Gilera Nexus 500SP Mk2 

Gilera Nexus 500SP Mk2 
WORKSHOP MANUAL
633721 - 633728
Nexus 500 euro 3
WORKSHOP
MANUAL
Nexus 500 euro 3
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 shown in this publication are available in all Countries. The availability of single versions
should be checked at the official Piaggio sales network.
"© Copyright 2005 - PIAGGIO & C. S.p.A. Pontedera. All rights reserved. Reproduction of this publication
in whole or in part is prohibited."
PIAGGIO & C. S.p.A. - Q.C.S./After sales V.le Rinaldo Piaggio, 23 - 56025 PONTEDERA (Pi)
www.piaggio.com
WORKSHOP MANUAL
Nexus 500 euro 3
This workshop manual has been drawn up by Piaggio & C. Spa to be used by the workshops of PiaggioGilera dealers. This manual is addressed to Piaggio service mechanics who are supposed to have a
basic knowledge of mechanics principles and of scooter mounting techniques and procedures. Any
important changes made to the scooters or to specific mounting operations will be promptly reported by
updates to this manual. Nevertheless, no mounting 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 special
tools, along with the special 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 Sections marked with this symbol indicate the correct use of the vehicle
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
ELECTRICAL SYSTEM
ELE SYS
ENGINE FROM VEHICLE
ENG VE
ENGINE
ENG
INJECTION
INJEC
SUSPENSIONS
SUSP
BRAKING SYSTEM
BRAK SYS
COOLING SYSTEM
COOL SYS
CHASSIS
PRE-DELIVERY
TIME
CHAS
PRE DE
TIME
INDEX OF TOPICS
CHARACTERISTICS
CHAR
Characteristics
Nexus 500 euro 3
This section describes the general specifications of the vehicle.
Rules
This section describes general safety rules for any maintenance operations performed on the scooter.
Safety rules
•
Should it be necessary to keep the engine running while servicing, make sure that the area
or room is well ventilated, and use special exhaust fans, if required. 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 in some conditions it can be explosive. Do not smoke in the
working area, and avoid open flames or sparks.
•
Clean the brake pads in a well ventilated environment, directing the compressed air jet so
as to not inhale the dust produced by the wear of the friction material. Even though the latter
contains no asbestos, dust inhalation is harmful.
Maintenance rules
•
Use original PIAGGIO spare parts and lubricants recommended by the Manufacturer. Nonoriginal or non-conforming spares may damage the vehicle.
•
Use only the special tools designed for this scooter.
•
Always use new gaskets, sealing rings and split pins upon reassembly.
•
After removal, clean the components using non-flammable or low fire-point solvent. Lubricate all the work surfaces except the tapered couplings before reassembly.
•
After reassembly, check that all components have been installed properly and that they are
in good working order.
•
For removal, overhaul and reassembly operations use only tools provided 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.
•
Should any interventions to the scooter electrical system be required, check that the electrical connections - especially earth and battery connections - have been implemented
properly.
CHAR - 2
Nexus 500 euro 3
Characteristics
Vehicle identification
Characteristic
Engine prefix:
M351M
Chassis prefix:
ZAPM35200
Dimensions and mass
WEIGHT
Specification
Dry weight
Width
Length
Wheel base
Saddle height
Height
Desc./Quantity
199 kg
765 mm
2090 mm
1515 mm
780 mm
1045 mm
CHAR - 3
Nexus 500 euro 3
Characteristics
Engine
ENGINE
Specification
Engine
Bore
Stroke
Cubic capacity
Compression ratio
Timing system
Valve clearance: intake:
Valve clearance: exhaust
Valve clearance adjustment
Engine idle speed
Air filter
CO % value (measured at the intake manifold)
Starting system
Lubrication
Lubrication pressure
Minimum allowed (at 100° C)
Fuel supply
Max. power (shaft)
Max. torque (shaft)
Cooling system
Desc./Quantity
single-cylinder four stroke
92 mm
69 mm
460 cm³
10.5: 1
Single overhead camshaft with integrated tone
wheel, control from flywheel side chain, 4 valves
and automatic start-up valve lifting device.
0.15 mm (when cold)
0.15 mm (when cold)
By threaded adjuster on the rockers
1500 ± 50 rpm
sponge, impregnated with mixture (50% petrol and
50% oil)
1 ÷ 1.5%
Electric starter system with freewheel.
By trochoidal pump (inside the crankcase), pressure adjustment by-pass and oil filter.
4 bar
0.8 bar
Electronic injection system with electric fuel pump,
Ø 38 mm throttle body and single injector.
29 kW (39 CV) at 7250 rpm
40 N·m (4 kgm) at 5500 rpm
Fluid circulation through a motor-driven pump, 3way thermostat and electric fan.
Transmission
TRANSMISSIONS
Specification
Transmission
Desc./Quantity
With automatic expandable pulley variator with torque server, V belt, automatic clutch, gear reduction unit and transmission housing with forced air
circulation cooling.
Capacities
CAPACITY
Specification
Engine oil (dry)
Engine oil (at oil and filter change)
Fuel tank (including reserve approx. 2 litres)
Rear hub
Cooling system
Front fork
CHAR - 4
Desc./Quantity
~ 1.7 litres
approx. 1.5 litres
approx. 14.5 litres
approx. 250 cc.
approx. 1.8 litres
approx. 242 ± 3 cc (in each fork leg)
Nexus 500 euro 3
Characteristics
Electrical system
ELECTRICAL SYSTEM
Specification
Electronic ignition
Spark plug
Spark plug
Battery
Generator
Desc./Quantity
inductive, high efficiency integrated with the injection system, with variable timing and separate HV
coil.
NGK CR7EKB
CHAMPION RG6YC
Dry-cell lead-acid battery, 12V-14Ah
Three-phase alternating current
Frame and suspensions
CHASSIS AND SUSPENSIONS
Specification
Chassis
Front suspension
Max. front fork travel
Rear suspension
Desc./Quantity
Welded tubular steel chassis with stamped sheet
reinforcements
Hydraulic telescopic fork with diameter 41 mm
stems
104 mm
Type "Power drive": Shock absorber (with doubleacting helicoidal spring and adjustment of the
spring preload in 7 positions) mounted in horizontal position, connected to a connecting rod pivoted
to a strut with variable length.
By varying the length of the strut it is possible to
modify the geometry and balance of the rear axle
(15 positions).
The motor has a fixed connection to the frame by
means of a shaft (direct link).
Brakes
BRAKES
Specification
Front brakes
Rear brakes
Desc./Quantity
Twin discs of stainless steel, dia. 260 mm, with
floating calliper and twin 28 mm diameter plungers
(Brembo) at front right and twin 26 mm diameter
plungers (Brembo) at front left.
Disc of stainless steel, dia. 240 mm, with fixed calliper and two opposed 34 mm diameter plungers
Wheels and tyres
WHEELS AND TYRES
Specification
Rims in light alloy: Front
Desc./Quantity
3.50 x 15"
CHAR - 5
Nexus 500 euro 3
Characteristics
Specification
Rims in light alloy: Rear
Rear tyres
Front tyres
Tyre pressure (cold) front
Tyre pressure (cold) rear
Desc./Quantity
4.50 x 14"
Bridgestone 160/60-R14" Tubeless 65H
Bridgestone 120/70-R15" Tubeless 56H
2.1 bar
2.3 bar (2.5 bar with passenger)
N.B.
CHECK AND ADJUST TYRE PRESSURE WITH TYRES AT AMBIENT TEMPERATURE. ADJUST
PRESSURE ACCORDING TO THE WEIGHT OF THE RIDER AND ACCESSORIES.
CAUTION
IT IS MANDATORY TO ADOPT EXCLUSIVELY "S" CLASS TYRES, WHICH GUARANTEE CORRECT VEHICLE PERFORMANCE AT THE DIFFERENT SCOOTER SPEEDS. USING ANY OTHER
TYRE MAY RESULT IN VEHICLE INSTABILITY. IT IS ADVISABLE TO USE TYRE TYPES RECOMMENDED BY PIAGGIO.
Tightening Torques
FRAME
Name
Electric pump locking ring nut
Torque in Nm
20
BRAKE SYSTEM
Name
Brake calliper coupling
Front brake disc mounting
Rear brake disc mounting
Front brake calliper mounting on fork
Rear calliper support clamp to crankcase
Pipe joint / brake calliper
Circuit bleed calliper fitting
Plastic protection retaining screw
Coupling for oil on the integral braking system
pump
Coupling on the integral braking system device
(from the pump)
Front brake calliper - integral braking system device coupling
Rear brake calliper - integral braking system device coupling
Torque in Nm
20 - 24
5÷6•
11 ÷ 13
20 ÷ 25
20 ÷ 25
20 ÷ 25
12 - 16
5-6
16 ÷ 20
20 ÷ 25
20 ÷ 25
20 ÷ 25
• Locking with Loctite threadlock medium 243
FRONT SUSPENSION
Name
Front wheel shaft
Holding torque of lower ring nut
Fork stem mounting to the plate
Lower steering ring nut
Upper steering ring nut
Stem upper cap
Screw securing handlebar to steering tube
CHAR - 6
Torque in Nm
45 ÷ 50
20 ÷ 25
20 ÷ 25
10 - 13 **
36 - 39
35 - 55
45 - 50
Nexus 500 euro 3
Characteristics
Name
Pumping element fixing screw
Safety screw on fork leg
Wheel fastening screws
Torque in Nm
25 - 35
6÷7
33 - 37
* Tighten and loosen completely. ** Tighten and loosen by 90°
REAR SUSPENSION
Name
Engine - chassis fixing pin
Central stand retainers
Muffler heat guard retainers
Side stand clamp
Rear wheel axle
Connection of rear shock absorber to support connecting rod
Rear shock absorber retainer to the chassis
Upper strut connection
Clamping of connection rod supporting strut and
shock absorber to frame
Clamping of rear strut support to hub cover
Lower strut clamping
Rear strut support clamping to crankcase
Assembly plate mounting on strut support
Torque in Nm
100 - 120
25 - 30
6-8
15 ÷ 20
104 ÷ 126
38 - 46
38 - 46
56 - 70
73 - 80
20 - 25
30 - 35
11 - 13
11 - 13
• Locking with Loctite threadlock medium 243
ENGINE ASSEMBLY
Name
Starter motor screws
Torque in Nm
11 ÷ 13
THERMAL UNIT AND TIMING SYSTEM
Name
Spark plug
Head fixing stud bolts:
Head fixing nuts
Exhaust / intake head fixing nuts:
Head lubrication control jet
coolant temperature sensor:
Lambda probe on exhaust manifold
injector fixing screw
Counterweight screw
Tensioner sliding block fixing screw:
Rpm timing sensor fixing screw:
Valve lifter mass stop bell fixing screws:
Inlet manifold screws
Tappet cover fixing screws:
Throttle body fixing screws
Head fixing screws
Camshaft retaining bracket screws:
Tightener screw:
Tightener fastening screws:
Torque in Nm
12 ÷ 14
***
10 - 12
10 - 12
5-7
10 - 12
10 - 12
3÷4
7 ÷ 8.5
10 - 14
3-4
30 - 35
11 ÷ 13
7-9
11 ÷ 13
10 - 12
4÷6
5-6
11 ÷ 13
*** Apply a preliminary torque of 7 N·m in a crossed sequence. - Tighten by 90° in a crossed sequence. - Tighten again by 90°
in a crossed sequence.
CHAR - 7
Nexus 500 euro 3
Characteristics
CRANKCASE AND CRANKSHAFT
Name
Countershaft fixing nut
Engine oil filter
Engine oil drainage plug
Engine-crankcase coupling screws
Oil pump screws
Gear mounting on crankshaft screws
Bulkhead screws for oil pump housing cover
Torque in Nm
25 - 29
12 - 16
24 ÷ 30
11 ÷ 13
5-6
10 -12
8 - 10
FINAL REDUCTION
Name
Rear hub cover screws
Torque in Nm
24 ÷ 27
TRANSMISSION COVER
Name
Driven pulley nut
Drive pulley nut
Anti-vibration roller screw
M8 retainers for transmission cover
M6 retainer
Anti-vibration roller retainer
Clutch ring nut
Air conveyor screws
Water pump cover screws
Outside transmission cover screws
Flywheel cover screws
Torque in Nm
92 - 100
160 - 175
16.7 - 19.6
23 - 26
11 ÷ 13
17 - 19
65 - 75
11 ÷ 12
3÷4
7÷9
11 - 13
FLYWHEEL COVER
Name
Chain guide sliding block retain plate fastening
screws
Flywheel fixing nut
Stator retainers
Blow-by recovery duct fixing screws
Screw fixing freewheel to flywheel
Stator cable harness guide bracket screws
Supporting screws with bulkhead
Minimum oil pressure sensor
Water pump impeller
Torque in Nm
3÷4
115 - 125
8 - 10
3-4
13 ÷ 15
3-4
0.3 - 0.4
12 ÷ 14
4÷5
LUBRICATION
Name
Oil pump cover screws
Screws fixing oil pump to the crankcase
See also
Refitting
Refitting
Fuel tank
Overhaul
CHAR - 8
Torque in Nm
0.7 ÷ 0.9
5-6
Nexus 500 euro 3
Characteristics
Overhaul data
This section provides the main information for scooter servicing.
Assembly clearances
Cylinder - piston assy.
(Values in mm)
HEIGHT AT WHICH THE DIAMETER SHOULD BE MEASURED
Specification
A:
B:
Desc./Quantity
10 mm
43 mm
CATEGORIES OF COUPLING
Name
Cylinder Piston
Cylinder Piston
Cylinder Piston
Cylinder Piston
Initials
A
B
C
D
Cylinder
91.990 - 91.997
91.997 - 92.004
92.004 - 92.011
92.011 - 92.018
Piston
91.954 - 91.961
91.961 - 91.968
91.968 - 91.975
91.975 - 91.982
Play on fitting
0.029 - 0.043
0.029 - 0.043
0.029 - 0.043
0.029 - 0.043
N.B.
THE PISTON MUST BE INSTALLED WITH THE ARROW FACING TOWARDS THE EXHAUST SIDE,
THE PISTON RINGS MUST BE INSTALLED WITH THE WORD «TOP» OR THE STAMPED MARK
FACING UPWARDS.
Piston rings
CHAR - 9
Nexus 500 euro 3
Characteristics
* Fit rings «2» and «3» with the word «TOP» facing upwards.
** Position the openings in the rings as shown here.
*** Value «A» of sealing ring inside the cylinder
**** Ring opening
SEALING RINGS
Name
1st Compression
ring
Middle piston ring
Oil scraper ring
Initials
A
Cylinder
0.15 ÷ 0.35
Piston
0.5
Play on fitting
</>
A
A
0.25 ÷ 0.50
0.25 ÷ 0.50
0.65
0.65
</>
</>
Crankcase - crankshaft - connecting rod
Crankcase / countershaft coupling
Besides considering it should match the crankshaft, the crankcase is chosen according to the centre
to centre distance between the seat of the crankshaft and that of the contra-rotating shaft.
Both the centre to centre distance and the pair of gears driving the contra-rotating shaft are divided into
two types (A and B) to be matched (A with A and B with B).
This selection is useful to keep the difference between the working distance of the gears and their
distance without clearance at a given value in order to avoid abnormal noise.
TYPE A
Specification
Centre to centre distance of the gears without
clearance
Centre to centre distance on the crankcase
Desc./Quantity
76.937 ÷ 76.867
77.022 ÷ 76.992
TYPE B
Specification
Centre to centre distance of the gears without
clearance
Centre to centre distance on the crankcase
Desc./Quantity
76.907 ÷ 76.837
76.992 ÷ 76.962
The gears with centre to centre distance without clearance between 76.867 and 76.907 are considered
universal and can be fitted to either crankcase type.
Either the pair of gears or the crankcase is identified with the letter referring to the type (on the crankcase, this mark is found at the cylinder mouth, flywheel side).
CHAR - 10
Nexus 500 euro 3
Characteristics
Diameter of crankshaft bearings.
Measure the capacity on both axes x-y.
CRANKSHAFT
Specification
Cat. 1
Cat. 2
Desc./Quantity
Standard diameter: 40.010 ÷ 40.016
Standard diameter: 40.016 ÷ 40.022
Crankshaft alignment
Specific tooling
020335Y Magnetic support for dial gauge
MAX. ADMISSIBLE DISPLACEMENT
Specification
A=
B=
C=
D=
Desc./Quantity
0.15 mm
0.010 mm
0.010 mm
0.10 mm
CHAR - 11
Nexus 500 euro 3
Characteristics
AXIAL CLEARANCE BETWEEN CRANKSHAFT AND CONNECTING ROD
Name
Transmission-side
shoulder
Transmission-side
half-shaft
Connecting rod
Flywheel-side
shoulder
Flywheel-side halfshaft
Complete drive
shaft
Description
Characteristic
Drive shaft / crankcase axial clearance:
0.1 - 0.5 mm (when cold)
CHAR - 12
Dimensions
0.8 ± 0.025
Initials
A
Quantity
D= 0.20 - 0.40
19.6 + 0.050
B
D= 0.20 - 0.40
22 0.10-0.15
13 ± 0.025
C
F
D= 0.20 - 0.40
D= 0.20 - 0.40
19.6 +0.050
E
D= 0.20 - 0.40
63.5+0.1-0.05
G
D= 0.20 - 0.40
Nexus 500 euro 3
Characteristics
Slot packing system
Shimming system for limiting the compression ratio Rc = 10.5 : 1
DISTANCE «A» IS A PROTRUSION OR RECESS VALUE OF THE PISTON CROWN WITH
RESPECT TO THE CYLINDER PLANE.
DISTANCE «A» HELPS DETERMINE THE
THICKNESS OF GASKET «B» THAT HAS TO
BE FITTED TO THE CYLINDER HEAD IN ORDER TO RESTORE COMPRESSION RATIO.
BASE GASKET «B» MUST BE THICKER THE
MORE THE PLANE FORMED BY THE PISTON
TOP PROTRUDES FROM THE PLANE
FORMED BY THE CYLINDER HEAD. ON THE
OTHER HAND, THE MORE THE PISTON TOP IS
RECESSED INTO THE CYLINDER TOP PLANE,
THE SMALLER THE GASKET THICKNESS.
BASE GASKET THICKNESS
Name
«A» MEASURE TAKEN
«A» MEASURE TAKEN
«A» MEASURE TAKEN
Measure A
- 0.185 - - 0.10
- 0.10 - + 0.10
+ 0.10 ÷ + 0.185
Thickness
0.4 ± 0.05
0.6 ± 0.05
0.8 ± 0.05
N.B.
VALUES INDICATED WITH «-» REFER TO PISTON CROWN RECESSES WITH RESPECT TO THE
CYLINDER PLANE.
N.B.
DISTANCE «A» MUST BE MEASURED WITHOUT ANY GASKET FITTED AT «B»
Products
PRODUCTS
Product
AGIP ROTRA 80W-90
AGIP FILTER OIL
AGIP CITY HI TEC 4T
AGIP BRAKE 4
SPECIAL AGIP PERMANENT
fluid
AGIP EXTRA POLISH
AGIP GP 330
AGIP CITY TEC 2T
Description
Rear hub oil
Specifications
SAE 80W/90 Oil that exceeds the
requirements of API GL3 specifications
Oil for air filter sponge
Mineral oil with specific additives
for increased adhesiveness
Engine oil
SAE 5W-40, API SL, ACEA A3,
JASO MA Synthetic oil
Brake fluid
FMVSS DOT 4 Synthetic fluid
coolant
Monoethylene glycol-based antifreeze fluid, CUNA NC 956-16
Muffler cleaning paste
special product for cleaning and
polishing stainless steel muffler
Grease for brake levers, throttle White calcium complex soapbased spray grease with NLGI 2;
ISO-L-XBCIB2
Mixer oil
synthetic oil for 2-stroke engines:
JASO FC, ISO-L-EGD
CHAR - 13
Characteristics
CHAR - 14
Nexus 500 euro 3
INDEX OF TOPICS
TOOLING
TOOL
Nexus 500 euro 3
Tooling
GOOD
TOOL - 2
SPECIAL TOOLS
Stores code
001330Y
Description
Tool for fitting steering seats
001467Y002
Driver for OD 73 mm bearing
001467Y006
Pliers to extract 20 mm bearings
001467Y007
Driver for OD 54 mm bearing
001467Y008
Pliers to extract 17 mm ø bearings
001467Y014
Pliers to extract ø 15-mm bearings
Nexus 500 euro 3
Tooling
Stores code
001467Y031
Description
Bell
001467Y034
Extraction pliers for ø 15 mm
bearings
001467Y035
Belle for OD 47-mm bearings
002465Y
Pliers for circlips
006029Y
Punch for fitting fifth wheel seat
on steering tube
020004Y
Punch for removing fifth wheels
from headstock
TOOL - 3
Nexus 500 euro 3
Tooling
TOOL - 4
Stores code
020055Y
Description
Wrench for steering tube ring nut
020150Y
Air heater support
020151Y
Air heater
020193Y
Oil pressure gauge
020201Y
020262Y
Spacer bushing driving tube
Crankcase splitting strip
020306Y
Punch for assembling valve seal
rings
Nexus 500 euro 3
Tooling
Stores code
020329Y
Description
MityVac vacuum-operated pump
020330Y
Stroboscopic light for timing control
020331Y
Digital multimeter
020333Y
Single battery charger
020334Y
Multiple battery charger
TOOL - 5
Nexus 500 euro 3
Tooling
TOOL - 6
Stores code
020335Y
Description
Magnetic support for dial gauge
020357Y
020358Y
020359Y
32 x 35 mm adaptor
37x40-mm adaptor
42x47-mm adaptor
020360Y
Adaptor 52 x 55 mm
020364Y
25-mm guide
020376Y
Adaptor handle
020382Y012
bush (valve removing tool)
Nexus 500 euro 3
Tooling
Stores code
020412Y
Description
15 mm guide
020424Y
Driven pulley roller casing fitting
punch
020431Y
Valve oil seal extractor
020434Y
Oil pressure control fitting
020439Y
17 mm guide
TOOL - 7
Nexus 500 euro 3
Tooling
TOOL - 8
Stores code
020444Y
Description
Tool for fitting/ removing the driven pulley clutch
020456Y
Ø 24 mm adaptor
020458Y
Puller for lower bearing on steering tube
020459Y
Punch for fitting bearing on steering tube
020460Y
Scooter diagnosis and tester
020467Y
Flywheel extractor
Nexus 500 euro 3
Tooling
Stores code
020468Y
Description
Piston fitting ring
020469Y
Reprogramming kit for scooter
diagnosis tester
020470Y
Pin retainers installation tool
020471Y
Pin for countershaft timing
020472Y
Flywheel lock wrench
TOOL - 9
Nexus 500 euro 3
Tooling
TOOL - 10
Stores code
020474Y
Description
Driving pulley lock wrench
020475Y
Piston position checking tool
020476Y
Stud bolt set
020478Y
Punch for driven pulley roller casing
020479Y
Countershaft lock wrench
020480Y
Petrol pressure check set
Nexus 500 euro 3
Tooling
Stores code
020481Y
Description
Control unit interface wiring
020482Y
Engine support
020483Y
30 mm guide
020512Y
Piston fitting fork
020527Y
Engine support base
020604Y011
020565Y
Fitting adapter
Flywheel lock calliper spanner
TOOL - 11
Nexus 500 euro 3
Tooling
TOOL - 12
Stores code
020623Y
Description
Pre-service gas extraction set
020625Y
Kit for sampling gas from the exhaust manifold
020640y
software euro3
INDEX OF TOPICS
MAINTENANCE
MAIN
Nexus 500 euro 3
Maintenance
Maintenance chart
EVERY 2 YEARS
60'
Action
Coolant - change
Brake fluid - change
AFTER 1,000 KM
Action
Safety locks - check
Throttle lever - adjustment
Engine oil - change
Electrical system and battery - check
Coolant level - check
Brake fluid level - check
Engine oil - replacement
Brake pads - check condition and wear
Tyre pressure and wear - check
Vehicle and brake test - road test
Hub oil - change
Crankcase breather - empty
Steering - adjustment
Injection system pipework - visual check
AFTER 10,000 KM AFTER 30,000 KM AFTER 50,000 KM AND AFTER 70,000 KM
Action
Safety locks - check
Spark plug - replacement
Driving belt - replacement
Throttle lever - adjustment
Air filter - check
Air filter belt compartment - check
Engine oil - change
Valve clearance - check
Electrical system and battery - check
Coolant level - check
Brake fluid level - check
Engine oil - replacement
Brake pads - check condition and wear
MAIN - 2
Nexus 500 euro 3
Maintenance
Action
Sliding block / variable speed rollers - change
Tyre pressure and wear - check
Vehicle and brake test - road test
Hub oil - check
Stand control roller - replace
Suspensions - check
Steering - Check
Injection system pipework - visual check
Crankcase breather - empty
AFTER 20,000 KM AFTER 40,000 KM AFTER 60,000 KM AND AFTER 80,000 KM
Action
Safety locks - check
Bushing of driven pulley
Spark plug - replacement
Driving belt - replacement
Throttle lever - adjustment
Air filter - check
Air filter belt compartment - check
Engine oil - change
Valve clearance - check
Electrical system and battery - check
Coolant level - check
Brake fluid level - check
Engine oil - replacement
Brake pads - check condition and wear
Sliding block / variable speed rollers - change
Tyre pressure and wear - check
Vehicle and brake test - road test
Hub oil - check
Stand control roller - replace
Crankcase breather - empty
Suspensions - check
Steering - Check
Injection system pipework - visual check
Fuel filter - check
Spark plug
Check and replacement
CAUTION
THE SPARK PLUG MUST BE REMOVED WITH
COLD ENGINE. THE SPARK PLUG SHOULD
BE CHECKED EVERY 6,000 KM AND REPLACED EVERY 12,000 KM. THE USE OF NONCONFORMING IGNITION CONTROL UNITS
AND SPARK PLUGS OTHER THAN THOSE
PRESCRIBED CAN SERIOUSLY DAMAGE THE
ENGINE.
Characteristic
Recommended spark plugs:
MAIN - 3
Maintenance
Nexus 500 euro 3
CHAMPION RG6YC - NGK CR 7 EKB
- Position the scooter on centre stand.
- Remove the side cover on the left-hand side of the scooter, loosening the three screws shown in the
figure.
- Disconnect the shielded spark plug cap
- Unscrew the spark plug.
- Check the conditions of the spark plug, make sure the insulation is intact, that the electrodes are not
excessively worn or grimy, the conditions of the washer, and measure the distance between the electrodes using the appropriate feeler gauge.
Characteristic
Electrode gap
0.7-0.8 mm
Adjust the gap if necessary, carefully bending the
earth electrode. In the event of irregularity, replace
the spark plug with a recommended type.
- Fit the spark plug with the correct inclination and
manually screw it all the way down, then use the
special spanner to tighten it.
Locking torques (N*m)
Spark plug 12 ÷ 14
- Insert the cap onto the spark plug and proceed with the reassembly operations.
Hub oil
MAIN - 4
Nexus 500 euro 3
Maintenance
Check
Check the oil in the rear hub.
Characteristic
Rear hub oil
Capacity approximately 250 cc
To check the rear hub oil level, proceed as follows:
- Park the scooter on flat ground resting on its centre stand.
- Set the strut that adjusts the level to its minimum height.
- Unscrew the oil dipstick, dry it with a clean cloth and reinsert it, screwing it in thoroughly.
- Pull out the dipstick and check that the oil level is
between the MAX and MIN notches indicated on
the dipstick; if the level is below the MIN value, restore the proper amount of oil in the hub.
