A). If it isoutside the tolerance range, replace the stops.Reed valve stop height: 4.0 ÷ 4.4 mm.

Never attempt to repair the reed valveor its support.

Fitting the reed valve unit

Remove the cloth that had previously been insertedinto the intake slot to prevent dirt from getting in.Fit, in the following order, a new gasket (3), the reedvalve (2) and the intake manifold (1).

Fasten the assembly by tightening the four screws.

CAUTION

1

2

3

Tightening torque: 8 Nm

Installing the carburettor

Place the carburettor in the intake manifold takingcare to fit the carburettor tongue between the twotongues on the manifold. This will ensure properpositioning of the carburettor. Attach the connections(oil delivery and petrol delivery).

Reconnect the pipes of the carburettorheating system by following these steps (as

viewed from above the vehicle, in the direction ofmotion): join the left-hand head connection to theupper carburettor connection, and the right-hand headconnection to the lower carburettor connection.Fasten the pipes with new clamps.


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NOTES

Oil Pump - Starter Motor MA50 - MY50

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B

B

T

T


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Disassembling the water pump

Remove the clamps (1) and detach the water feedpipe and the pipe that delivers water to the cylinder.Loosen the three fixing screws (2) and remove thewater pump cover and the related O-ring.

Removing the flywheel cover

Loosen the three fixing screws and remove the coverof the flywheel magneto.

Checking the water pump

Check the general condition of the water pump, of thefeed pipes and of the plastic driving devices.Check that the water pump bearings slide smoothlywith no sticking. Replace any defective bearings.

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2

21

Remove the seeger ring (1) from the flywheelmagneto cover, and then extract, in the

following order, the driving device (2), the retaining pin(3), the impeller water pump pin (4) and the relatedelastic washer (5).Using a drift of suitable size, extract the water pumpbearings (6) and the related spacer (7). 1

23

4 5

6

7


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Reassembling the water pump

Fit the water pump bearings (1) using a drift of suit-able size after interposing the spacer (2).Fit, in the following order, the impeller water pump pin(3) with a new elastic washer (4), the fastening pin (5),the driving device (6), and then fix everything in placewith the seeger ring (7).

Fit the pump body to the engine and fasten it with thethree screws (8).

Fit the water pump cover with a new O-ring and fastenit to the flywheel cover by means of the three fixingscrews (1). Reconnect the water feed and deliverypipes and fix them in place with new clamps.

Removing the flywheel magneto

Remove the rotor nut and the related washer whileholding the flywheel with the specially designed tool.Remove the rotor using the specific extractor.

: Since the flywheel locknut is tight-ened with a considerable torque, caution shouldbe exercised in order to prevent injury.

Removing the stator

Loosen the two fixing screws and remove, in thefollowing order, the plate with the stator, the pick-upand its wiring, the key and the gasket.

CAUTION

Flywheel retaining tool: 8106702Moryama flywheel extractor: 8140207Ducati flywheel extractor: 8140208

1

1

1

1

8

8

12

3

4

56

7

8


chap. 55-4 Release 00 2000-01

Removing the oil pump

Remove the two fixing screws and extract the pumpwith the oil feed pipe and the pipe that delivers oil tothe carburettor.

: To ensure proper fitting, pay specialattention to the passage of the oil delivery pipe.

Remove the seeger ring (1), the pump driving gear(2), the pin and the other seeger ring.

Loosen the fixing screw and remove the oil seal stopplate.

Checking the oil pump

Check the general condition of the oil pump. Remem-ber that wear or malfunction can alter the settings ofthe pump.

CAUTION

1

2


chap. 5 5-5

5

Release 00 2000-01

This, however, occurs very rarely. Should the pumpappear to be malfunctioning, check the feed duct.Check the sealing ring and if necessary replace it.Also check the pump driving gear and replace it incase of excessive wear.Also check the condition of the pump oil feed and oildelivery pipes, making sure they contain no air bub-bles.IMPORTANT: It is very important for the oil feedand oil delivery pipes to contain no air. If airbubbles are found in either of the pipes, it isessential to identify and repair the part that let theair in before restarting the engine.

