PIAGGIO B 125 Instruction manual

WORKSHOP MANUAL
618162
B 125-250

WORKSHOP
MANUAL
B 125-250
The descriptions and illustrations given in this publication are not binding. While the basic specifications
as described and illustrated in this manual remain unchanged, PIAGGIO-GILERA reserves the right, at
any time and without being required to update this publication beforehand, to make any changes to
components, parts or accessories, which it considers necessary to improve the product or which are
required for manufacturing or construction reasons.
Not all versions/models shown in this publication are available in all countries. The availability of single
versions should be checked at the official Piaggio sales network.
"©Copyright2007-PIAGGIO&C.S.p.A.Pontedera.Allrightsreserved.Reproductionofthispublication
in whole or in part is prohibited."
PIAGGIO & C. S.p.A. - After-Sales
V.le Rinaldo Piaggio, 23 - 56025 PONTEDERA (Pi)

WORKSHOP MANUAL
B 125-250
This workshop manual has been drawn up by Piaggio & C. Spa to be used by the workshops of Piaggio-
Gilera dealers. This manual is addressed to Piaggio service mechanics who are supposed to have a
basic knowledge of mechanics principles and of vehicle fixing techniques and procedures. Any important
changes made to the vehicles or to specific fixing operations will be promptly reported by updates to this
manual. Nevertheless, no fixing work can be satisfactory if the necessary equipment and tools are
unavailable. It is therefore advisable to read the sections of this manual relating to specific tools, along
with the specific tool catalogue.
N.B. Provides key information to make the procedure easier to understand and carry out.
CAUTION Refers to specific procedures to carry out for preventing damages to the vehicle.
WARNING Refers to specific procedures to carry out to prevent injuries to the repairer.
Personal safety Failure to completely observe these instructions will result in serious risk of personal
injury.
Safeguarding the environment Sectionsmarked with this symbol indicatethe correct use of thevehicle
to prevent damaging the environment.
Vehicle intactness The incomplete or non-observance of these regulations leads to the risk of serious
damage to the vehicle and sometimes even the invalidity of the guarantee.

INDEX OF TOPICS
CHARACTERISTICS CHAR
TOOLING TOOL
MAINTENANCE MAIN
TROUBLESHOOTING TROUBL
ELECTRICAL SYSTEM ELE SYS
ENGINE FROM VEHICLE ENG VE
ENGINE ENG
SUSPENSIONS SUSP
BRAKING SYSTEM BRAK SYS
COOLING SYSTEM COOL SYS
CHASSIS CHAS
PRE-DELIVERY PRE DE
TIME TIME

INDEX OF TOPICS
CHARACTERISTICS CHAR

Rules
This section describes general safety rules for any maintenance operations performed on the vehicle.
Safety rules
- If work can only be done on the vehicle with the engine running, make sure that the premises are well-
ventilated, using special extractors if necessary; never let the engine run in an enclosed area. Exhaust
fumes are toxic.
- The battery electrolyte contains sulphuric acid. Protect your eyes, clothes and skin. Sulphuric acid is
highly corrosive; in the event of contact with your eyes or skin, rinse thoroughly with abundant water
and seek immediate medical attention.
- The battery produces hydrogen, a gas that can be highly explosive. Do not smoke and avoid sparks
or flames near the battery, especially when charging it.
- Fuel is highly flammable and it can be explosive given some conditions. Do not smoke in the working
area, and avoid open flames or sparks.
- Clean the brake pads in a well-ventilated area, directing the jet of compressed air in such a way that
you do not breathe in the dust produced by the wear of the friction material. Even though the latter
contains no asbestos, inhaling dust is harmful.
Maintenance rules
- Use original PIAGGIO spare parts and lubricants recommended by the Manufacturer. Non-original or
non-conforming spares may damage the vehicle.
- Use only the appropriate tools designed for this vehicle.
- Always use new gaskets, sealing rings and split pins upon refitting.
- After removal, clean the components using non-flammable or low flash-point solvents. Lubricate all
the work surfaces except the tapered couplings before refitting.
- After refitting, make sure that all the components have been installed correctly and work properly.
- For removal, overhaul and refit operations use only tools with metric measures. Metric bolts, nuts and
screws are not interchangeable with coupling members with English measurement. Using unsuitable
coupling members and tools may damage the scooter.
- When carrying out maintenance operations on the vehicle that involve the electrical system, make
suretheelectricconnectionshavebeenmadeproperly,particularlythegroundandbatteryconnections.
B 125-250 Characteristics
CHAR - 7

