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WBE 0701
Workshop Manual
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GGP WBE 0701, WBE 0704 Workshop Manual

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WBE 0701 WBE 0704
The manufacTurer reserves The righT To make all The necessary Technical or commercial improvemenTs To iTs
producTs, so There may be some differences beTween The series of engines and The conTenTs of This manual.
h
owever The basic specificaTions and differenT operaTing procedures will remain The same.
© by global garden producTs no use of The illusTraTions or duplicaTion, reproducTion or
TranslaTion, even parTial, of The TexTs in This documenT may be made wiThouT expliciT auThorizaTion.
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CONTENTS
INTRODUCTION ..................................................................................................... 5
1. RULES AND PROCEDURES FOR SERVICE CENTRES .......................................... 6
1.1. Guarantee validity ...................................................................................................................................6
1.2. Service repairs after guarantee period ..................................................................................................
1.3. Faultnotication .......................................................................................................................................
1.4. Spare parts request ..................................................................................................................................
2. GENERAL AND SAFETY REGULATIONS ............................................................. 7
2.1. Qualicationofoperators .......................................................................................................................7
2.2. Safety measures .......................................................................................................................................
2.3. Precautions during servicing ...................................................................................................................
2.4. Etichette di sicurezza ...............................................................................................................................
2.5. Necessary equipment .............................................................................................................................
2.6. Symbols and terms used for safety purposes ........................................................................................
6 6 6
7 7 8 8 8
3. TECHNICAL DATA AND SPECIFICATIONS ........................................................ 9
3.1. Identication .............................................................................................................................................9
3.2. Technical data .........................................................................................................................................
3.3. Adjustments ..............................................................................................................................................
3.4. Expendable materials ..............................................................................................................................
3.5. Use limits ....................................................................................................................................................
3.6. Tightening torques ..................................................................................................................................
3.7. Table of Tightening torques ...................................................................................................................
3.8. Identicationofengineunits .................................................................................................................
10 11 12
4. ENGINE TUNING AND TESTING ...................................................................... 13
4.1. Operating guidelines .............................................................................................................................13
4.2. Engine tuning program ..........................................................................................................................
4.3. Functional test ........................................................................................................................................
13 14
5. TANK AND SUPPLY .......................................................................................... 15
5.1. Emptying and removing the tank ......................................................................................................... 16
5.2. Cleaning the tank ..................................................................................................................................
5.3. Checking and cleaning the breather pipe .........................................................................................
16 17
9 9 9 9
6. STARTING SYSTEM ........................................................................................... 18
6.1. Removing the starter assembly ............................................................................................................18
6.2. Replacing the rope ................................................................................................................................
6.3. Replacing the hooks ..............................................................................................................................
18 19
7. INTAKE SYSTEM ............................................................................................... 20
7.1. Maintenanceoflteringelement .........................................................................................................20
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Service manual
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CONTENTS
8. CARBURATION ................................................................................................ 21
8.1. Removing and cleaning the carburettor .............................................................................................21
8.2. Replacing the carburettor .....................................................................................................................
8.3. Adjusting minimum speed ....................................................................................................................
8.4. Adjusting maximum speed ...................................................................................................................
8.5. Adjusting the carburation ......................................................................................................................
24 24 24 24
9. GOVERNOR SYSTEM OF THE CARBURETTOR ................................................. 25
9.1. Adjusting of accelerator cable ............................................................................................................25
9.2. Adjusting maximum speed ...................................................................................................................
9.3. Replacing the lever support ..................................................................................................................
26 27
10. IGNITION ....................................................................................................... 28
10.1.Checkingtheefciencyoftheignitionsystem ..................................................................................28
10.2. Adjusting the air gap and checking the coil ......................................................................................
10.3. Replacing the coil ..................................................................................................................................
29 30
11. TURNING OFF AND STOPPING THE ENGINE ................................................ 31
11.1. Checking the control cable .................................................................................................................. 31
11.2. Checking the ignition off microswitch .................................................................................................
11.3. Checking the brake ...............................................................................................................................
11.4. Replacing the system for turning off and stopping the engine .........................................................
31 32 33
12. EXHAUST SYSTEM .......................................................................................... 34
12.1.Removingandreplacingthemufer ...................................................................................................34
13. ENGINE BLOCK - External operations ........................................................ 35
13.1. Checking the compression ...................................................................................................................35
13.2. Adjusting the valve clearance .............................................................................................................
13.3. Dismantling and cleaning the cylinder head .....................................................................................
13.4 Overhauling the cylinder head and valves ........................................................................................
13.5.Dismantlingandreplacingthemagnetoywheel .............................................................................
13.6. Checking the oil breather .....................................................................................................................
13.7.Replacingtheuppercompressionringoftheengineshaft(ywheelside) ....................................
13.8.Replacingthelowercompressionringoftheengineshaft(sumpside) ..........................................
36 37 38 40 41 41 42
14. ENGINE BLOCK - Overhauling internal parts ............................................. 43
14.1. Removing the engine from the lawnmower ........................................................................................43
14.2. Carter opening .......................................................................................................................................
14.3. Dismantling and checking the camshaft and counterweight governor ..........................................
14.4. Dismantling and checking the piston, piston rings, connecting rod and engine shaft ..................
44 45 47
15. TROUBLESHOOTING ...................................................................................... 53
Service manual
pag. 4
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pag. 16
Release 00 - 02/2008
Engine WBE 0701-WBE 0704
Service manual
5.1. Emptying and removing the tank
1 - Remove the ring (1) of the petrol pipe(2) from the tank side anddrain all thefuel fromthe tank and the pipe into a suitable container.
2 - Unscrew the two screws (3) at the side and the nut at the rear (4) and remove the tank (5).
3 - When fitting, performthe aboveoperations in reverse.
WARNING: Before refilling the tank with new fuel, check that the petrol pipe is intact.
5.2. Cleaning the tank
1 - Remove the tank [ 5.1].
2 -Remove the clamp (1) from the side ofthe tank and disconnect the petrol pipe (2).
3- Slide outthe filter tube (6)and blow compressed air through it so as to remove any deposits inside.
4 - Keeping the hole (7) in the spigot closed,pour about 100 cc of clean petrol into th e tank and shake it vigorously to clean the inside.
5. TANK AND SUPPLY
5
3
4
3
6
7
6
2

INTRODUCTION

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The purpose of this manual is to provide to Service Centres the information necessary for a correct maintenance, dismantling and repair procedure for motori WBE 0701 - WBE 0704 engines. Interventions on the engine must be performed in accordance with instructions in the following pages and with safety regulations in force in the country in which the engine is operated, and only by authori­sed and appropriately trained personnel.
In every manual page the following informations are described:
B
A
C C
Certain symbols are used in the manual, highlighting particularly important information, risks, warnings and prescriptions:
Warns of operations that should be carried
out with utmost care to avoid impairing the functionality and safety of the lawnmower.
Warns of operations that should be carried
out with utmost care to avoid injury to the operator.
 NOTE:Referstospecicadvicebythema-
nufacturer.
Reference to another procedure or part of
the manual.
Recommends that washers and O-rings are
checked and replaced if necessary.
Refers to use of special tools.
NOTE: During the description of procedures,
the indications “right”, “left”, “front”, “rear”, “upper” and “lower” refer to the engine mounted on the lawn tractor seen from the user’s perspective.
Please read all the contents of this manual to be-
DEF
come familiar with the basics of the engine, which is fundamental for operating in a logical manner without making errors or wasting time.
A: Motor typ for which the page is valid;
B: Reference to the chapter and the argument
with the relative numbering;
C: Presence of previous or following chapters from
D: Issue date or possible audit;
E: Audit number;
F: Page progressive numbering.
the present chapter;
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Service manual

1. RULES AND PROCEDURES FOR SERVICE CENTRES

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1.1. Guarantee validity

The warranty is supplied under the terms, procedu­res and limits stated in the contract.