Checking the flywheel

Check the mechanical condition of all flywheel compo-nents. Check the wear condition of the woodrouchkeyand of the woodrouchkey groove on the crankshaft.Replace any worn-out components.

Checking the statorTo verify the electrical operation of the stator, conductthe following checks with a digital multimeter set tomeasure resistance.Connect the two multimeter probes as shown in thefollowing table:

Ignition type Pick-up resistance Charging coil resistance(red-white and white wires) (red-black and white wires)

FACIND 110 Ω 600 ΩMORYAMA >500 Ω >830 ΩDUCATI 120 Ω 720 Ω

Check the continuity (0 Ohms) of the windings bymeasuring resistance between the yellow-red andwhite wires of the stator.

IMPORTANT: Depending on the instrument used,the measurements shown in the table can vary byas much as 10 percent.The check can be conducted without removing theflywheel cover.


chap. 55-6 Release 00 2000-01

Fitting the oil pump

Fit the oil seal stop plate and fasten it with the fixingscrew.

Fit, in the following order, the seeger ring, the pin, thepump driving gear, and the other seeger ring.

Fit the pump paying special attention to the passageof the oil delivery pipe, and then fasten it with the twoscrews.

IMPORTANT: When working on the oil pump, airbubbles may enter and remain in the pipes and inthe pump itself, and subsequently hinder lubrica-tion while the engine is running. For this reason,be sure to bleed the pump before starting theengine.Remove the drain screw from the pump and allowthe oil and any air bubbles to come out. When theoil starts flowing out with no bubbles, the bleed-ing is complete and the screw can be retightened.

: To allow the oil pump to expel all theair, fill the fuel tank with at least 1/2 litre of 2%petrol-oil mixture.

: To avoid serious skin damage dueto prolonged contact with oil, accurately wash thehands after handling the lubricant.

When handling products with a base of petroleum, it isstrongly recommended to wear disposable latex ornitrile gloves.


CAUTION

CAUTION


chap. 5 5-7

5

Release 00 2000-01

Fitting the stator

Fit a new gasket on the right-hand crankcase coverand fix the stator assembly to the crankcase with thetwo screws. Thread the wires through the hole in thecrankcase and fasten them with the specially de-signed rubber.


Fitting the flywheel magneto

Fit, in the following order, the key (1), the CDI magnet(2), the plain washer (3) and the nut (4). Apply thread-braking Loctite (see Table of Lubricants).

Hold the flywheel with the specially designed tool andfasten it by tightening the locknut.

: Since the flywheel locknut is tight-ened with a considerable torque, caution shouldbe exercised in order to prevent injury.

Tightening torque: 38 NmFlywheel retaining tool: 8106702

CAUTION

Fitting the flywheel cover

Fit the flywheel cover and fasten it with the three fixingscrews shown in the figure.

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234



chap. 55-8 Release 00 2000-01

Removing the starter motor

If the starter motor fails to operate, check and ifnecessary restore the electrical connections beforeremoving the motor.Remove the two screws that fix the motor to thecrankcase, and then pull off the motor.

Fitting the starter motor

Ensure that the O-ring is properly seated in its groove,apply a thin film of special grease for oil seals (seeTable of Lubricants), then fit the starter motor andfasten it to the crankcase using the two fixing screws.

Fitting the water pump cover

Fit the water pump cover with the related O-ring andfasten it using the three fixing screws (1). Connect thewater feed pipe and the pipe that delivers water to thecylinder. Fix the pipes with the related clips (2).

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Starting System - Clutch MA50 - MY50

chap. 6 6-1

6

Release 00 2000-01

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B

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B

B


chap. 66-2Release 00 2000-01

Disassembling the starting system

Remove the starter lever fixing screw and then thepedal. Remove the 12 crankcase cover fixing screws.Remove the cover and the related gasket payingspecial attention to the two reference pins.