-Retighten the oil dipstick again and make sure it
is locked properly into place.
Replacement
- Prepare a suitable container.
- Remove the oil filler plug shown in the figure.
MAIN - 5
Maintenance
- Unscrew the oil drainage plug and drain out all
the oil.
- Tighten the drainage plug with its gasket and refill.
- Tighten the oil filler plug.
Characteristic
Rear hub oil
Capacity approximately 250 cc
Recommended oil:
TUTELA ZC 90
Air filter
- Raise the saddle.
- Remove the piston ring and the battery cover.
- Loosen the 4 mounting screws shown in the figure.
- Loosen the mounting screw located under the intake manifold.
MAIN - 6
Nexus 500 euro 3
Nexus 500 euro 3
Maintenance
- Replace the air filter and reassemble the various
components, reversing the removal procedure.
- An inspection and possible cleaning (with compressed air) of the air filter is scheduled every 6000
km in any case.
- The air jet must be directed from the inside to the
outside of the filter (i.e. opposite the direction of
the air flow during normal operation of the engine).
- Any deposits of condensate out of the engine oil
caused by blow-by can be removed via the pipe
shown in the figure.
N.B.
FAILURE TO OBSERVE THE RULES REGARDING CLEANING OF THE FILTER ELEMENT
CAN LEAD TO IMPROPER LUBRICATION OF
THE ELEMENT. POOR LUBRICATION AFFECTS THE FILTERING CAPACITY. EXCESSIVE LUBRICATION AS WITH A SOILED FILTER CAUSES AN EXCESSIVELY RICH FUEL/
AIR MIXTURE.
CAUTION
WHEN TRAVELLING ON DUSTY ROADS, THE
AIR FILTER MUST BE CLEANED MORE OFTEN
THAN SHOWN IN THE SCHEDULED MAINTENANCE CHART.
WARNING
DO NOT RUN THE ENGINE IF THE AIR FILTER
IS NOT IN PLACE THIS WILL RESULT IN EXCESSIVE WEAR TO ALL THE PARTS OF THE
COOLING SYSTEM.
Engine oil
In 4T engines, the engine oil is used to lubricate the distribution elements, the bench bearings and the
thermal group. An insufficient quantity of oil can cause serious damage to the engine.
In all 4T engines, the deterioration of the oil characteristics, or a certain consumption should be considered normal, especially if during the run-in period. Consumption levels in particular can be influenced
by the conditions of use (e.g.: oil consumption increases when driving at "full throttle".
MAIN - 7
Maintenance
Nexus 500 euro 3
Check
This operation must be carried out with the engine cold and following the procedure below:
1) Rest the scooter on the central stand and on a
flat ground.
2) Unscrew the cap/dipstick "A", dry it with a clean
cloth and reinsert it, screwing it thoroughly.
3) Remove the cap/dipstick again and check that
the level is between the max. and min levels; top
up, if required.
Topping up from the MIN to MAX. level requires
around 1700 cc.
If the check is carried out after the vehicle has
been used, and therefore with a hot engine, the
level line will be lower; in order to carry out a correct check it is necessary to wait at least 10 minutes after the engine has been stopped, so as to
get the correct level.
Oil top up
The oil should be topped up after having checked the level and in any case by adding oil without ever
exceeding the MAX. level.
The restoration level between the MIN and MAX levels implies a quantity of oil of approx. 400 cc.
Engine oil filter
CAUTION
DO NOT DISPOSE OF OIL IN THE ENVIRONMENT. OIL, GASKET AND FILTER SHOULD BE DISPOSED OF ACCORDING TO THE REGULATIONS IN FORCE.
WARNING
AVOID TOUCHING PARTS OF THE ENGINE WHEN HOT, AS THIS MAY CAUSE BURNS.
- Remove the muffler.
- Remove the filler plug.
MAIN - 8
Nexus 500 euro 3
Maintenance
- Remove and clean the mesh pre-filter of the drain
cap with compressed air.
- Use a belt spanner for filters to remove cartridge
filter "C".
- Make sure the pre-filter and drain cap O-rings are
in good condition.
- Lubricate them and refit the mesh filter and oil
drain cap by tightening to the prescribed torque.
- Refit a new cartridge filter making sure to lubricate the O-ring before fitting, then screw until it
comes into contact with the seal and further tighten
to the prescribed torque.
- Refit the muffler.
- Add recommended engine oil.
- Start the engine and let it run for a few minutes and then turn it off.
After 5 minutes check the level and top up, if necessary, never exceed the MAX. level.
N.B.
IF THE OIL IS CHANGED WITHOUT CHANGING THE CARTRIDGE FILTER (1ST COUPON) ADD
AROUND 1500 CC OF OIL INSTEAD OF 1700 CC SINCE PART OF THE LUBRICATION CIRCUIT
IS FILLED.
Characteristic
Engine oil:
1700 cm³
Locking torques (N*m)
Engine oil drainage plug 24 ÷ 30 Engine oil filter 12 - 16
MAIN - 9
Maintenance
Nexus 500 euro 3
Oil pressure warning light
Warning light (low oil pressure)
The vehicle is equipped with a warning light on the
instrument panel that lights up when the key is
turned to the "ON" position. However, this light
should switch off once the engine has been started.
If the light comes on during braking, at idling
speed or while turning, it is necessary to first
switch off the engine and then to check the oil
level and the lubrication system
Checking the valve clearance
- To check the clearance in the valves collimate
the references between the cam shaft control pulley and head.
- Use a feeler to make sure the clearance between
the valve and register screw correspond to the indicated values. If the clearance does not correspond, adjust it by loosening the counternut using
a screwdriver on the register screw as shown in
the figure.
Characteristic
Valve clearance: intake:
0.15 mm (when cold)
Valve clearance: exhaust
0.15 mm (when cold)
Cooling system
If noise or loss of liquid at the drain bore of the water pump is discovered, it will be necessary to overhaul
the pump as described in chapter "Flywheel cover".
Proceed to carry out a few preliminary operations as described below:
- Place the scooter on its centre stand and on flat ground.
- Remove the right footrest as described in the «Bodywork» Chapter.
- Remove the muffler to access the flywheel cover, as described in the «Engine» Chapter.
- Empty the cooling system by removing the couplings on the pump cover and the filler plug on the
expansion tank.
MAIN - 10
Nexus 500 euro 3
Maintenance
CAUTION
THIS OPERATION MUST BE CARRIED OUT WHEN THE ENGINE IS COLD.
- Remove the water pump cover as indicated in the
figure by loosening the 6 retaining screws.
- Proceeding as described in chapter "Engine",
partially drain the system and overhaul the pump.
- Refill and drain the system again once after having repaired the damaged and reinstalled all the
components.
N.B.
FOR CHANGING THE COOLANT AND BLEEDING THE SYSTEM, SEE CHAPTER "COOLING
SYSTEM".
Characteristic
Cooling system
approx. 1.8 litres
Level check
The coolant level must checked every 6,000 kilometres with a cold engine, in the way shown below:
- Place the scooter on its centre stand and on flat
ground.
- Remove the cap of the expansion tank.
- To check the level, it is necessary to look inside
the expansion tank:
The reference mark in the figure shows the correct
coolant level.
-The coolant consists of an ethylene glycol and corrosion inhibitor based 50% demineralised waterantifreeze solution mix.
CAUTION
DO NOT EXCEED THE MAX. LEVEL WHEN FILLING SO AS TO AVOID THE COOLANT ESCAPING
FROM THE EXPANSION TANK WHEN THE vehicle IS IN USE.
N.B.
THE COOLANT CONSISTS OF A MIXTURE OF DE-IONISED WATER AND FLUID FOR SEALED
CIRCUITS. THE MIXTURE THUS OBTAINED LOWERS THE FREEZING POINT OF THE COOLANT
TO - 40°C. THE MIXTURE IN COMBINATION WITH THE PRESSURE OF 0.9 BAR RAISES THE
BOILING POINT TO APPROX. 125°C. THE RECOMMENDED LIQUID ALSO PROVIDES PROTECTIVE FUNCTIONS FOR THE ALUMINIUM ALLOYS. THIS CHARACTERISTIC MAY DECREASE
OVER THE COURSE OF TIME; THIS IS WHY A PERIODIC REPLACEMENT OF THE COOLANT IS
INDISPENSABLE.
N.B.
MAIN - 11
Maintenance
Nexus 500 euro 3
FOR THE REPLACEMENT OF THE COOLANT AND THE FLUSHING OF THE SYSTEM, SEE
CHAPTER COOLING SYSTEM.
Braking system
Level check
- Position the vehicle on a flat surface and on the
centre stand.
- Check the brake fluid level via the special indicator located on the pump.
N.B.
THE LEVEL TENDS TO DROP AS THE BRAKE PADS GET WORN, A MINIMUM LEVEL SHOULD
NOT BE REACHED. IF THE LEVEL IS TOO LOW, CHECK AND FIX THE SYSTEM SEALS, IF REQUIRED. TOP UP THE PUMP TANK, IF REQUIRED, CONSIDERING THAT THE "MAX." LEVEL
MUST ONLY BE OBTAINED WITH NEW PADS.
Top-up
CAUTION
ONLY USE DOT 4-CLASSIFIED BRAKE FLUID.
Proceed as follows:
- Position the scooter on a flat surface and on the
centre stand.
- Remove the tank cap by removing the two
screws, remove the gasket and top up using only
the liquid specified without exceeding the maximum level.
CAUTION
MAIN - 12
Nexus 500 euro 3
Maintenance
MAKE SURE THE BRAKE FLUID DOES NOT GET INTO YOUR EYES OR ON YOUR SKIN OR
CLOTHES. IF THIS HAPPENS ACCIDENTALLY, WASH WITH WATER.
WARNING
BRAKE CIRCUIT FLUID IS VERY CORROSIVE; MAKE SURE THAT IT DOES NOT COME INTO
CONTACT WITH THE PAINTWORK
WARNING
THE BRAKE FLUID IS HYGROSCOPIC, IN OTHER WORDS, IT ABSORBS MOISTURE FROM THE
SURROUNDING AIR. IF THE HUMIDITY IN THE BRAKING FLUID EXCEEDS A CERTAIN VALUE,
IT WILL LEAD TO INEFFICIENT BRAKING; FOR THIS REASON, NEVER USE BRAKING FLUID
FROM CONTAINERS THAT HAVE ALREADY BEEN OPENED, OR PARTIALLY USED.
Characteristic
Prescribed fluid:
TUTELA TOP 4
Under normal climatic conditions, the fluid must be changed every 20,000 km or anyway every two
years.
N.B.
SEE THE BRAKING SYSTEM CHAPTER WITH REGARD TO THE CHANGING OF BRAKE FLUID
AND THE BLEEDING OF AIR FROM THE CIRCUITS.
Headlight adjustment
- Place the scooter in use conditions, with tyres inflated to the prescribed pressure on flat ground at 10
m from a white screen placed in dim light.
- Make sure that the scooter's axle is perpendicular to the screen.
- Turn the headlight on and check that the limit of the light beam projected onto the screen does not
exceed 9/10 of the headlight centre height from the ground and that it is not less than 7/10.
MAIN - 13
Maintenance
Nexus 500 euro 3
- Otherwise, adjust the right headlight by the screw
shown in the figure, which can be accessed by removing the front shield connecting member.
N.B.
THE ABOVE PROCEDURE COMPLIES WITH
THE EUROPEAN STANDARDS REGARDING
MAXIMUM AND MINIMUM HEIGHT OF LIGHT
BEAMS. REFER TO THE STATUTORY REGULATIONS IN FORCE IN EVERY COUNTRY
WHERE THE vehicle IS USED.
Checking the end compression pressure
- Remove the spark plug cap with the engine cold.
- Remove the spark plug.
- Fit a compression test gauge into the spark plug seat using a 10 mm spark plug union at the proper
tightening torque.
- Turn the switch to "ON", wait a few seconds and the disconnect the connector of the revolution sensor
to prevent the function of the injector and the spark plug.
- Allow the engine to run using the starter and with the throttle body in fully open position as long as the
gauge value is steady.
- If the pressure is higher than specified, remove the tool and reassemble the scooter.
- If the pressure is less than indicated, check the rpm at which the test is carried out; if it is less than
450 rpm, check the starter system.
If the final compression pressure is less than specified, remove the pressure gauge connector and inject
a few cc of oil into the combustion chamber, then turn the engine over (preferably by hand) to lubricate
the cylinder.
Repeat the compression test:
If the new value is also too low, check the valve seating.
Higher compressions on a new engine indicate poor seating of the segments.
Characteristic
Compression ratio
10.5: 1
Locking torques (N*m)
Spark plug 12 ÷ 14
MAIN - 14
INDEX OF TOPICS
ELECTRICAL SYSTEM
ELE SYS
Electrical system
KEY:
1. Magneto flywheel
2. Voltage regulator
3. Engine rev sensor
4. Throttle valve position sensor
5. Ambient temperature sensor
6. Stepping motor for idle nozzle
7. Electric fan
8. Engine temperature sensor
9. Remote control for electric fan
10. Overturn sensor
11. Injection load remote control
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
16. Horn button
17. Horn
18. Engine stop remote control
19. Diode
ELE SYS - 2
Nexus 500 euro 3
Nexus 500 euro 3
Electrical system
20. Battery
21. Starter motor
22. Start-up remote control switch
23. Starter push button
24. Starter enable remote control
25. Engine stop switch
26. Centre stand switch
27. Rear brake stop button
28. Front brake stop button
29. Saddle opener actuator
30. Saddle opener receiver
31. 12V 180W socket
32. Helmet compartment light switch
33. Helmet compartment light
34. Preparation for anti-theft device
35. Left rear turn indicator bulb
36. Twin filament bulb tail light / stop light
37. Licence plate bulb
38. Right rear turn indicator bulb
39. Left front turn indicator bulb
40. Front right light assembly
A. Low beam light
B. Tail light
41. Front left light assembly
B. Tail light
C. High beam light
42. Right front turn indicator bulb
43. Headlight remote control
44. High beam passing mode switch
45. Light switch
46. Turn indicator assembly
47. Handlebar warning lights
A. Emergency lights
B. Tail lights
C. High beam light
48. Turn indicator switch
49. Electric control system
50. Mode button
ELE SYS - 3
Electrical system
Nexus 500 euro 3
51. Emergency light switch
52. Oil pressure sensor
53. Instrument panel
A. Rpm indicator
B. Instrument panel bulbs
54. Instrument panel
A. Instrument panel bulbs
B. Immobilizer LED
C. Speedometer
D. Digital display
E. Engine Warning indicator light
F. Low fuel warning light
G. Oil warning light
55. Immobilizer aerial
56. Fuel pump / fuel level transmitter
57. Immobilizer decoder
58. Fuel injector
59. Spark plug
60. Tone wheel
61. HV coil
62. Lambda probe
63. Diagnostic socket
64. Fuel injection electronic control unit
Ar = Orange, Az = Sky Blue, Bi = White, Bl = Blue, Gi = Yellow, Gr = Grey, Ma = Brown, Ne = Black,
Ro = Pink, Rs = Red, Ve = Green, Vi = Purple
Components arrangement
Diagnostic socket
In order to access the diagnostic socket, remove the supports of the passenger footrest.
Overturn sensor
In order to access the overturn sensor, remove the
central union.
ELE SYS - 4
Nexus 500 euro 3
Electrical system
During assembly, observe the installation direction
shown in the figure.
H.V. coil
In order to access the high-voltage coil, remove
the left-hand side fairing.
Saddle opening ECU remote control.
Resetting of the remote control
Electronic control unit ECU
In order to access the immobilizer control unit, remove the upper shield back plate.
ELE SYS - 5
Electrical system
In order to access the connector, remove the windshield with the respective support and the metal
plate holding the control unit ECU, decoder and
saddle opener remote control.
N.B.
AFTER INSERTING THE INTERFACE CABLE
OR THE ELECTRONIC CONTROL UNIT, RETIGHTEN THE SCREW AND THE GROUND CABLE.
Immobiliser decoder
In order to access the immobilizer decoder, remove the upper shield back plate.
Relays and diode group
In order to access the relays and the diode group,
remove the upper shield back plate.
Voltage regulator
In order to access the voltage regulator, remove
the lower cover.
ELE SYS - 6
Nexus 500 euro 3
Nexus 500 euro 3
Electrical system
Lambda probe
The lambda probe is mounted on the exhaust
manifold
Conceptual diagrams
Ignition
KEY:
3. Engine rpm sensor
11. Injection load remote control
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
ELE SYS - 7
Electrical system
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
54. Instrument panel
A. Instrument panel bulbs
B. Immobilizer LED
C. Speedometer
D. Digital display
E. Engine Warning indicator light
F. Low fuel warning light
G. Oil warning light
55. Immobilizer aerial
57. Immobilizer decoder
59. Spark plug
61. HV coil
64. Fuel injection electronic control unit
Battery recharge and starting
KEY:
ELE SYS - 8
Nexus 500 euro 3
Nexus 500 euro 3
Electrical system
1. Magneto flywheel
2. Voltage regulator
12. Key switch
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
21. Starter motor
22. Start-up remote control switch
23. Starter push button
24. Starter enable remote control
25. Engine stop switch
26. Centre stand switch
27. Rear brake stop button
28. Front brake stop button
36. Twin filament bulb position light / stop light
Level indicators and enable signals section
KEY
ELE SYS - 9
Electrical system
3. Engine rev sensor
4. Throttle valve position sensor
5. Ambient temperature sensor
6. Stepping motor for idle nozzle
8. Engine temperature sensor
11. Injection charge remote control
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
52. Oil pressure sensor
54. Instrument panel
A. Instrument panel light
B. Immobilizer LED
C. Speedometer
D. Digital display
E. Engine Warning indicator light
F. Low fuel warning light
G. Oil warning light
56. Fuel pump / fuel level transmitter
58. Fuel injector
60. Tone wheel
62. Lambda probe
64. Fuel injection electronic control unit
ELE SYS - 10
Nexus 500 euro 3
Nexus 500 euro 3
Electrical system
Devices and accessories
KEY
7. Electric fan
8. Engine temperature sensor
9. Remote control for electric fan
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
16. Horn button
17. Horn
18. Engine stop remote control
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
29. Saddle opener actuator
30. Saddle opener receiver
31. 12V 180W socket
ELE SYS - 11
Electrical system
32. Helmet compartment light switch
33. Helmet compartment bulb
64. Fuel injection electronic control unit
Lights and turn indicators
LEGENDA
12. Commutatore a chiave
13. Scatola portafusibili A
14. Fusibile principale
15. Scatola portafusibili B
20. Batteria
34. Predisposizione antifurto
35. Lampada indicatore di direzione posteriore Sx
36. Lampada doppio filamento Luce di posizione/Luce stop
37. Lampada luce targa
38. Lampada indicatore di direzione posteriore Dx
39. Lampada indicatore di direzione anteriore Sx
40. Gruppo ottico anteriore Dx
A. Lampada anabbagliante
B. Luce di posizione
ELE SYS - 12
Nexus 500 euro 3
Nexus 500 euro 3
Electrical system
41. Gruppo ottico anteriore Sx
B. Luce di posizione
C. Lampada abbagliante
42. Lampada indicatore di direzione anteriore Dx
43. Teleruttore proiettore
44. Pulsante abbagliante modalità Pass
45. Deviatore luci
46. Dispositivo lampeggiatori
47. Spie gruppo manubrio
A. Lampeggiatori di emergenza
B. Luci di posizione
C. Luce abbagliante
48. Commutatore indicatori di direzione
49. Dispositivo gestione comandi elettrici
51. Interruttore lampeggiatori di emergenza
53. Quadro strumenti
A. Contagiri
B. Lampade illuminazione strumento
54. Quadro strumenti
A. Lampade illuminazione strumento
B. Led immobilizer
C. Tachimetro
D. Display digitale
E. Spia Warning motore
F. Spia Riservacarburante
G. Spia olio
H.
Checks and inspections
Battery recharge circuit
The recharge system is provided with a three phase alternator with permanent flywheel.
The alternator is directly connected to the voltage regulator.
This, in its turn, is connected directly to the ground and the battery positive terminal passing through
the 30A protective fuse.
This system therefore requires no connection to the key switch.
ELE SYS - 13
Nexus 500 euro 3
Electrical system
The three- phase generator provides good recharge power and at low revs a good compromise is
achieved between generated power and idle stability.
Stator check
Stator winding check-up
WARNING
THE CHECK-UP CAN BE MADE WITH THE STATOR PROPERLY INSTALLED.
1) Remove the central chassis cover.
2) Disconnect the connectors between stator and regulator with the three yellow cables.
3) Measure the resistance between each of the yellow terminals and the other two.
Electric characteristic
Resistance:
0.2 - 1 Ω
4) Check that there is insulation between the each
yellow cable and the ground.
5) If values are incorrect, replace the stator.
Recharge system voltage check
VOLTAGE REGULATOR/RECTIFIER
Specification
Type
Voltage
Desc./Quantity
Non-adjustable three-phase transistor
14 ÷ 15V at 5000 rpm with lights off
Maximum current output check.
- With engine off and panel set to "ON" turn on the lights and let the battery voltage set to 12V.
- Connect ammeter pliers to the 2 recharge positive poles in output from the regulator.
- Keep the lights on and start the engine, bring it to normal speed and read the values on the ammeter.
With an efficient battery a value must be detected: > 20A
Check the charging current
WARNING
BEFORE CARRYING OUT THE CHECK, MAKE SURE THAT THE BATTERY IS IN GOOD WORKING ORDER.
1) Place the vehicle on its centre stand
ELE SYS - 14
Nexus 500 euro 3
Electrical system
2) With the battery correctly connected to the circuit, place the tester terminals between the battery
terminals..
3) Start the engine, ensure that the lights are all out, increase the engine speed and at the same time
measure the voltage.
Electric characteristic
Voltage ranging between 14.0 and 15.0V at 5000 rpm.
Look for any leakage
1) Check that the battery exhibits no liquid leaks before checking the output voltage.
2) Turn the ignition key to OFF and connect the tester terminals between the battery negative pole (-)
and the Black cable.
3) With the tester terminals connected, disconnect the Black cable from the battery negative (-) pole.
4) With ignition key still at OFF, the reading detected by the amperometer must be ≤ 0.5 mA.
Turn signals system check
The circuit of the turn indicators is controlled by the electrical control device and the instrument panel.
In the event of a malfunction, proceed as follows:
1. Check the function of the bulbs
2. Check the function of the turn signal indicator switch
3. Without disconnecting the instrument panel, with the key switch in position ON and with the engine
stop switch in position RUN, check for intermittent voltage between terminals 9-ground and 10-ground
of the large 20-pin connector.
If there is no voltage, check the wiring and the correct function of the electrical control units. If the fault
persists, replace the instrument panel.
Lights list
LIST OF BULBS
1
2
3
4
5
6
Specification
High-beam / low-beam headlights
Position light / front headlight
Turn indicator bulb
Tail light bulb and light
Licence plate bulb
Helmet compartment bulb
Desc./Quantity
2 12V-55W, halogen (H7)
2 12V-5W, all-glass
4 12V-10W, spherical
1 12V-21/5W, spherical, twin-filament
1 12V-5W, all-glass
1 12V-5W, cylindrical
ELE SYS - 15
Nexus 500 euro 3
Electrical system
Fuses
The electrical system is equipped with:
1. Six fuses "A" located on the shield back plate
2. Five fuses "B" located in the helmet compartment
3. One fuse of 30A "D" (main fuse), located near
the battery on the left-hand side, under which is
also a replacement fuse.
The rating of the various fuses are stamped on the
fuse holders "C".
To replace the fuse, use the gripper provided in the
tool bag.
The table shows the position and characteristics
of the fuses installed in the scooter.
CAUTION
BEFORE REPLACING THE BLOWN FUSE,
FIND AND SOLVE THE FAILURE THAT
CAUSED IT TO BLOW. NEVER TRY TO REPLACE THE FUSE WITH ANY OTHER MATERIAL (E.G., A PIECE OF ELECTRIC WIRE).
FUSIBILE PRINCIPALE
Specification
Generale
1
Desc./Quantity
Nominazione: Fuse 1
Soglia di intervento: 30A
Collocazione: Vano batteria
PORTAFUSIBILI «B»
Specification
Non utilizzato
1
2
License plate bulb - position lights - instrument panel lights
3
Instrument panel power supply
ELE SYS - 16
Desc./Quantity
Nominazione: Soglia di intervento: Collocazione: Vano portacasco
Designation:Fuse 2
Threshold of operation: 3 A
Location: Helmet compartment
Designation:Fuse 3
Threshold of operation: 7.5 A
Nexus 500 euro 3
Electrical system
Specification
4
Seat opener receiver power supply - antitheft device preparation
5
Horn - emergency stop warning light - instrument panel permanent power supply - light
controller
Helmet compartment light - socket
12V-180W - anti-theft device preparation
6
Desc./Quantity
Location: Helmet compartment
Designation:Fuse 4
Threshold of operation: 7.5 A
Location: Helmet compartment
Designation:Fuse 5
Threshold of operation: 7.5 A
Location: Helmet compartment
Designation:Fuse 6
Threshold of operation: 15 A
Location: Helmet compartment
FUSE HOLDER "B"
1
Specification
Immobilizer decoder power supply - ignition
ECU power supply
2
Ignition ECU - immobilizer decoder (+ permanent power supply)
3
Stop light - starter remote control coil
4
High-beam lamp with warning light
5
Low beam lamp
6
HV coil - fuel injector - fuel pump - remote
control injection load
Desc./Quantity
Designation:Fuse 7
Threshold of operation: 3 A
Location: Shield back plate
Designation:Fuse 8
Threshold of operation: 5A
Location: Shield back plate
Designation:Fuse 9
Threshold of operation: 7.5 A
Location: Shield back plate
Designation:Fuse 10
Threshold of operation: 7.5 A
Location: Shield back plate
Designation:Fuse 11
Threshold of operation: 7.5 A
Location: Shield back plate
Designation:Fuse 12
Threshold of operation: 10 A
Location: Shield back plate
ELE SYS - 17
Nexus 500 euro 3
Electrical system
Remote control switches
The electrical system has 6 remote control
switches located under the front shield.
In order to access the remote control switches:
•
Remove the front shield.
•
- Remove the front knee guard.
The following table shows the functions of each
remote control switch:
Remote
Description
control
switch
A
Immobiliser remote control switch
B
Electric fan remote control switch
C
Light remote control switch
D
Engine stop remote control switch
E
Electronic control unit remote
control switch
F
Starter remote control switch
Dashboard
The digital display has two service symbols:
SERVICE (Service coupon):
The lamp should come on after reaching 1000 km
or 1 year after initial activation, then every 6000 km
or 1 year after the last activation.
BELT:
This lamp should come on every 12000 km.
ELE SYS - 18
Nexus 500 euro 3
•
Electrical system
Press buttons "MODE" and "ODO/SET" simultaneously at the moment you turn the key to
"ON" for more than 3 seconds: The "BELT" symbol starts to flash.
•
Pressing the button "MODE" for less than 1 second displays the symbols in turn. The selected symbol remains lit.
•
Pressing button "MODE" for longer than 3 seconds resets the kilometre reading for the
symbol selected, in "SERVICE" mode the date is also reset.
N.B.
•
•
AT THE MOMENT THE DATE IS RESET, THE "SERVICE" SYMBOL IS ACTIVATED
AGAIN.