1.2. Service repairs after guarantee period

The Service Centre must write a report for each intervention containing the serial number of the engine [ 3.1], and summary information about the problems complained of, the intervention made and possible spare parts used.. A copy of these reports must be kept and made available to the manufacturer together with the replaced parts, in case clients should make further complaints.
1.3. Faultnotication
The manufacturer should be informed of all faults that recur frequently; this allows it to carefully exa­mine the problem and make corrections on the production line. Similarly, the manufacturer shall report any faults traced on its engines, indicating the best trouble­shooting procedure.

1.4. Spare parts request

When asking for spare parts, you must quote their code by referring to the exploded views corresponding to the year of manufacture reported on the nameplate [ 3.1].
Service manual
pag. 6
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2. GENERAL AND SAFETY REGULATIONS

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IMPORTANT: Before commencing with any
intervention, carefully read the information provided in the present manual, in particular the following safety regulations.
2.1. Qualicationofoperators
All maintenance, disassembly and repairs must be carried out by expert mechanics who are familiar with all the accident prevention and safety regu­lations after reading through the procedures in this manual.

2.2. Safety measures

All the engines are built in conformity with the Eu­ropean safety regulations in force. To maintain initial safety levels in the long term, the Service Centre should take proactive measures by making checks whenever possible. Every time you are asked to service the engine (or the lawnmower on which it is installed), you should:
• check:

2.3. Precautions during servicing

As well as following the usual accident prevention regulations that apply to most repair shops, we recommend you:
- disconnect the spark plug cap before servi­cing;
- protect hands with suitable working gloves, es­pecially when working near the cutting unit;
- check that you do not cause accidental petrol leaks or other losses;
- do not smoke when working on the tank or when handling petrol;
- do not inhale oil or petrol fumes;
- clean up all traces of spilt petrol immediately;
- test the engine in a well-ventilated environment or where there are adequate exhaust fume ex­traction systems;
- do not pollute the environment with oil, petrol or other waste and dispose of all waste in accor­dance with the laws in force;
- that the safety devices function correctly;
- that the casings and protection covers have not been removed;
- thatthenameplatesorspecicationlabelshave
not been removed or made illegible, (as they
formanintegralpartofthesafetydevices).
• also:
- restore to proper working order any safety de­vices which have been manipulated or remo­ved;
- replace ineffective, damaged or missing guards and covers;
- replace illegible labels;
- donotcarryoutoperationsormodicationson
the lawnmower or on the engine that could af­fect their performance or lead to an improper or different use from the one for which it has been designed and approved;
- warn the customer that the failure to comply with the above points automatically voids the warranty and the responsibility of the manufac­turer.
Exhaust gas contains carbon monoxide, whi-
ch is highly toxic, odourless and colourless. Avoid inhaling.
- Perform tests on the engine in a well-ventilated environment or in the presence of adequate exhaust gas extraction systems.
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Service manual
• - • • • - • • • • •
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2. GENERAL AND SAFETY REGULATIONS

2.4. Etichette di sicurezza

On the canopy motor, in a immediately identica­tion position, are some indication or prescription plates for the safety operator. The plates are as follows:
1 2 3
4
1 - Fire hazard due to:
- Petrol or oil
Prevent by following the precautions below:
- Do not smoke or ignite a ame in the vicinity of
the petrol or oil;
- Turn engine off before adding petrol;
- Do not spill petrol on overheated or electric parts of the engine;
- Handle or store petrol or oil in well-ventilated areas;
- Use non-ammable oil for cleaning engine parts.
-Accumulationofammablematerial
Prevent by following the precautions below:
- Remove dry leaves, chips, pieces of paper, dust or
other ammable material which has accumulated
in or is attached to the engine.
adequate ventilation and, therefore, avoid gas poisoning.
4 - Motor label (see [ 3.1])

2.5. Necessary equipment

All the operations can be carried out with the tools normally used in a good garage.
The , symbol used for certain interventions indicates that special tools or equipment are re­commended.

2.6. Symbols and terms used for safety purposes

Some paragraphs in this manual are preceded by symbols which indicate the following:
Operations that should be carried out with ut-
most care to avoid impairing the functionality and safety of the engine and/or lawnmower on which it is installed.
Operations that should be carried out with
utmost care to avoid injury to operators.
“WARNING” stresses the risk of injury to oneself and others if instructions and regulations are not observed.
- Electrical cabling
Short circuits can cause res. Prevent by following
the precautions below:
- Always keep the electrical connections of the machine clean and tightly sealed;
- Tighten any loose connectors or cabling clamps. Replace those that are damaged.
2 - Observe the instructions and warnings contained in the present manual and on the safety plates on the engine.
Inappropriate functioning and maintenance can result in serious injury or even death.
3 - Ventilation of closed areas:
In the event that it is necessary to start the engine in a closed environment or if petrol or cleaning oil is being used, open doors and windows to ensure
Service manual
pag. 8
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3. TECHNICAL DATA AND SPECIFICATIONS

3.4. Expendable materials

3.1. Identication
Every motor is marked with a serial number on the base and applied on the canopy; this serial number is composed with 9 numeric characters and can identify:
• - • • • - • • • • •
Year of
manufacture
Date
The serial number must be reported on every ope­rating sheet in the warranty application and is fun­damental for identifying and ordering spare parts.
Daily progressive number
Petrol
Engine oil
Spark plug
- from 5 to 35 °C
- from -15 to +5 °C
- from -25 to + 35°C
Unleaded (green)
minimum 90N.O.
SAE 30
5W30-10W30
Synthetic 5W30-10W30
RC12YC (Champion)
or equivalent
Starter rope ø 3,5x2500 mm

3.5. Use limits

The following table gives the use limits of certain components subject to wear, after which the com­ponent must be replaced.
Compression when new 8,0:1 (01)/8,0:1
Minimum inlet valve stem diameter 5,32 mm
Minimum exhaust valve stem diameter
Minimum inlet valve head rim thickness
Minimum exhaust valve head rim thi­ckness
Valve seat depth 1,8 mm
Min. 4 bar
5,27 mm
0,5 mm
0,5 mm

3.2. Technical data

WBE 0701 WBE 0704
Displacement 160 cc 200 cc
Bore 65 mm 70 mm
Stroke 48 mm 51 mm
Minimumspeed(SLOW)
Maximumspeed(FAST)
Fuel tank capacity
Oil sump capacity 0,55 litres
Dry weight 11,75 kg 12,80 kg
1800 (±150) r.p.m.
2900 (±100) r.p.m.
1,0 litres

3.3. Adjustments

Distance between spark plug electrodes
Coil air gap 0,25 - 0,40 mm
Inlet valve clearance 0,10 - 0,15 mm
0,6 - 0,8 mm
Minimum valve spring length 28,5 mm
Maximum gap between ends of cylin­der rings
Max. axial gap for compression rings 0,15 mm
Minimum gudgeon pin diameter
Max. gudgeon pin-piston seat diame­ter
Ma x. conn ec­ting rod diame­ter
gudgeon pin side 13,07 mm
crank side 26,07 mm
1 mm
12,95 mm
13,05 mm
Exhaust valve clearance 0,15 - 0,20 mm
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Service manual

3.6. Tightening torques

8-10 Nm
8-10 Nm
8-10 Nm
8-10 Nm
8-12 Nm
16-18 Nm
50-55 Nm
15 Nm
8-12 Nm
8-10 Nm
8-10 Nm
80-90 Nm
4-6 Nm 8-12 Nm
8-10 Nm
8-12 Nm
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3. TECHNICAL DATA AND SPECIFICATIONS
Service manual
pag. 10
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3. TECHNICAL DATA AND SPECIFICATIONS