Checking the starting shaft

Check the starting system for signs of damage andwear, and if necessary replace it.Check the return spring and, if it is shows signs ofyielding, replace it.Also check that the spring tension is 150 ÷ 250 g.

CAUTION

Remove the seeger ring (1).

: The spring in precharged.

Release the pressure spring (1) using a hook or ascrewdriver. Extract the sector gear (2) and the pinion(3).

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1

2

3

Starting System - Clutch

chap. 6 6-3

6

MA50 - MY50

Release 00 2000-01

Reassembling the starting system

Refit, in the following order, the return spring, thepedal shaft, the bush, the plain washer and the circlip.

Attach the return spring to the pedal spindle and,using a spring pull hook, fix the other end to the pin.

IMPORTANT: When hooking the spring, avoidpulling it too hard.

: Excessive pulling may cause thespring to yield.

: This is a dangerous operation.

Fit, in the following order, the pinion gear and thespring. Slightly shift the pedal shaft to facilitate theinsertion of the gear.

IMPORTANT: Lubricate the spring and the sectorgear with the grease mentioned in the table oflubricants.

Removing the primary pulley

Loosen the pulley locknut using the specially designedtool.

CAUTION

Pulley spanner: 8106707

DANGER


chap. 66-4Release 00 2000-01

Remove, in the following order, the locknut (1), theconed washer (2), the start coupling (3), the spider(4), the (fixed) primary pulley (5) and the shim (6).

Simultaneously remove the (movable) primary pulley,the lug holder, the bush, and the related washer.

: To prevent the six weights fromfalling inside, take care not separate the pulleyfrom the lug holder.

Separate the pulley from the lug holder and removethe six weights.

Checking the primary pulley

Check the (fixed and movable) primary pulley and thebush for signs of wear, breakage, scoring or otherdamage, and replace as necessary.Check that the bush slides smoothly inside the (mov-able) primary pulley. If not, or if the play is excessive,replace the pulley and the bush.

CAUTION

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chap. 6 6-5

6

MA50 - MY50

Release 00 2000-01

Check the condition of the lug holder and of the threedriving lugs. Replace any worn lugs.

Removing the starting clutch

Remove the two fixing screws of the idler gear stopplate, the idler gear itself, and the front and rearwashers.

Simultaneously remove the starting clutch, the gear,the roller bearing and the bush, taking care not to dropthe grub screws from inside the starting clutch.

Check that the outside diameter (D) of the weights isnot less than the wear limit, and if necessary replacethem.

Wear limit D: 14.5 mm


chap. 66-6Release 00 2000-01

Checking the starting clutch

Check the general condition of the starting clutch.When pushed in the directions shown in the figure, therollers should slide smoothly in their seats and returnto their original positions when released. Replace asnecessary.

Check the condition of the gear teeth, the inner andouter surface of the gear (starting wheel) and of theroller bearing. Replace any worn-out or damagedcomponents.

Removing the clutch and the secondarypulley

Remove the clutch bell housing locknut while holdingthe part with the specific tool.

: Since the clutch locknut is tightenedwith a considerable torque, caution should beexercised in order to prevent injury.

Simultaneously remove the clutch bell housing, theclutch, the secondary pulley assembly and the belt.

: Take care not to twist the belt duringthe operation.

CAUTION

Specific tool: 8106702

CAUTION


chap. 6 6-7

6

MA50 - MY50

Release 00 2000-01

Compress the assembly with the clutch spring supportand remove the clutch locknut.

: The spring is compressed.

Remove, in the following order, the clutch blocksupport (1), the counterspring (2), the fixed secondarypulley (3), the pin (4), the spring seat using twowedges (5) (for example, two screwdrivers) and themoveable secondary pulley (6).

Checking the clutch

Check the inside surface of the clutch housing. If itshows signs of rust or scoring, remove and clean withemery cloth. Also check that inside diameter (d) is105.0 ÷ 107.0 mm.