Vehicle identification
VEHICLE IDENTIFICATION (125)
Specification Desc./Quantity
Chassis prefix (125) ZAPM 28400 ÷ 1001
Engine prefix (125) M284M
VEHICLE IDENTIFICATION (250)
Specification Desc./Quantity
Chassis prefix (250) ZAPM 28500 ÷ 1001
Engine prefix (250) M285M
Dimensions and mass
WEIGHTS AND DIMENSIONS
Specification Desc./Quantity
Kerb weight in running order 149 kg
Width (over mirrors) 837 mm
Length 2100 mm
Wheelbase 1455 mm
Saddle height 785 mm
Engine
ENGINE
Specification Desc./Quantity
Engine type Single-cylinder, four-stroke, four-valve, liquid-cooled.
Timing system Single overhead camshaft driven by chain on left side, three-
arm rockers with threaded adjuster.
Bore x stroke (125) 57 x 48,6 mm
Bore x stroke 72 x 60 mm
Cubic capacity (125) 124 cm³
Cubic capacity 244,290 cm3
Compression ratio (125) 12:1
Compression ratio (250) 10,5 - 11,5 : 1
Keihin Carburettor (125 - 250) CVEK-30
Walbro Carburettor (125) WVF 7G* Ø 29
Walbro Carburettor (250) WVF-7S*
Engine idle speed 1650 ± 50 rpm
CO adjustment 3,8 ± 07%
Air filter Sponge-type damped with a 50% Selenia Air Filter Oil - 50%
unleaded petrol mixture
Starter System Electric starter motor
Lubrication Enginelubricationwithlobepump(insidecrankcase)controlled
by a chain with double filter: mesh and paper.
Fuel supply with unleaded petrol; carburettor and vacuum pump.
Max. power (crankshaft) 125cc 11 kw (15 CV) at 9700 rpm
Max. power (crankshaft) 250cc 16,18 Kw (22CV) a 8250 g/min.
Top speed (125) 105 Km/h
Top speed (250) 124 Km/h
*The identification marking may change whenever the carburettor is updated
Characteristics B 125-250
CHAR - 8

Transmission
TRASMISSION
Specification Desc./Quantity
Transmission With automatic expandable pulley variator with torque server,
V belt, self-ventilating automatic centrifugal dry clutch, gear re-
ductionunitandtransmissionhousingwith forced aircirculation
cooling.
Capacities
CAPACITIES
Specification Desc./Quantity
Engine oil (125) ~ 1100 cc
Engine oil (250) ~ 1200 cc
Petrol tank approx. 10 l (including reserve approx. 2.5 l)
Rear hub oil 250 cc
Electrical system
ELECTRICAL COMPONENTS
Specification Desc./Quantity
Ignition type Electronic capacitive discharge ignition (CDI) and variable ad-
vance, with separate HV coil.
variable ignition advance (before T.D.C.) 125 10°±1° at 2000 rpm - 34°±1° at 6000 rpm
Ignition advance (before T.D.C) 10° ± 1 at 2000 rpm.
28° ± 1 at 6500 rpm.
Spark plug (125) NGK CR 8EB
Spark plug (250) CHAMPION RG4HC
Battery 12V-12Ah
Fuses N° 2 15A, N°1 10A, N° 2 7,5A, N° 3 4A
Generator alternating current
BV 125: spark-plug
We inform you that the spark-plug NGKCR8EB has been replaced by the CHAMPION RG4HC starting
with engine number M281M14016 , in order to improve the general performance of the engine. The
distance between the electrodes does not change and is still at 0,7 ÷ 0,8 mm.
Frame and suspensions
FRAME AND SUSPENSIONS
Specification Desc./Quantity
Type of chassis Welded tubular steel chassis with stamped sheet reinforce-
ments.
Front suspension Hydraulic telescopic fork with advanced wheel pin and Ø 35
mm stem
Front fork max. stroke 104 mm
Rear suspension Engine with swinging fork attached to frame by means of an
arm with 2 degrees of freedomPair of double-acting hydraulic
shock absorbers and coaxial springs with preloading adjust-
ment in four positions.
Rear shock absorber max. travel 95.5 mm
B 125-250 Characteristics
CHAR - 9