3.7. Table of Tightening torques

Chapter Ref. Description of screw Tightening torques
5 Tank xing screws 8 - 10 Nm
5 Tank xing nut 8 - 10 Nm
6 Fixing nuts, starter assembly 8 - 10 Nm
6 Starter screw 4 - 6 Nm
7 Fixing nuts carburettor and lter 8 - 12 Nm
9 Support screw, governor assembly 8 - 10 Nm
10 - 13 Spark plug tightening torque 16 - 18 Nm
10 Fixing screw reel 8 - 10 Nm
10 Coil xing stud 8 - 10 Nm
11 Brake support screws 8 - 10 Nm
11 Brake support stud 8 - 10 Nm
12 Mufer xing nuts 8 - 10 Nm
13 Screws valve cover 8 - 12 Nm
13 Fixing head screws 50 - 55 Nm
13 Attachment bolt ywheel 80 - 90 Nm
13 Screws small plate drop wire 8 - 12 Nm
14 Union screws under carter and sump 8 - 12 Nm
14 Counterweight governor xing screw 8 - 10 Nm
14 Fixing screws lower connecting rod cap 15 Nm
P.S. For the coupling tourque of all standard screws refer to the single table.
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Service manual
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3. TECHNICAL DATA AND SPECIFICATIONS
3.8. Identicationofengineunits
For ease of reference, this manual has subdivided maintenance operations into different sections, each of which refers to an engine component unit as indicated in the diagrams below.
Ignition
Turning off and Stopping
Tank and Supply
Engine block
Carburettor
Carburation control
Air intake
Starting system
Exhaust system
Service manual
pag. 12
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4. ENGINE TUNING AND TESTING

4.1. Operating guidelines

The engine requires a series of interventions (shown in the table below) in order to ensure minimum basic maintenance.
Operation First 5 hours
Check oil level
Change oil *
Clean mufer and engine
Check air cleaner *
Replace air cleaner *
Check spark plug
Replace spark plug
(1)
*
Replace the oil every 25 hours if the engine is working at full load or at high temperatures.
(2)
*
Clean the air lter more often if the machine is working in dusty areas.
(1)
(2)
(2)
- ■ - - -
■ - - ■ -
- ■ - - -
- ■ - - -
- - ■ - -
- ■ - - -
- - - ■ -
For the operations that are not difcult for the nal
user the assistance centre must maintain the mo-
tor in perfect efciency, in accordance with two
intervention lines:
Every 5 hours
or daily
8.1 and 8.3];
- inspecting the condition of the spark plug; che­cking the distance between the electrodes [
- Tuning the engine whenever possible.
- Recommending the client a routine maintenan­ce program at set intervals (e.g. at the end of the
- tightening the screws [ 11.2];
- functional test [ 4.3].
Every 25
hours or
every season
10.1];
season or before a long period of inactivity).
Should the checks and adjustments fail to achieve a satisfactory result, refer to chapter [ 15] for

4.2. Engine tuning program

troubleshooting.
As part of general engine tuning or any intervention on the lawn tractor, it is recommended that the Ser­vice Centre performs a series of operations aimed
at maintaining the engine’s efciency.
Every 50
hours or
every season
Every 100
hours
Tuning should involve:
- external blowing and cleaning the cylinder
- checking the oil level, topping up or replacing
- inspecting the condition of the starter rope and
- cleaning and oiling the air lter [ 5.1];
- emptying and cleaning the fuel tank and che-
- adjusting minimum and maximum speeds [
head, cylinder and mufer by removing any
remains of grass and mud;
parts if necessary;
checking that it functions correctly [ 6.2];
cking the breather pipe [ 5.2];
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Service manual
4. ENGINE TUNING AND TESTING
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4.3. Functional test

A functional test needs to be carried out at the end of each servicing operation, to check that the operations made are effective. The test must be performed in compliance with the safety regula­tions regarding the use of the lawnmower on which the engine is installed.
The functional test is carried out as follows:
a. Refuelling and checking the supply system
When you have refuelled the tank with new petrol, check the seal of the tank, the cap and the car­burettor pipe.
b. Cold starting test
With the throttle control in “CHOKE”, start the engine a few times to check it runs normally.
c. Check the engine rpm
When the engine is hot enough, check the engine speed with the throttle control set to “SLO” and “FAST”; the readings should be equal to the speci­cations [ 3.2].
d. Hot start test
With the engine hot and the throttle control set to “SLOW”, start the engine a few times to check it runs normally.
If all of these operations have a positive result, the engine can be considered fully serviceable and be returned to the client.
Service manual
pag. 14
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5. TANK AND SUPPLY

IMPORTANT: Carefully read the information below before commencing any intervention.
General Information
The fuel supply system comprises the petrol tank connected to the carburettor by a pipe; a mesh lter at the bottom of the tank prevents deposits and impurities from reaching the carburettor.
The supply to the carburettor oat chamber is caused by gravity and the volume of petrol taken from the
tank as the engine runs is compensated by a breather pipe in the cap.
See the relevant section [ 15] for advice on resolving problems due to the malfunctioning of the petrol supply system.
WARNING: All interventions on the supply system must be performed in safe conditions, therefore:
- do not smoke;
- workinaventilatedenvironmentawayfromnakedamesorunprotectedsourcesofheat;
- Collect any remaining petrol by positioning a suitable container under the engine, avoiding soiling the work bench;
- remove all traces of spilt petrol immediately;
- check you have connected the pipes before pouring petrol back into the tank.
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Service manual
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5. TANK AND SUPPLY

5.1. Emptying and removing the tank

1 - Remove the ring (1) of the petrol pipe (2) from the tank side and drain all the fuel from the tank and the pipe into a suitable container.
2 - Unscrew the two screws (3) at the side and the nut at the rear (4) and remove the tank (5).
2
6
3 - When tting, perform the above operations in
reverse.
5
WARNING:Beforerellingthetankwithnew
fuel, check that the petrol pipe is intact.
3

5.2. Cleaning the tank

1 - Remove the tank [ 5.1].
4
3
2 - Remove the clamp (1) from the side of the tank and disconnect the petrol pipe (2).
6
3 - Slide out the lter tube (6) and blow compressed air through it so as to remove any deposits inside.
Service manual
7
4 - Keeping the hole (7) in the spigot closed, pour about 100 cc of clean petrol into the tank and shake it vigorously to clean the inside.
pag. 16
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5. TANK AND SUPPLY
5 - Empty the tank and dispose of the petrol used for cleaning in accordance with the laws in force.
8
6 - Ret the tank [ 5.1] tightening the screws (3) and the nut (4) to the torques indicated.
WARNING:Beforerellingthetankwithnew
fuel, check that the petrol pipe is intact.

5.3. Checking and cleaning the breather pipe

8
1 - Remove the cap (8) and pull out the gasket (9) and the sponge (10).
9
2 - Check that:
- the gasket (9) is intact and without cracks or
ssures;
11
10
- the air passages (11) inside the cap are not clog­ged;
- the sponge (10) is not crushed or broken.
NOTE: Always replace the entire cap if the
gasket or sponge is damaged.
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Tightening torques
3 Tank xing screws 8-10 Nm
4 Tank xing nut 8-10 Nm
Service manual
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6. STARTING SYSTEM

General information The starter assembly inside the cover consists of a rope wound around a pulley. The movement from the
pulley to the ywheel (and the engine shaft) is transmitted by a pair of hooks. The rope is returned and
rewound by a spiral spring.
See the relevant section [ 15] for advice on resolving problems due to the malfunctioning of the star­ting system.
3
1
2

6.1. Removing the starter assembly

1 - To get access to the starter assembly (1), the cover (2) must be removed by unscrewing the three nuts (3).
2 - Ret the starter assembly (1) by tightening the cover nuts (3) to the torque indicated.
3

6.2. Replacing the rope

1 - Remove the starter assembly [ 6.1].
2 - Keep hold of the pulley (4) and slowly unwind (clockwise) the entire rope (5) to gradually release the return spring.
4
5
If the rope breaks, the spring will be already relea­sed and you will only have to unwind the rope.
5
Service manual
4
pag. 18
3 - Undo or cut the knot at the end of the rope (5) and remove the section still attached to the pulley.
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6. STARTING SYSTEM
4 - Insert one end of the rope (5) (ø 3.5mm - length 2500mm), through the guide in the ventilation grille, into the hole in the pulley (4), and fasten it by tying
5
6
4
a knot.
5 - Insert the other end of the rope into the grip (6) and fasten it with a knot.
6 - Rotate the pulley (4), without winding the rope onto it, through about 6 complete turns anti­clockwise in order to load the spring. Carefully release the pulley to allow the rope to rewind itself completely onto the pulley.
7 - Check that the pulley rotates freely.
8 - After pulling the entire length of the rope, check that the pulley (4) is able to complete another 2-3 turns before compressing the spring.
9 - Ret the starter assembly [ 6.1].