Wear limit (d): 105.4 ÷ 107.4 mm

Check the clutch blocks and if necessary reface withcoarse-grained abrasive paper. Thoroughly clean aftercompleting the operation.

: Refer to the notes contained in theGeneral Information chapter (Section 1) of thismanual.

Dry out the blocks with compressed air. If the clutchblocks have vitrified, the deposit can easily be re-moved with emery paper.

IMPORTANT: After removing the vitrified deposit,use compressed air to thoroughly clean the clutchblocks of the sanding residues.

Clutch spring tool: 8140259Clutch removing spanner: 8106703

DANGER

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chap. 66-8Release 00 2000-01

Check that the thickness of the shoes does notexceed the wear limit (S) of 2.5 mm.

Checking the secondary pulley

Check the condition and sliding of the secondarypulley, and if necessary replace it. Check that therace, the guide pin and the retaining ring show nosigns of damage or wear, and if necessary replacethem.

Measure the free length of the (secondary pulley)counterspring and, if it falls outside the allowablerange, replace it.Free length: 121.7 mmMinimum allowable length: 106.7 mm

Checking the belt

Check that the belt shows no signs of cuts, cracks orexcessive wear, and that it is not impregnated with oil.If any of the above defects is present, replace the belt.Measure the head width at several points along thebelt and, if it falls outside the allowable range, replacethe belt.P = Standard depth: 16.6 mmP = Wear limit: 15.2 mm


chap. 6 6-9

6

MA50 - MY50

Release 00 2000-01

Disassembling the transmission

: Before removing the transmissioncover, remove the drain screw (1) from the lowerpart of the gearbox and drain all the oil.

Then loosen the six fixing screws and remove thetransmission cover together with the main gear, thetwo reference grub screws and the related gasket.

Remove the output shaft and the double idler gear.

Checking the transmission

Check that the output shaft gears (1), the double idlergear (2) and the drive shaft (3) show no signs of wear.Replace any worn components.

Check that the transmission bearings show no signsof scoring or seizing. Replace as necessary.

CAUTION

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chap. 66-10Release 00 2000-01

Check that the drive shaft slides smoothly. Repair orreplace in case of malfunction.

Reassembling the transmission

Fit, in the following order, the double idler gear (1), theoutput shaft (2), the coned washer (3) and the plainwasher (4) after lubricating the bearings and the oilseals with lithium soap grease and the gears withengine oil.

Fit the coned spring washer as shown in the figure.

Before fitting the gearbox, lubricate the bearing of theoutput shaft with engine oil (see Table of Lubricants).Grease the cover gasket with lithium soap grease(see Table of Lubricants). Fit the gasket, insert thepegs in their housings, position the transmission coverwith the output shaft, and then tighten the 6 fixingscrews. Tighten the oil drain screw (1) after fitting itwith a new washer (2).Pour in 0.12 l of transmission oil through the hole (3).

Tightening torque for fixing screws: 12 NmTightening torque for oil drain screw: 18 Nm

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chap. 6 6-11

6

MA50 - MY50

Release 00 2000-01

Fitting the secondary pulley

Before fitting the pulley, clean its sliding surface, and ifnecessary add grease in the fixed half pulley (seeTable of Lubricants).

: Wrap adhesive tape around pulleyend “A” in order to avoid overturning the lips ofthe oil seals while fitting the pulley.

Fit the pin and apply grease in the groove of themovable pulley.Grease the O-rings (1) of the movable secondarypulley before fitting them.

After fitting the spring seat, check the sliding of thepulley and then fit the return spring.

: Remove any excess grease.

Fitting the clutch

Clean the mating surfaces between the nut and theclutch holder.Fit the clutch locknut while compressing the pulleywith the clutch spring support.

: The spring is compressed.

: Do not attempt to perform thisoperation without the specially designed tools(refer to Chapter 2).

Clutch spring tool: 8106704Clutch removing spanner: 8106703

CAUTION

CAUTION

CAUTION

DANGER


chap. 66-12Release 00 2000-01

Fitting the starting clutch

Fit the bush on the crankshaft.