Brakes
BRAKES
Specification Desc./Quantity
Front brake Disc brake, diameter 260 mm and floating calliper with twin
plungers and hydraulic control (lever on the far right of the han-
dlebar)
Rear brake Disc brake, diameter 260 mm and calliper with two counteract-
ing plungers and hydraulic control (lever on the far left of the
handlebar)
Wheels and tyres
WHEELS AND TYRES
Specification Desc./Quantity
Front wheel rim Light alloy, 3.00 x 16"
Rear wheel rim Light alloy, 3.50 x 16"
Front tyre 110/70-16" M/C 52P Tubeless
Rear tyre 140/70-16" M/C 65P Tubeless
Front wheel tyre pressure (when cold) 2.1 bar
Rear wheel tyre pressure (when cold) 2.3 bar
Rear wheel tyre pressure (with driver and passenger) (when
cold) 2.5 bar
N.B.
CHECK AND ADJUST TYRE PRESSURE WITH TYRES AT AMBIENT TEMPERATURE. REGU-
LATE PRESSURE ACCORDING TO THE WEIGHT OF THE RIDER AND ACCESSORIES
Secondary air
The SAS for 125cc leader engines operates in a similar manner to the SAS for 2T engines.
The differences are the following:
insteadofenteringthroughthemufflerasfor2Tengine,thesecondaryairentersdirectlyinthedischarge
pipe on the head.
Characteristics B 125-250
CHAR - 10

The2Treed valvehasadiaphragm.Theunit,indicated byanarrowinthefigure,hasacut-off connected
to the depression intake on the inlet manifold that cuts the air inlet in deceleration, to avoid explosions
in the muffler.
Air is drawn through the opening «A», goes through the first filter and is channelled through the opening
«B».
Air gets to the second filter «B» through the opening shown in the figure. Now, the filtered air enters
the diaphragm device, and then is channelled to the head.
The air passes through a rigid pipe connected to the head and reaches a discharge joint in order to
supply oxygen to the unburned gases before the catalytic converter, thus favouring an improved reac-
tion of the catalytic converter.
B 125-250 Characteristics
CHAR - 11

The working principle of the SAS for Quasar 250
cc Euro 2 engines is entirely similar to the SAS
employed on 2-stroke engines. The main differen-
ces are the following:
Secondary air enters directly into the exhaust duct
on the cylinder head, instead of entering through
the exhaust pipe as in two-stroke engines.
The reed valve found on 2-stroke engines is here
replaced by a membrane.
Unit «A», shown in the figure, is provided with a
cut-off connected to the vacuum inlet on the intake
manifold to shut air inlet during deceleration, so to
prevent detonations in the silencer. Air is sucked
in through hole «B» and flows inside the duct into
air-box «C» where it is filtered by filtering element
«D».
The filtered air now enters membrane device «A»,
through duct «E» and is then guided towards the
head.
Flowing through pipe «F», flanged to the head,
secondary air reaches the exhaust duct thus pro-
viding oxygen addition to the unburnt gases just
before they enter the catalytic converter.
The efficiency of the catalyzing process is there-
fore increased.
Characteristics B 125-250
CHAR - 12