PERFORM THE RESET PROCEDURE ONLY AT THE MOMENT OF DELIVERY OF THE
SCOOTER TO THE CUSTOMER IN ORDER THAT THIS SYMBOL SIGNALS THE NEED
FOR THE FIRST SERVICE IN RELATION TO THE DISTANCE TRAVELLED AND THE
TIME SINCE THE ACTIVATION.
The scooter has an instrument panel subdivided
into 3 sections: Digital instrument with LCD display
and analogue speedometer, analogue rpm indicator and warning light group.
• Warning light group
The warning light group includes:
- Emergency light warning light (red)
- Position light and low-beam warning light (green)
- High beam warning light (blue)
- Spare warning light
- The emergency control unit may be switched ON
and OFF only with the key in position "ON" and
must continue to function with the key in position
"OFF".
• Digital instrument
The digital section provides the displays of:
- Injection warning light (amber)
- Low fuel warning light (amber)
- Oil pressure warning light (red)
- Turn signal warning light (green)
- Immobilizer LED (red)
ELE SYS - 19
Electrical system
Nexus 500 euro 3
The digital section of the instrument panel is completed by a liquid crystal display and 3 control
buttons (MODE - CLOCK - ODO/SET).
- The LCD panel provides a 5-digit display for the visualisation of:
• Total kilometres
• Trip kilometres
• Clock
N.B.
IT IS POSSIBLE TO CHANGE THE DISPLAY TO KM OR MILES BY PRESSING THE BUTTONS
"MODE" AND "CLOCK" SIMULTANEOUSLY FOR LONGER THAN 3 SECONDS AT THE MOMENT
YOU TURN THE KEY TO POSITION "ON". THE WORD "SET" WILL BE DISPLAYED.
- Pushing the "MODE" button for less than a second displays the following function sequence:
1. Average speed
The word "MEAN" appears together with km/h or mph.
The value is calculated on the basis of the trip kilometre reading.
2. Maximum speed
The word "MAX" appears together with km/h or mph.
The value is calculated on the basis of the trip kilometre reading.
3. Average consumption
The fuel symbol, the word "MEAN" and km/h or mph appear.
The value is calculated on the basis of the trip kilometre reading.
4. Momentary consumption
The fuel symbol and km/h or mph appear.
5. Range
The fuel icon appears.
If the range drops below 40 km, the symbol appears automatically and flashes for 60 seconds.
When the low fuel warning light comes on permanently, dashes appear instead of the range value.
6. Battery voltage
The battery symbol appears
Pressing button "MODE" for longer than 3 seconds returns you to function "1" of the sequence (average
speed).
ELE SYS - 20
Nexus 500 euro 3
Electrical system
- The display also contains the symbols:
BELT:
Indicates the need to replace the transmission
belt
This lamp should come on and flash every 12000
km.
SERVICE (Service coupon):
Indicates the need to carry out the scheduled maintenance operations.
The lamp should come on after reaching 1000 km or 1 year after initial activation, then every 6000 km
or 1 year after the last activation.
WARNING
THE SCOOTER SHOULD BE SERVICED IN ANY CASE AT THE KILOMETRE INTERVALS INDICATED IN THE OPERATING AND MAINTENANCE MANUAL; DO NOT RELY ON THE SERVICE
DISPLAY THAT APPEARS ON THE INSTRUMENT PANEL.
Data check function
Setting the clock.
To set the clock, press the button "CLOCK" for more than 3 seconds.
The figures showing the hours start to flash.
Set the hours with the button "ODO/SET".
Press button "CLOCK" again and the figures showing the minutes start to flash.
Set the minutes with the «ODO/SET» button.
Press the «CLOCK» button again to start the clock moving normally.
During the reset process, not pressing any buttons for 8 seconds ends the process and the display will
automatically show the modified time.
Setting the date.
Set the "DATE" using the "CLOCK".
If the button "CLOCK" is pressed for longer than 3 seconds, the figures showing the days start to flash.
Set the day with the «ODO/SET» button.
Press the "CLOCK" button again; the numbers showing the months start to flash.
ELE SYS - 21
Electrical system
Nexus 500 euro 3
Set the month with the "ODO/SET" button.
Press the "CLOCK" button again; the numbers showing the years start to flash.
Set the year with the "ODO/SET" button.
Press the «CLOCK» button again to start the clock moving normally.
During the reset process, not pressing any buttons for 8 seconds ends the process and the display will
automatically show the modified date.
Sealed battery
Sealed battery start-up operations
If the vehicle is provided with a sealed battery, the only maintenance required is the check of its charge
and recharging, if necessary.
These operations should be carried out before delivering the vehicle, and on a six-month basis while
the vehicle is stored in open circuit.
Besides upon pre-delivery it is therefore necessary to check the battery charge and recharge it, if required, before storing the vehicle and afterwards every six months.
INSTRUCTIONS FOR BATTERY REFRESH AFTER OPEN CIRCUIT STORAGE
1) Voltage check
Before installing the battery on the vehicle, check the open circuit voltage with a regular tester.
- If voltage exceeds 12.60 V, the battery can be installed without any renewal recharge.
- If voltage is below 12.60 V, a renewal recharge is required as explained in 2).
2) Constant voltage battery charge mode
- Constant voltage charge equal to 14.40 ÷ 14.70V
-Initial charge voltage equal to 0.3 ÷ 0.5 for Nominal capacity
- Charge time:
10 to 12 h recommended
Minimum 6 h
Maximum 24 h
3) Constant current battery charge mode
-Charge current equal to 1/10 of the nominal capacity of the battery
- Charge time: 5 h
Specific tooling
020333Y Single battery charger
020334Y Multiple battery charger
Cleaning the battery
The battery should always be kept clean, especially on its top side, and the terminals should be coated
with Vaseline.
CAUTION
ELE SYS - 22
Nexus 500 euro 3
Electrical system
NEVER USE FUSES WITH A CAPACITY HIGHER THAN THE RECOMMENDED CAPACITY. USING
A FUSE OF UNSUITABLE RATING MAY SERIOUSLY DAMAGE THE VEHICLE OR EVEN CAUSE
A FIRE.
CAUTION
CHARGE THE BATTERY BEFORE USE TO ENSURE OPTIMUM PERFORMANCE. FAILURE TO
CHARGE THE BATTERY ADEQUATELY BEFORE BEING PUT INTO OPERATION WILL LEAD TO
A PREMATURE FAILURE OF THE BATTERY.
If the scooter is not used for a given time (1 month or more) it will be necessary to periodically recharge
the battery.
The battery runs down completely in the course of three months. If it is necessary to refit the battery in
the vehicle, be careful not to reverse the connections, remembering that the ground wire (black) marked
(-) must be connected to the negative clamp while the other two red wires marked (+) must be connected to the clamp marked with the + positive sign.
Dry-charge battery
- Remove the short closed tube and the caps, then
pour sulphuric acid into the cells using the type
specified for batteries with a specific gravity of
1.26, corresponding to 30 Bé at a minimum temperature of 15°C until the upper level is reached.
- Allow to stand for at least 2 hours, then top up the
level with sulphuric acid.
- Within 24 hours, recharge using the special battery charger (single) or (multiple) at an intensity of
about 1/10 of the battery nominal capacity and until
the acid gravity is about 1.27, corresponding to 31
Bé and such values become steady.
- After charging, top up the acid (adding distilled
water). Close and clean carefully.
- After carrying out the operations above, install the
battery on the scooter, observing the connections
described in point 3) of paragraph "Battery recharge".
Specific tooling
020333Y Single battery charger
020334Y Multiple battery charger
1 Keep the pipe in vertical position
2 Inspect visually
3 The float must be freed
Checking the electrolyte level
ELE SYS - 23
Electrical system
Nexus 500 euro 3
The electrolyte level must be checked frequently and must reach the upper level. Only use distilled
water, to restore this level. If it is necessary to add water too frequently, check the vehicle's electrical
system: the battery works overcharged and is subject to quick wear.
Charging status check
After topping-up the electrolyte level, check its density using special density gauge.
When the battery is charged, you should detect a density of 30 to 32 Bé corresponding to a specific
weight of 1.26 to 1.28 at a temperature of no lower than 15° C.
A density reading of less than 20° Bé indicates that the battery is completely flat and it must therefore
be recharged.
If the scooter is not used for a given time (1 month or more) it will be necessary to periodically recharge
the battery.
The battery runs down completely in the course of three months. When refitting the battery onto the
scooter pay attention not to invert the cables, bearing in mind that the earth (black) wire marked with
a (-) must be connected to the negative terminal whilst the other two red wires, marked with a (+) must
be attached to the positive, + terminal.
Battery recharge
WARNING
BEFORE RECHARGING THE BATTERY, REMOVE THE PLUGS OF EACH CELL. KEEP SPARKS
AND NAKED FLAMES AWAY FROM THE BATTERY WHILE RECHARGING.
Remove the battery from the vehicle removing the negative clamp first.
Normal bench charging must be performed using the special battery charger (single) or (multiple), setting the battery charge selector to the type of battery that requires recharging (i.e., at a current equal
to 1/10 of the battery rated capacity). Connections to the power supply source must be implemented
by connecting corresponding poles (+ to + and - to - ).
Specific tooling
020333Y Single battery charger
020334Y Multiple battery charger
The battery should always be kept clean, especially on its top side, and the terminals should be coated
with Vaseline.
CAUTION
NEVER USE FUSES WITH A CAPACITY HIGHER THAN THE RECOMMENDED CAPACITY. USING
A FUSE OF UNSUITABLE RATING MAY SERIOUSLY DAMAGE THE VEHICLE OR EVEN CAUSE
A FIRE.
CAUTION
ORDINARY AND DRINKING WATER CONTAINS MINERAL SALTS THAT ARE HARMFUL FOR
THE BATTERY. FOR THIS REASON, YOU MUST ONLY USE DISTILLED WATER.
CAUTION
CHARGE THE BATTERY BEFORE USE TO ENSURE OPTIMUM PERFORMANCE. FAILURE TO
CHARGE THE BATTERY ADEQUATELY BEFORE BEING PUT INTO OPERATION WILL LEAD TO
A PREMATURE FAILURE OF THE BATTERY.
ELE SYS - 24
Nexus 500 euro 3
Electrical system
Phonic wheel
- Ensure that the tone wheel is correctly installed on the scooter and connected to the electrical system.
- Turn the key switch to "ON".
- Access the tone wheel connector on the system side.
- Carry out the following measurements using the special tool.
Specific tooling
020331Y Digital multimeter
Check the supply voltage.
Keeping the connector in the position shown in the
photo, check for battery voltage (12 V) with the
polarity shown.
If incorrect values are measured, check the electrical system and the digital instrument.
N.B.
A DROP IN VOLTAGE OF 1 V IN RELATION TO
THE BATTERY VOLTAGE CAN BE CONSIDERED NORMAL.
Check the signal
Move the positive rod to the position shown in the
photo. Turn the front wheel very slowly and check
that the measured voltage is 0 V or battery voltage,
depending on the position taken up.
This condition should be repeated 16 times during
a complete revolution of the wheel.
N.B.
THE DIGITAL MULTIMETER IS NOT ABLE TO
DISPLAY THE VOLTAGE WHEN THE WHEEL
IS ROTATED FAST.
If other voltages are measured or there is no alternation, replace the tone wheel.
Connectors
ELE SYS - 25
Nexus 500 euro 3
Electrical system
ECU
Layout of the system-side connectors and the connectors on the electronic control unit.
ECU
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
ELE SYS - 26
Specification
Throttle potentiometer power supply
Oxygen sensor
Rpm indicator / consumption counter
Engine temperature
86 electric fan remote control switch
Stepper motor
Engine rpm sensor
Oxygen sensor
EMS diagnostic connector
EMS diagnostic connector
Throttle potentiometer signal
Engine rpm sensor
Injector control
Stepper motor
Injection warning light
Decoder (serial)
Battery power supply
Air temperature sensor
Fuel pump
H.V. coil
Stepper motor
Sensor power supply
Control unit negative
Stepper motor
Turn indicator control device
Continuous power supply
Desc./Quantity
+5 V
(-)
(+)
Stepper motor
(+)
(negative)
Stepper motor
(-)
Overturn sensor
(+)
(+)
(-)
(negative control)
Stepper motor
(-)
Stepper motor
(positive)
Nexus 500 euro 3
Electrical system
Seat opening receiver
RECEIVER CONTROL UNIT FOR SADDLE OPENER
1
2
3
4
5
6
7
8
9
10
11
12
Specification
Radio aerial
Actuator positive output 1
Reset / Input cancel
Battery positive
(Not connected)
Live positive
Earth
(Not connected)
(Not connected)
Selection input CH1 / CH3
Positive output actuator 1
Data for alarm output
Desc./Quantity
Immobiliser decoder
IMMOBILIZER DECODER
1
2
3
4
5
6
7
8
Specification
Immobilizer LED control
Base power supply
Negative
Electronic control unit EMS
Continuous power supply (positive)
Desc./Quantity
(negative)
(positive)
(serial)
Immobilizer aerial
ELE SYS - 27
Nexus 500 euro 3
Electrical system
Engine rev. sensor
REV SENSOR
1
2
3
Specification
M:
F:
S:
Desc./Quantity
Male
Female
Shielding
Dashboard
The instrument panel is provided with two connectors ("A" with 20 pins and "B" with 12 pins) shown
in the figure.
Connector "A"
KEY:
1. Wheel sensor (+)
2. Wheel sensor signal
3. Wheel sensor (-)
4. Lights
5. Engine rpm signal
6.Water temperature
7.Water temperature (-)
8. Oil pressure
9. Right turn indicator
ELE SYS - 28
Nexus 500 euro 3
Electrical system
10. Left turn indicator
11. Fixed battery
12. Immobilizer LED
13. Permanent power supply (+)
14. Turn indicator assembly
15. Pump level sensor
16. 17. Injection LED
18. Right turn indicator warning light
19. Left turn indicator warning light
20. Emergency warning flashers
Connector "B"
KEY:
1. Rpm indicator (D)
2. Rpm indicator (B)
3. 4. 5. ICP/ID "NEXUS 500"
6. ICP/ID "NEXUS 250"
7. Rpm indicator (C)
8. Rpm indicator (A)
9. 10. 11. 12. ICP/ID "COMAND ID"
Analogue odometer
ANALOGUE RPM INDICATOR
Specification
1
2
3
4
Desc./Quantity
STEPPER MOTOR A
STEPPER MOTOR B
STEPPER MOTOR C
STEPPER MOTOR D
Remote seat opening
The vehicle is equipped with a remote control to open the saddle.
ELE SYS - 29
Electrical system
Nexus 500 euro 3
This remote control is supplied together with the keys and at the manufacturing stage, it has been
programmed to work together with the ECU that control the opening device.
If the remote control is lost, a new one can be requested and programmed, by resetting the ECU memory
and following the same steps as per programming the immobilizer system in the keys.
Battery replacement
The remote control for the black key is powered by
inner batteries that get discharged after extended
use.
You may need to replace the batteries if the remote control fails or if its range of operation is
reduced.
To perform such operation remove the three
screws and open the two half shells.
Electric characteristic
Batteries used:
CR1616
Zeroing
- Remove the front shield to gain access to the receiver control unit / seat opener controller.
- Within the electrical wiring harness there are two
cables, one black (ground) and one black/blue
coming from pin 3 of the control unit.
- Connect the two cables for at least 10 seconds
to cancel all the remote control commands stored
in the control unit.
Programming
- Follow these steps to program the remote controls:
1. Insert the remote control key to be programmed in the steering lock key block.
ELE SYS - 30
Nexus 500 euro 3
Electrical system
2. Turn the key to ON, press the button of the remote control, release the button, turn the key from ON
back to OFF, all within four seconds.
3. Wait for 1 to 8 seconds.
4. Repeat steps 2 and 3 for 4 times without removing the key. The control unit confirms the programming
has been successfully executed by opening the saddle.
N.B.
THE CONTROL UNIT CAN PROGRAMME UP TO 7 REMOTE CONTROLS.
ELE SYS - 31
Electrical system
ELE SYS - 32
Nexus 500 euro 3
INDEX OF TOPICS
ENGINE FROM VEHICLE
ENG VE
Engine from vehicle
Exhaust assy. Removal
- Loosen the two mountings of the exhaust manifold at the cylinder head.
- Remove the Lambda probe from its support and
disconnect it.
Remove the screw indicated in the photograph.
- Loosen the screw shown in the figure so as to
loosen the muffler strap and remove the whole
muffler.
ENG VE - 2
Nexus 500 euro 3
Nexus 500 euro 3
Engine from vehicle
N.B.
DUE TO MUFFLER DIMENSIONS IT IS NOT
POSSIBLE TO ACTUATE ON THE SCREW
PERPENDICULARLY TO REMOVE IT; USE A
COMMERCIALLY AVAILABLE "BONDUS"
MALE HEXAGONAL WRENCH.
Remove the lambda probe from the manifold.
Removal of the engine from the vehicle
Fitting the engine on the vehicle
- Perform the operations for removal but in reverse order according to the locking torque indicated in
«Specifications» Chapter.
CAUTION
PAY PARTICULAR ATTENTION TO POSITIONING THE THROTTLE COMMAND TRANSMISSION
PROPERLY.
Check that with valve in abutment against the register there is a small clearance.
-Check the engine oil level and if necessary top it up with the recommended type.
- Top up the cooling circuit.
- Check the functioning of the accelerator and the electrical devices.
Removal of engine
WARNING
CARRY OUT THESE OPERATIONS WHEN THE ENGINE IS COLD.
- Disconnect the battery
- Remove the underseat compartment.
- Drain the coolant.
- Remove the complete muffler assembly.
- Remove the rear wheel.
- Remove the swinging arm.
- Remove the throttle control transmission.
ENG VE - 3
Engine from vehicle
Nexus 500 euro 3
- Remove the air filter coupling and the collector.
- Disconnect the ground cable from the engine.
- Disconnect the carburettor electrical devices and the starter motor power supply cable.
- Disconnect the fuel delivery and return pipes from the carburettor and the cooling system piping (outlet
from the head and inlet to the thermostat).
- Disconnect the HV cable from the spark plug.
- Disconnect the alternator cable from the electrical system of the scooter.
WARNING
BE VERY CAREFUL WHEN HANDLING FUEL.
CAUTION
WHEN INSTALLING THE BATTERY, ATTACH THE POSITIVE LEAD FIRST AND THEN THE NEGATIVE LEAD.
ENG VE - 4
INDEX OF TOPICS
ENGINE
ENG
Engine
This section describes the operations to be carried
out on the engine and the tools to be used.
Automatic transmission
Transmission cover
- Using a screwdriver, remove the driven pulley
axle cover near the bottom of the cap.
- Loosen the driven pulley shaft fastening nut using
a misaligned wrench and prevent the pulley shaft
rotation using a machine hexagon bush.
- Remove the nut and the two washers.
N.B.
DUE TO THE HIGH TIGHTENING TORQUE, USING DIFFERENT WRENCHES - SUCH AS A
CONVENTIONAL POLYGONAL BUSH - MAY
DAMAGE THE HEXAGON OBTAINED ON THE
SHAFT OR BREAK THE BUSH ITSELF.
- Remove the six M6 screws.
ENG - 2
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Remove the four M8 screws.
- Remove the transmission cover.
- Check that the bearing rotates freely, otherwise
replace it.
- Loosen the 4 fastening screws
- Extract the outside plastic transmission cover.
Air duct
- Remove the transmission cover.
- Unscrew the two screws shown in the figure to
remove the air conveyor.
Locking torques (N*m)
Air conveyor screws 11 ÷ 12
- Remove the external transmission cover.
- Unscrew the 4 fastening screws shown in the figure to remove the external air conveyor.
ENG - 3
Engine
Air duct filter
- Remove the external air conveyor.
- Unscrew the 2 fastening screws shown in the figure to remove the conveyor filter.
Removing the driven pulley shaft bearing
- Remove the transmission cover.
- Remove the seeger ring.
- Place transmission cover on a wood surface and
use the special tool so that it is adequately supported.
- Pull out the bearing using the special tool.
N.B.
BELL MUST BE PLACED INTO THE TRANSMISSION COVER, CLOSE TO THE BEARING
SEAT AND THE WOODEN SURFACE, SINCE
WITHOUT BELL THE ENTIRE COVER STRUCTURE WOULD BEND. NOT ONLY IN THE AREA
OF MAXIMUM STURDINESS.
Specific tooling
001467Y002 Driver for OD 73 mm bearing
020376Y Adaptor handle
020375Y Adaptor 28 x 30 mm
020439Y 17 mm guide
ENG - 4
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Refitting the driven pulley shaft bearing
- Heat the transmission cover interior using the
heat gun.
N.B.
BE CAREFUL NOT TO OVERHEAT THE COVER AS THIS WOULD DAMAGE THE OUTSIDE
PAINTED SURFACE.
Specific tooling
020151Y Air heater
- Place the bearing onto the special tool with a little
grease to prevent it from coming out.
- Install the new bearing using the special tool.
N.B.
PROPERLY SUPPORT THE OUTSIDE COVER
TO PREVENT DAMAGING THE PAINTED SURFACE.
Specific tooling
020376Y Adaptor handle
020358Y 37x40-mm adaptor
020439Y 17 mm guide
Baffle roller
Plastic roller
Installation of belt anti-vibration roller
- Install the anti-flapping roller with the lip facing
the engine crankcase.
- Tighten the central screw to the prescribed torque.
N.B.
TURN THE DRIVEN AND/OR DRIVING PULLEY
UNTIL A CORRECT TENSIONING OF THE
BELT IS OBTAINED.
Locking torques (N*m)
Anti-vibration roller screw 16.7 - 19.6
ENG - 5
Engine
- Check that the roller does not show signs of wear
and that it turns freely.
- Loosen the retaining bolt using a 13 mm spanner.
- Remove the complete roller with bearing.
N.B.
IF THE ROLLER DOES NOT ROTATE FREELY,
REPLACE THE COMPLETE ROLLER.
Removing the driven pulley
- Remove the driven pulley assembly with the belt.
Inspecting the clutch drum
- Remove the clutch bell.
- Check that the clutch bell is not worn or damaged.
- Measure the clutch bell inside diameter.
N.B.
CHECK THE ECCENTRICITY MEASURED, 0.2
MM MAX.
Characteristic
Max. value:
160.5 mm
Standard value:
ENG - 6
Nexus 500 euro 3
Nexus 500 euro 3
Engine
160.2 mm
Removing the clutch
- To remove the clutch with the driven pulley it is
necessary to use the special tool;
- Arrange the tool with the mean pins screwed in
position "E" on the inside;
- Install the driven pulley unit onto the tool inserting
the pins into the ventilation holes;
- Move the rear stop screw in abutment against the
fixed driven pulley as shown in the figure.
CAUTION
THE TOOL SHOULD BE FIRMLY SECURED IN A VICE USING THE SPECIAL TOOL. DO NOT
TIGHTEN THE REAR SCREW TOO MUCH AS THIS COULD CAUSE AN IRREVERSIBLE TOOL
DEFORMATION.
USING THE SPECIAL 55-MM WRENCH, REMOVE THE FASTENING RING NUT.
LOOSEN THE TOOL SCREW AND DISASSEMBLE THE DRIVEN PULLEY UNIT, CLUTCH, SPRING
WITH SHEATH.
Specific tooling
020444Y Tool for fitting/ removing the driven pulley clutch
Pin retaining collar
- Extract the collar using 2 screwdrivers.
- Remove the 4 guide pins.
- Extract the moving driven half-pulley.
ENG - 7
Engine
Nexus 500 euro 3
Removing the driven half-pulley bearing
- Check that the bushing is free from wear and
damage; otherwise replace the fixed driven halfpulley.
- Remove the lock ring using pliers.
- Using the special tool inserted through the roller
bearing, pull out the ball bearing.
N.B.
PROPERLY SUPPORT THE PULLEY TO PREVENT DAMAGING THE THREADING.
Specific tooling
020376Y Adaptor handle
020456Y Ø 24 mm adaptor
020363Y 20 mm guide
N.B.
IF YOU NEED TO OVERHAUL THE BEARINGS ON AN ASSEMBLED DRIVEN PULLEY UNIT, IT IS
NECESSARY TO SUPPORT THE UNIT BY THE BELL
Specific tooling
001467Y002 Driver for OD 73 mm bearing
- Remove the roller bearing using the special tool,
supporting the fixed half-pulley with the bell.
Specific tooling
020376Y Adaptor handle
020375Y Adaptor 28 x 30 mm
020364Y 25-mm guide
001467Y002 Driver for OD 73 mm bearing
ENG - 8
Nexus 500 euro 3
Engine
Inspecting the driven fixed half-pulley
- Check that the belt contact surface is free from
wear.
- Measure the outer diameter of the pulley bushing.
Characteristic
Minimum admissible diameter
49.96 mm
Standard diameter:
49.965 mm
Inspecting the driven sliding half-pulley
- Check that the belt contact surface is free from
wear.
- Remove the 2 inside sealing rings and the 2 outside O-rings.
- Measure the movable half-pulley bushing inside
diameter.
Characteristic
Maximum admissible diameter:
50.08 mm
Standard diameter:
50.085 mm
Refitting the driven half-pulley bearing
- Install a new roller bearing using the special tool.
N.B.
PLACE THE BEARING WITH THE WRITINGS AND THE EMBEDDED OIL GUARD FACING OUTWARDS.
- Properly support the half-pulley to prevent damaging the threading.
If you are working on the driven pulley unit fully assembled, use the special tool.
ENG - 9
Engine
Nexus 500 euro 3
Specific tooling
020478Y Punch for driven pulley roller casing
001467Y002 Driver for OD 73 mm bearing
- Install a new ball bearing using the special tool.
Specific tooling
020376Y Adaptor handle
020477Y Adaptor 37 mm
020363Y 20 mm guide
- Insert the seeger lock ring.
Refitting the driven pulley
- Insert the new oil guards
- Insert the new O-rings
N.B.
O-RINGS ARE OF TWO SIZES. THE LARGE ONE IS INSTALLED ON THE MACHINING END RADIUS, AT THE BASE OF THE HALF-PULLEY.
- Install the half-pulley on the bushing being careful
not to damage the top sealing ring during the introduction.
- Make sure the pins and collar are not worn, reassemble the pins and collar.
- Using a bent beak greaser, lubricate the driven pulley unit with about 10 gr. of grease, this operation
should be carried out through one of the two holes into the bushing to obtain the exit of the grease from
the opposite hole. This operation is necessary to avoid the presence of grease beyond the O-rings.
Recommended products
AGIP GREASE SM 2 Grease for the tone wheel revolving ring
ENG - 10
Nexus 500 euro 3
Engine
Soap-based lithium grease containing NLGI 2 Molybdenum disulphide; ISO-L-XBCHB2, DIN KF2K-20
Inspecting the clutch spring
- Measure the length of the spring, while it is relaxed.
Characteristic
Standard length:
125.5 mm
Admissible limit after use:
120 mm
- Check the thickness of the clutch mass friction material.
Characteristic
Minimum thickness permitted:
1 mm
- The masses must exhibit no traces of lubricants;
in that case, check the driven pulley unit seals.
N.B.
UPON RUNNING-IN, THE MASSES MUST EXHIBIT A CENTRAL CONTACT SURFACE AND MUST
NOT BE DIFFERENT FROM ONE ANOTHER. VARIOUS CONDITIONS CAN CAUSE THE CLUTCH
TO TEAR.
- Do not open the masses using tools to prevent a variation in the return spring load.
ENG - 11
Engine
Nexus 500 euro 3
Refitting the clutch
Bell assembly
- Install the bell and the spacer.