Fit, in the following order, the starting gear (1) lubri-cated with transmission oil, the roller bearing (2), thestarting clutch (3), the washer (4), the starting gear (5)lubricated with oil, and the other washer (6). Fastenplate (7) by tightening the two fixing screws (8).

CAUTION

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8

To complete the installation of the clutch, tighten thelocknut.Preload the snerve spring and fit the belt between thepulleys to allow the insertion of the clutch unit in theinput shaft.

: This operation allows for optimumtightening of the primary fixed pulley, and pre-vents the belt from getting jammed.The belt must be fitted with the arrow pointing inthe direction of rotation.

Fit the bell housing around the pulley and, whileholding it with a suitable tool, tighten the nut as shownin the figure.





chap. 6 6-13

6

MA50 - MY50

Release 00 2000-01

Fitting the primary pulley

Thoroughly clean the sliding surfaces of the centrifu-gal weights and then fit them in their slots. Fit thedriving lugs on the lug holder, fit the latter to thepulley, and then insert the bush.

Fit the movable primary pulley while holding the lugholder to prevent the weights from falling.

: Take care not to nip your fingersbetween the pulley and the crankcase.

Fit, in the following order, the shim, the fixed primarypulley, the spider, the start coupling, the washer andthe nut.Hold the crankshaft with the pulley spanner andtighten the nut.

CAUTION

Tightening torque: 33 NmPulley spanner: 8106707

Reassembling the starting system

Fit the pegs in their respective housings. Fit a newgasket on the crankcase cover and secure the latterby means of the twelve fixing screws shown in thefigure.Fit the starting pedal and fasten it with the fixingscrew.

Tightening torque for fixing screws: 12 Nm


chap. 66-14 Release 00 2000-01

NOTES

Crankcase - Crankshaft

chap. 7 7-1

7

MA50 - MY50

Release 00 2000-01

F

T

T

B

Crankcase - Crankshaft MA50 - MY50

chap. 77-2 Release 00 2000-01

Removing the right-hand crankcase andthe crankshaft

Remove the 6 screws fixing the right-hand crankcase.

Tension the crankcase separator after fixing it to thetwo cast supports (S in the figure above) with an M8thread.

: Tighten the tool support boltsmaking sure that the tool is parallel with thecrankcase.

: Lubricate between the spacer tubeand the crankcase bearings. Hit the axle whileapplying a rotary effort with the crankcase separator.Use a mallet on the half crankcase, taking care to hitthe reinforced part, not the gasket contact surface.

Remove the crankshaft with the crankcase separatorafter fitting the latter to the two cast supports with anM8 thread.

: Tighten the tool support boltsmaking sure that the tool is parallel with thecrankcase.

Checking the crankcase, the crankshaftand the connecting rod

Check the crankshaft bearings by rotating their innerraces. Replace any bearing that does not rotatesmoothly, or that shows any radial play or excessiveside play. If the inner race of the bearing is stiff, cleanit thoroughly, apply a little lubricant to the bearing, andthen perform the test again. Uneven rotation of thebearing may be due to the presence of dirt or foreignbodies in the pin. Once the pin has been thoroughlycleaned, the inner race of the bearing should nolonger be stiff or rotate jerkily when turned manually. Ifthe rotation is still abnormal, replace the bearing.

CAUTION

CAUTION

CAUTION

SS

Crankcase separator: 8106698

Crankcase separator: 8106698


chap. 7 7-3

7

MA50 - MY50

Release 00 2000-01

Fitting the bearings

Fit two new bearings (C) on the crankshaft by press-ing a length of tube of suitable diameter on the innerrace of each bearing.Push the bearing home using a mallet or a hydraulicpress.

Using an automatic heater, heat the crankcase toapproximately 150° C (~10 minutes’ operation) andthen drive the connecting rod assembly into the left-hand crankcase as described in the paragraph “Fittingthe crankshaft”.