Carburettor
125cc Version
Kehin
KEIHIN CARBURETTOR 125
Specification Desc./Quantity
Depression type CVEK30
Printing on the body CVK
Device CUT-OFF Not present
Max. jet 105
Minimum jet 35
Max. air jet 70
Minimum air jet 130
Minimum mixture set screw initial opening 2 ± ¼
Conical pin Ø 2,450
Diffuser nozzle Ø 2.8
Starter air jet Ø 1,5
Starter jet 42
Starter device resistance ~ 20 Ω
Venturi choke Ø 29
Throttle valve Ø 30,5
Choke maximum cone Ø 47
Walbro
WALBRO CARBURETTOR
Specification Desc./Quantity
Type to depression WVF-7G*
Body stamping 7GO
Device CUT-OFF Not present
Max. jet 108
Minimum jet 36
Max. air jet 115
Minimum air jet 100
Throttle valve spring 100 g
Minimum mixture set screw initial opening 2 5/8 ± 1/2
Tapered pin stamping 51C
Tapered pin notches from above 2
Diffuser nozzle Ø 2.7
Gasoline inlet hole Ø 1.5
Starter air jet 200
B 125-250 Characteristics
CHAR - 13

Specification Desc./Quantity
Starter diffuser jet 130
Starter jet 50
Starter pin diameter Ø 1,78
Starter device resistance ~ 40 Ω
Venturi diffuser Ø 29 (30.3x27)
Throttle valve Ø 33
Choke maximum cone Ø 48,0
250cc Version
Keihin
KEIHIN CARBURETTOR 250
Specification Desc./Quantity
Depression type CVEK30
Printing on the body CVK
CUT-OFF device Present
Max jet 100
Minimum jet 38
Max. air jet 70
Minimum air jet 115
Idle mixture adjustment screw initial opening 2½ ± ¼
Conical pin Ø 2,530
Diffuser nozzle Ø 2.8
Starter air jet Ø 1,5
Starter jet 42
Starter device resistance ~ 20 Ω
Venturi choke Ø 29
Throttle valve Ø 30,5
Choke maximum cone Ø 47
Walbro
WALBRO CARBURETTOR250
Specification Desc./Quantity
Depression type WVF-7S*
Printing on the body 7S
CUT-OFF device Present
Max. jet 118
Minimum jet 34
Max. air jet 150
Minimum air jet 31
Throttle valve spring 120 g
Idle mixture adjustment screw initial opening 3 ± ½
Conical pin 465
Conical pin top notches 3
Diffuser nozzle Ø 2.7
Gasoline inlet hole Ø 1.5
Starter air jet 200
Starter diffuser jet 130
Starter jet 50
Starter pin diameter Ø 1,78
Starter device resistance ~ 40 Ω
Venturi diffuser Ø 29 (30.3x27)
Throttle valve Ø 33
Choke maximum cone Ø 48,0
*The identification letter can vary every time the carburettor is updated.
Characteristics B 125-250
CHAR - 14