6.3. Replacing the hooks

1 - Remove the starter assembly [ 6.1].
2 - Undo the screw (7) clockwise and remove the cover (8), setting aside the spring and washer.
4
7
Take care that the pulley (4) does not slide out of its housing.
8
NOTE: The screw (7) has a left-handed
thread and therefore should be unscrewed clockwise.
3 - Move the return springs (9) gently out of the way, rotate the hooks (10) clockwise and remove them.
NOTE: Always replace the complete set
consisting of hooks, return springs, cover and screw, as a unit.
9
4 - When tting, tighten the screw (7) to the torque indicated.
10
Release 00 - 02/2008
pag. 19
5 - Ret the starter assembly [ 6.1].
Tightening torques
3
Fixing nuts, starter assembly
8-10 Nm
7 Starter screw 4-6 Nm
Technical information
Starter rope dimensions ø 3,5x2500 mm
Service manual
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7. INTAKE SYSTEM

General information
The intake system uses an air lter directly connected to the carburettor by means of a manifold which conveys the air/petrol mixture to the inlet valve.
See the relevant section [ 15] for advice on resolving problems due to the malfunctioning of the air intake system.
Aninefcientltercanletdustordebrisenterthecylinder,causingprematureweartothepistonringsand
cylinder.
The air lter is found on the left hand side of the engine and can be inspected without having to remove
other parts.
7.1. Maintenanceoflteringelement
2
WARNING: Never run the engine without air
lter.Theenginewouldcertainlybedama­ged.
1 - Clean the area around the lter cover (1) by blowing it with compressed air.
1
2 - Remove the cover (1) by exerting pressure on the two upper tongues (2) and remove the lter element (3).
3 - Check carefully that the element has no holes or tears, and replace it if it is damaged.
3
Service manual
pag. 20
4 - Bang the air lter element on a hard surface so
as to remove excess dirt, and blow it through with compressed air, outwards from the inside. Replace the element if it is too dirty.
5 - Ret the element (3) and the cover into their housings.
Release 00 - 02/2008
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8. CARBURATION

General information The carburettor has a oat with a xed jet and a “CHOKE” control.
See the relevant section [ 15] for advice on resolving problems due to carburation.
The carburettor is located on the left-hand side of the engine. For maintenance operations it is necessary
to dismantle the air intake lter in the sequence shown below.
Dismantle the engine from the machine following the instructions in section [ 14.1].
WARNING! All operations on the tank and
supply system must be carried out in safe conditions, so:
- do not smoke;
- always empty the tank if petrol is not strictly necessary for the operation to be carried out;
- work in a ventilated environment away from
nakedamesorunprotectedsourcesofheat;
1
- collect petrol in a suitable container with a cap using a funnel and avoid spilling it on the work bench;
- remove all traces of spilt petrol immediately;
- check you have connected the pipes before pouring petrol back into the tank.
2

8.1. Removing and cleaning the carburettor

1 - Remove the lter element (1) [ 7.1].
4
3
2 - Pull off the breather tube (2), unscrew the two nuts (3) holding the lter carrier (4) to the engine and remove it.
3 - Remove the clamp (5) for the petrol pipe (6) from the side of the carburettor and use a suitable container to collect all the petrol in the tank and
6
the pipe.
Release 00 - 02/2008
5
pag. 21
Service manual
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8. CARBURATION
4 - Remove the gasket (7) and move the intake
buttery rod to the minimum position.
7
5 - Using pliers, disconnect the intake buttery rod
(8) and slide the small rod (9) for the relative com­pensation spring upwards.
8
9
12
15
10
13
6 - Disconnect the wire (10) from the choke but-
tery lever, remove the carburettor (11) and the gasket (12).
11
7 - Loosen the central screw (13) fastening the oat chamber (14), remove the relative gasket (15)
and carefully collect all the petrol left in the oat
chamber.
14
Service manual
pag. 22
Release 00 - 02/2008
18
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17
20
19
8. CARBURATION
8 - Pull out the pin (16), dismount the oat (17) and remove the gasket (18).
9 - Undo the main jet (19) and pull out the pilot jet (20).
16
10 - Check that no impurities or dirt are deposited in the seat of the needle (21) and of the pilot jet (20).
Verify that the rubber tip of the needle is not marked or worn.
11 - Clean the carburettor (11), the main jet (19) and the pilot jet (20) thoroughly by immersing them in clean petrol (or a detergent) for 24 hours. Dry with compressed air, blowing well through the carburettor holes.
21
23
12 - Mount the carburettor following the previous points 8, 7 and 6 in reverse order, remembering that:
- It is always advisable to replace the washer
(18) and the gasket (15) of the float chamber;
- the oat (17) must oscillate freely on the pin (16);
- the jet (19) should never be modied or replaced
with others even if they seem to have the same
specications;
- the choke (22) must open and close regularly;
- the oat chamber drain screw (23) must be facing
forwards.
13 - Remount the tie rods (8), (9) and (10) checking that the governor system moves smoothly without stopping.
Release 00 - 02/2008
22
pag. 23
14 - Always replace washers (7) and (12) when re-mounting the carburettor onto the engine.
15 - Fit the lter and tighten the relative nuts (5) to the torque indicated. Ret the lter element [
6.1].
Service manual
8. CARBURATION
SLOW
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8.2. Replacing the carburettor

1 - Perform operations 1 - 2 - 3 - 4 - 5 - 6 - 12 - 13 - 14
- 15 indicated in section [ 8.1] above.

8.3. Adjusting minimum speed

1 - Check that the throttle cable is adjusted cor­rectly [ 9.1].
2 - Let the engine heat up for a few minutes, then set the throttle control to “SLOW”.
24
23
Check the rotation speed on the speed indi-
cator (23).
NOTE: The engine’s minimum speed must be
between 1800 (±150) rpm.
3 - Turn the screw (24) until you achieve a stable minimum speed within the above values.

8.4. Adjusting maximum speed

NOTE: This operation is carried out by adju-
sting the governor system [ 9.2].

8.5. Adjusting the carburation

NOTE: The carburation is set in the factory
and does not normally need changing. In the event of irregular functioning, clean the carburettor as indicated in section [
8.1].
Service manual
pag. 24
Tightening torques
6 Carburettor nuts/lter 8-12 Nm
Technical information
Minimum speed (SLOW) 1800 (±150) r.p.m.
Special equipment
24 Speed indicator
Release 00 - 02/2008
CHOKE
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9. GOVERNOR SYSTEM OF THE CARBURETTOR

General information
The carburettor governor system uses a engine shaft linkage tted on a support xed to the left-hand side of the engine, completed by a counterweight device, driven by the camshaft, and thus sensitive to changes in the engine’s revolution pattern depending on load.
The force of the counterweights, transferred to the control lever, tends to shut the main carburettor butter-
y, in opposition with the spring that would keep it open; the balance between the spring loading and the thrust of the counterweights on the control lever modies the buttery opening and adapts the ow of fuel
to the engine so that the revolution speed is kept constant with engine load changes.
See the relevant section [ 15] for advice on resolving problems related to the governor system.