Check the condition of the connecting rod. Check ifthe axle shafts are worn or scored. Check the condi-tion of the connecting rod big-end bearing by rotatingit around its pin. Check that the float of the connectingrod big end (C) is 0.4 to 0.8 mm. Check that the sideplay of the connecting rod (B) is 0.20 to 0.50 mm. If,after the component has been carefully cleaned, thebig-end bearing is still stiff, does not rotate smoothly,or has an excessive play, proceed to replace it.

: The replacement of the big-endbearing should be carried out by a skilled techni-cian using the special tools required and a largehydraulic press. DO NOT ATTEMPT to replace thebig-end bearing if you do not possess the neces-sary tools and technical skills. Please contactAprilia’s Customer Care.Also check that the connecting rod is not bent,and that its travel is exactly perpendicular to theaxle shafts. Using a series of V-blocks, measurethe eccentricity of the two axle shafts at the pointsshown in the figure. The eccentricity (A) must notexceed 0.03 mm. Should this limit be exceeded,please contact Aprilia’s Customer Care to have theaxle shafts realigned.

CAUTION

Crankcase separator: 8106698Crankshaft bearing extractor: 8140152


chap. 77-4 Release 00 2000-01

Fitting the crankshaft

: Apply grease to the oil seals and oilto the bearings so as to protect the crankshaftagainst possible scoring and facilitate the fitting.

Connect the crankshaft fitting tool, and then fit theadaptor and the spacer.

Install the crankshaft in the left-hand crankcase.

IMPORTANT: Move the connecting rod to the topdead centre and hold it with one hand. Rotate theinstalling tool with the other hand until the lowerpart of the crankshaft rests on the bearing.

Fitting the crankcase

Apply a sealant to the mating surfaces of both crank-case halves.

Crankshaft assembly installing tool: 8140234

CAUTION

Fit the spacer tube and the reference grub screws.


chap. 7 7-5

7

MA50 - MY50

Release 00 2000-01

Position the right-hand crankcase, connect the crank-shaft installing tool and use it to bring the two crank-case halves into contact.

IMPORTANT: Keep the connecting rod at the topdead centre with one hand. With the other handrotate the tool nut until the lower part of the right-hand crankcase comes into contact with the left-hand crankcase.

Tighten the six fixing screws in a crosswise pattern innumerical order.

After completing the operation, check that the crank-shaft has been properly installed.

IMPORTANT: If necessary, use a plastic mallet torestore the axial play.

: Carry out this operation with aplastic or rubber mallet, not an iron hammer. Takecare not to hit the crankcase.

CAUTION

Crankshaft assembly installing tool: 8140234

Using an automatic heater, heat the right-hand crank-case to approximately 150° C (~10 minutes’ opera-tion) and fix the connecting rod assembly into theright-hand crankcase as described in the followingparagraph.

Tightening torque: 9 Nm.


chap. 77-6 Release 00 2000-01

Fit the oil seal in the right side of the engine takingcare to smear the oil seal rims with lithium soapgrease (see Table of Lubricants).

Once the parts are in place, check that the oil seal lip(1) is seated in the crankcase recess (2) as shown inthe figure.

Fitting the crankshaft oil seal

Fit the oil seal (1) and then the centring bush (2)taking care to smear the lip of the oil seal with lithiumsoap grease (see Table of Lubricants).

To facilitate the fitting, use a tube of suitable diameter.


chap. 7 7-7

7

MA50 - MY50

Release 00 2000-01

NOTES


chap. 77-8

MA50 - MY50

Release 00 2000-01

NOTES

aprilia s.p.a.

Via G. Galilei, 130033 Noale (VE)Tel. +39 (0) 41 - 5829111Fax +39 (0) 41 - 441054www.aprilia.comwww.serviceaprilia.comItaly

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Aprilia Workshop Manual Minarelli MA 50 MY 50

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Transcript of Aprilia Workshop Manual Minarelli MA 50 MY 50