Tightening Torques
STEERING
Name Torque in Nm
Upper steering ring nut 30 ÷ 36
Steering lower ring nut 10 ÷ 13 then loosen by 90°
Handlebar fixing screw (*) 45 ÷ 50
Fixing screws for handlebar control assembly U-bolts 7 ÷ 10
FRAME ASSEMBLY
Name Torque in Nm
Engine-swinging arm bolt 64 - 72
Chassis-swinging arm pin nut 64 - 72
Spacer locking threaded bushing 13 ÷ 17
Spacer locking threaded bushing lock nut 90 ÷ 110
Frame arm-engine arm coupling pin nut 33 ÷ 41
Bolt of the Silent block support plate 64 - 72
Centre stand bolt 25 ÷ 30
Side stand fixing bolt 35 ÷ 40
Side stand switch screw 5 ÷ 7
FRONT SUSPENSION
Name Torque in Nm
Fixing screw for pumping elements to lower fork plate 20 ÷ 25
Front wheel axle 45 ÷ 50
Fork leg screw 6 ÷ 7
front mudguard to plate fixing screw 4.5 ÷ 7
Fixing screw for mudguard plate to fork 9 ÷ 11
FRONT BRAKE
Name Torque in Nm
Brake fluid pump-hose fitting 16 ÷ 20
Brake fluid pipe-calliper fitting 16 ÷ 20
Calliper to fork tightening screw 20 ÷ 25
Disc tightening screw (°) 5 - 6
Oil bleed screw 12 - 16
Pad fastening pin 19.6 ÷ 24.5
REAR SUSPENSION
Name Torque in Nm
Left lower shock absorber support bolt 20 ÷ 25
Upper shock absorber clamp 33 ÷ 41
Lower shock absorber clamp 33 ÷ 41
Rear wheel axle 104 ÷ 126
Fixing screw for wheel rim to hub 34 ÷ 38
Muffler support arm to engine screws (*) 20 ÷ 25
REAR BRAKE
Name Torque in Nm
Brake fluid pump-hose fitting 16 ÷ 20
Brake fluid pipe-calliper fitting 16 ÷ 20
Flexible/ rigid oil pipe coupling 9 ÷ 11
Rear disc tightening bolt 11 ÷ 13
Oil bleed screw 12 - 16
Screw tightening calliper to the support 20 ÷ 25
Screw fixing rear brake calliper support to engine 20 ÷ 25
Pad fastening pin 20 ÷ 25
B 125-250 Characteristics
CHAR - 15

MUFFLER
Name Torque in Nm
Screw fixing manifold to muffler 15.5 ÷ 18.5
Muffler heat guard fixing screw 5 - 6
Exhaust fumes inlet screw 22 ÷ 26
Screw fixing muffler support arm to crankcase 33 ÷ 41
Nuts fixing muffler to support arm 27 ÷ 30
Nut fixing muffler to cylinder head 16 ÷ 18
LUBRICATION
Name Torque in Nm
Hub oil drainage plug 15 ÷ 17
Oil filter on crankcase fitting 27 ÷ 33
Engine oil drainage plug/mesh filter 24 ÷ 30
Oil filter 4 ÷ 6
Oil pump cover screws 0.7 ÷ 0.9
Screws fixing oil pump to crankcase 5 - 6
Oil pump control crown screw 10 ÷ 14
Oil pump cover plate screws 4 ÷ 6
Oil sump screws 10 ÷ 14
Minimum oil pressure sensor 12 ÷ 14
CYLINDER HEAD
Name Torque in Nm
Spark plug 12 ÷ 14
Nuts fixing head to cylinder (1) (^) 9 ÷ 11 + 180°
Head fixing side screws 11 ÷ 12
Starter ground screw 7 ÷ 8.5
M5 side screw fastening washers on cam shaft (125 cc) 7 ÷ 8,5
Tappet set screw lock nut 6 ÷ 8
Timing chain tensioner slider screw 10 ÷ 14
Starter ground support screw 11 ÷ 15
M6 central screw fastening washers on cam shaft (125 cc) 11 ÷ 15
Timing chain tensioner support screw 11 ÷ 13
Timing chain tensioner central screw 5 - 6
Camshaft retention plate screw 4 ÷ 6
TRANSMISSION
Name Torque in Nm
Belt support roller screw 11 ÷ 13
Clutch unit nut on driven pulley 45 ÷ 50
Drive pulley nut 75 ÷ 83
Transmission cover screws 11 ÷ 13 Nm
Driven pulley shaft nut 54 ÷ 60
Rear hub cover screws 24 ÷ 27
FLYWHEEL
Name Torque in Nm
Flywheel cover fixing screws 5 - 6
Stator assembly screws (°) 3 ÷ 4
Flywheel nut (125) 52 ÷ 58
Flywheel nut (250) 94 ÷ 102
Pick-Up clamping screws 3 ÷ 4
Screw fixing freewheel to flywheel 13 ÷ 15
CRANKCASE AND CRANKSHAFT
Name Torque in Nm
Internal engine crankcase bulkhead (transmission-side half
shaft) screws 4 ÷ 6
Engine-crankcase coupling screws 11 ÷ 13
Starter motor screws 11 ÷ 13
Crankcase timing system cover screws (°) 3.5 ÷ 4.5
Characteristics B 125-250
CHAR - 16