9.1. Adjusting of accelerator cable

1 - Loosen the screw (1) of the clamp (2) so that the cable casing (3) is free to move.
3
1
2
2 - Set the throttle control lever (4) to “CHOKE”.
4
3 - Move governor control lever (5) forward as far as possible and, by keeping it in this position, lock the casing (3) full tightening the screw (1) of the clamp (2).
5
Release 00 - 02/2008
2
3
1
pag. 25
Service manual
FAST
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9. GOVERNOR SYSTEM OF THE CARBURETTOR

9.2. Adjusting maximum speed

1 - Check that the throttle cable is adjusted cor­rectly [ 9.1].
2 - Let the engine heat up for a few minutes then set the throttle control to “FAST”.
3 - Check the rotation speed on the speed indicator (6).
12
11
6
4 - Act on the regulation screw (7) to establish the correct value of the maximum turn system.
8
7
During the regulation, verify that the move-
mentofthemobilelevels(8)don’tdamagethecon­tactwithlevelairsupport(9)(position“CHOKE”).
NOTE: The engine’s maximum speed must be
9
between 2900 (±100) rpm; if you do not read this value, proceed as follows.
5 - Check:
- that the spring (10) is intact and positioned at the
8
attachment point furthest from the fulcrum of the control lever;
- that the wire (11) and the relative spring (12) are intact and not deformed;
- that the moving levers (8) are not bent or defor­med and replace the entire support if necessary [
9.3].
Service manual
10
pag. 26
Release 00 - 02/2008
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9. GOVERNOR SYSTEM OF THE CARBURETTOR
6 - If the above checks do not show any faults,
13
14
15
the phasing of the governor’s control lever (13) with respect to the counterweight device must be checked:
- stop the engine and move the accelerator control
to “FAST”;
- slacken off the control lever (14) locknut (13);
- without changing the lever (13) position determi-
ned by the spring (12) and tie-engine shaft (11), use a screwdriver to turn pin (15) clockwise to the end of its stroke and then lock the nut (14).

9.3. Replacing the lever support

1 - Position the choke lever to minimum (“SLOW” position).
17
16
18
19
10
18
3
2 - Remove the carburettor [ 8.1].
3 - Disconnect the accelerator cable (3) and remo­ve the breather pipe (16) and the spring (10).
4 - Disconnect the choke buttery wire (17) and undo the two screws (18) securing the support (19) to the engine.
5 - Perform the above operations in reverse order when assembling.
6 - Ret the carburettor [ 8.1].
7 - Adjust the maximum speed [ 9.2].
Release 00 - 02/2008
pag. 27
Tightening torques
Suppor t screw, governor
18
assembly
Technical information
Maximum speed (FAST)
Special equipment
6 Speed indicator
8-10 Nm
2900 (±100) r.p.m.
Service manual
0,6 - 0,8 mm
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10. IGNITION

General information The ignition system has a ywheel with an electronic coil which supplies high voltage to the spark plug.
See the relevant section [ 15] for advice on resolving problems related to the ignition.
The coil and magneto ywheel are accessible by removing the cowl.
Dismount the engine from the machine by following the instructions in section [ 14.1].

10.1. Checking the efficiency of the igniti on system

2
1 - Dismount the spark plug (1) and look at the co­lour on the end of the thread. This can give you a good idea of the carburation:
- black: mixture too greasy due to clogged air
lter;
- nut brown: regular carburation.
1
Replace the spark plug (with one of the same or
equivalent characteristics)iftheelectrodes(2)are
burnt or if the porcelain is broken or cracked.
4
FIRE HAZARD:
- do not check the ignition system if the spark
plug is not screwed in place;
-
 always usethe specic toolfor the
spark test.
3
2 - Connect the tester (3) to the spark plug cap (4) and to earth on the engine (5). Activate
5
the starter and see in the instrument if the spark jumps.
3 - If the test has a positive result, clean the electro­des (2) with compressed air and adjust the distance to 0.6-0.8 mm. Remount the spark plug and tighten
it to the specied levels.
Service manual
pag. 28
Unless otherwise required, proceed to verify system components as indicated in section [ 10.2].
Release 00 - 02/2008
10. IGNITION
0,25÷0,40 mm
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10.2. Adjusting the air gap and checking the coil

1 - Remove the starter assembly [ 6.1].
11
7
8
2 - Make sure that the earth cable faston (6) of the coil (7) is not oxidized; if it is, disconnect, clean and remount it, spraying it with a special antioxidant.
3 - Check that the coil earth cable is intact. The black spark plug cable (8) should not have any
6
cracks or signs of deterioration or burns which re-
duce its efciency and insulation level.
10
4 - Slack off the screw (9) and the stud (10) which secure the coil (7).
9
At the bottom of the machine to which the engine
is tted, release the safety brake. Rotate the ywheel (11) so as to bring the magnetic
inserts next to the poles of the core of the coil.
5 - Insert a 0.35 mm thickness gauge (12) between the ywheel (11) and the coil poles (7). Push the coil until the poles come in contact with the thickness gauge and secure screw (9) nd stud (10); with the
ywheel locked, the airgap must be between 0.25
mm and 0.40 mm.
 NOTE: Anaccurate inspection of the ef-
ciency of a coil can only be carried out in a laboratory equipped with a oscilloscope.
To make a brief check, proceed as follows:
6 - Disconnect the earth cable faston (6) of the coil (7).
6
Release 00 - 02/2008
pag. 29
Service manual
10. IGNITION
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7 - Perform a spark test as indicated in [
10.1].
- If the spark jumps: the coil functions properly and
in the event of malfunction, verify that the cut-off cable (13) is not earthed.
- if the spark does not jump: the coil is faulty and
must be replaced [ 10.3].
10
13
8 - Ret the starter assembly [ 6.1].

10.3. Replacing the coil

1 - Remove the starter assembly [ 6.1].
7
9
2 - Disconnect the faston of the earth cable (6).
3 - Undo the screw (9) and the stud (10) and remove the coil (7).
6
4 - Mount the new coil and regulate the air gap according to the procedure indicated in points 4 and 5 in section [ 10.2].
5 - Connect the faston of the earth cable (6).
Service manual
pag. 30
8 - Ret the starter assembly [ 6.1].
Tightening torques
1 Spark plug tightening torque 16-18 Nm
9 Coil xing screw 8-10 Nm
10 Coil xing stud 8-10 Nm
Technical information
Type of spark plug RC12YC (Champion) or equivalent
Distance between electrodes 0,6-0,8 mm
Air gap/ywheel 0,25-0,40 mm
Special equipment
3 Tester for spark test
Release 00 - 02/2008
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11. TURNING OFF AND STOPPING THE ENGINE

General information
The engine is turned off and stopped by releasing a lever on the lawnmower. The cable acts on a lever which simultaneously activates a microswitch that sends the coil to earth as well as a brake which acts
on the ywheel.
The brake must be able to stop the engine within 3 seconds after it is turned off.
To solve problems in the system for turning off and stopping the engine, see the relevant chapter [
15].
To get access to the system for turning off and stopping the engine, remove the starter assembly and the fan.

11.1. Checking the control cable

5
1 - Remove the starter assembly [ 6.1].
2 - Remove the lter assembly [ 7.1].
1
3 - Check that the sheath (1) is not bent, that the wire (2) is securely connected to both the lawn-
4
3
2
mower lever and the lever (3) on the engine and that the terminal (4) is correctly fastened to the support (5).
4 - Check that the wire (2) runs freely inside the sheath (1) when you move the lever.
7
6
8
5 - Check that the end of the wire (2) is slightly loose when you release the lawnmower lever.
6 - Ret the lter assembly [ 7.1].
7 - Ret the starter assembly [ 6.1].