- Prepare the special tool as for removal;
- Preassemble the driven pulley unit with the drive
belt according to its direction of rotation;
- Insert the driven pulley unit, the spring with
sheath and clutch into the tool.
Specific tooling
020444Y Tool for fitting/ removing the driven
pulley clutch
- Compress the spring and insert the clutch on the driven pulley bushing.
N.B.
BE CAREFUL NOT TO DAMAGE THE SHEATH OR THE BUSHING THREADED END.
- Tighten the ring nut by hand and complete the
tightening using the special wrench to the prescribed torque.
Specific tooling
020444Y Tool for fitting/ removing the driven
pulley clutch
Locking torques (N*m)
Clutch ring nut 65 - 75
- To facilitate reassembly on the engine, turn the moving driven pulley and insert the belt onto the smaller
diameter.
ENG - 12
Nexus 500 euro 3
Engine
Refitting the driven pulley
- Install the driven pulley assembly with belt.
Drive-belt
- Check that the driving belt is not damaged.
- Check the width of the belt.
Characteristic
Minimum width:
25 mm
Standard width:
26.2 mm
Removing the driving pulley
- Using a 27 mm wrench, turn the central pulley nut
to horizontally align the central inside holes and
install the special tool.
Specific tooling
020474Y Driving pulley lock wrench
ENG - 13
Engine
Nexus 500 euro 3
- First install the lock ring of the special tool onto
the pulley so that the splines are completely engaged.
- Then, insert the tool so as to insert the stud bolts
on the ring into the holes obtained onto the tool
itself.
- Tighten the two tool fastening nuts, also by hand.
- Loosen the central nut.
- Remove the spring washer and the flat washer.
- Remove the fixed driving half-pulley.
- Remove the bushing connection washer.
- Move the belt downwards.
- Suitable support the roller contrast and extract
the mobile driving half-pulley with the relevant
bushing and the rear washer, being careful not to
make the rollers come out.
Inspecting the rollers case
- Check that the inside bushings shown in the figure are not worn and measure the inside diameter.
CAUTION
DO NOT LUBRICATE OR CLEAN THE BUSHINGS
Characteristic
Maximum admissible diameter:
30.12 mm
Standard diameter:
30.021 mm
- Measure the pulley sliding bushing outside diameter shown in the figure.
Characteristic
ENG - 14
Nexus 500 euro 3
Engine
Minimum admissible diameter
Ø 29.95 mm
Standard diameter:
Ø 29.959 mm
- Check that the rollers are not damaged or worn.
Characteristic
Minimum admissible diameter
Ø 24.5 mm
Standard diameter:
Ø 24.9 mm
- Check the guide shoes for the variator back-plate
are not worn.
- Check the wear of the roller housings and of the
belt contact surfaces on both pulley halves.
Refitting the driving pulley
Installing the fixed driving half-pulley
- Insert the spacer.
- Install the fixed driving half-pulley and check that
it is in contact with the spacer and with the guide
bushing of the moving driving pulley.
ENG - 15
Engine
- Remove the flat washer and the spring washer
as shown in the figure.
- Insert the nut in the original position (nut side in
contact with the belleville washer).
- Turn the central pulley nut to horizontally align
the holes and install the special tool.
N.B.
CHECK THAT THE STOP WRENCH TOOL IS
EASILY INSERTED INTO THE PULLEY AND IN
THE ENGINE CRANKCASE.
Specific tooling
020474Y Driving pulley lock wrench
- Install the lock ring from the rear so that the
splines are completely engaged.
- Finally install the tool by siding the nuts by hand
and ensuring the tool is resting flatly.
- Tighten the driving pulley fastening nut to the
prescribed torque
- Remove the special tool.
Locking torques (N*m)
Drive pulley nut 160 - 175
ENG - 16
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Installing the roller container
- Install the spacer with the internal chamfer facing
towards the inside.
- Position the rollers on the half-pulley as shown in
the figure.
- The closed side must rest on the inside thrust
face of the roller container.
- Assembly the half-pulley with the roller contrast
plate and sliding blocks.
- Insert the half-pulley on the crankshaft.
- Insert the spacer bushing.
ENG - 17
Engine
Nexus 500 euro 3
Refitting the transmission cover
- Install the driving pulley shaft cover, positioning
the tooth gap on the lower part with the reference
mark on the transmission crankcase.
N.B.
ENSURE THAT THE AIR INTAKE AND EXHAUST OPENINGS ARE COMPLETELY FREE.
- Install the outside plastic transmission cover.
- Tighten the 4 fastening screws to the prescribed
torque.
Locking torques (N*m)
Outside transmission cover screws 7 ÷ 9
- Ensure the correct installation on the crankcase
of the 2 centring dowels.
- Insert the transmission cover with the bearing
and install the relevant retainers.
- Lock the four M8 retainers.
Locking torques (N*m)
M8 retainers for transmission cover 23 - 26
ENG - 18
Nexus 500 euro 3
Engine
- Lock the 7 M6 retainers.
Locking torques (N*m)
M6 retainer 11 ÷ 13
- Insert the washers on the driven pulley shaft.
N.B.
INSERT THE SMALLER WASHER FIRST, THEN THE LARGER ONE.
- Insert the flanged nut.
- Prepare the torque wrench for LHS locking using
a machine hexagon wrench.
- Tighten the driven pulley shaft fastening nut using
an offset wrench.
N.B.
DUE TO THE HIGH TIGHTENING TORQUE, USING DIFFERENT WRENCHES - SUCH AS A
CONVENTIONAL POLYGONAL BUSH - MAY
DAMAGE THE HEXAGON OBTAINED ON THE
SHAFT OR BREAK THE BUSH ITSELF.
Locking torques (N*m)
Driven pulley nut 92 - 100
End gear
Removing the hub cover
- Drain the rear hub oil through the oil drainage cap
located under the engine.
- Drain the rear hub oil through the oil drainage cap
located under the engine.
-Remove the 7 fastening screws. Remove the hub
cover and the relevant gasket.
ENG - 19
Engine
Removing the wheel axle
- Remove the countershaft.
- Remove the wheel axis complete with gear.
Removing the hub bearings
- Support the hub cover using the column kit.
- Pull out the bearing using the special tool.
Specific tooling
020476Y Stud bolt set
001467Y006 Pliers to extract 20 mm bearings
001467Y007 Driver for OD 54 mm bearing
- Check all bearings (wear, clearance and noise).
In case of anomalies, proceed as follows.
To remove the gear shaft bearing on the engine
crankcase, use the following parts.
Specific tooling
001467Y014 Pliers to extract ø 15-mm bearings
001467Y034 Extraction pliers for ø 15 mm bearings
001467Y031 Bell
ENG - 20
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Use the special extractor to disassemble the
bearing on the engine chassis of the countershaft.
Specific tooling
001467Y006 Pliers to extract 20 mm bearings
001467Y035 Belle for OD 47-mm bearings
Removing the wheel axle bearings
- Take out the clip on the outside of the gearbox
cover.
- Support the hub cover using the column kit.
- Pull out the bearing using the special tool.
Specific tooling
020476Y Stud bolt set
020376Y Adaptor handle
020477Y Adaptor 37 mm
020483Y 30 mm guide
- Remove the oil guard using a screwdriver.
ENG - 21
Engine
Removing the driven pulley shaft bearing
- If you have to remove the driven pulley shaft, the
relevant bearing and the oil guard, remove the
transmission cover and the clutch unit as described in the Automatic transmission chapter.
- Extract the driven pulley shaft from its bearing.
- Remove the oil guard using a screwdriver into the
hub gear box.
- Remove the seeger ring shown in the figure.
- Pull out the driven pulley shaft bearing from the
engine crankcase using the special tool.
Specific tooling
020376Y Adaptor handle
020358Y 37x40-mm adaptor
020364Y 25-mm guide
Inspecting the hub shaft
- Check that the 3 shafts exhibit no wear or deformation on the grooved surfaces, at the bearings
and at the oil guards.
- In case of faults, replace the damaged parts.
Characteristic
Connection diameter for countershaft:
A = diameter 20 - 0.01 -0.02 mm
Connection diameter for wheel shaft:
B = diameter 30 - 0.010 -0.023 mm
C = diameter 15 - 0.01 -0.02 mm
Connection diameter for shaft driven pulley:
D = diameter 17 - 0.01 -0.02 mm
E = diameter 20 - 0.01 -0.02 mm
F = diameter 25 - 0.01 -0.02 mm
ENG - 22
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Inspecting the hub cover
- Check that the mounting surface is not damaged or deformed.
- Check the bearing bearings.
In case of faults, replace the hub cover.
Refitting the driven pulley shaft bearing
- Heat the crankcase using the heat gun.
Specific tooling
020151Y Air heater
- Insert the driven pulley shaft bearing until it abuts
against the bottom of the seat using the special
tool.
N.B.
PLACE IT WITH THE BALLS FACING THE HUB
(THIS APPLIES TO BEARINGS WITH PLASTIC
CAGE).
Specific tooling
020376Y Adaptor handle
020360Y Adaptor 52 x 55 mm
020364Y 25-mm guide
- Heat the intermediate gear bearing seat.
- Insert the intermediate shaft bearing using the
special tool.
N.B.
PLACE IT WITH THE BALLS FACING THE HUB
(THIS APPLIES TO BEARINGS WITH PLASTIC
CAGE).
Specific tooling
020376Y Adaptor handle
020359Y 42x47-mm adaptor
020363Y 20 mm guide
ENG - 23
Engine
- Heat the gear shaft bearing seat on the crankcase.
- Insert the gear shaft bearing in the upper crankcase seat using the special tool.
N.B.
PLACE IT WITH THE BALLS FACING THE HUB
(THIS APPLIES TO BEARINGS WITH PLASTIC
CAGE).
Specific tooling
020376Y Adaptor handle
020359Y 42x47-mm adaptor
020412Y 15 mm guide
- Place the safety lock seeger ring of the driven
pulley shaft bearing.
N.B.
PLACE IT IN THE POSITION SHOWN IN THE
FIGURE.
- Insert the pulley shaft oil guard on the transmission side.
ENG - 24
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Refitting the hub cover bearings
- Heat the bearing seats on the cover using the
heat gun.
- Support the hub cover using the column kit.
Specific tooling
020151Y Air heater
020476Y Stud bolt set
- Insert the intermediate shaft bearing on the cover
using the special tool.
N.B.
PLACE IT WITH THE BALLS FACING THE HUB
(THIS APPLIES TO BEARINGS WITH PLASTIC
CAGE).
Specific tooling
020376Y Adaptor handle
020360Y Adaptor 52 x 55 mm
020363Y 20 mm guide
- Heat the gear shaft bearing seat from the cover
outside.
- Insert the gear shaft bearing on the cover using
the special punch until abutment.
Specific tooling
020376Y Adaptor handle
020360Y Adaptor 52 x 55 mm
020483Y 30 mm guide
- Replace the snap ring
ENG - 25
Engine
Nexus 500 euro 3
- Support the hub cover using the column kit.
- Insert the wheel shaft oil guard with the sealing
lip facing the inside of the cover.
- Place the oil guard flush with the crankcase.
Specific tooling
020376Y Adaptor handle
020360Y Adaptor 52 x 55 mm
020476Y Stud bolt set
Refitting the hub bearings
- Place the 3 shafts as shown in the figure.
Refitting the ub cover
- Check the proper position of the centring dowels.
- Install a new gasket.
- Fit the gearbox cover, making sure the breather
pipe is in the correct position.
- Position the 7 set screws, tighten them to the prescribed torque, being careful of the position of the
bands holding the vent tube, and the position of the 3 shortest screws as indicated in the figure.
- Refill with the prescribed oil to the Max. level.
Recommended products
AGIP ROTRA 80W-90 rear oil hub
SAE 80W/90 Oil that exceeds the requirements of API GL3 specifications
Characteristic
Quantity:
approx. 250 cc
ENG - 26
Nexus 500 euro 3
Engine
Locking torques (N*m)
Rear hub cover screws 24 ÷ 27
Flywheel cover
- Remove the three bands shown in the figure for
an easier removal of the flywheel cover, remove
the feed hoses and disconnect the return hose
from the pump cover.
N.B.
THE BANDS MUST BE REPLACED. TO REMOVE THEM, OPEN WITH A SCREWDRIVER
OR CUT THEM.
BE CAREFUL NOT TO DAMAGE THE PLASTIC
UNIONS.
Removing the hub cover
- Drain the engine oil by removing the drainage
cap.
- Prepare a suitable container to collect the oil.
- Remove the pre-filter.
ENG - 27
Engine
Nexus 500 euro 3
- Remove the oil filter using a filter tape or shaped
cup wrench.
- Loosen the 14 fastening screws.
- Remove the flywheel cover with the relevant gasket and the cooling system sleeve support.
N.B.
THE SCREWS ARE OF 4 DIFFERENT
LENGTHS. NOTE THE RELEVANT POSITIONS.
CAUTION
REMOVE THE COVER AVOIDING ANY POSSIBLE INTERFERENCE BETWEEN STATOR AND
ROTOR.
CAUTION
BE CAREFUL TO PREVENT SLIPPAGE OF THE BY-PASS VALVE AND OF THE RELEVANT
SPRING.
Removing the flywheel cover components
- Loosen the six mounting screws and remove the
water pump cover.
ENG - 28
Nexus 500 euro 3
Engine
- Remove the by-pass and the relevant spring.
- Remove the oil pump seal.
Removing the stator
- Remove the two retaining screws and the cable
guide bracket.
- Unscrew the 3 fastening screws and remove stator and its wiring.
- Loosen the two retaining screws and remove the
reed valve support with bulkhead.
ENG - 29
Engine
- Remove the blow-by reed valve with the relevant
sealing gasket.
- Unscrew the fastening screw and remove the gas
outlet union with the relevant O-ring.
- Remove the water pump impeller by unscrewing
it from the relevant shaft.
N.B.
THE THREADING IS CLOCKWISE. IT IS ADVISABLE TO PREVENT THE SHAFT ROTATION
BY INSERTING A 12-MM WRENCH INTO THE
DRIVE.
- Extract the shaft with the relevant abutment
washer.
ENG - 30
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Remove the sealing ring.
- Remove the ceramic ring and the relevant gasket.
- Remove the sealing ring for the pump shaft lubrication using a suitably shaped tool.
- Remove the engine oil filling cap/dipstick and the
check hole cover for the distribution timing.
- Remove the minimum oil pressure sensor.
ENG - 31
Engine
Inspecting the cover components
- Install a new oil filter, lubricate the gasket, screw
on and finally tighten to the prescribed torque.
Locking torques (N*m)
Engine oil filter 12 - 16
- Install the supply hose to the cylinder and connect the return hose to the pump cover using 3 new
clamps.
N.B.
TIGHTEN THE CLAMPS USING APPROPRIATE
PLIERS, PAYING ATTENTION NOT TO CONSTRICT THE HOSES BUT ALSO TAKING CARE
TO TIGHTEN THE CLAMPS SUFFICIENTLY.
- Install the pre-filter again and insert the engine oil
drain plug, tightening to the prescribed torque.
- Refill the engine with the prescribed type of oil.
Recommended products
AGIP CITY HI TEC 4T Engine oil
SAE 5W-40, API SL, ACEA A3, JASO MA Synthetic oil
Locking torques (N*m)
Engine oil drainage plug 24 ÷ 30
- Check the condition of the stator and of the respective cable harness.
ENG - 32
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Check the continuity between the 3 phases.
N.B.
VALUES ARE STATED AT AMBIENT TEMPERATURE. A CHECK WITH THE STATOR AT OPERATING TEMPERATURE MAY RESULT IN
VALUES HIGHER THAN THOSE STATED.
Electric characteristic
Resistance:
0.2 - 1 Ω
- Check the ground insulation of each phase.
- If a fault is found, carry out a thorough check of
the cable harness that contains two types of cable:
Rigid cables close to the stator and flexible cables
close to the connector.
- Check that the winding is positioned so as not to
interfere with the heads of the retaining screws.
- Check that the mounting surface of the crankcase
is not worn or deformed.
- Check that the by-pass valve seat, the torque
limiter and the water pump shaft are free from
wear.
Characteristic
By-pass housing hole diameter:
13.9 mm
Connection diameter for start-up gear shaft:
12 mm
Connection diameter for pump shaft:
8 mm
ENG - 33
Engine
- Check that the oil filter union and matching surface exhibit no deformations or wear.
Refitting the stator
- Install the stator assembly together with the wiring harness, tightening the 3 screws to the prescribed torque.
N.B.
INSERT THE RUBBER WIRING SEALING GASKET INTO THE SPECIAL SEAT ON THE
CRANKCASE.
Locking torques (N*m)
Stator retainers 8 - 10
- Install the wiring guide bracket tightening the 2
screws to the prescribed torque.
Locking torques (N*m)
Stator cable harness guide bracket screws 3 4
- Temporarily install the distribution timing check
hole cover and the engine oil filling cap/bar.
- Insert the blow-by recovery duct using a new Oring.
- Tighten the screws to the prescribed torque.
Locking torques (N*m)
Blow-by recovery duct fixing screws 3 - 4
ENG - 34
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Insert the spring and the by-pass piston on the
flywheel cover.
N.B.
LUBRICATE THE BY-PASS VALVE.
Refitting the flywheel cover components
- Before reassembling, check that all components
are perfectly clean.
- For the cover, carefully check all lubrication channels, in particular:
- The 3 by-pass channels.
- Oil feeding duct at the water pump shaft connection.
- Pump drainage duct.
ENG - 35
Engine
- Oil pressure sensor feeding duct.
- Oil vapour decantation chamber
- Reinstall the blow-by reed valve using a new
sealing gasket.
- Reinstall the support with head and tighten the
screws to the prescribed torque.
Locking torques (N*m)
Supporting screws with bulkhead 0.3 - 0.4
- Install a new sealing ring for the pump shaft using
the special tool
- Install the oil minimum pressure sensor and tighten to the prescribed torque.
Specific tooling
020376Y Adaptor handle
020412Y 15 mm guide
Locking torques (N*m)
Minimum oil pressure sensor 12 ÷ 14
ENG - 36
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Pre-assemble the ceramic seal and the relevant
gasket.
N.B.
PLACE THE CHAMFERING TOWARDS THE
GASKET BEING CAREFUL NOT TO FOUL THE
CERAMIC RING WITH OIL OR GREASE,
WHICH WOULD IMPAIR THE SEAL.
- Insert the ceramic seal on the flywheel cover.
N.B.
ASSEMBLE BY HAND TO PREVENT DAMAGES TO THE CERAMIC SEAL.
- Insert the water pump shaft after lubricating the
flywheel cover seat.
- Insert the mechanical seal on the shaft up to the
impeller abutment surface.
N.B.
THE FINAL INTRODUCTION DEPTH WILL BE
DETERMINED BY THE IMPELLER.
- Screw the impeller and tighten to the prescribed
torque.
Locking torques (N*m)
Water pump impeller 4 ÷ 5
Refitting the flywheel cover
- Lubricate the intermediate gear seat with torque
limiter on the flywheel cover.
- Align the water pump movement sensor with a
reference and install the flywheel cover as described in the Flywheel cover chapter.
ENG - 37
Engine
Nexus 500 euro 3
- Install a new gasket on the engine crankcase.
- Check the presence of the three centring dowels.
- Turn the crankshaft in order to align the countershaft movement sensor with a reference point on
the crankcase (see figure).
- Repeat the alignment for the water pump crankshaft using the same reference point on the engine.
N.B.
THIS PREPARATION IS USEFUL PARTICULARLY IN THE EVENT OF REPAIRS WITH THE
WATER PUMP COVER INSTALLED.
- Install the flywheel cover on the engine, paying attention to avoid interference between the stator and
rotor.
WARNING
FAILURE TO OBSERVE THIS INSTRUCTION MAY RESULT IN DESTRUCTION OF THE CERAMIC
MAGNETS.
- Tighten the 14 retaining bolts of the cover to the
prescribed torque.
N.B.
THE BOLTS HAVE FOUR LENGTHS:
- THE 3 SHORTEST ARE INSERTED AS
SHOWN IN THE FIGURE.
- THE LONGEST IS INSERTED UNDER THE ENGINE OIL FILLER PLUG.
ENG - 38
Nexus 500 euro 3
Engine
N.B.
- THE INTERMEDIATE BOLTS FOR THE REMAINING MOUNTING POINTS WITH THE EXCEPTION OF THE BOLT FOR THE MANIFOLD
SUPPORT (SHOWN IN THE FIGURE) ARE
SLIGHTLY LONGER.
Locking torques (N*m)
Flywheel cover screws 11 - 13
Flywheel and starting
The starter is sold as a complete part.
Before deciding to replace it, carry out the following tests:
1 - Battery
Check the voltage after not running (a few hours):
Voltage >12.5V
Check the density of the electrolyte of each cell:
Bé = 30 ÷ 32
Specific weight: 1.25 - 1.26
YES go to 2 NO go to 3
2 - Make sure the negative terminals (battery negative and starter negative) are correctly connected
to each other and to the frame.
YES go to 4 NO go to 5
3 - Recharge and if necessary replace the battery.
4 - Connect the diagnostic tester (see chapter "Injection system").
Connect the induction clamp of an ammeter to the positive power supply cable of the starter motor.
Remove the 10A fuse no. 12 (see "fuses" chapter).
Switch in position "ON" with interrupt switch in position "RUN" and side stand raised.
Select the "PARAMETERS" function.
Start the engine (so that it cannot move) long enough to measure the rpm and starter absorption.
N.B.
THE DECLARED RPM VALUE IS THAT INDICATED BY THE TESTER, THE RPM READING IS NOT
THE REAL ONE, BUT IS VALID FOR DIAGNOSTIC PURPOSES.
Specific tooling
020460Y Scooter diagnosis and tester
Electric characteristic
Absorption at trailing speed:
ENG - 39
Engine
Nexus 500 euro 3
80 - 120 A
Revolution speed =
approx. 300-400 rpm
YES go to 6 NO go to 7 NO go to 8 NO go to 9
5 - Restore the connections
6- The values are correct.
Finally carry out a check of the power consumption at idle speed.
Remove the starter motor (see the flywheel and starter system).
Reconnect the earth and positive and perform the test.
Electric characteristic
Current consumption at idle speed:
<40 A
YES go to 10 NO go to 11
7- Low trailing speed
High electrical absorption
Carry out a test of the engine rotation (example: possible melting of the bushes) and if no anomalies
are found, replace the starter motor.
8- Low trailing speed
Low electrical absorption
Repeat the test, bridging the power terminals of the starter remote control switch or even better replacing
them.
Check the new values.
YES go to 12 NO go to 13
9 - High trailing speed
Low electrical absorption
The engine turns too freely, check the compression end pressure.
If the values are not correct proceed as follows.
10 - The starter motor works properly.
11 - Check the rotation of the armature.
12 - Replace the starter remote control switch.
13 - Test the battery again and if necessary replace the starter motor.
ENG - 40
Nexus 500 euro 3
Engine
N.B.
IF THE TRAILING SPEED OF THE CRANKSHAFT IS LOW AND COMBINED WITH STRANGE
NOISE, CHECK THE FREEWHEEL OF THE TORQUE LIMITER (SEE THE "FLYWHEEL AND
STARTER SYSTEM" CHAPTER).
STARTER MOTOR
Specification
Type
Power
Desc./Quantity
Mitsuba sm13d
0.9 kW
BATTERY
Specification
Capacity
Starting current
Desc./Quantity
14 Ah
125 A
START-UP REMOTE CONTROL SWITCH
Specification
Type
Maximum load
Desc./Quantity
SEALED
150 A continuous
STARTER TRANSMISSION
Specification
Ring gear and freewheel coaxial to the flywheel.
Desc./Quantity
Intermediate gear with built-in torque limiter.
The starter system has a transmission between the motor armature and engine shaft equipped with
freewheel coaxial to the flywheel and torque limiter on the intermediate shaft.
The limiter is calibrated to 10 kgm (100 Nm); this component protects the structure of the engine and
the starter kinematic mechanism in the event of incorrect starting with consequent inverse rotations.
The freewheel is used for a sufficiently silent starting.
The starter control (energised remote control) is slaved to enabling signals by the side stand and the
emergency OFF/RUN switch, which does not allow starting given dangerous conditions.
The starter control circuit is not controlled by the immobilizer system, therefore before insisting on the
starter system, check the consensus of the immobilizer.
As for checking the consensus circuit, see the "Electrical system" chapter, while for checking the engine
shaft control transmission, follow what is described in the "Flywheel and starter system" chapter.
- Remove the three bands shown in the figure for
an easier removal of the flywheel cover, remove
the feed hoses and disconnect the return hose
from the pump cover.
N.B.
THE BANDS MUST BE REPLACED. TO REMOVE THEM, OPEN WITH A SCREWDRIVER
OR CUT THEM.
BE CAREFUL NOT TO DAMAGE THE PLASTIC
UNIONS.
ENG - 41
Engine
Nexus 500 euro 3
Removing the starter motor
N.B.
THIS OPERATION MAY ALSO BE CARRIED OUT WITH FLYWHEEL COVER ASSEMBLED.
- Loosen the two fastening screws.
- Extract the complete starter motor.
Removing the flywheel magneto
N.B.
IF YOU MUST REMOVE THE FLYWHEEL, IT IS NECESSARY TO REMOVE THE CHAIN GUIDE
SLIDING BLOCK RETAIN PLATE FIRST.
- Unscrew the 3 fastening screws and remove the
chain guide sliding block retain plate and the startup rim.
- Align the holes obtained on the flywheel with the
crankcase housing to allow the introduction of the
special tool.
ENG - 42
Nexus 500 euro 3
Engine
- Tighten the bushing of the flywheel lock tool on
the removing tool threading.
- Insert the special tool as shown in the figure,
making sure that the pins are perfectly inserted into the previously aligned holes and that it is perfectly abutted and almost flush with the flywheel.
Specific tooling
020472Y Flywheel lock wrench
- Loosen the magneto flywheel fastening nut.
- Remove the special tool and the fastening nut.
- Remove the washer.
ENG - 43
Engine
- Insert the nut again so as to slightly uncover the
shaft and free the space that was occupied by the
washer.
CAUTION
THIS OPERATION IS REQUIRED AS THE FLYWHEEL IS STRONGLY LOCKED; THE CONE
DETACHMENT MAY THEREFORE CAUSE THE
ROTOR SLIPPAGE, WITH THE CONSEQUENT
BREAKAGE OF THE MAGNETS.
- Insert the special removing tool.
- Using a 27-mm wrench and a 19-mm bushing,
release the flywheel.
Specific tooling
020467Y Flywheel extractor
- Remove the extractor.
- Remove the nut and extract the flywheel with the
start-up rim.
- Remove the crankshaft key.
- To remove the start-up rim from the freewheel it
is necessary to turn it clockwise and pull it out.
ENG - 44
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Remove the freewheel from the flywheel by loosening the 6 fastening screws.
SINCE THE FREEWHEEL MUST BE REMOVED,
IT IS ADVISABLE TO LOOSEN THE 6 FASTENING SCREWS IN ADVANCE WITH THE FLYWHEEL STILL INSTALLED ON THE CRANKSHAFT.
- The freewheel is coupled to the flywheel with high
precision; if removal is difficult, use 2 screws as
gripping points and as removing tools, if required.
- Extract the intermediate gear provided with torque limiter.
Inspecting the flywheel components
- Check the integrity of the magnets.
- Check that the magnet support cage is free from
deformation or cracks.
- Check that the flywheel splines exhibit no loosening.
ENG - 45
Engine
Nexus 500 euro 3
Starter gear rim
- Check that there is no wear or abnormal impressions on the "rollers" of the freewheel and on the
surface of the starter ring gear hub.