COOLING
Name Torque in Nm
Water pump rotor cover 3 ÷ 4
Screws for water pump rotor driving link 3 ÷ 4
Thermostat cover screws 3 ÷ 4
Bleed screw: 3
(°) Apply LOCTITE 242 medium-strength threadlock
(*) The two screws must be tightened to the prescribed torque after having done so with the rear wheel
axle nut. Safety locks: see "Pre-delivery operations".
(^) Fasten the nuts in two crossed passes.
(1) Before fitting the nuts lubricate them with engine oil
Overhaul data
Assembly clearances
Cylinder - piston assy.
ENGINE 125 COUPLING CATEGORIES
Name Initials Cylinder Piston Play on fitting
Cylinder A 56.997 ÷ 57.004 56.945 ÷ 56.952 0.045 - 0.059
Cylinder B 57.004 ÷ 57.011 56.952 ÷ 56.959 0.045 - 0.059
Piston C 57.011 ÷ 57.018 56.959 ÷ 56.966 0.045 - 0.059
Piston D 57.018 ÷ 57.025 56.966 ÷ 56.973 0.045 - 0.059
Cylinder 1st Oversize A1 57.197 ÷ 57.204 57.145 ÷ 57.152 0.045 - 0.059
Cylinder 1st Oversize B 1 57.204 ÷ 57.211 57.152 ÷ 57.159 0.045 - 0.059
Piston 1st Oversize C 1 57.211 ÷ 57.218 57.159 ÷ 57.166 0.045 - 0.059
Piston 1st Oversize D 1 57.218 ÷ 57.225 57.166 ÷ 57.173 0.045 - 0.059
B 125-250 Characteristics
CHAR - 17

Name Initials Cylinder Piston Play on fitting
Cylinder 2nd Oversize A2 57.397 ÷ 57.404 57.345 ÷ 57.352 0.045 - 0.059
Cylinder 2nd Oversize B 2 57.404 ÷ 57.411 57.352 ÷ 57.359 0.045 - 0.059
Piston 2nd Oversize C 2 57.411 ÷ 57.418 57.359 ÷ 57.366 0.045 - 0.059
Piston 2nd Oversize D 2 57.418 ÷ 57.425 57.366 ÷ 57.373 0.045 - 0.059
Cylinder 3rd Oversize A 3 57.597 ÷ 57.604 57.545 ÷ 57.552 0.045 - 0.059
Cylinder 3rd Oversize B 3 57.604 ÷ 57.611 57.552 ÷ 57.559 0.045 - 0.059
Piston 3rd Oversize C 3 57.611 ÷ 57.618 57.559 ÷ 57.566 0.045 - 0.059
Piston 3rd Oversize D 3 57.618 ÷ 57.625 57.566 ÷ 57.573 0.045 - 0.059
COUPLING CATEGORIES ENGINE 250
Name Initials Cylinder Piston Play on fitting
Cylinder / piston A 71.990 ÷ 71.997 71.953 ÷ 71.960 0.030 - 0.044
Cylinder / piston B 71.997 ÷ 72.004 71.960 ÷ 71.967 0.030 - 0.044
Cylinder / piston C 72.004 ÷ 72.011 71.967 ÷ 71.974 0.030 - 0.044
Cylinder / piston D 72.011 ÷ 72.018 71.974 ÷ 71.981 0.030 - 0.044
Piston rings
UPRATING TABLE MOTOR 125
Name Description Dimensions Initials Quantity
Compression ring 57 x 1 A 0.15 ÷ 0.30
Characteristics B 125-250
CHAR - 18