11.2. Checking the ignition of f microswitch

1 - Disconnect the faston (6) from the micro­switch.
Release 00 - 02/2008
pag. 31
2 - Using an Ohmmeter tester (7) make con­tact with the prods on terminals “1-COM” of the microswitch (8) and engine earth connection; The instrument should read:
- ∞ = microswitch pressed (lever pulled);
- 0 = microswitch free (lever released);
Otherwise, replace the system for turning off and stopping the engine.
Service manual
> 2 mm
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11.3. Checking the brake

10
1 - Remove the starter assembly [ 6.1].
9
2 - Check that the thickness of the friction pad (9) is not less than 2 mm at its thinnest point.
3 - Make sure that the control lever (10) moves freely and remove any remains of grass and mud.
4 - Ret the starter assembly [ 6.1].
5 - Start the engine, release the lawnmower lever and check that the engine stops within 3 secon­ds.
6 - If it stops after 3 seconds, replace the entire as­sembly [ 11.4], because the spring or the fric-
3
2
tion pad are not capable of ensuring compliance with braking times.
WARNING! Never return the lawnmower to
yourclientwithoutcheckingbrakeefcien­cy.
Service manual
pag. 32
Release 00 - 02/2008
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11. TURNING OFF AND STOPPING THE ENGINE
11.4. Replacing the system for turning off and stop-
ping the engine
1 - Remove the starter assembly [ 6.1].
2 - Remove the lter assembly [ 7.1].
11
8
6
3 - Disconnect the brake wire (2) from the lever (3).
4 - Disconnect the faston (6) from the microswitch (8).
12
11
5 - Undo the two screws (11) and the stud (12) which secure the support bracket (13).
6 - When tting, perform the above operations in
reverse, tightening the screws (11) and the stud (12) to the torque indicated.
13
7 - Ret the starter assembly [ 6.1] and the lter
assembly [ 7.1].
8 - Start the engine, release the lawnmower lever and check that the engine stops within 3 secon­ds.
Release 00 - 02/2008
pag. 33
WARNING! Never return the lawnmower to
yourclientwithoutcheckingbrakeefcien­cy.
Tightening torques
11 Brake support screws 8-10 Nm
12 Brake support stud 8-10 Nm
Special equipment
7 Universal tester
Service manual
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12. EXHAUST SYSTEM

General information
The exhaust system consists of a mufer installed on the cylinder together with a gasket, a spacer and a heatproof bafe.
To solve problems in the exhaust system, see the relevant chapter [ 15].
12.1. Removingandreplacingthemufer
1 - Remove the two nuts (1) that x the guard (2) and the mufer.
1
2
1
2 - Take out the mufer (3) and the heatproof bafe
(4).
3 - On assembly::
- thoroughly clean the cylinder contact surface,
removing all deposits or fragments on the hea-
tproof bafe;
- always replace damaged mufers;
4
3
- always replace the heatproof bafe (
broken or cracked;
4) if it is
- tighten the two nuts (1) to the specied levels.
Tightening torques
1 Mufer nuts 8-10 Nm
Service manual
pag. 34
Release 00 - 02/2008
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13. ENGINE BLOCK - External operations

13.1. Checking the compression

1 - Remove the cap (1) and take out the spark plug (2).
2 - anually set the piston to the TDC (Top Dead Centre) of the compression stroke so that both valves are closed.
2
1
3 - Screw the terminal of the compression te­sting tool (3) into the spark plug hole and connect the supply pipe to a compressed air socket with a pressure of approximately 4 bar (58 psi).
4 - On opening the air tap (4), the manometer gauge on the engine side should position itself in the green zone and remain there for about 30 se­conds. If the gauge falls rapidly it means that the compression is poor
4
3
NOTE: Lack of compression could be due
to:
- incorrect valve clearance [ 13.2];
- cylinder head loose or cylinder head gasket worn
[ 13.3].
- lack of seal in the valves [ 13.4];
- piston rings worn [ 13.3].
5 - Ret the spark plug (2) and close it to the indi- cated couple.
Release 00 - 02/2008
pag. 35
Service manual
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13. ENGINE BLOCK - External operations

13.2. Adjusting the valve clearance

WARNING: The adjustment must be made
with the engine is cold.
1 - Remove the cover and demount the spark plug
[ 13.1].
6
5
2 - Remove lid (5) which is secured with four screws (6) and remove the washer (7).
3 - Manually set the piston to the TDC (Top Dead Centre) of the compression stroke so that both valves are closed.
4 - Use a feeler gauge (8) to check the gap between the rocker arm and the tip of the valve stem; the
7
gauge should pass between without forcing and without a further gap.
5 - The gap is adjusted by slackening off the nut (9)
8
and suitably adjusting the register nut (10) to obtain the following values:
Inlet - IN = 0,10 - 0,15 Exhaust - EX = 0,15 - 0,20
Service manual
12
10
6 - Following adjustment, check that the pushrods (11) are properly inserted in the rocker arm housings (12) and always fully tighten the nut (9).
7 -
When reassembling check the condition of the gasket (7) of the cover (5) and replace it if it is damaged.
Tighten the screws (6) to the torque
indicated.
11
8 - Assemble the spark plug [ 13.1].
9
pag. 36
Release 00 - 02/2008
EX
IN
EX
IN
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13. ENGINE BLOCK - External operations
13
13
14
13
13
14

13.3. Dismantling and cleaning the cylinder head

1 - Remove the carburettor [ 8.2].
2 - Remove the exhaust mufer [ 12.1].
3 - Remove the cover and demount the spark plug
[ 13.1].
4 - Remove the starter assembly [ 6.1].
5 - Remove lid (5) which is secured with four screws (6) and remove the washer (7).
6 - Unscrew the screws (13) and remove the cylinder head (14).
7 - Remove the gasket (15).
16
15
8 - Clean the cylinder head (14) and cylinder sur­faces (16).
9 - Carefully clean the inside of the combustion chamber and remove possible deposits from the valve seats.
10 - Turn the ywheel by hand to move the piston
and check the internal surface of the cylinder (16).
11 - When mounting:
- the gasket (15) must always be replaced;
- Remount the cylinder head (14) screwing the four screws (13) without fully tightening, then tighten them to the given torque values, using a cross-over sequence. Take care that the pushrods are positioned cor­rectly in their housings.
Release 00 - 02/2008
pag. 37
12 - Remount the items removed in the reverse order used in dismantling.
Service manual
A
B
C
18
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19
13. ENGINE BLOCK - External operations

13.4 Overhauling the cylinder head and valves

NOTE - These paragraphs describe all the
operations for checking and overhauling the cylinder head;
it is left to the operator to assess the advisabi-
lity of performing all the operations described
17
1 - Dismount the cylinder head [ 13.3].
2 - Move the rocker arms (17); press down the spring seal cap (18) and move it sideways to remove from the valve stem (19).
IMPORTANT - The inlet and exhaust valves are dif-
ferent from eachother and canbe identiedby
the marking «IN» (inlet) and «EX» (exhaust), on the valve head.
or only part of them, depending on the type of engine problems encountered.
21
20
3 - Use an emery cloth to remove all incrustations from the valve head and check the thickness of the rim (A); the valve must be replaced if the margin (A) is less than 0.5 mm (inlet - IN) or 0.5 mm (exhaust
- EX), or if it shows signs of burning.
4 - Check the diameter of stem (B) in several points and replace the valve if it is less than the following, even if only in one point:
5,32mm(inlet-IN) 5,27mm(exhaust-EX)
NOTE - The valve seats must be ground by
hand, using a special grinding tool with an angle of 45°.
5 - Insert the pin (20) in the cylinder head valve guide and then the grinding tool (21).
NOTE - Grinding must be done taking care
to remove as little material as possible.
Service manual
6 - Use a caliper gauge to check the depth of the valve seat (C), which must be 1.8 mm; the cylinder head must be replaced if a greater value is mea­sured.
pag. 38
Release 00 - 02/2008
EX
IN
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13. ENGINE BLOCK - External operations
7 - Apply abrasive paste for grinding around the rim of the valve head (19) and then insert the valve into its seat.
19
8 - Use the special manually operated tool (22) to grind the seat and rim of the valve.
23
9 - Remove the valve and use clean petrol to ca­refully clean all traces of paste or metal residues from the valve seat and rim.
22
10 - Check the free length of the spring (23) and replace the spring of it is less than 28,5 mm.
11 - When mounting:
- carefully clean the valve guides and housings of any foreign body;
- apply a lm of oil on the valve stems before inser­ting them in their respective housings;
- ensure the correct position of the inlet valve and the exhaust valve, marked, respectively, with «IN» and «EX» on the valve head.
Release 00 - 02/2008
pag. 39
12 - Remount the cylinder head [ 13.3] and x the screws to the indicated couple.
13 - The valve clearances must be checked whe-
never the cylinder head is removed and retted [
13.2].
Service manual
25
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29
13. ENGINE BLOCK - External operations
13.5. Dismantling and replacing the magneto
24
26
ywheel
1 - Remove the starter assembly [ 6.1].
2 - Using an airgun, undo the nut (24) and extract the fan (25), setting aside the starter cup (26).
3 - Undo the screw (28) and the stud (29) and re­move the electronic coil (27).
27
28
4 - Using a suitable extraction tool, remove the
ywheel (30) as indicated in the diagram. Ensure that the engine shaft key is retained.
30
5 - When tting the ywheel check that the key (31) is in good condition and replace it if it is deformed; t the starter cup (26) and the fan. Close the nut to the indicated couple (24) and utilize a gun.
6 - Ret the coil (27), tightening the screw (28) and the stud (29) to the torque indicated.
Service manual
31
pag. 40
7 - Readjust the airgap until it is correct [
10.2].
8 - Ret the starter assembly [ 6.1].
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13. ENGINE BLOCK - External operations