- Check the hub outside diameter.
Characteristic
Hub outside diameter:
Diameter 45.665 + 0.008 +0.005 mm
- Check the inside diameter of the bushing of the
starter gearing.
- Check that the toothing is not worn.
Characteristic
Inside diameter of the bushing:
Diameter 27 + 0.020 +0.041 mm
N.B.
IF THE FAULTS DISCOVERED AFFECT THE HUB, REPLACE THE STARTER RING GEAR AND
FREEWHEEL.
IF ONLY THE BUSHING IS WORN, IT IS POSSIBLE TO REPLACE ONLY THE COMPLETE STARTUP RIM. IN THAT CASE, CHECK ALSO THE DIAMETER AND THE SURFACE OF THE CONNECTION ON THE CRANKSHAFT. IN CASE OR IRREGULARITIES, REPLACE THE CRANKSHAFT.
Intermediate gear
- Check that the toothing is not worn.
- Check the diameter of the two bearings.
Characteristic
Gear bearing diameter:
12 - 0 0.011 mm
ENG - 46
Nexus 500 euro 3
Engine
Also check the shaft diameter on the flywheel cover and on the engine crankcase.
Characteristic
Bearing diameter on the flywheel cover
12 + 0.034 -0.016 mm
Bearing diameter on the engine crankcase:
12 + 0.034 -0.016 mm
N.B.
THE TORQUE LIMITER IS PROVIDED WITH 4 GEARS THAT HAVE THE FUNCTION OF CLUTCH
DRIVE PLATES.
Driven plates consist of 4 Belleville springs provided with grooved profiles; this assembly allows
transmitting torque lower than 10 kgm.
In case of incorrect start-up manoeuvres, the limiter prevents any kicks, with consequent reversal
of direction of the crankshaft which would impair
the engine structure.
The limiter assembly cannot be overhauled. In case of irregularities on the toothed discs, replace the
assembly.
Refitting the free wheel
- Make sure the freewheel faying surfaces are in good condition.
- Thoroughly clean the free wheel to remove LOCTITE residue.
- Degrease the threading of the holes in the free wheel and the clamping screws.
- Apply the recommended product to the end of the screws.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
ENG - 47
Engine
- Fit the freewheel on the magneto flywheel making
sure that the ground side is in contact with the flywheel itself, i.e. with wheel Seeger ring visible.
- Lock the six clamping screws in criss-cross fashion to the prescribed torque.
Locking torques (N*m)
Screw fixing freewheel to flywheel 13 ÷ 15
- Oil the free wheel "rollers".
Refitting the intermediate gear
- Lubricate the gear housing on the engine crankcase.
- Insert the intermediate gear with torque limiter
ENG - 48
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Lubricate the inside bushing and the starter ring
gear hub surface.
- Install the start-up rim on the flywheel turning it
clockwise and inserting at the same time.
Refitting the flywheel magneto
- Insert the key on the crankshaft.
- Install the flywheel checking the proper insertion
of the key and engaging the torque limiter gear
with the start-up rim.
- Insert washer and nut on the crankshaft.
ENG - 49
Engine
- Tighten thoroughly the guide bushing of the flywheel lock tool and loosen by 1/4 turn.
N.B.
FAILURE TO OBSERVE THIS RULE CAUSES
THE LOCKING OF THE GUIDE ON THE FLYWHEEL.
Specific tooling
020472Y Flywheel lock wrench
- Align the 2 holes of the flywheel with the case
housing to allow the introduction of the special tool.
- Insert the special tool checking that the pins are
perfectly introduced into the seat.
Specific tooling
020472Y Flywheel lock wrench
- Tighten the flywheel lock nut to the prescribed
torque.
Locking torques (N*m)
Flywheel fixing nut 115 - 125
ENG - 50
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Install the chain guide retain plate tightening the
3 screws to the prescribed torque.
N.B.
BEFORE TIGHTENING THE SCREWS, MOVE
THE START-UP RIM IN CONTACT WITH THE
CRANKCASE AND CHECK THAT IT IS FREE
TO ROTATE IN ANTICLOCKWISE DIRECTION.
Locking torques (N*m)
Chain guide sliding block retain plate fastening screws 3 ÷ 4
Refitting the starter motor
- Check that the O-ring is in good working order
and lubricate it.
- Insert the starter motor.
- Tighten the 2 fastening screws to the prescribed
torque.
Locking torques (N*m)
Starter motor screws 11 ÷ 13
Cylinder assy. and timing system
- Remove the external and internal transmission
cover.
- Remove the flywheel cover, the flywheel and the
torque limiter.
ENG - 51
Engine
Removing the intake manifold
- Remove the 3 mounting screws.
- Remove the intake manifold unit.
Removing the rocker-arms cover
- Loosen the 6 special screws with stop and the
relevant rubber gaskets.
- Remove the tappet cover with relevant gasket.
Removing the timing system drive
- Turn the engine to close the intake valves, i.e.,
moving the reference on the tone wheel to the top,
as shown in the figure.
ENG - 52
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Remove the central screw and the valve lifting
device mass stop bell using the special tool.
Specific tooling
020565Y Flywheel lock calliper spanner
- Remove the return spring and the valve lifting
mass with relevant travel end washer.
N.B.
BE CAREFUL NOT TO ALLOW THE WASHER
AND SPRING TO FALL INTO THE ENGINE
THROUGH THE CHAIN COMPARTMENT.
- Align the references located on the tone wheel
and on the head.
- Loosen the central screw on the tensioner first.
- Unscrew the 2 fastening screws and remove the
tensioner with relevant gasket.
ENG - 53
Engine
Remove the inside hexagon screw and the counterweight as shown in the figure.
- Remove the timing belt rim from the camshaft.
- Remove the timing belt rim.
- Remove the tone wheel.
- Remove the engine revolution timing sensor and
relevant O-ring by loosening the fastening screw
and removing the mounting band from the special
hole obtained on the head gasket.
N.B.
TO CHECK THIS COMPONENT, SEE THE INJECTION CHAPTER.
ENG - 54
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Removing the cam shaft
- Unscrew the 3 fastening screws and remove
camshaft retaining bracket.
N.B.
REMOVING THE FASTENING SCREWS MAY
BE DIFFICULT. BE CAREFUL NOT TO DAMAGE THE INSIDE HEXAGON. IF NECESSARY,
SEPARATE THE THREADS IN ADVANCE.
- Remove the cam shaft.
- Remove pins and rocking levers by the transmission side holes.
Removing the cylinder head
- Remove the spark plug.
- Remove the cooling system outlet sleeve with
thermostat.
ENG - 55
Engine
Nexus 500 euro 3
- Remove the coolant temperature sensor.
N.B.
THE SENSOR CONTROLS BOTH INJECTION
AND THE ANALOGUE INSTRUMENT ON THE
PANEL. TO CHECK THIS COMPONENT, SEE
THE INJECTION CHAPTER.
- Remove the 2 fastening nuts on the head, on the
exhaust and on the intake side.
- Remove the two M6 screws into the distribution
channel and the M6 screw on the spark plug side
with the thermostat support.
N.B.
THE HEAD MAY BE REMOVED WITH THE CAMSHAFT, ROCKING LEVER PINS AND FITTING
BRACKET IF NECESSARY.
- Loosen the 4 head-cylinder fastening nuts in 2 or
3 times and in a crossed sequence.
- Remove the head, the 2 centring dowels, the
gasket and the lower chain guide sliding block.
N.B.
DO NOT REMOVE THE DOWELS IF THEY ARE
FORCED INTO THEIR SEAT.
CAUTION
WHEN YOU HAVE TO REMOVE THE HEAD, PREPARE A SUITABLE CONTAINER SINCE THE
THERMAL UNIT CONTAINS COOLANT.
ENG - 56
Nexus 500 euro 3
Engine
Removing the valves
- Using the appropriate tool fitted with an adaptor,
remove the cotters, caps, springs and valves.
Specific tooling
020382Y Valve cotters equipped with part 012
removal tool
020382Y012 bush (valve removing tool)
CAUTION
ARRANGE THE VALVES SO AS TO RECOGNISE THE ORIGINAL POSITION ON THE HEAD (FLYWHEEL SIDE AND TRANSMISSION SIDE).
- Remove the oil guards using the special tool.
Specific tooling
020431Y Valve oil seal extractor
- Remove the spring supports.
N.B.
BLOW THE SEATS WITH COMPRESSED AIR
TO FACILITATE THE SPRING SUPPORT REMOVAL.
ENG - 57
Engine
Removing the cylinder - piston assy.
- Remove the timing chain.
- Loosen the fastening screw and remove the
spacer and the tightening sliding block.
N.B.
IT IS ADVISABLE TO MARK THE CHAIN IN ORDER TO ENSURE THAT THE INITIAL DIRECTION OF ROTATION IS MAINTAINED.
- Extract the cylinder with the relevant gasket and
the centring dowel.
N.B.
THE SECOND CENTRING IS ENSURED BY A
PIN SET INTO THE CYLINDER.
CAUTION
TO PREVENT DAMAGES TO THE PISTON,
SUPPORT IT WHILE REMOVING THE CYLINDER.
- Remove the 2 piston pin locking rings by the specific housings.
- Extract the pin and remove the piston.
N.B.
USE PAPER OR A CLOTH TO CLOSE THE CYLINDER HOUSING MOUTH ON THE CRANKCASE TO PREVENT SLIPPAGE OF ONE OF
THE PIN LOCKING RINGS INTO THE CASE.
- Remove the piston sealing rings and the oil scraper.
CAUTION
NOTE THE ASSEMBLY POSITIONS OF THE
LININGS TO PREVENT INVERTING THE POSITION IN CASE OF REUSE.
N.B.
BE CAREFUL NOT TO DAMAGE THE SEALING
RINGS DURING REMOVAL.
ENG - 58
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Inspecting the small end
- Using a bore gauge, measure the connecting rod
small end diameter.
N.B.
IF THE CONNECTING ROD SMALL END DIAMETER EXCEEDS THE STANDARD DIAMETER,
EXHIBITS WEAR OR OVERHEATING, PROCEED TO REPLACE THE CRANKSHAFT AS
DESCRIBED IN CHAPTER CRANKCASE AND
CRANKSHAFT.
Characteristic
Standard diameter:
22 + 0.025 +0.015 mm
Inspecting the wrist pin
- Check the pin outside diameter using a micrometer.
Characteristic
Standard diameter:
22 0 - -0.004 mm
- Calculate the coupling clearance between pin
and connecting rod end.
Characteristic
Standard clearance:
0.015 ÷ 0.029 mm
- Measure the capacity diameter on the piston.
Characteristic
Standard diameter:
22 + 0.006 + 0.001 mm
ENG - 59
Engine
Nexus 500 euro 3
- Calculate the piston pin coupling clearance.
N.B.
THE PIN HOUSINGS HAVE 2 LUBRICATION
CHANNELS. FOR THIS REASON, MEASUREMENT MUST BE MADE ACCORDING TO THE
PISTON AXIS.
Characteristic
Standard clearance:
0.001 ÷ 0.010 mm
Inspecting the piston
- Measure the outside diameter of the piston, perpendicular to the gudgeon pin axis.
- Take the measurement in the position shown in
the figure.
Characteristic
A=
43.2 mm
Piston diameter:
92 mm
- Using a bore meter, measure the inner cylinder
diameter at three different points according to the
directions shown in the figure.
Characteristic
Standard diameter:
92 + 0.018 +0.010 mm
- Check that coating is free from flakes.
- Check that the head matching surface exhibits no deformations or wear.
Characteristic
Maximum allowable run-out:
0.05 mm
- Pistons and cylinders are classified into categories based on their diameter. The coupling is carried
out in pairs (A-A, B-B, C-C, D-D).
ENG - 60
Nexus 500 euro 3
Engine
- Carefully clean the seal housings.
- Measure the coupling clearance between the
seal rings and the grooves using suitable sensors,
as shown in the diagram.
- If the clearance is greater than that indicated in
the table, replace the piston.
N.B.
MEASURE THE CLEARANCE BY INSERTING
THE BLADE OF THE FEELER GAUGE FROM
THE SECOND SEAL SIDE.
Fitting clearance (Cylindrin/Pison)
Standard coupling clearance A 0.9 - 0.005 -0.030mm B 1.5 - 0.005 -0.03mm Maximum permissible
clearance after use C 0.9 + 0.03 +0.01mm D 2 + 0.05 +0.02mm Standard coupling clearance </>
1.2 - 0.005 mm </> </> Maximum permissible clearance after use </> 1.25 + 0.03 mm </> </>
Standard coupling clearance </> 2.5 - 0.005 mm </> </> Maximum permissible clearance after
use </> 2.5 + 0.03 mm </> </>
Inspecting the piston rings
- Alternately insert the three sealing rings into the
cylinder, in the area where it retains its original diameter. Using the piston, insert the rings perpendicularly to the cylinder axis.
- Measure the opening (see figure) of the sealing
rings using a feeler gauge.
- If higher values than those prescribed are measured, replace the linings.
N.B.
BEFORE REPLACING ONLY THE PISTON RINGS, ENSURE THAT THE CLEARANCE BETWEEN
THE PISTON RINGS AND THE PISTON RING GROOVES, AND BETWEEN THE PISTON AND THE
CYLINDER, IS AS SPECIFIED. IN ANY CASE, NEW PISTON RINGS USED IN COMBINATION WITH
A USED CYLINDER MAY HAVE DIFFERENT BEDDING CONDITIONS THAN THE STANDARD.
Fitting clearance (Cylindrin/Pison)
Compression ring 0.15 ÷ 0.35 mm Max. value. 0.5 mm </> Oil scraper ring 0.25 ÷ 0.50 mm Max.
value. 0.65 mm </> Oil scraper ring 0.25 ÷ 0.50 mm Max. value. 0.65 mm </>
ENG - 61
Engine
Nexus 500 euro 3
Removing the piston
- Install piston and wrist pin onto the connecting
rod, aligning the piston arrow the arrow facing towards the exhaust.
- Insert the locking ring into the special tool, with
the opening in the position indicated on the tool.
S = left
D= right
- Place the wrist pin stop ring into position using a
punch
- Install the pin lock using the key shown in the
figure.
Specific tooling
020470Y Pin retainers installation tool
N.B.
THE TOOL FOR INSTALLING THE STOP RINGS MUST BE USED MANUALLY.
CAUTION
USING A HAMMER MIGHT DAMAGE THE STOPS' HOUSING.
ENG - 62
Nexus 500 euro 3
Engine
Choosing the gasket
- Provisionally fit the piston into the cylinder, without any base gasket.
- Install a comparator on the special tool using the short union, as shown in the figure.
Specific tooling
020475Y Piston position checking tool
- Using an abutment plane, reset the comparator
with a preload of a few millimetres.
- Finally fix the comparator.
- Check the perfect sliding of the feeler pin.
- Install the tool on the cylinder without changing
the comparator position.
- Lock the tool using the original head fixing nuts.
- Rotate the crankshaft until TDC (the inverted
point of the dial gauge rotation)
- Measure the deviation from the reset value.
- Identify the thickness of the cylinder base gasket to be used for reassembly by the table below. Correctly identify the cylinder base gasket thickness to keep the correct compression ratio.
- Remove the special tool and the cylinder.
N.B.
IF DEVIATIONS (OR RECESSES OR PROJECTIONS) CLOSE TO THE CHANGE OF CATEGORY
ARE MEASURED, REPEAT THE MEASUREMENT AT THE OPPOSED SIDE. TO DO SO, REPEAT
THE TOOL INSTALLATION BY INVERTING ITS POSITION.
Characteristic
Recess / Projection measured 1
- 0.185 - - 0.10
Gasket thickness 1
0.4 ± 0.05
Recess / Projection measured 2
- 0.10 - + 0.10
Gasket thickness 2
0.6 ± 0.05
Recess / Projection measured 3
ENG - 63
Engine
+ 0.10 - + 0.185
Gasket thickness 3
0.8 ± 0.05
Refitting the piston rings
- Place the scraper ring spring on the piston.
- Install the scraper ring keeping the opening opposed to the spring junction and with the writing
"top" facing the piston top. The chamfered side of
the oil scraper ring should always be facing the
piston crown.
- Fit the second lining with the identification letter
or the writing "top" facing the piston crown. In any
case, the step must be facing opposite the piston
top.
- Install the first compression lining in the direction
imposed by the housing.
- It is advisable to use a fitter to facilitate the installation of the linings.
N.B.
THE TWO PISTON RINGS ARE MADE WITH A
TAPERED CYLINDRICAL CONTACT CROSSSECTION. THIS IS TO ACHIEVE A BETTER
BEDDING.
- Misalign the lining openings at 120° as shown in the figure.
- Lubricate the components with engine oil.
- The engine uses the first compression lining with an L section.
Refitting the cylinder
- Insert the cylinder base gasket with the thickness
determined above.
- Using the fork and the ring clamp, fit the cylinder
as shown in the figure.
N.B.
BEFORE FITTING THE CYLINDER, CAREFULLY BLOW THE LUBRICATION DUCT AND LUBRICATE THE CYLINDER LINER. CHECK THE
PRESENCE OF THE TWO REFERENCE DOWELS.
Specific tooling
ENG - 64
Nexus 500 euro 3
Nexus 500 euro 3
Engine
020468Y Piston fitting ring
020512Y Piston fitting fork
Inspecting the cylinder head
- Using a trued bar and feeler gauge check that the cylinder head surface is not worn or distorted.
Characteristic
Maximum allowable run-out:
0.1 mm
- In case of irregularities, replace the head.
- Check the sealing surfaces for the intake and exhaust manifold.
- Check that the camshaft and the rocker pin capacities exhibit no wear.
- Check that the head cover surface is not worn.
- Check that the coolant sealing pad exhibits no
oxidation.
STANDARD DIAMETER
Specification
A
B
C
Desc./Quantity
13 + 0.018 0
20 + 0.021 0
42 + 0.025 0
- If wear is discovered, replace the head and check also the corresponding component.
Inspecting the timing system components
- Check that the guide shoe and the tensioner shoe
are not worn out.
- Check that the crankshaft pinion and the camshaft timing gear and crankshaft pinion exhibit no
wear.
In case of wear of the sliding blocks, replace them.
In case of wear of the chain or rim, replace the entire unit.
N.B.
IF THE CHAIN HAS DAMAGED THE PINION, REPLACE THE CRANKSHAFT AS DESCRIBED IN
CHAPTER CRANKCASE AND CRANKSHAFT.
ENG - 65
Engine
Nexus 500 euro 3
- Remove the centre screw with the washer and
the tensioner spring. Check that the one-way
mechanism is not worn.
- Check the condition of the tensioner spring.
- If examples of wear are found, replace the whole
assembly.
Inspecting the valve sealings
- Insert the valves into the cylinder head.
- Alternatively check the intake and exhaust
valves.
- The test is carried out by filling the manifold with
petrol and checking that the head does not ooze
through the valves when these are just pressed
with the fingers.
- Visually inspect the valve sealing surface.
CAUTION
DO NOT REVERSE THE FITTING POSITIONS OF THE VALVES (RIGHT - LEFT).
- If the sealing surface of the valve is found to be
interrupted at one or more points or is not flat, replace the valve.
ENG - 66
Nexus 500 euro 3
Engine
Inspecting the valve housings
- Clean the valve seats of any carbon residues.
- Using the Prussian blue, check the width of the
impression on the valve seat "V".
- Measure the inside diameter of each valve guide.
- Measure according to the rocking lever thrust direction at three different heights.
Characteristic
Standard value:
1 - 1.3 mm
Admissible limit:
1.6 mm
- If the impression width on the valve seat is larger than the prescribed limits, true the seats with a 45°
mill and then grind.
- In case of excessive wear or damages, replace the head.
Inspecting the valves
- Measure the diameter of the valve stems in the three positions indicated in the diagram.
STANDARD DIAMETER
Specification
Inlet:
Outlet:
Desc./Quantity
4.987 - 4.972 mm
4.975 - 4.960 mm
MINIMUM ADMISSIBLE DIAMETER
Specification
Inlet:
Outlet:
Desc./Quantity
4.96 mm
4.945 mm
- Calculate the clearance between valve and valve guide.
ENG - 67
Nexus 500 euro 3
Engine
- Check the deviation of the valve stem by resting
it on a "V" shaped abutment and measuring the
extent of the deformation with a comparator.
Characteristic
Limit values admitted:
0.1 mm
- Check the concentricity of the valve head by arranging a comparator at right angle relative to the
valve head and rotate it on a "V" shaped abutment.
Characteristic
Admissible limit:
0.03 mm
Inspecting the valve stem guide clearance
- After measuring the valve guide diameter and the valve stem diameter, check the clearance between
guide and stem.
INLET
Specification
Standard clearance:
Admissible limit:
Desc./Quantity
0.013 - 0.04 mm
0.08 mm
OUTLET
Specification
Standard clearance:
Admissible limit:
ENG - 68
Desc./Quantity
0.025 ÷ 0.052 mm
0.09 mm
Nexus 500 euro 3
Engine
STANDARD VALVE LENGTH
Specification
Inlet:
Outlet:
Desc./Quantity
95.0 ± 0.3 mm
94.2 ± 0.3 mm
- Check that there are no signs of wear on the surface of contact with the articulated register terminal.
- If the checks above give no failures, you can use
the same valves. To obtain better sealing performance, grind the valve seats. Grind the valves gently
with a fine-grained lapping compound. During the
grinding, keep the cylinder head with the valve axes in a horizontal position. This will prevent the
lapping compound residues from penetrating between the valve stem and the guide (see figure).
CAUTION
TO AVOID SCORING THE CONTACT SURFACE, DO NOT KEEP ROTATING THE VALVE WHEN
NO LAPPING COMPOUND IS LEFT. CAREFULLY WASH THE CYLINDER HEAD AND THE
VALVES WITH A SUITABLE PRODUCT FOR THE TYPE OF LAPPING COMPOUND BEING USED.
CAUTION
DO NOT REVERSE THE FITTING POSITIONS OF THE VALVES (RIGHT - LEFT).
Inspecting the springs and half-cones
- Check that the upper spring caps and the cotter
halves show no signs of abnormal wear.
ENG - 69
Nexus 500 euro 3
Engine
- Measure the unloaded spring length.
Characteristic
Standard length:
44.4 mm
Admissible limit after use:
42.4 mm
Refitting the valves
- Place the valve spring support washers on the
head.
- Alternately insert the 4 oil guards using the special tool.
- Lubricate the oil guards and the valve guides.
Specific tooling
020306Y Punch for assembling valve seal
rings
- Fit the valves, the springs and the spring retaining
washers. Using the appropriate tool with adapter,
compress the springs and insert the cotters in their
seats.
Specific tooling
020382Y Valve cotters equipped with part 012
removal tool
020382Y012 bush (valve removing tool)
N.B.
DO NOT CHANGE THE VALVE FITTING POSITION. FIT THE VALVE SPRINGS WITH THE REFERENCE COLOUR ON COTTER SIDE (TURNS WITH GREATER PITCH).
Inspecting the cam shaft
- Check that the camshaft ends exhibit no scores or irregular wear.
- Using a micrometer, measure the camshaft capacity.
STANDARD DIAMETER
Specification
Bearing A Ø:
Bearing B diameter:
ENG - 70
Desc./Quantity
42 - 0.060 -0.085 mm
20 - 0.020 -0.041 mm
Nexus 500 euro 3
Engine
MINIMUM ADMISSIBLE DIAMETER
Specification
Bearing A Ø:
Bearing B diameter:
Desc./Quantity
41.910 mm
19.940 mm
-Using a gauge, measure the cam height.
STANDARD HEIGHT
Specification
Intake
Exhaust:
Desc./Quantity
33.988 mm
33.417 mm
ADMISSIBLE LIMITS
Specification
Intake
Exhaust:
Standard axial clearance:
Maximum admissible axial clearance:
Desc./Quantity
33.740 mm
33.170 mm
0 - 0.22 mm
0.3 mm
ENG - 71
Engine
- If any of the above dimensions are outside the
specified limits, or there are signs of excessive
wear, replace the defective components with new
ones.
- Check that the retaining plate seat shown in the
figure exhibits no wear.
- Check that the automatic valve lifting device cam,
the travel end roller and the rubber abutment on
the containment bell are free from wear.
- Check that the valve lifting spring has not yielded.
- Replace any defective or worn components.
- Check that the rocking lever pins exhibit no scores or wear.
Characteristic
Standard diameter:
13 - 0.010 -0.018 mm
- Measure the inside diameter of each rocking lever.
Characteristic
Standard diameter:
13 + 0.026 +0.015 mm
- Check that the cam contact sliding block and the
articulated register plate is free from wear.
- In case of wear, replace the component.
ENG - 72
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Refitting the head and timing system components
- Insert the chain guide sliding block.
- Insert the two centring dowels between head and
cylinder.
- Install the head gasket.
N.B.
THE FIGURE SHOWS THE INSERTION POSITION OF THE TWO CENTRING DOWELS BETWEEN
HEAD AND CYLINDER. THE DIRECTION OF INSTALLATION FOR THE GASKET IS FORCED BY
THE DOWELS.
- The head gasket is made of steel and has a
standard thickness.
- Check that the head lubrication channel is perfectly clean. Clean with compressed air jets, if
required.
- Insert the head.
- Lubricate the stud bolts and the 4 fixing stud
bolts.
- Tighten the 4 fastening columns crosswise to the
prescribed torque as shown in the figure.
- Tighten the 4 screws by 90° in the sequence
shown in the figure.
- Further tighten by 90° in the sequence shown in
the figure.
Locking torques (N*m)
Head fixing stud bolts: ***
ENG - 73
Engine
- Tighten the fastening nuts on the exhaust and on
the intake side to the prescribed torque.
Locking torques (N*m)
Exhaust / intake head fixing nuts: 10 - 12
- Tighten the 3 side screws to the prescribed torque.
Locking torques (N*m)
Head fixing screws 10 - 12
- Install the coolant temperature sensor with the
washer and tighten to the prescribed torque.
CAUTION
FAILURE TO OBSERVE THE TIGHTENING
TORQUE CAN DAMAGE THE SENSOR.
Locking torques (N*m)
coolant temperature sensor: 10 - 12
- Install the spark plug and tighten to the prescribed torque.
Locking torques (N*m)
Spark plug 12 ÷ 14
- Insert the timing control belt on the crankshaft
according to the initial direction of rotation.
- Install the tensioner shoe with its spacer, tightening the bolt to the prescribed torque, using the
recommended product.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
Locking torques (N*m)
Tensioner sliding block fixing screw: 10 - 14
ENG - 74
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Insert pins and rocking levers on the flywheel
side.
- Lubricate the two rocking levers through the
holes at the top.
- Clean the camshaft by blowing with little compressed air jets, especially the retaining plate
housing.
- Lubricate the 2 shafts.
- Insert the camshaft into the head with the cams
opposite the rocking levers.
- Remove any LOCTITE residues from the screws fixing the camshaft retaining bracket using a brush.
- Apply the recommended product to the fixing screws and tighten the screws after wiping off any
threadlock deposits.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
- Insert the camshaft retain bracket with visible
countersinks and tighten the 3 fastening screws to
the prescribed torque, being careful not to damage
the inside hexagon.
Locking torques (N*m)
Camshaft retaining bracket screws: 4 ÷ 6
ENG - 75
Engine
- Check that the toothing and the housing of the
tone wheel timing peg are free from deformations
or dents.
- Insert the wheel speed sensor on the camshaft
keeping the stroke reference visible.