Name Description Dimensions Initials Quantity
Oil scraper ring 57 x 1 A 0.10 ÷ 0.30
Oil scraper ring 57 x 2.5 A 0.15 ÷ 0.35
OVERSIZES MOTOR 250
Name Description Dimensions Initials Quantity
Compression ring 72 x 1.5 A 0.15 ÷ 0.30
Oil scraper ring 72 x 1 A 0.20 ÷ 0.40
Oil scraper ring 72 x 2.5 A 0.20 ÷ 0.40
Crankcase - crankshaft - connecting rod
CRANKCASE - CRANKSHAFT- CRANKSHAFT HALF-BEARINGS
Name Description Dimensions Initials Quantity
Crankshaft half-bearing Type A - red 1.970 ÷ 1.973
Crankshaft half-bearing Category B - blue 1.973 ÷ 1.976
Crankshaft half-bearing Type C - yellow 1.976 ÷ 1.979
Crankshaft class 1 -
Crankcase class 1 C - C
Crankshaft class 1 -
Crankcase class 2 B - B
Crankshaft class 2 -
Crankcase class 1 B - B
Crankshaft class 2 -
Crankcase class 2 A - A
Crankshaft Category 1 28.998 ÷ 29.004
Crankshaft Class 2 29.004 ÷ 29.010
Crankcase Category 1 32.959 ÷ 32.965
Crankcase Class 2 32.953 ÷ 32.959
Fitting clearance
Crankshaft/ crankcase axial clearance 0.15 - 0.40 mm (when cold)
CRANKSHAFT/ CRANKCASE AXIAL CLEARANCE
Name Description Dimensions Initials Quantity
Half-shaft, transmission
side 16.6 +0-0.05 A D = 0.20 - 0.50
B 125-250 Characteristics
CHAR - 19

Name Description Dimensions Initials Quantity
Flywheel-side half-shaft 16.6 +0-0.05 B D = 0.20 - 0.50
Connecting rod 18 -0.10 -0.15 C D = 0.20 - 0.50
Spacer tool 51.4 +0.05 E D = 0.20 - 0.50
Slot packing system
Characteristic
Compression ratio, 125 models
Cr: 11.50 ÷ 13:1
Measurement«A»tobe taken,isavalueof pistonprotrusion.Itindicatesby howmuch theplaneformed
by the piston crown protrudes from the plane formed by the upper part of the cylinder. The further the
piston protrudes from the cylinder, the thicker the base gasket to be used (to restore the compression
ratio) and vice versa.
N.B.
NO GASKETS AND SEALS SHOULD BE ASSEMBLED BETWEEN THE CRANKCASE AND CYL-
INDER AND THE DIAL GAUGE EQUIPPED WITH SUPPORT SHOULD BE SET TO ZERO FOR
MEASUREMENT «A» TO BE TAKEN WITH THE PISTON AT TOP DEAD CENTRE POSITION AND
ON A RECTIFIED PLANE.
VERSION 125 WITH FIBRE HEAD GASKET (1.1)
Name Measure A Thickness
Shimming 125 - Cylinder 67 - Head gas-
ket 1.1 - Base gasket 0.4 2.20 ÷ 2.45 0.4 ± 0.05
Shimming 125 - Cylinder 67 - Head gas-
ket 1.1 - Base gasket 0.6 2.45 ÷ 2.70 0.6 ± 0.05
Characteristic
Compression ratio, 125 models
Characteristics B 125-250
CHAR - 20