13.6. Checking the oil breather

1 - Remove the magneto ywhee [ 13.5].
32
33
2 - Unscrew the two screws (32) xing the closing plate (33).
3 - Check that the reed (34) is not blocked or de­formed. Replace if this is the case. If necessary, wash the metal lter (36) with water and neutral detergents or blow it clean with com­pressed air.
35
34
31
37
36
4 - If necessary, replace the gasket (35) and
ret the closure plate (33), tightening the screws to the torque indicated.
5 - Ret the magneto ywheel [ 13.5].
13.7. Replacing the upper compression ring of the
engineshaft(ywheelside)
1 - Remove the magneto ywheel [ 13.5].
2 - Take out the spline key (31).
3 - Use a thin screwdriver inserted under the sealing lip to extract the oil seal ring (37).
39
38
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4 - The new ring (38) must be inserted with the help of a pipe (39) with a diameter of approximately 50-55 mm, taking care not to damage the sealing lip.
5 - Ret the key (31) and the magneto ywheel [
13.5].
Service manual
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13. ENGINE BLOCK - External operations
13.8. Replacing the lower compression ring of the
engineshaft(sumpside)
41
NOTE - Before executing this operation di-
scharge all the oil from the bowl and rotate 180° the motor.
1 - Remove the blade (40) and hub (41).
40
2 - Take out the spline key (42).
3 - Use a thin screwdriver inserted under the sealing
42
lip to extract the oil seal ring (43).
46
44
43
45
4 - Make a paper tube (44) around the shaft to protect the sealing lip and insert the new ring (45) so that it enters its housing.
5 - Complete the insertion with the help of a pipe (46) of a diameter of approximately 30-35 mm.
Tightening torques
2 Spark plug tightening torque 16-18 Nm
6 Valve cover xing screws 8-12 Nm
13
Cylinder head screws 50-55 Nm
24 Flywheel xing nut 80-90 Nm
32
Screws small plate louver 8-12 Nm
Technical information
Compression Min. 4 bar
Inlet valve clearance 0,10-0,15 mm
Exhaust valve clearance 0,15-0,20 mm
Minimum inlet valve stem diameter 5,32 mm
Minimum exhaust valve stem diameter
Min. inlet valve head rim thickness
Min. exhaust valve head rim thickness
5,27 mm
0,5 mm
0,5 mm
Valve seat depth 1,8 mm
Minimum valve spring length 28.5 mm
Special equipment
3 Compression testing tool
21 Valve seat grinding tool
22 Valve grinder
Service manual
pag. 42
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14. ENGINE BLOCK - Overhauling internal parts

2
moval of the engine from the lawnmower.

14.1. Removing the engine from the lawnmower

1 - Empty the tank of fuel [ 5.1].
1
2 - Drain the oil in the sump by removing the ller
plug and turning the mower on its side.
3 - Disconnect the throttle cable (1) and the engine
All the operations described below require the re-
3
3
brake cable (2).
4 - Remove the blade assembly and undo the four screws (3) which are accessible from the bottom of the lawnmower.
Grasp the engine at points which offer a
secure grip, taking account of the overall weight
3
3
given in the relevant table [ 3.2].
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Service manual
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14. ENGINE BLOCK - Overhauling internal parts

14.2. Carter opening

1 - Position the engine on a stable support and remove the sparkplug.
2 - Turn the engine up-side-down and position it so that the shaft projects upwards.
6
3 - Open the crankcase sump by unscrewing the seven screws (6).
5 - verify the phasing between:
- the engine shaft and the camshaft;
If necessary, re-set the phasing, referring to the indications provided.
6 - On assembly, follow the steps described in re­verse and:
- always replace the gasket (7) between cover and sump;
- ensure that the two centring pins (8) are correctly inserted;
- always replace the compression ring from the sump side [ 13.8].
7
8
- ensure that the governor lever (9) is facing upwar­ds;
- close the screws (6) intersection lock bowl to the indicated couple;
Service manual
7 - After installing the engine on the machine:
- rell the sump and make sure that the ller plug
is tight.
- check the adjustment of the throttle cable [
9.1] and the brake cable [ 11.1].
8 - Following reassembly it is advisable to check the engine’s peak rpm [ 9.2].
9
pag. 44
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14. ENGINE BLOCK - Overhauling internal parts

14.3. Dismantling and checking the camshaft and counterweight governor

10
1 - Remove the engine from the machine and open the cover [ 14.2].
2 - Remove the camshaft (10).
3 - Measure seat (A) of the camshaft, checking for wear and tear. The value must not be lower than 28,05 mm (IN) and 27,72 (EX).
(EX)
12
15
(IN)
A
4 - Check the regular movement of the pressure reducer (11) and the efciency of the spring (12); the whole group must always be replaced in the case of breakage or irregular operation of the pressure reducer.
11
5 - Check that the irregolar centrifugal (13) that are
not present ruptures of the lubrication pallets.
13
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14
pag. 45
6 - Turn the governor’s gears quickly and check that the counterweights (14) expand correctly, causing the pin (15) to be moved axially.
Service manual
18
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16
14. ENGINE BLOCK - Overhauling internal parts
7 - In the case of breakage or irregular operation
of the counterweights the whole group, xed by a
plate (16) and a screw (17) must be replaced.
17
8 - When assembling the new group, care must be
20
19
taken over the correct positioning of one scraper washer (18) under the sliding pin (19) and the other (20) on the opposite side.
21
9 - Before tting the camshaft ensure that the two
tappets (21) are correctly housed in their seats.
21
Service manual
pag. 46
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26
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24
14. ENGINE BLOCK - Overhauling internal parts
10 - When retting the camshaft, maximum care
must be taken to match up the two references (22) and (23) punched on the gears, so as to ensure
22
23
correct distribution phasing.
11 - During assembly, refer to the operations in section [ 14.2] always remembering to re­place the washer (7) between the sump and the housing.