- Install the engine revolution timing sensor using
a new O-Ring, orientating it as shown in the figure.
Tighten the 2 fastening screws to the prescribed
torque.
N.B.
TO CHECK THIS COMPONENT, SEE CHAPTER
"INJECTION".
Locking torques (N*m)
Rpm timing sensor fixing screw: 3 - 4
- Install the intermediate gear with torque limiter,
the flywheel and its cover, as described in Chapter
"Flywheel and start-up system", and in Chapter
"Flywheel cover".
N.B.
FOR MORE CONVENIENCE, INSTALL THE
FLYWHEEL COVER WITHOUT THE COOLING
SYSTEM SLEEVES.
ENG - 76
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Using the TORX wrench, remove the timing
check cap.
- Align the wheel speed sensor references with the
head as shown in the figure.
- Keeping the belt slightly pulled, turn the crankshaft using the driving pulley to make the reference
on the magnet support collimate with that on the
flywheel cover.
- Insert the belt on the camshaft control timing rim.
- Insert the timing rim on the camshaft checking
that the references are aligned.
N.B.
DURING THE STROKE CHECK, KEEP THE
BELT TENSIONED BY PRESSING ON THE
TIGHTENER COMPARTMENT SIDE.
ENG - 77
Engine
Nexus 500 euro 3
- Install the counterweight mass.
- Centre using the bell fastening screw.
- Lock the mass fixing screws to the prescribed
torque, using the recommended product.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
Locking torques (N*m)
Counterweight screw 7 ÷ 8.5
- Remove the central screw.
- Install the valve lifting mass being careful to the
proper positioning of the travel end ring.
- Lubricate the mass and de-compressor control
pin.
- Install the return spring and load it by about 3/4
turn.
- Turn the engine to move the references to the top
as shown in the figure (intake end).
- Insert the valve lifting device mass stop bell.
- Tighten the retaining screw to the prescribed torque, using the recommended product.
N.B.
THE BELL TIMING IS ENSURED BY THE COUNTERWEIGHT MASS FASTENING SCREW HEAD.
Recommended products
ENG - 78
Nexus 500 euro 3
Engine
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
- Check that the decompression mass is free and
that it is pulled by the spring.
Locking torques (N*m)
Valve lifter mass stop bell fixing screws: 30 35
- Place the engine with the valve clearance adjustment timing references aligned with the head.
- Check the clearance between valve and rocking lever using a thickness gauge.
PRESCRIBED CLEARANCE
Specification
Inlet
drainage
Desc./Quantity
0.15 mm (engine cold)
0.15 mm (engine cold)
- In case different values are found, adjust by loosening the lock nut and use a screwdriver for the set
screw as shown in the figure.
Refitting the timing chain
This section described the operations to be carried out on the manifold components.
The ignition advance is determined electronically on the basis of parameters known by the control unit.
For this reason it is not possible to declare the reference values based on the engine rpm.
The ignition timing value is detectable any time using the diagnostic tester.
It is possible to check whether the ignition advance determined by the system does in fact correspond
with the value actually activated on the engine, by means of the stroboscopic light.
Specific tooling
020460Y Scooter diagnosis and tester
020330Y Stroboscopic light for timing control
ENG - 79
Engine
Proceed as follows:
- Remove the outside transmission cover as described in the automatic transmission chapter.
- Remove the TDC reference inspection cap between flywheel and crankcase cover. See the flywheel cover chapter.
- By the driving pulley, turn the engine to find the
alignment of the references to identify the TDC.
- Repeat for the reference between driving pulley
and transmission housing.
ENG - 80
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Replace the inspection cap on the flywheel side.
- Connect the diagnostic tester.
- Start the engine.
- Select the menu on the "parameter" function.
- Select the stroboscopic light command in the traditional four-stroke engine position (1 spark 2
revs).
- Check that the real values of rpm and ignition
advance match those measured using the diagnostic tester.
Specific tooling
020460Y Scooter diagnosis and tester
If the values do not match, check:
- distribution timing
- revolution-timing sensor
- Injection control unit
Inspecting the radial air gap
- Align a tooth of the tone wheel with the revolution timing sensor.
- Check the air gap using a probe.
Characteristic
Standard air gap:
from 0.20 to 0.70 mm
- Repeat the check at 3 - 4 points.
ENG - 81
Engine
- Place the tightener cursor in the rest position,
keeping the retain tab pressed.
- Install a new tightener on the cylinder using a new
gasket.
- Tighten the two fastening screws to the prescribed torque.
Locking torques (N*m)
Tightener fastening screws: 11 ÷ 13
- Insert the spring with the central screw and the
washer.
- Tighten the central screw to the prescribed torque.
Locking torques (N*m)
Tightener screw: 5 - 6
Refitting the rocker-arms cover
- Check that the gasket is in good working order.
ENG - 82
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Tighten the two screws indicated in the figure with
"1" and "2" to limit the reciprocal sliding of the cover
surface with the head surface.
- Tighten the remaining 4 screws in a crossed sequence (3, 4, 5, 6).
N.B.
CHECK THE PROPER POSITION OF THE GASKET.
Locking torques (N*m)
Tappet cover fixing screws: 7 - 9
- Install the transmission cover and the relevant net
filter and the outside transmission cover as described in the "Automatic transmission" chapter.
- Install the cooling system sleeves using new
bands, as described in the "Flywheel cover" chapter.
Refitting the intake manifold
- Install the intake manifold on the engine.
- Insert the 3 fastening screws, one of which with
a support band for the cooling system sleeve, and
tighten to the prescribed torque.
Locking torques (N*m)
Inlet manifold screws 11 ÷ 13
ENG - 83
Engine
Crankcase - crankshaft
- Remove the outside and inside transmission cover and the complete driving pulley as described in
"Automatic transmission".
- Remove the flywheel cover with the cooling system sleeves, as described in the "Flywheel cover"
chapter.
- Remove the flywheel with the starting system following the instruction given in "Flywheel and Starting system".
- Remove the thermal unit (cylinder, head, piston)
as described in the Thermal unit and timing system
chapter.
ENG - 84
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Before opening the crankcase, check the crankshaft axial clearance.
For this purpose, use a plate (e.g. the special tool)
and a support with special tool comparator.
Specific tooling
020262Y Crankcase splitting strip
020335Y Magnetic support for dial gauge
Characteristic
Standard clearance:
0.10 - 0.50 mm
Admissible increase limit after use:
0.60 mm
- Upper clearances are an indication of wear on the surfaces of the crankshaft casing support.
- To carry out an accurate measurement, measure the clearance in both directions between crankcase
and crankshaft.
Splitting the crankcase halves
- Remove the engine support retain screw on the
flywheel side half-crankcase.
ENG - 85
Engine
- Remove the 14 crankcase coupling screws.
N.B.
THE FASTENING SCREWS ARE OF 3 DIFFERENT LENGTHS. NOTE THEIR CORRECT POSITION.
- Split the crankcases while keeping the crankshaft
inserted on the flywheel side half-crankcase.
- Remove the coupling gasket.
N.B.
THE BUSHING SUPPORT CAN BE LEFT IN THE
FLYWHEEL SIDE HALF-CRANKCASE.
Removing the crankshaft
- Before removing the crankshaft, check the timing
with the countershaft. To carry out this check, turn
the crankshaft to align the two holes obtained on
the crankshaft with the hole on the countershaft
control gear.
This is an optimal position also to remove the
crankshaft.
- Remove the crankshaft with the shim adjustment
washer on the flywheel side.
CAUTION
WHILE OPENING THE CRANKCASE AND REMOVING THE CRANKSHAFT, CHECK THAT
THE SHAFT THREADED ENDS DO NOT INTERFERE WITH THE MAIN BEARINGS. FAILURE
TO OBSERVE THIS PRECAUTION CAN DAMAGE THE MAIN BEARING.
ENG - 86
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Removing the oil pump and countershaft control gear.
- To remove the control gear, loosen the 4 fastening screws.
Remove the gear only if actually required.
CAUTION
THE SCREWS HAVE A COUNTERSUNK HEAD
AND THEIR THREADING IS LOCKED BY LOCTITE. BE CAREFUL NOT TO DAMAGE THE
CONTROL HEXAGON. TO OBTAIN BETTER
RESULTS IT IS PREFERABLE TO USE AN INSIDE HEXAGON SOCKET WRENCH.
Removing the countershaft
- Place the special tool as shown in the figure.
Specific tooling
020479Y Countershaft lock wrench
- Remove the fastening nut with relevant washer.
- Remove the special tool and extract the countershaft with the control gear.
ENG - 87
Engine
Replacing the countershaft bearings
- Check that the bearings are free from irregular
noise or clearance. If it is, replace it.
Flywheel-side half-crankcase
- Remove the inside seeger ring.
- Upturn the half-crankcase.
- Remove the bearing from the flywheel side halfcrankcase using the special tool and a mallet.
Specific tooling
020376Y Adaptor handle
020358Y 37x40-mm adaptor
020439Y 17 mm guide
- Remove the bearing from the transmission side
half-crankcase using the special tool.
Specific tooling
001467Y008 Pliers to extract 17 mm ø bearings
001467Y007 Driver for OD 54 mm bearing
- Before installing a new bearing, heat the flywheel
side half-crankcase using the special tool.
- Place the half-crankcase on a wooden base.
Specific tooling
020151Y Air heater
ENG - 88
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Insert a new bearing on the special tool after
greasing the guide seat.
- Install the new bearing on the half-crankcase using the special tool.
N.B.
IF A BEARING WITH PLASTIC CAGE IS USED,
KEEP THE BALLS VISIBLE FROM THE
CRANKCASE INTERNAL SIDE.
Specific tooling
020376Y Adaptor handle
020359Y 42x47-mm adaptor
020439Y 17 mm guide
- Fit the seeger ring.
- Before installing the new bearing on the transmission side crankcase, heat the seat using the
special tool.
Specific tooling
020151Y Air heater
- Insert a new bearing on the special tool after
greasing the guide seat.
- Install the new bearing on the engine crankcase
using the special tool.
N.B.
IF A BEARING WITH PLASTIC CAGE IS USED,
KEEP THE BALLS VISIBLE FROM THE
CRANKCASE INTERNAL SIDE.
Specific tooling
020376Y Adaptor handle
ENG - 89
Engine
020359Y 42x47-mm adaptor
020439Y 17 mm guide
Inspecting the crankshaft components
- Check the axial clearance on the connecting rod.
Characteristic
Standard clearance:
0.20 ÷ 0.40 mm
- Check the connecting rod diametrical clearance.
Characteristic
Standard clearance:
0.046 ÷ 0.076 mm
-Check the surfaces that limit the axial free-play
are not scored and measure the width of the crankshaft between these surfaces, as shown in the
diagram.
N.B.
BE CAREFUL NOT TO LET THE MEASUREMENT BE AFFECTED BY THE UNIONS WITH
THE CRANKSHAFT ENDS.
Characteristic
Standard dimensions:
63.6 - 63.45 mm
CAUTION
THE CRANKSHAFT CAN BE REUSED WHEN
THE WIDTH FALLS WITHIN THE STANDARD
VALUES AND THE SURFACES ARE FREE
FROM SCRATCHES.
Shimming
- Check the overall height of the crankshaft - shoulders - gear assembly.
Characteristic
ENG - 90
Nexus 500 euro 3
Nexus 500 euro 3
Engine
Standard thickness:
71.804 - 72.000 mm
- Check that shim adjustment is free from scratches.
N.B.
IN CASE OF NEW UTILISATION, MAINTAIN THE FIRST FITTING POSITION.
Specific tooling
020074Y Support base for checking crankshaft alignment
- If the crankshaft - crankcase axial clearance is higher than the standard value and the crankshaft
exhibits no irregularity, the problem is caused by wear or by a wrong machining on the engine crankcase.
- Check the diameters of both the bearings of the
crankshaft in accordance with the axes and surfaces shown in the figure. Half-shafts are classified
into two categories, Cat. 1 and Cat. 2.
STANDARD DIAMETER
Specification
Cat. 1
Cat. 2
Desc./Quantity
40.010 ÷ 40.016
40.016 ÷ 40.022
Inspecting the crankshaft alignment
- Install the crankshaft on the support and measure the displacement at the 4 points shown in the figure.
Specific tooling
020074Y Support base for checking crankshaft alignment
MAX ADMISSIBLE DISPLACEMENT:
Specification
A
B
C
D
Desc./Quantity
= 0.15 mm
= 0.01 mm
= 0.01 mm
= 0.10 mm
ENG - 91
Engine
Nexus 500 euro 3
- Check that the driving shaft cone, the tab seat, the oil seal capacity, the toothed gear and the threaded
tangs are in good working order.
- In case of failures, replace the crankshaft.
N.B.
MAIN BEARINGS CANNOT BE MODIFIED.
The connecting rod cannot be replaced. To check the connecting rod small end diameter, see chapter
"Thermal unit and timing system".
- When cleaning the crankshaft, be careful to prevent any impurity from entering into the shaft lubrication
hole.
N.B.
IN CASE OF REPLACEMENT OF A CRANKSHAFT CONSISTING OF TWO HALF-SHAFTS OF DIFFERENT CATEGORY, REPLACE THE TWO HALF-CRANKCASES AS WELL, COUPLING THE TWO
COMPONENTS (SHAFT AND CRANKCASE) WITH THE SAME CATEGORY.
- To check the gearing of the crankshaft, see section "Thermal unit and timing system".
See also
Cylinder assy. and timing system
Inspecting the crankcase halves
- Before proceeding to check the crankcase
halves, thoroughly clean the all surfaces and oil
ducts.
- For the transmission-side half-crankcase, special
attention should be given to the bushings, to the
cooling jet on the transmission side (see figure)
and to the lubrication duct.
ENG - 92
Nexus 500 euro 3
Engine
N.B.
THE JET IS FED THROUGH THE MAIN BUSHINGS. PROPER OPERATION OF THIS COMPONENT IMPROVES PISTON CROWN COOLING.
CLOGGING HAS EFFECTS THAT ARE DIFFICULT TO DETECT (PISTON TEMPERATURE
INCREASE). FAILURE OR LEAKS CAN CAUSE
A CONSIDERABLE DROP IN THE LUBRICATION PRESSURE FOR MAIN BUSHINGS AND
CONNECTING ROD .
- For the flywheel side half-crankcase, special attention should be given to the lubrication channels
for the main bearings and to the compartment and
the channels for the oil pump, as well as to the duct
for the by-pass located on the flywheel cover.
N.B.
AS ALREADY DESCRIBED IN THE "LUBRICATION" CHAPTER, IT IS ESPECIALLY IMPORTANT THAT THE BY-PASS HOUSING ON THE
FLYWHEEL COVER IS FREE FROM WEAR
THAT MAY IMPAIR THE PROPER SEALING OF
THE LUBRICATION PRESSURE ADJUSTMENT
PISTON. THE HEAD LUBRICATION CHANNEL
IS PROVIDED WITH A SHUTTER JET; THIS
GIVES A "LOW PRESSURE" HEAD LUBRICATION. THIS CHOICE WAS MADE TO REDUCE
THE OIL TEMPERATURE IN THE SUMP.
The jet clogging impairs the head lubrication and the timing mechanisms.
A jet failure causes a decrease of the main bearing and connecting rod lubrication pressure.
- Check that the surfaces are free from dents or deformations, with special attention to the crankcase
coupling and the crankcase-cylinder surfaces.
- Any defects in the crankcase gasket or matching surfaces (see Flywheel cover coupling) can cause
pressurised oil leaks, thereby affecting the connecting rod and main bearing lubrication pressure.
- Check the main bearing seats that limit axial clearance in the crankshaft show no signs of wear. For
the dimensional check, refer to the instructions relating to the axial clearance and dimensions check on
the crankshaft
ENG - 93
Nexus 500 euro 3
Engine
Inspecting the crankshaft plain bearings
- To obtain a good bushing lubrication it is necessary to have both an optimal lubricating pressure
(4 bar) and a good oil flow rate; the bushings must
be correctly positioned so as not to obstruct the oil
supply channels.
- The main bushings are comprised of two halfbearings, one with holes and channels for lubrication whereas the other is solid.
- The solid half-bearing is intended to stand the thrusts caused by combustion, and for this reason it is
arranged opposite the cylinder.
- To prevent obstructions in the oil feeding channels, the matching surface of the two half-bearings must
be perfectly perpendicular to the cylinder axis, as shown in the figure.
- The oil feeding channel section is also affected by the bushings driving depth compared with the
crankshaft axial clearance of the limiting surface.
N.B.
TO KEEP THE BUSHINGS ON THE CRANKCASE IN SUCH POSITION, DRIVING IS FORCED ON
CAST-IRON RINGS INSERTED IN THE CASTING OF BOTH CRANKCASE HALVES.
- Check the inside diameter of the main bushings
in the three directions indicated in the diagram.
- Repeat the measurements for the other bushing
half. see diagram.
N.B.
DO NOT TAKE THE MEASUREMENT ON THE
TWO HALF-SHELL COUPLING SURFACE
SINCE THE ENDS ARE RELIEVED TO ALLOW
BENDING DURING THE DRIVING OPERATION.
- The standard bushing diameter after driving is variable on the basis of a coupling selection.
- The bushing seats into the crankcases are classified into 2 categories as for the drive shaft Cat. 1 and
Cat. 2.
- Bushings are divided into 3 categories according to their thickness. See the table below:
CHECK THE BENCH BUSH
Name
Type A - Red
Type B - Blue
Type C - Yellow
ENG - 94
Description
Dimensions
1.982 - 1.987
1.987 - 1.992
1.992 - 1.997
Initials
Quantity
Nexus 500 euro 3
Engine
Coupling chart
COUPLING THE SEMI-SHAFTS WITH THE SEMI-CHASSIS AND BUSHES
Name
Half-shaft category
1 - Bushing category B
Half-shaft category
2 - Bushing category C
Half-shaft category
1 - Bushing category A
Half-shaft category
2 - Bushing category B
Description
Dimensions
Initials
Spare crankcase
set-up FC1 - Dis.
CM1033015001
Spare crankcase
set-up FC1 - Dis.
CM1033015001
Spare crankcase
set-up FC2 - Dis.
CM1033015002
Spare crankcase
set-up FC2 - Dis.
CM1033015002
Quantity
N.B.
FOR SERVICING WITH SPARE PARTS, MATCH THE SHAFT WITH TWO SHOULDERS OF CATEGORY 1 TO CRANKCASE FC1 (OR CATEGORY 2 TO CRANKCASE FC2).
A spare crankcase cannot be combined with a driving shaft with mixed categories. Spare shafts have
half-shafts of the same category.
N.B.
TO REPLACE THE HALF-SHAFTS, REMOVE THE COUNTERSHAFT BEARINGS AS DESCRIBED
ABOVE. REMOVE THE COMPLETE DRIVEN PULLEY AND THE ANTI-FLAPPING ROLLER FROM
THE TRANSMISSION SIDE HALF-CRANKCASE, AS DESCRIBED IN CHAPTER "AUTOMATIC
TRANSMISSION", AND THE HUB COVER WITH THE RELEVANT GEARS AND BEARINGS AS
DESCRIBED IN CHAPTER "FINAL REDUCTION".
Countershaft
- Using a micrometer, measure the 2 bearings of
the countershaft as shown in the figure.
Characteristic
Standard diameter:
17 - 0.01 - 0.02 mm
- Check that the water pump drive is not worn.
Refitting the crankshaft
- Check that the oil pump and countershaft control gear are free from deformations or dents. Replace,
if required.
N.B.
IF YOU HAVE TO REPLACE THE OIL PUMP AND COUNTERSHAFT CONTROL GEAR IT IS NECESSARY TO REPLACE THE COUNTERSHAFT GEAR AS WELL.
ENG - 95
Engine
Nexus 500 euro 3
- Before installing the gear on the crankshaft, carefully clean the two matching surfaces removing
any residues of LOCTITE from the holes using a
brush.
Blow with compressed air and degrease the mounting holes on both surfaces to make the new LOCTITE
grip.
Apply the recommended product to the holes again.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
- Repeat the same procedure for the 4 fastening screws.
- Insert the control gear on the crankshaft with the hole countersink visible.
- Tighten the 4 fastening screws to the prescribed torque.
N.B.
TO AVOID DAMAGING THE SCREW CONTROL HEXAGON, IT IS PREFERABLE TO USE AN INSIDE HEXAGON SOCKET WRENCH.
Locking torques (N*m)
Gear mounting on crankshaft screws 10 -12
- Lubricate the main bearing on the flywheel side
half-crankcase.
- Lubricate the shim adjustment washer.
- Insert the shim adjustment washer on the crankshaft in its original position.
- Insert the special timing tool in the hole on the
countershaft.
Specific tooling
020471Y Pin for countershaft timing
ENG - 96
Nexus 500 euro 3
Engine
- Insert the crankshaft on the pin and into the bushing.
- Before inserting thoroughly, make the oil pump
gear align with the control gear.
- Insert thoroughly and remove the special tool.
N.B.
WHEN INSERTING THE SHAFT ON THE HALF-CRANKCASE, BE CAREFUL NOT TO DAMAGE
THE MAIN BEARING WITH THE THREADED TANG OF THE CRANKSHAFT AND WITH THE TIMING CONTROL TOOTHED PINION.
- Install the oil pump closing plate.
- Tighten the 2 flanged fastening screws to the
prescribed torque.
Locking torques (N*m)
Bulkhead screws for oil pump housing cover
8 - 10
Refitting the crankcase halves
- Remove the oil guard from the transmission side
half-crankcase using a screwdriver.
- Install a new oil guard after lubricating it, using
the special tool, arranging it at a 0.5 mm recess
from the crankcase plane.
CAUTION
A WRONG POSITIONING OF THE OIL GUARD
AFFECTS THE LUBRICATION OIL CIRCULATION.
Specific tooling
020360Y Adaptor 52 x 55 mm
ENG - 97
Engine
Nexus 500 euro 3
020376Y Adaptor handle
- Insert the gasket on the flywheel side half-crankcase.
- Lubricate the main bearing on the transmission
side half-crankcase.
- Couple the 2 half-crankcases being careful
not to damage the bushing on the transmission side half-crankcase with the threaded
tang of the crankshaft.
- Insert the engine support retain screw on the flywheel side half-crankcase without tightening.
- Insert the 14 fastening screws by arranging the
single shorter screw "A" and the single longer
screw "B" as shown in the figure.
- Tighten the screws thoroughly and tighten to the prescribed torque.
- Check that the crankshaft rotates freely.
N.B.
REMOVE ANY EXCESS FROM THE CRANKCASE COUPLING GASKET ON THE CYLINDER
PLANE, TO ENSURE BETTER SEALING PERFORMANCE.
Locking torques (N*m)
Engine-crankcase coupling screws 11 ÷ 13
- Install the thermal unit (cylinder, head, piston) as
described in section "Thermal unit and timing system".
ENG - 98
Nexus 500 euro 3
Engine
- Install the flywheel with start-up control as described in the "Flywheel and start-up" chapter.
- Install the flywheel cover with the cooling system
sleeves, as described in the "Flywheel cover chapter".
- Install the complete driving pulley, the transmission cover and the relevant mesh filter and the
outside transmission cover as described in the
section "Automatic transmission".
See also
Cylinder assy. and timing system
Flywheel cover
Lubrication
TECHNICAL SPECIFICATIONS
SUMP CAPACITY
Specification
Overhaul
Oil and filter replacement
Desc./Quantity
1.7 l
1.5 l
RECOMMENDED ENGINE OIL
Product
AGIP CITY HI TEC 4T
Description
Engine oil
Specifications
SAE 5W-40, API SL, ACEA A3,
JASO MA Synthetic oil
ENG - 99
Nexus 500 euro 3
Engine
OIL PUMP
Specification
Type
Rotor thickness
Assembly clearances
Outside rotor radial clearance
Rotor axial clearance
Desc./Quantity
Trochoidal
8 mm
Lobe ends 0.05-0.008 mm
0.05- 0.12 mm
0.025 - 0.065 mm
BY-PASS
Specification
Type
Plunger diameter
Spring free length
Calibration pressure
Desc./Quantity
with piston
13.9 - 0.039 -0.057 mm
62.5 mm
4 bar
PRE-FILTER
Specification
Type
Desc./Quantity
mesh, plastic
OIL FILTER
Specification
Type
Desc./Quantity
Paper with pressure relief and anti-drain back bypass valves
OIL MINIMUM PRESSURE INDICATOR LIGHT SWITCH
Specification
Calibration
Desc./Quantity
0.3 - 0.6 bar
HEAD LUBRICATION CONTROL JET
Specification
Diameter
Desc./Quantity
1 ± 0.05 mm *
* Tightening torque 5÷7 N·m
PISTON COOLING NOZZLE
Specification
Diameter
Desc./Quantity
0.8 ± 0.05 mm
CRANKCASE VENTILATION CHECK
Specification
Device
ENG - 100
Desc./Quantity
metal reed valve and decantation chamber
Nexus 500 euro 3
Engine
Conceptual diagrams
PRINCIPLE DIAGRAM
Specification
A
B
C
D
E
F
G
H
L
M
N
O
Desc./Quantity
Camshaft
Cylinder-head plane
Cylinder-crankcase plane
Water pump impeller
Minimum oil pressure sensor
Oil filter cartridge
To the oil sump
By-pass valve
Oil pump
Mesh pre-filter
Crankshaft
Connecting rod
General characteristics
Lubrication circuit is split into two sections:
- High pressure
- Low pressure
The high pressure section includes all components located on the engine crankcase, while the low
pressure section only refers to the thermal unit.
The trochoidal pump is installed into the sump and is controlled through a couple of gears.
To guarantee the integrity of the pump, a pre-filter is installed.
The pre-filter is of the screw-in type and the plug serves at the same time as an engine oil drain plug.
ENG - 101
Engine
Nexus 500 euro 3
The pump is controlled by means of a piston by-pass calibrated to 4 bar. This is located before the
cartridge filter and both are installed on the flywheel cover, so that the seal of the filter is subject to the
pressure of the circuit.
The by-pass located before the cartridge filter improves the operating conditions for the filter proper,
particularly with cold oil.
The filter is equipped with an anti-cavitation valve and a pressure relief valve; the latter intervenes when
the filtering element causes a pressure drop exceeding 1± 0.2 bar.
These conditions naturally occur only with cold oil and at high engine revs or if the filter is clogged.
The filtered oil is used to lubricate the shaft of the water pump and once at the engine crankcase, to
lubricate the crankcase bearings, the connecting rod head and the piston cooling nozzle located on the
bearings on the transmission side.
The crankcase bearing on the transmission side is provided with an oil seal and the respective drain
line.
The supply line for the timing system comes from the flywheel-side bearing; the supply to the head is
controlled by the respective spray jets in the engine crankcase.
The components of the timing system function with low-pressure oil.
The camshaft bearings are marked directly on the aluminium of the head; the axial clearance of the
camshaft is partly compensated by the oil supplied to the small end bearings.
The camshaft supplies the lubricant to the rocking levers via the bores provided; these are installed in
a position to ensure that the lubrication is maintained even after the scooter has stopped. This is achieved when the camshaft reaches its most usual and likely position when the engine is switched off.
The oil used to lubricate the head returns to the sump via the ducts in the chain casing and hence also
provides lubrication for the chain.
In order to avoid the gas collecting in the bottom of the tank carrying oil out of the housing, a non-return
valve and a decantation chamber are used. The one-way valve is of metal sheet design; the decantation
chamber is provided with a drainage bore. If they fail oil can get into the pipe supplying air to the engine.
Excessive oil vapours may result in a blockage in the ducts of the throttle body.
In order to signal low oil pressure in the circuit, a pressure switch is used, located immediately after the
oil filter outlet.
The lubrication circuit does not include the countershaft; its lubrication comes from the oil transported
by the gearing or by the centrifugal effect of the crankshaft.
The same applies to the piston or the pin, but in this case the cooling nozzle is particularly important.
Diagnosis guide
1 - Minimum oil pressure warning light on with hot engine.
AHEAD - go to 2
2 - Remove the minimum pressure switch electric connector.
Check that the warning light turns off.
ENG - 102
Nexus 500 euro 3
Engine
YES - go to 3 NO go to 11
3 Check the actual oil pressure.
AHEAD - go to 4
4 - Remove the switch and fit the special tool with the relevant gasket.
Specific tooling
020193Y Oil pressure gauge
020434Y Oil pressure control fitting
- Remove the dipstick with the oil filling cap and insert a cap fitted with the temperature probe supplied
with the special tool. Insert the probe to feel contact with the crankcase bottom and pull back a few
millimetres.
Specific tooling
020331Y Digital multimeter
AHEAD - go to 5
5 - Measure the pressure with cold and idling engine.
STANDARD VALUES
Specification
20°C Temperature
1400 rpm
Desc./Quantity
approx. 4.5 bar
N.B.
RPM CAN BE MEASURED BOTH BY THE EXHAUST GAS ANALYSER AND BY THE DIAGNOSTIC
TESTER
Specific tooling
020460Y Scooter diagnosis and tester
YES go to 6 NO go to 12
6 - Let the engine warm up and repeat the check with hot oil.
STANDARD VALUES
Specification
80°C Temperature
1400 rpm
Desc./Quantity
ENG - 103
Engine
Nexus 500 euro 3
approx. 1.5 bar
YES go to 7 NO go to 8
7 - Replace the oil minimum pressure switch.
8 - If pressure lower than 1.3 - 1.5 bar is measured.
AHEAD go to 9
9 - Replace the oil filter and repeat the pressure check with oil at 80°C.
YES go to 10 NO go to 13
10 - The failure was fixed.
It is recommended to respect the suggested number of kilometres covered.
11 - Check and restore the electrical system.
12 - If pressure lower than 4 bar is measured.
AHEAD go to 9
13 - Remove the flywheel cover and check the by-pass and the cover sealing gasket efficiency towards
the case internal side, as described in the "Flywheel cover" chapter.
YES go to 14 NO go to 15
14 - Check whether there is an irregular clearance on the crankshaft:
- axial clearance (see the "Crankcase and crankshaft" chapter)
- radial clearance, especially in the direction of the cylinder axis
- clearance according to the direction of rotation with the connecting rod in quadrature
YES go to 16 NO go to 17
15 - Replace the faulty components ("Flywheel cover" chapter).
16 - Overhaul the engine ("Crankcase and crankshaft" chapter).
17 - Open the engine crankcase and remove the oil pump, as described in the "Crankcase and crankshaft" chapter.
- Check the oil pump as described in the following pages.
- Check that the cooling nozzle and the timing feeding jet are properly installed.
- Visually inspect the crankshaft couplings and their size ("Crankcase and crankshaft" chapter).
N.B.
POTENTIAL IRREGULARITIES IN COUPLINGS AND THE TIMING SYSTEM COMPONENTS CANNOT BE DETECTED WHEN INSPECTING THE LUBRICATION PRESSURE. THEY MAY BECOME
EVIDENT BY AN INCREASE IN NOISE.
N.B.
IN CASE OF IRREGULAR PRESSURE ON THE CRANKCASE, CARRY OUT A VISUAL AND DIMENSIONAL INSPECTION OF THE TIMING SYSTEM COMPONENTS (SEE "THERMAL GROUP
AND TIMING SYSTEM" CHAPTER).
Oil pressure check
1 - In case of oil leaks from the oil filter or from the flywheel cover coupling gasket, check the lubrication
pressure.
AHEAD go to 2
ENG - 104
Nexus 500 euro 3
Engine
2 - Install the special tool.
Specific tooling
020193Y Oil pressure gauge
020434Y Oil pressure control fitting
AHEAD go to 3
3 - Check the system pressure with cold engine and medium - high speed.
Standard pressure < 6 bar
YES go to 4 NO go to 5
4 - Replace the damaged components.
5 - Check the working order of the adjustment by-pass (see "flywheel cover" chapter) and restore proper
sliding.
N.B.
STANDARD PRESSURES ARE OBTAINED USING OIL WITH THE PRESCRIBED VISCOSITY. A
HIGHER VISCOSITY CAUSES AN INCREASE OF THE SYSTEM PRESSURE.
1 - If oil consumption is above 250 g/1000 km on a run-in engine, proceed as follows.
AHEAD go to 2
2 - Check the presence of oil at the scavenge duct on the filter box.
YES go to 3 NO go to 4
3 - Check the one-way reed valve and the decantation chamber drainage hole.
YES go to 5 NO go to 4
4 - Check the thermal group seals (piston rings, valve guides and oil guards), see "Thermal group and
Timing system" chapter.
5 - Restore the valve or the drainage hole efficiency.
Oil pump
Removal
- Remove the closing plate of the oil pump housing
by loosening the 2 retaining screws with their
washers.
ENG - 105
Engine
- Remove the oil pump complete with the gearing
by loosening the 2 retaining screws through the
eyes machined in the gearing proper.
- Remove the gasket.
- Remove the two screws and the oil pump cover.
- Remove the inside rotor retaining snap ring turning it to move the opening at the shaft face.
ENG - 106
Nexus 500 euro 3
Nexus 500 euro 3
Engine
- Remove and wash the rotors thoroughly with petrol and compressed air.
- Extract the shaft with its gear and check that it is
in good working order and free from wear.
- Reassemble the rotors in the pump body, keeping the two reference marks visible
- Insert the shaft with the gear and install the lock
ring; then, turn it with the opening opposed to the
shaft face.
- Check any irregular clearance between shaft and
pump body.
- Using a thickness gauge, check the distance between the rotors in the position shown in the figure.
Characteristic
Admissible limit clearance:
0.012 mm
- Check the distance between outside rotor and
pump body; see figure.
Characteristic
Admissible limit clearance:
0.25 mm
ENG - 107
Engine
Nexus 500 euro 3
- Check the rotor axial clearance using a rectified
bar as reference plane, as shown in the figure.
Characteristic
Limit values admitted:
0.1 mm
Inspection
- For tests on the oil pump, see the "Lubrication"
chapter.
Refitting
- Make sure the gasket is in the correct position.
N.B.
THE TOOTH OF THE GASKET MUST BE IN ITS
SEAT.
- Insert the oil pump with gear
- Insert the 2 retaining screws through the slots on the gear and tighten to the prescribed torque.
N.B.
THE ASSEMBLY POSITION OF THE PUMP IS FIXED BY INSTALLATION OF THE SCREWS.
ENG - 108
Nexus 500 euro 3
Engine
Failure to observe the tightening torque may alter
the coupling clearance of the rotors with the pump
body.
Locking torques (N*m)
Screws fixing oil pump to the crankcase 5 - 6
- Insert the countershaft with gearing into the flywheel-side half-crankcase.
- Install the special tool in the position shown in the
figure.
Specific tooling
020479Y Countershaft lock wrench
- Keep the countershaft in position and insert the
washer with the nut.
- Tighten the nut to the prescribed torque, using
the recommended product.
- Remove the special tool.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
Locking torques (N*m)
Countershaft fixing nut 25 - 29
- Lubricate the internal rotors.
- Check there are no signs of scoring or wear on
the oil pump cover.
- If non-conforming values or signs of wear are
found, replace the pump.
- Fit the pump cover in the position that permits the
crankcase fixing screws to be aligned.
- Tighten the two fastening screws to the prescribed torque.
Locking torques (N*m)
ENG - 109
Engine
Oil pump cover screws 0.7 ÷ 0.9
ENG - 110
Nexus 500 euro 3
INDEX OF TOPICS
INJECTION
INJEC
Injection
Nexus 500 euro 3
EMS injection system
The injection system is of the integrated injection and ignition type.
Injection is indirect in the manifold through electronic injector.
Injection and ignition are timed on the 4-stroke cycle using a tonne wheel pivoted on the camshaft control
and a reluctance variation sensor.
Combustion and ignition are managed on the basis of the engine speed and the throttle valve opening.
Further corrections are made according to the following parameters:
- Coolant temperature.
- Temperature of the intake air
- Ambient pressure
The system implements an idle feeding correction with cold engine through a stepper motor on a bypass circuit of the throttle valve. The control unit manages the stepper motor and the injector opening
time, thereby ensuring the idle steadiness and the proper combustion.
In all conditions of use, fuel preparation is managed by modifying the injector opening time.
The fuel feed pressure is held steady in accordance with the environmental pressure.
The feed circuit consists of:
- Fuel pump
- Fuel filter
- Injector
- Pressure regulator
Pump, filter and regulator are placed into the fuel tank using a single support.
The injector is connected by two pipes provided with quick couplings. This allows obtaining a continuous
circulation, thereby avoiding the risk of fuel boiling. The pressure regulator is situated at the end of the
circuit.
The fuel pump is controlled by the EMS control unit; this ensures the scooter's safety
The ignition circuit consists of:
- H.V. coil
- H.V. cable
- Screened cap
- EMS control unit
- Spark plug
The EMS control unit manages the ignition with optimum timing, ensuring the timing on the 4-stroke
cycle (ignition only during compression).
The EMS injection/ignition system manages the engine function according to a preset program.
Should any input signals fail, an acceptable working order of the engine is ensured to allow the user to
reach a service station.
Of course, this cannot happen when the rev counter signal is missing, or when the failure concerns the
control circuits:
INJEC - 2
Nexus 500 euro 3
Injection
- Fuel pump
- H.V. coil
- Injector
The control unit is provided with a self-diagnosis
system connected to an indicator light in the instrument panel.
Failures are detected and restored by the diagnostic tester.
In any case, when the fault is no longer present,
the data storage is automatically cleared after 16
cycles of use (cold start, running at regular engine
temperature, stop).
The diagnostic tester is also required to adjust the
idle mixture.
Specific tooling
020460Y Scooter diagnosis and tester
The EMS injection-ignition system has a control
function over the rpm indicator and the radiator
cooling electric fan.
The EMS is connected to the antitheft immobilizer
system decoder.
In turn, the decoder is connected to a flashing diagnostic LED that also serves as deterrent.
The EMS control unit power supply is further controlled by the emergency switch and by the side
stand switch, to allow further safety of the scooter.
INJEC - 3
Injection
Nexus 500 euro 3
Precautions
1. Before fixing any part of the injection system, check to see if there are any registered faults. Do not
disconnect the battery before checking for faults.
2. The fuel supply system is pressurised at 300 kPa (3 BAR). Before disconnecting the quick coupler
of a pipe in the fuel supply system, check that there are no naked flames, and do not smoke. Act with
caution to prevent spraying in the eyes.
3. When fixing electric components, operate with battery connected only when actually required.
4. When functional checks are performed, check that the battery voltage is over 12V.
5. Before trying to start the vehicle, check to make sure there is at least two litres of fuel in the tank.
Failure to respect this norm will damage the fuel pump.
6. If the scooter is expected to remain unused for a long time, refill the tank up to a little over half the
level. This will ensure the pump will be covered by fuel.
7. When washing the vehicle, be careful with the electric components and wiring.
8. When an ignition problem is detected, start the checks from the battery and the injection system
connections.
9. Before disconnecting the EMS control unit connector, perform the following operations in the order
shown:
- Set the switch to «OFF»
- Disconnect the battery
Failure to respect this norm may damage the control unit.
10. Do not invert the polarity when fitting the battery.
11. In order to prevent damages, disconnect and reconnect the EMS connectors only if actually required.
Before reconnecting, check that the connectors are dry.
12. When carrying out electric inspections, do not force the tester probes into the connectors. Do not
take measurements not specifically foreseen by the manual.
13. At the end of every check performed with the diagnostic tester, protect the system connector with
its cap. Failure to observe this norm may damage the EMS control unit.
14. Before reconnecting the quick couplers of the power supply system, check that the terminals are
perfectly clean.
Terminals setup
Layout of the system-side connectors and the connectors on the electronic control unit.
INJEC - 4
Nexus 500 euro 3
Injection
ELECTRONIC CONTROL UNIT SIDE
SYSTEM SIDE
ECU
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Specification
Throttle potentiometer power supply
Oxygen sensor
Rpm indicator / consumption counter
Engine temperature
86 electric fan remote control switch
Stepper motor
Engine rpm sensor
Oxygen sensor
EMS diagnostic connector
EMS diagnostic connector
Throttle potentiometer signal
Engine rpm sensor
Injector control
Stepper motor
Injection warning light
Decoder (serial)
Battery power supply
Air temperature sensor
Fuel pump
H.V. coil
Stepper motor
Sensor power supply
Control unit negative
Stepper motor
Turn indicator control device
Continuous power supply
Desc./Quantity
+5 V
(-)
(+)
Stepper motor
(+)
(negative)
Stepper motor
(-)
Overturn sensor
(+)
(+)
(-)
(negative control)
Stepper motor
(-)
Stepper motor
(positive)
INJEC - 5
Nexus 500 euro 3
Injection
IMMOBILIZER DECODER
1
2
3
4
5
6
7
8
Specification
Immobilizer LED control
Base power supply
Negative
Electronic control unit EMS
Continuous power supply (positive)
EMS circuit diagram
KEY:
3. Engine rev sensor
INJEC - 6
Desc./Quantity
(negative)
(positive)
(serial)
Immobilizer aerial
Nexus 500 euro 3
Injection
4. Throttle valve position sensor
5. Ambient temperature sensor
6. Stepper motor for idle nozzle
8. Engine temperature sensor
11. Injection load remote control
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
52. Oil pressure sensor
54. Instrument panel
A. Instrument panel light
B. Immobilizer LED
C. Speedometer
D. Digital display
E. Engine Warning indicator light
F. Low fuel warning light
G. Oil warning light
55. Immobilizer aerial
56. Fuel pump / fuel level transmitter
58. Fuel injector
60. Tone wheel
62. Lambda probe
63. Diagnostic socket
64. Fuel injection electronic control unit
Troubleshooting procedure
This section makes it possible to find the solutions to use in troubleshooting.
INJEC - 7
Nexus 500 euro 3
Injection
Engine does not start
ENGINE DOES NOT START IF ONLY PULLED
Possible Cause
Immobiliser enabling signal
Operation
System not encoded
System not efficient, repair according to the indications of the self-diagnosis
Presence of faults detected by the self diagnosis
Pump relay
HV coil
Injector
revolution timing sensor
Fuel supply
Fuel in the tank
Fuel pump activation
Fuel pressure (low)
Injector capacity (low)
Power to the spark plug
Shielded spark-plug cap HV coil (secondary insulation)
Parameter reliability
Coolant temperature
Distribution timing - injection ignition
Intake air temperature
End of compression pressure
End of compression pressure
Starting difficulties
ENGINE START-UP PROBLEMS
Possible Cause
Presence of faults detected by the self diagnosis
Start-up speed
End of compression pressure
Power to the spark plug
Fuel supply
Correctness of the parameters
INJEC - 8
Operation
Pump relay
H.V. coil
Injector
revolution timing sensor
Air temperature
Coolant temperature.
Atmospheric pressure
Starter motor and remote control
Battery
Ground connections
End of compression pressure
Spark plug
Shielded cap
HV coil
Revolution timing sensor
Ignition advance
Fuel pressure (low)
Injector capacity (low)
Injector sealing (poor)
Coolant temperature
Stepper throttle valve position intake air temperature (steps and actual opening)
Cleaning of the auxiliary air pipe and throttle valve;
air filter efficiency
Nexus 500 euro 3
Injection
Engine stops at idle
ENGINE DOES NOT HOLD IDLING/ IDLING IS UNSTABLE/ IDLING TOO LOW
Possible Cause
Presence of faults detected by the self diagnosis
Ignition efficiency
Correctness of the parameters
Intake system cleaning
Intake system sealing (infiltrations)
Fuel feed (low pressure)
Analysis of exhaust fumes before the catalytic converter
Operation
Pump relay
H.V. coil
Injector
revolution timing sensor
Air temperature
Coolant temperature.
Atmospheric pressure
Spark plug
Ignition timing
Throttle valve position sensor
Stepper
Coolant temperature sensor
Intake air temperature sensor
Air filter
Diffuser and throttle valve
Additional air pipe and Stepper
Intake manifold - head
Throttle body - manifold
Intake sleeve
Filter box
Fuel pump
Pressure regulator
Fuel filter
Injector capacity
Trimmer value adjustment (CO % adjustment)
Engine does not rev down
ENGINE DOES NOT RETURN TO THE IDLING SPEED/IDLING SPEED TOO HIGH
Possible Cause
Presence of faults detected by the self diagnosis
Ignition efficiency
Correctness of the parameters
Intake system sealing (infiltrations)
Fuel feed (low pressure)
Operation
Pump relay
H.V. coil
Injector
revolution timing sensor
Air temperature
Coolant temperature.
Atmospheric pressure
Ignition timing
Throttle valve position sensor
Stepper
Coolant temperature sensor
Intake air temperature sensor
Intake manifold - head
Throttle body - manifold
Intake sleeve
Filter box
Fuel pump
Pressure regulator
INJEC - 9
Nexus 500 euro 3
Injection
Possible Cause
Analysis of exhaust fumes before the catalytic converter
Operation
Fuel filter
Injector capacity
Trimmer value adjustment (CO % adjustment)
Exhaust backfires in deceleration
EXHAUST BACKFIRES WHEN DECELERATING
Possible Cause
Presence of faults detected by the self diagnosis
Correctness of the parameters
Intake system sealing (infiltrations)
Fuel feed (low pressure)
Exhaust system seal (infiltrations)
Analysis of exhaust fumes before the catalytic converter
Operation
Pump relay
H.V. coil
Injector
revolution timing sensor
Air temperature
Coolant temperature.
Atmospheric pressure
Throttle valve position sensor
Stepper
Coolant temperature sensor
Intake air temperature sensor
Intake manifold - head
Throttle body - manifold
Intake sleeve
Filter box
Fuel pump
Pressure regulator
Fuel filter
Injector capacity
Manifold - cylinder head
Manifold - muffler
Analyser socket
Muffler welding
Trimmer value adjustment (CO % adjustment)
Engine revs irregularly
IRREGULAR PROGRESS OF THE ENGINE WITH VALVE SLIGHTLY OPEN
Possible Cause
Presence of faults detected by the self diagnosis
Intake system cleaning
Intake system seal
INJEC - 10
Operation
Pump relay
H.V. coil
Injector
revolution timing sensor
Air temperature
Coolant temperature.
Atmospheric pressure
Air filter
Diffuser and throttle valve
Additional air pipe and Stepper
Intake sleeve
Filter box
Nexus 500 euro 3
Possible Cause
Ignition system
Parameter reliability
TPS reset successful
Analysis of exhaust fumes before the catalytic converter
Injection
Operation
Spark plug wear check
Throttle valve position signal
Coolant temperature indicator
Intake air temperature indicator
Ignition advance
TPS reset successful
Trimmer value adjustment (CO % adjustment)
Poor performance at full throttle
POOR ENGINE PERFORMANCE AT FULL POWER/ IRREGULAR ENGINE PROGRESS
ON PICKUP
Possible Cause
Presence of faults detected by the self diagnosis
Spark plug power supply
Intake system
Parameter reliability
Fuel supply
Operation
Pump relay
H.V. coil
Injector
revolution timing sensor
Air temperature
Coolant temperature.
Atmospheric pressure
Spark plug
Shielded cap
HV cable
HV coil
Air filter
Filter box (sealing)
Intake sleeve (sealing)
Throttle valve position signal
Coolant temperature indicator
Intake air temperature indicator
Ignition advance
Fuel level in the tank
Fuel pressure
Fuel filter
Injector capacity
Engine knocking
PRESENCE OF KNOCKING (OVERHEAD KNOCKING)
Possible Cause
Presence of faults detected by the self diagnosis
Ignition efficiency
Parameter reliability
Operation
Pump relay
H.V. coil
Injector
revolution timing sensor
Air temperature
Coolant temperature.
Atmospheric pressure
Spark plug
Throttle valve position signal
Coolant temperature indicator
INJEC - 11
Nexus 500 euro 3
Injection
Possible Cause
Intake system seal
TPS reset successful
Fuel supply
Selection of the cylinder base gasket thickness
Operation
Intake air temperature indicator
Ignition advance
Intake sleeve
Filter box
TPS reset successful
Fuel pressure
Fuel filter
Injector capacity
Fuel quality
Selection of the cylinder base gasket thickness
Decoder master-box circuit
This section describes the operations to be carried out to check the power supply circuit.
Constant supply circuit check
The decoder basic power supply is necessary for the deterrent flashing management. The injection
control unit power supply is necessary for the stepper motor management.
A power supply failure disables both ignition and injection.
In case of power supply faults, the diagnostic tester gives the information "NO REPLY FROM THE
CONTROL UNIT".
To carry out the check, proceed as follows:
Specific tooling
020460Y Scooter diagnosis and tester
1 - Check whether the immobiliser system LED indicates that the switch is in position "ON" and that
the deterrent flashing is on.
YES go to 2 NO go to 7
2 - The decoder is properly programmed.
YES go to 3
3 - Switch set to "ON" with side stand raised and
emergency switch set to "OFF". The injection indicator turns on for about 3 seconds.
YES go to 5 NO go to 4
4 - Check the instrument unit and its power supply.
YES go to 3
5 - Set the emergency switch to "RUN". The injection warning light comes on for about 5 seconds.
YES go to 6 NO go to 7
6 - The injection control unit is certainly powered.
7 - Check that fuses 3 and 7 are in working order.
INJEC - 12
Nexus 500 euro 3
Injection
YES go to 10 NO go to 8
8 - Fix any wiring short circuits and replace the
fuse.
YES go to 1 NO go to 9
9 - Check any short circuit on decoder or control
unit and replace, if necessary.
YES go to 1
10 - Place the special tool between control unit and
power supply system. Disconnect the main decoder connector and check the following conditions:
Terminal no. 3= battery positive
Terminal no. 4= battery negative
YES go to 11 NO go to 13
Specific tooling
020481Y Control unit interface wiring
11 - Decoder with proper base power supply.
Use the special tool to check the control unit power
supply:
Pin 17 = battery positive
Pin 23 = battery negative
YES go to 12 NO go to 13
12 - Control unit with proper base power supply.
13 - If the battery negative is not present, check
continuity between Pin 23 of the special tool and
earth.
Detect the presence of the battery positive on Pin
17 of the special tool and on pin 3 of the decoder
connector.
YES go to 12 NO go to 14
YES go to 11
14 - Fix the cable harness.
INJEC - 13
Injection
Nexus 500 euro 3
Key-switch power supply circuit check
A failure of the constant power supply disables both ignition and injection functions. In case of power
supply faults, the diagnostic tester gives the information "NO REPLY FROM THE CONTROL UNIT".
Specific tooling
020460Y Scooter diagnosis and tester
1 - Check whether the immobilizer system LED indicates switching to "ON"
YES go to 2 NO go to 4
2 - Raise the side stand. Set the emergency switch
to "OFF". Turn the key switch to "ON". Set the
emergency switch to "RUN". Check whether the
injection warning light turns on for 5 seconds
YES go to 3 NO go to 4
3 - Continuous power supplies are regular
4 - Check the function of fuse No. 8, check the function of the engine stop remote control.
YES go to 5 NO go to 6
5 - Place the special tool between control unit and injection system.
YES go to 7
Specific tooling
020481Y Control unit interface wiring
6 - Fix any short circuits and replace the fuse.
Check decoder and control unit, if necessary
YES go to 1
7 - Disconnect the main decoder connector and
check the following conditions: switch set to "ON",
switch to "RUN" and side stand raised
Terminal no. 8 = battery positive
Terminal no. 4= battery negative
YES go to 8 NO go to 10
INJEC - 14
Nexus 500 euro 3
Injection
8 - Decoder with proper continuous power supply.
Use the special tool to check the control unit continuous power supply. Switch set to "ON", switch
to "RUN" and side stand raised.
Pin 26 = battery positive
Pin 23 = battery negative
YES go to 9 NO go to 10
Specific tooling
020481Y Control unit interface wiring
9 - Control unit with proper continuous power supply.
10 - If only one component is not powered check
the relevant connector. If the problem involves
both the decoder and CPU check the continuity of
the decoder CPU power supply line.
Pin 26 electronic control unit - Pin 87 engine stop
remote control switch = continuity
Pin 8 decoder - Pin 87 engine stop remote control
switch = continuity
YES go to 12 NO go to 11
11 - Fix the wiring or the connection
YES go to 10
12 - Proper continuous power supply
YES go to 13
13 - Check the connector and the continuity of the key switch set to "ON"
Pin B - F = Continuity
YES go to 14
14 - Check the engine stop remote control switch connector and the switch efficiency.
The connector can be recognised by its larger section white lead.
85 - 86 = approx. 70W
YES go to 15
N.B.
CHECK THE COIL RESISTANCE
INJEC - 15
Injection
Nexus 500 euro 3
15 - Check the signal circuit:
- emergency switch and connector
- side stand switch and connector
YES go to 16
16 - Check the cable harness continuity. Check the utility control main remote control switch.
Disconnect the master remote control switch.
Check the diode installed on the earth connection of the main remote control switch pickup.
86 - earth = continuity with high resistance (connect the tester: positive with 86; negative with earth).
When the polarity is inverted there should be no continuity.
Diagnostic circuit
* CONNECTOR FOR DIAGNOSTIC TESTER
A = INJECTION CONTROL UNIT
Connect the diagnostic tester.
Specific tooling
020460Y Scooter diagnosis and tester
If the diagnostic tester displays "No reply from the
control unit", disconnect the continuous power
supply for 10 seconds and switch to "ON" again; if
the message is still displayed, proceed as follows:
1 - Check the diagnostic tester connections.
YES go to 2 NO go to 3
INJEC - 16
Nexus 500 euro 3
Injection
2 - Check the control unit base and continuous
power supplies.
YES go to 4
3 - Restore
4 - Place the special tool between control unit and
system. Keep the control unit disconnected.
YES go to 5
Specific tooling
020481Y Control unit interface wiring
5 - Check the following conditions:
PIN 1 diagnostic socket - PIN 10 control unit =
continuity
PIN 2 diagnostic socket - PIN 23 control unit =
continuity with earth
PIN 3 diagnostic socket - PIN 9 control unit = continuity
10 - 23 = insulation (>1 MΩ)
9 - 23 = insulation (>1 MΩ)
YES go to 6 NO go to 7
6 - The circuit is in good working order. Check the control unit.
7 - Fix the interruption or short-circuit.
INJEC - 17
Injection
Injection warning light circuit
KEY:
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
54. Instrument panel
A. Instrument panel light
B. Immobilizer LED
C. Speedometer
D. Digital display
E. Engine Warning indicator light
F. Low fuel warning light
G. Oil warning light
INJEC - 18
Nexus 500 euro 3
Nexus 500 euro 3
Injection
64. Fuel injection electronic control unit
REFERENCE VALUES
1
Specification
TERMINAL: 15 - 23
2
TERMINAL: 15 - 23
Desc./Quantity
CONDITIONS: DURING THE CHECK
- Switch set to "ON"
- Side stand raised
- Switch to "RUN"
STANDARD VALUES : O V
CONDITIONS: AFTER THE CHECK
- Switch set to "ON"
- Side stand raised
- Switch to "RUN"
STANDARD VALUES : Battery voltage
The injection warning light is controlled upon every switching to "ON" by the 3-second timing generated
by the digital instrument. This step is normally interrupted by the injection control unit control. The timing
lasts 5 seconds.