14.4. Dismantling and checking the piston, piston rings, connecting rod and engine shaft

NOTA - These paragraphs describe all the
operations for checking and overhauling the thermal components of the engine; it is left to the operator to assess the advisability of performing all the operations described or only part of them, depending on the type of engine problems encountered.
27
27
28
25
1 - Remove the engine from the machine [
14.1].
2 - Remove the magneto ywheel [ 13.5].
3 - Open the cover [ 14.2].
4 - Remove the camshaft [ 14.3].
5- Dismantle the connecting rod (24) cap (25), xed with two screws (26) (take note of any reference
marks for retting).
6 - Push the connecting rod (25) so as to cause the piston (27) to come out of the cylinder (28).
7 - Use the special expanding tool (29) to re­move the two compression rings and the oil scraper ring from the piston (27).
29
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pag. 47
8 - Carefully remove all carbon deposits from the compression rings, the inside of the cylinder and the piston head.
Service manual
30
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31
14. ENGINE BLOCK - Overhauling internal parts
9 - To check the wear in the compression rings, insert them one at a time into the cylinder (28) by about 10-15 mm and measure the gap between the two ends with a feeler gauge (30); the rings must be replaced if the gap is more than 1 mm.
NOTE - If a gap of more than 0.6 mm is measu-
red with new rings it means that the cylinder is worn beyond the acceptable limits and must be replaced. The cylinder must be replaced if it shows striping due to a seizure.
10 - Use a section of an old ring (31) to carefully clean the inside of the piston (27) ring housings, en­suring that the oil passage holes are not blocked.
27
34
33
32
11 - To check the wear in the piston ring housings,
t a new ring and measure the residual space with
a feeler gauge (32). The piston must be replaced if it is greater than 0.15 mm in the two compression ring housings.
12 - Use a screwdriver to remove the clamping ring (33) and remove the gudgeon pin (34) from the piston (27).
Service manual
pag. 48
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34
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14. ENGINE BLOCK - Overhauling internal parts
13 - Check the diameter of the gudgeon pin (34) in several places and replace it if it is less than 12.95 mm, even at a single point.
14 - Check the diameters of the gudgeon pin hou­sings (A) on the piston (27) and replace the piston if they are more than 13.05 mm, even at a single point.
A
24
15 - Fit the cap (24) to the connecting rod (25) and check the diameter from the gudgeon pin side and the crank side; replace the connecting rod if the values are greater than:
B : 13,07 mm on the gudgeon pin side;
C : 26,07 mm on the crank side.
B
25
If the connecting engine shaft is outside measure­ment tolerances or has small scratches or marks, it is necessary to replace it.
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C
pag. 49
Service manual
10
20
30
40
50
60
70
80
90
37
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14. ENGINE BLOCK - Overhauling internal parts
16 - Remove the engine shaft (35), checking the diameter of the connecting rod pin with a digital gauge. The value must not be less than 25,92 mm or the engine shaft will have to be replaced.
35
NOTE - In the case of seizing, the manifolds
canbepolishedwithneemerycloth,only
removing foreign matter and checking that thenalsizeremainswithintheaforementio­ned limit.
17 - To check the alignment between the manifol­ds and the protruding part of the shaft, place the engine shaft on two prismatic guides (36) and, with the help of a comparator (37) placed at the end, check the displacement by rotating the shaft. The shaft must be replaced if the displacement exceeds
0.10 mm.
38
39
40
33
34
36
36
IMPORTANT: A bent shaft must never be re-
paired!
WARNING - DANGER: A bent shaft causes ab-
normal vibrations and could be dangerous when the machine is used!
18 - To ret the rings to the piston, rst t the three
oil scraper rings (38), then the ring with a round edge (39) and nally the ring with a sharp edge (40), being careful over the markings (which must face the piston head) and in arranging the gaps to ensure that they are not aligned with each other.
19 - Fit the connecting rod (25), gudgeon pin (34) and clamping rings (33) to the piston (27), taking care over the connecting rod marking, which must face the intake side, with the piston marking facing the exhaust side.
27
Service manual
33
25
pag. 50
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14. ENGINE BLOCK - Overhauling internal parts
41
20 - Put the piston into the ring compression tool (41).
21 - Oil the inside of the piston liberally and insert the piston, with the marking facing the exhaust.
41
26
24
22
35
22 - Mount the engine shaft (35) and the connecting rod cap (24) with the relative screws (26), taking care with the position references (42) so as to avoid inverting the mounting direction of the cap.
Closethescrews(26)totheindicatedcouple.
42
23 - After having xed the connecting rod cap, take
the greatest care to ensure that the two position references (22) and (23) punched on the engine shaft and camshaft gears, coincide, ensuring the correct distribution phasing.
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23
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Service manual
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14. ENGINE BLOCK - Overhauling internal parts
24 - Close the carter and x the screws (6) to the indicated couple [ 14.2].
25 - Whenever the engine shaft is dismantled and
retted, it is always necessary to:
- replace the sealing ring on the ywheel side [
13.7];
- replace the sealing ring on the sump side
[
13.8].
6
26 - During assembly perform the operations indicated in section [ 14.2] always remembe­ring to replace the washer (7) between the sump and the housing.
Tightening torques
6
Union screws under carter and sump
Counterweight governor fixing
17
screw
Fixing screws lower connecting
28
rod cap
8-12 Nm
8-10 Nm
15 Nm
Technical information
Oil sump capacity 0,55 litri
Diameter aspiration cam 28,05 mm
Diameter discharge cam 27,72 mm
Maximum segments gap in the cylinder 1,0 mm
Max. compression ring axial gap
0,15 mm
Minimum gudgeon pin diameter 12,95 mm
Max. gudgeon pin housing diameter on piston
13,05 mm
Max. connecting rod diameter
gudgeon pin side 13,07 mm
crank side 26,07 mm
Diam. connecting rod’s pin on engine shaft
25,92 mm
Verify the engine shaft extremes 0,10 mm
Special equipment
31
Piston ring removal expander
43
Piston ring compressing tool
Service manual
pag. 52
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15. TROUBLESHOOTING

PROBLEM CAUSE SOLUTION
The engine does not start or
starts badly
The engine brake cable is faulty or unfastened
The microswitch is faulty
Coil earth connection
Earth wire is attened
The coil is faulty and does not supply current or the air gap is too large.
Carburettor dirty
Poor seal of carburettor needle val­ve
Choke blocked
The spark plug is badly connected or faulty
Adjust and/or replace the cable [
11.1]
Repl a c e th e mi croswitch [
11.2]
Check electrical cabling of earth wire
[ 10.2]
Replace earth wire [ 10.2]
Check coil [ 10.2]
Check and clean the carburettor [
8.1]
Clean the carburettor housing and needle valve [ 8.1] or replace the carburettor [ 8.2]
Check and clean the carburettor and the choke [ 8.1]
Check spark [ 10.1] or replace spark plug
Startingisdifcultandstrains
the rope
The engine starts but does
not run
Blocked air lter
Fouling in the combustion chamber
Insufcient pressure
Oil in the cylinder head
Pressure reducer fault
The tank cap has a clogged breather pipe
Fouling in the combustion chamber
Insufcient pressure
Execute the lter cleaning [ 7.1]
Dismount the cylinder head and re­move fouling [ 13.3]
Check tightness of cylinder head screws, replace washer if necessary. Check wear and tear of the piston rings [ 14.4]
Dismount the cylinder head and clean it [ 13.3]
Check the pressure reducer and couterweights [ 14.3]
Clean and/or replace the cap [
5.3];
Dismount the cylinder head and re­move fouling [ 13.3]
Check tightness of cylinder head screws, replace washer if necessary. Check wear and tear of the piston rings [ 14.4]
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Service manual
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15. TROUBLESHOOTING
PROBLEM CAUSE SOLUTION
Theengineisinefcientor
the runs irregularly
The engine overreved
The throttle cable is not well adju­sted
The governor malfunctions or there is a problem with the rods
Tralamenti d’aria nel carburatore
Carburettor dirty
Insufcient pressure
The coil air gap has been poorly adjusted
Oxidation or loosening of spark plug connections
Governor blocked due to breakage of centrifugal assembly or breakage of external governor springs.It is pos­sible that the governor is dirty.
Check and/or adjust the throttle ca­ble [ 9.1]
Check the entire governor system [
9]
Sostituire le guarnizioni del carbura­tore [ 8.1]
Check and clean the carburettor [
8.1]
Check tightness of cylinder head screws, replace washer if necessary. Check wear and tear of the piston rings [ 14.4]
Adjust the air gap [ 10.2] and if the problem persists, replace the coil
[ 10.3]
Perform spark test [ 10.1] or re­place spark plug
Check the entire governor system [
9 and 14]
The engine judders
The engine does not turn off
The engine does not stop
within 3 seconds after it has
turned off
The engine uses a lot of oil
Engine screws loose Tighten the screws
Check wear and tear of the connec-
Engine timing faulty
ting rod of the engine shaft, replace shaft if necessary [ 14.4]
The engine brake cable is bent or jammed
The earth cable is disconnected or broken
Faulty or no clutch lining
Defective breather valve operation
Poor piston ring seal
Excessive gap between the guide and the inlet valve stem
Ring assembly error
Check and/or adjust the cable [
11.1]
Check and/or replace oil breather tab [ 11.2]
Replace the engine stopping system
[ 11.4]
Check and/or replace the breather valve [ 13.6]
Replace the rings [ 14.4]
Check and/or replace the valve [
13.4]
Check the assembly of the rings [
14.4]
Service manual
pag. 54
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Release 00 - 02/2008
pag. 55
Service manual
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Service manual
pag. 56
Release 00 - 02/2008
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