The diagnostic tester is not programmed to check this circuit.
Proceed as follows:
Specific tooling
020460Y Scooter diagnosis and tester
1 - Turn the switch to the "ON" position Turn the emergency switch to position "RUN". Keep the side
stand raised. Make sure the light goes on for 5 seconds.
YES go to 2 NO go to 3
2 - The system is working.
3 - Put the special tool between the control unit and system.
YES go to 4
Specific tooling
020481Y Control unit interface wiring
4 - Switch in "ON" position Emergency switch on
"RUN".
Side stand up Wait more than 5 seconds.
15 - 23 = battery voltage
YES go to 5 NO go to 6
INJEC - 19
Injection
Nexus 500 euro 3
5 - Check the CPU connector. Check the electronic
control unit.
6 - Check the continuity between pin 15 of the ECU
and pin 17 of the connector 20 input connector of
the instrument panel.
The injection CPU manages the negative of the light. The light must go off after the initial check. The
light goes on again when the CPU autodiagnosis detects a fault. When the fault disappears the light
goes back off, however, the related operating tests need to be carried out. The light can go on whether
the engine is able to run or not.
Self-diagnosis system
The injection control unit is provided with an auto-diagnosis function.
When a failure is detected, the control unit:
- turns on the injection indicator (only when it is current).
- enables the engine management check according to the data entered in the control unit (where possible).
- stores the failure (always).
In the event of intermittent failures, the indicator follows the failure trend and storage remains active.
Stored data are automatically deleted when the failure does not occur for over 16 usage cycles of the
scooter (heating - use - cooling). The battery disconnection does not delete stored data.
Checking stored failures
Connect the diagnostic tester to the scooter system.
Select the function "ERROR" in the menu.
Specific tooling
020460Y Scooter diagnosis and tester
INJEC - 20
Nexus 500 euro 3
Injection
The tester pages display the list of errors detectable by the auto-diagnosis.
Errors detected by the auto-diagnosis are marked
by one or two reference dots.
They are arranged on two lines:
Line A = current failures (present)
Line M = stored failures
Errors detectable by the auto-diagnosis may refer to the following system circuits or sectors of the
control unit:
- Throttle valve position signal
- ambient pressure signal
- coolant temperature signal
- sucked air temperature signal
- wrong battery voltage
- Injector and relevant circuit
- HV coil and relevant circuit
- Stepper and relevant circuit
- Pump relay circuit
- Electric fan relay circuit
- RAM memory
- ROM memory
- EEPROM
- Microprocessor
- Signals panel (stroke - revolution signal - unsteady cycle)
Underlined failures cause the engine to stop.
In the other cases, the engine works managed by the basic data.
Deleting stored failures
After mounting any failures, connect the diagnostic
tester.
Select the menu on the "errors deleting" function.
Press "OK" and follow the instructions. Perform a
trial cycle and check whether the failure occurs
again.
Specific tooling
020460Y Scooter diagnosis and tester
For troubleshooting for any faults see the related chapter sections.
INJEC - 21
Injection
Nexus 500 euro 3
Fuel supply system
Fuel is fed to the injector by a pump, a filter and a
pressure regulator integrated with the fuel level indicator inside the tank.
The pump unit is connected to the injector by:
2 semi-flexible pipes
4 quick unions
1 T union with O-ring and retain bracket for the injector
The pipes are crossed and fixed to the intake manifold to prevent wear of the quick unions connected
to the T union for the injector.
N.B.
BEFORE WORKING ON THE FUEL SUPPLY SYSTEM, CAREFULLY CLEAN THE PARTS TO
PREVENT DAMAGING THE FAST-RELEASE COUPLING SEAL OR TO PREVENT DIRT GETTING
INTO THE DUCTS.
CAUTION
THE SYSTEM IS UNDER PRESSURE.
DO NOT SMOKE DURING ANY OPERATION.
PREVENT ANY FUEL SPRAYING.
WARNING
- BEFORE STARTING THE ENGINE, CHECK WHETHER THERE IS FUEL IN THE TANK.
- DO NOT USE THE SCOOTER IN RESERVE FOR A LONG TIME, UP TO THE POSSIBILITY OF
RUNNING OUT OF FUEL.
- IF THE SCOOTER IS EXPECTED TO REMAIN UNUSED FOR A LONG TIME, REFILL THE TANK
AT LEAST TO HALF THE LEVEL.
FAILURE TO OBSERVE THESE RULES CAN DAMAGE THE PUMP.
INJEC - 22
Nexus 500 euro 3
Injection
Circuit diagram
KEY
11. Injection load remote control
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
56. Fuel pump / fuel level transmitter
58. Fuel injector
59. Spark plug
61. HV coil
64. Fuel injection electronic control unit
Removing the injector
N.B.
INJEC - 23
Injection
Nexus 500 euro 3
ONLY REMOVE THE INJECTOR FROM THE MANIFOLD IN THE EVENT OF A PROVEN DEFECT.
OPERATING TEST OF THE INJECTOR MUST BE PERFORMED WITH THE INJECTOR INSTALLED
ON THE MANIFOLD (SEE "INJECTION").
- To remove the injector, remove the central set
screw of the "T" shunt acting as a support for the
injector.
- Remove the injector from the manifold.
- Once the engine is repaired check the CO% value again while idling to make sure it is within the
prescribed limits. If the CO% is not in conformity, proceed with calibration as described in the "Carburetion adjustment" chapter.
Refitting the injector
Carefully check to make sure the components are
clean.
- Fit new O-rings and grease them.
- Apply the recommended product to the set
screws and tighten to the prescribed torque.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
Locking torques (N*m)
injector fixing screw 3 ÷ 4
N.B.
ONCE THE ENGINE IS REPAIRED CHECK THE CO% VALUE WHILE IDLING TO MAKE SURE IT
IS WITHIN THE PRESCRIBED LIMITS. IF THE CO% IS NOT IN CONFORMITY, PROCEED WITH
CALIBRATION AS DESCRIBED IN THE ADJUSTING IDLE CARBURETION PARAGRAPH.
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Nexus 500 euro 3
Injection
Removing the butterfly valve
N.B.
THE THROTTLE BODY IS A PART WHICH INCLUDES VARIOUS COMPONENTS AND IS USUALLY SUPPLIED COMPLETE. TO TEST THESE COMPONENTS SEE THE "INJECTION" CHAPTER.
- Remove the 3 retaining screws indicated in the
figure.
CAUTION
THE THROTTLE BODY COMES PRE-CALIBRATED. TAMPERING WITH THE THROTTLE STOP
REGISTER IS TO BE ABSOLUTELY AVOIDED. THIS REGISTER HAS BEEN SEALED FOR THIS
PURPOSE. FOR PROBLEMS WITH IDLING SEE THE "INJECTION" CHAPTER.
N.B.
REMOVAL OF THE THROTTLE BODY CAN BE EFFECTED WITH THE MANIFOLD ON OR OFF
THE ENGINE.
- Make sure the seal rims on the coupling surfaces
between the manifold-throttle body and manifoldhead are in good condition.
CAUTION
IF AIR GETS IN IT CAN JEOPARDISE THE OPERATION OF THE INJECTION SYSTEM, ESPECIALLY WHEN THE ENGINE IS IDLING.
- Make sure the throttle valve and related conduit
are clean.
- Make sure the supplementary air channel managed by the stepper motor is clean.
N.B.
IF THE THROTTLE BODY IS REPLACED RESET THE T.P.S. AND ADJUST THE CO%.
ONCE THE ENGINE IS REPAIRED CHECK THE CO% VALUE WHILE IDLING TO MAKE SURE IT
IS WITHIN THE PRESCRIBED VALUES.
IF THE CO% IS NOT IN CONFORMITY, PROCEED WITH CALIBRATION AS DESCRIBED IN THE
ADJUSTING IDLE CARBURETION CHAPTER.
throttle body
INJEC - 25
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Injection
Upon analysing the material sent and covered by the warranty, it seems several throttle bodies have
been mistakenly replaced due to valve fouling. Dirt deposited on that valve, mainly on the inlet manifold
side, can be easily removed. Once clean, the throttle body guarantees an air flow exactly the same as
the original. Throttle valve fouling is phenomenon that happens at different times depending on how
the scooter is used, weather conditions and idle speed adjustment. This phenomenon can be easily
detected as a gradual poor idle signals it. Carry out a thorough check with a scooter diagnostic tester,
drw. 020460y. With engine temperature of at least 90°, the parameters may be as follows:
Standard
Dirty throttle body
1500±5
< 1400
Ignition advance
5°÷7°
10°
Throttle valve opening
5.24°
5.24°
Engine revs
The error menu displays the signals stored in the "RPM sensor". This takes place only when the engine
stops with the key switch set to "on." An exhaust fumes analysis will show a very rich and non adjustable
idle carburetion (CO > 4% - CO2 < 12%). Measure with the tool in drw. 020625y. It is evident that,
except for cases of early fouling, cleaning should not be carried out when still covered by the warranty.
After cleaning the throttle body, check and, if necessary, adjust C0. If these indications occur when the
injection warning light turns on or further errors or wrong parameters are present, it is necessary to carry
out the relevant controls indicated in the manual. In such a case, there is a real fault evidently.
Refitting the butterfly valve
- Carry out the operations in the reverse order of
the disassembly, tighten the 3 set screws to the
prescribed torque.
Locking torques (N*m)
Throttle body fixing screws 11 ÷ 13
Pump supply circuit
The control unit starts the pump in the following conditions:
- by setting the switch to "ON" with emergency switch to "RUN" and side stand raised. The pump does
not supply.
- If the phase rotation signal is received. Continuous supply.
The initial timing is useful to bleed the system especially after a stop with engine in temperature. In
these conditions, the fuel altered by boiling will be mixed with that in the tank.
INJEC - 26
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Injection
During use, the pump operation will be subject to the engine speed.
Circuit check
Proceed as follows:
1 - Set the switch to "ON" with emergency switch to "RUN" and side stand raised. The pump rotates for
2 seconds.
YES go to 2 NO go to 3
2 - Try to start up. Check that the engine speed matches the pump rotation.
YES go to 4 NO go to 5
3 - The pump does not rotate, or it rotates uninterruptedly.
YES go to 5
4 - The pump power supply is conforming.
5 - Connect the diagnostic tester to the scooter system.
YES go to 6
Specific tooling
020460Y Scooter diagnosis and tester
6 - Try to start up. Select the function "ERRORS"
in the menu. Check whether there are any failures.
YES go to 7 YES go to 8 NO go to 28
7 - Pump control relay circuit failure.
YES go to 9
8 - Failure of:
- injector
- H.V. coil
- Signals panel
YES go to 18
9 - The control unit has detected a failure on the line of pin 19
YES go to 10 YES go to 11
10 - Line to earth. In this case, the pump always starts to rotate if there is a continuous power supply.
YES point 12
11 - Interrupted line. The relay cannot control the pump feeding
INJEC - 27
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Nexus 500 euro 3
YES go to 13
12 - Check and restore the earth insulation of the control unit line 19 and of the pump remote control
switch line 85.
YES go to 14
13 - Install the special tool between control unit and the injection system.
YES go to 15
Specific tooling
020481Y Control unit interface wiring
14 - Delete the code and check from the beginning.
15 - Set the switch to "ON" with switch to "RUN"
and side stand raised. Wait more than two seconds and check the following conditions:
19 - 23 = battery voltage
YES go to 16 NO go to 17
16 - Replace the control unit.
17 - Check the presence of voltage (+ batt.) between pin 86 of the pump remote control switch
and pin 23 of the control unit. Fix the wiring, if required. Check the relay coil continuity.
85 - 86 = 100 ± 50Ω
18 - Check that fuse 12 is in working order
YES go to 20 NO go to 19
19 - Disconnect the following connectors: fuel
pump, H.V. coil, injector
YES go to 22
20 - Check the efficiency of the pump remote control switch. Check the wiring continuity between
remote control switch and pump.
87 (remote control switch) - green/black (pump) =
continuity
NO go to 21
INJEC - 28
Nexus 500 euro 3
Injection
21 - Fix the wiring and repeat the check from the
beginning.
22 - Check the earth insulation of wiring
87 (pump remote control switch) - 23 = insulation
(>1 MΩ)
YES go to 24 NO go to 23
23 - Restore the wiring insulation and replace the
fuse.
24 - Check the ground insulation of the primary
winding of the HV coil and of the injector coil.
YES, go to 25
25 - Check the pump winding resistance: approx.
1.5Ω
YES go to 26 NO go to 27
26 - Replace the fuse and check the pump.
27 - Check the absorbed current.
28 - Select the diagnostic tester menu on the "ACTIVE DIAGNOSIS" function. Select the fuel pump
simulation function. Enable the function with continuous power supply on and engine off.
YES go to 29
Specific tooling
020460Y Scooter diagnosis and tester
29 - The tester prompts the control unit to start the pump for 30 seconds
YES go to 30
30 - Acoustically check the following conditions:
- Relay closure
- Pump rotation
- Relay opening
YES go to 31 NO go to 32
31 - The pump is fed. Perform a functional check of the pump.
32 - Check the efficiency of the pump connector.
YES go to 33 NO go to 34
33 - Replace the fuel pump.
34 - Restore
INJEC - 29
Injection
Nexus 500 euro 3
The injection CPU manages the negative of the light. The light must go off after the initial check. The
light goes on again when the CPU autodiagnosis detects a fault. When the fault disappears the light
goes back off, however, the related operating tests need to be carried out. The light can go on whether
the engine is able to run or not.
The ignition system control unit is programmed to ensure optimal carburetion while riding along streets.
The idle carburetion needs to be adjusted to compensate for the production tolerances and engine
settlement.
This adjustment is done by modifying the injector opening time with the engine running at idle.
To adjust, proceed as follows:
1 - Idle carburetion adjustment must be performed on an engine ready for precision adjustment.
Check in advance:
- spark plug
- that air filter is clean
- that throttle body is clean
- intake system for sealing
- exhaust system for sealing
- valve clearance
- fuel filter
- Fuel pressure
N.B.
IDLE SPEED IS OBTAINED BY PRECALIBRATING THE THROTTLE BODY AND ACTIVATING THE
STEPPER.
Characteristic
Engine idle speed
1500 ± 50 rpm
Check that the throttle body is not tampered.
YES go to 2
2 - Preheat and check the zero setting of the exhaust fumes analyser.
Remove the exhaust manifold cover and connect
the extension to the coupling clamp for the analyser pipe.
YES go to 3
INJEC - 30
Nexus 500 euro 3
Injection
3 - Connect the diagnostic tester.
Set the switch to "ON" with switch to "RUN" and
side stand raised.
YES go to 4
4 - Select the menu on the "ERRORS" function.
Check whether there are any failures.
YES go to 6 NO go to 5
5 - Select the menu on the "PARAMETERS" function.
YES go to 7
6 - Repair according to indications supplied.
YES go to 4
7 - Start the engine and let it warm up until the
following conditions are present:
- coolant temperature = over 80°C
- intake air temperature = 25 ÷ 30°C
YES go to 8
8 - Activate the exhaust fumes analyser and check
the following conditions are present:
- CO = 1.25±0.25%
- CO2 = 14.50±1%
YES go to 9 NO go to 10
9 - The adjustment is correct.
10 - If a different CO value is read, adjust the idle
injection timing.
YES go to 11
11 - Select the diagnostic tester menu on the «CO
CALIBRATION» option.
Activate the adjustment function.
YES point 12
12 - «TRIMMER VALUE» is displayed.
The numbers displayed can be positive or negative.
YES go to 13
13 â To increase the CO the injection time needs to be increased.
To decrease the CO the injection time needs to be decreased.
Adjust the trimmer value according to the indications in the table:
YES go to 14
INJEC - 31
Nexus 500 euro 3
Injection
TRIMMER VALUE
INJECTION TIME
CO
+100
HIGH
INCREASE
+ 50
Ã
Ã
+ 10
LOW
Ã
0
Ã
DECREASE
- 10
MEDIUM
- 50
-100
N.B.
THE TRIMMER VALUE 0 CORRESPONDS TO THE AVERAGE INJECTION TIMING.
AFTER ADJUSTMENT ENGINES CAN HAVE CARBURETION WITH BOTH POSITIVE AND NEGATIVE TRIMMER VALUES.
THIS IS DUE TO NORMAL PRODUCTION TOLERANCES.
14 - After having modifying a trimmer value, wait
until the CO value becomes steady.
In case of incorrect adjustment, press OK to store
the value in the control unit memory.
YES go to 15
15 - Select «PARAMETERS» and «ECU DATA»
to confirm the new trimmer change has been stored.
N.B.
WHEN THE CO PERCENTAGE IS RIGHT AND THE CO2 PERCENTAGE DOES NOT FALL INTO
THE SPECIFIED VALUES, THE LAMBDA VALUE IS ALSO DISTORTED. IF THIS OCCURS, CAREFULLY CHECK THE EXHAUST SYSTEM FOR ADEQUATE SEALING.
When the CO percentage is correct and the HC (PPM) value exceeds the maximum limit allowed, check:
- spark plug
- valve clearance
- timing system phase
- outlet valves for sealing
When the control unit is replaced, reset TPS and pre-program the trimmer value of the original control
unit (if available) preventively.
In any case, check the CO value again.
INJEC - 32
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Injection
N.B.
WHEN THE CO PERCENTAGE IS RIGHT AND THE CO2 PERCENTAGE DOES NOT FALL INTO
THE SPECIFIED VALUES, THE LAMBDA VALUE IS ALSO DISTORTED.
If this occurs, carefully check the exhaust system for adequate sealing.
When the CO percentage is correct and the HC (PPM) value exceeds the maximum limit allowed, check:
- spark plug
- valve clearance
- timing system phase
- outlet valves for sealing
When the control unit is replaced, reset TPS and pre-program the trimmer value of the original control
unit (if available) preventively.
In any case, check the CO value again.
Circuit leak test
Before performing the checks concerning the system pressure, it is necessary to proceed by carefully cleaning all feeding system components.
To perform the inspections it is necessary to use
the special tooling kit for fuel pressure check.
Specific tooling
020480Y Petrol pressure check set
Before disconnecting any fastener, reduce the system pressure.
Detach the electrical connector from the pump support with the engine running and wait for the shutdown.
The engine stops at approximately 1.5 bar.
CAUTION
CAREFULLY DETACH THE HOSE TERMINAL PREVENT POSSIBLE SPRAYS FROM COMING
INTO CONTACT WITH THE EYES.
The special tool is equipped with fast-release fittings, similar to those provided for the circuit.
In order to disconnect the female terminals (injector side), it is necessary to press the two extensions and draw them.
CAUTION
DO NOT FORCE THE TERMINAL IF THIS DOES
NOT COME LOOSE; EVENTUALLY, TRY
TWISTING IT. THE TERMINAL IS DESIGNED
SO THAT AN INCREASE IN TENSION INCREASES THE LOCKING FORCE.
INJEC - 33
Injection
To detach male type terminals (pump side) it is
necessary to press the coaxial rings towards the
pump, and extract the terminals.
CAUTION
DO NOT FORCE THE TERMINAL IF THIS DOES
NOT COME LOOSE; EVENTUALLY, TRY
TWISTING IT. THE TERMINAL IS DESIGNED
SO THAT AN INCREASE IN TENSION INCREASES THE LOCKING FORCE.
The system pressure check must be carried out,
for practical reasons, by connecting on the pump
side.
Connect the manometer to the outlet duct (RHS)
and the extension tube to the inlet duct (LHS).
CAUTION
BEFORE REASSEMBLING CHECK THE TOOL
DUCTS ARE CLEAN.
Pressure regulator check
1 - Connect the diagnostic tester.
Specific tooling
020460Y Scooter diagnosis and tester
Select the menu on the "ACTIVE DIAGNOSIS"
function.
Select the "PUMP DIAGNOSIS" function.
YES go to 2
2 - Enable the function with continuous power supply on and engine off.
The control unit starts the pump for 30 seconds
YES go to 3
3 - Let the system bleed for a few seconds.
Make sure that there are no external leaks.
INJEC - 34
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Nexus 500 euro 3
Injection
Check the regulation pressure with pump power
supply voltage higher than 12 V.
Regulation pressure = 300 - 320KPa (3 - 3.2 BAR)
YES go to 4 NO go to 5
4 - The pressure regulator is efficient.
5 - Pressure too high
Check that the return duct is not clogged or
squashed
YES go to 6 NO go to 7
6 - Replace the pressure regulator.
7 - Pressure regulation too low
Start the pump rotation again. Using pliers with flat
and long tips, temporarily clamp the return duct by
the extension of the specific tool (the serial pipe
does not allow this operation).
fuel pressure = over 300 KPa (3 BAR)
YES go to 8 NO go to 9
8 - Replace the pressure regulator.
9 - Replace the fuel pump.
Fuel pump and filter check
This procedure is useful during maintenance to check the filter efficiency in delivery.
Connect the diagnostic tester.
Connect the fuel pressure check kit.
Specific tooling
020460Y Scooter diagnosis and tester
020480Y Petrol pressure check set
1 - Select the diagnostic tester menu on the «ACTIVE DIAGNOSIS» function.
Select the «PUMP DIAGNOSIS» function.
The pump starts for 30 seconds.
YES go to 2
INJEC - 35
Injection
2 - Let bleed for a few seconds.
Make sure that there are no leaks.
Using pliers with flat and long tips, temporarily
clamp the return duct by the extension of the special tool with pump power supply voltage higher
than 12 V, check the system maximum pressure.
Maximum pressure = > 600 KPa (6 BAR)
YES go to 3 NO go to 4
Specific tooling
020480Y Petrol pressure check set
3 - Check the system seal.
Start the pump for 30 seconds using the diagnostic tester.
When the pump stops, wait 3 minutes.
Check the system pressure.
Fuel pressure = over 200 KPa (2 BAR)
YES go to 5 NO go to 6
Specific tooling
020460Y Scooter diagnosis and tester
4 - If pressure is lower, carefully check the voltage
with pump under stress.
If voltage is higher than 12 V, replace the pump.
5 - The system seal is efficient.
Check the free flow rate.
AHEAD go to 16
6 - Repeat the test. When the pump stops, use pliers with flat and long tips to temporarily clamp the
return duct by the extension of the special tool.
This causes an increase of the fuel pressure.
AHEAD go to 7
INJEC - 36
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Injection
7 - Check whether the pressure decreases with the
same trend as the system when free from bottlenecks
AHEAD go to 8
8 - Pressure decreases much more slowly
YES go to 9 NO go to 10
9 - Replace the pressure regulator. Check the system seal again.
10 - There occur trend variations
YES go to 11 NO go to 13
11 - Repeat the test clamping the pipe of the special tool in the portion between the branch and the
injector.
Check whether the pressure decreases with the
same trend as the system when free. Pressure
decreases much more slowly
YES go to 12 NO go to 13
Specific tooling
020480Y Petrol pressure check set
12 - Check and replace the injector, if required,
due to an insufficient seal.
(see "THERMAL UNIT AND TIMING SYSTEM ")
13 - There are no trend variations
Repeat the test clamping the pipe of the special
tool in the portion between the branch and the
pump. Check whether pressure decreases much
more slowly.
YES go to 14 NO go to 15
Specific tooling
020480Y Petrol pressure check set
14 - The pump unidirectional valve is faulty. Replace the pump. (see Pump bracket overhaul)
15 - Check the pipe and the injector union seals more carefully.
Check the component seals again, if necessary.
A POOR SYSTEM SEAL ONLY AFFECTS THE START-UP VELOCITY.
INJEC - 37
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Nexus 500 euro 3
16 - Disconnect the pump connector, start the engine, wait until it stops and connect the connector
again.
Disconnect the fuel return pipe from the pump support (left pipe).
AHEAD go to 17
17 - Introduce the return pipe into a graduated
container.
Using the diagnostic tester, start the fuel pump for
10 seconds.
Make sure that the power supply voltage is more
than 12V.
Measure the amount of fuel delivered.
Pump free flow rate = 300 - 320 cc.
YES go to 18 NO go to 19
Specific tooling
020460Y Scooter diagnosis and tester
18 - The fuel filter is not clogged.
The scooter can be used respecting the limit of 48000 km.
19 - The flow rate is less than 250 cc.
The fuel filter is dirty. Replace the pump support.
Pump electrics check
This section describes the operations to be carried out to perform electric checks on the pump.
Resistor check
Disconnect the connector from the pump support.
Using a tester, measure the pump winding resistance.
Connect the tester probes to the pump support
pins as shown in the figure.
Electric characteristic
Resistance:
approx. 1.5 Ω
In case of infinite resistance, replace the pump.
INJEC - 38
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Injection
With infinite resistance, the pump does not rotate.
With resistance close to 0 Ω, the pump power consumption is too high, with the possibility of blowing
the fuse No. 12. Carry out the following check.
Pump consumption check
The pump power consumption may vary according
to:
- Power supply voltage
- Pump running-in
- Regulation pressure
- Delivery filter cleaning
To check the current consumption, proceed as follows
- Disconnect the pump remote control switch connector.
- With key switch set to "OFF", connect the jumpers 30-87 on the connector using the tester probes
in ammeter function (see figure).
- Check the pump rotation and power consumption
N.B.
THIS CONSUMPTION REFERS TO:
- POWER SUPPLY VOLTAGE = approx. 12 V
- PUMP RUN IN
- SYSTEM PRESSURE = 300 KPA (3 BAR)
- FUEL FILTER CLEAN
Electric characteristic
Current consumption:
approx. 3.5 - 4.2 A
The a dirty filter causes an increase of the absorption. If the overpressure valve opens, the pump absorbs approx. 6-7A.
In case of excessive absorption(5A), replace the filter. See pump support overhaul.
If the fault continues, replace the pump.
Fuel filter check
To check the fuel filter inspect the following:
- Free flow
- Current absorbed by the pump. A clogged filter causes:
- Poor performance especially at full power
- Pump absorption increase
INJEC - 39
Injection
Nexus 500 euro 3
N.B.
DO NOT BLOW THE FILTER WITH COMPRESSED AIR. A DAMAGED FILTER MAY CAUSE THE
INJECTOR CLOGGING.
Pump bracket overhaul
To remove the pump support from the tank, proceed as follows:
- Disconnect the electric connector.
- Start the engine and wait for the spontaneous
stop.
- Clean the tank and the pump support (wash and
blow with compressed air, if necessary).
- Disconnect the delivery and return pipes by the
quick unions.
CAUTION
PREVENT ANY FUEL SPRAYING.
- Loosen the pump support mounting ring nut (RH
threading).
- Remove the pump support and the sealing gasket.
N.B.
WHEN EXTRACTING, BE CAREFUL NOT TO
DEFORM THE FLOATING ARM.
INJEC - 40
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Injection
To replace the components, proceed as follows:
(1) Level indicators:
- Note the assembly position and the path of the
two connecting wires.
Pos 2 = wire connected to the circuit
Pos 3 = wire connected to the mobile arm
Pass the wires through the hole obtained between
filter and pressure regulator.
- Disconnect and extract the wires
- Using a screwdriver on the retain tab as shown
in the figure, extract the level indicator from the
support
- Level indicator check
The check may also be carried out before removal from the support.
Measure the resistance between the two level indicator wires.
Moving the float arm, check that the resistance is subject to gradual variations according to the arm
motion.
LIMIT VALUES
1
2
Specification
Empty tank position:
Full tank position:
Desc./Quantity
95 - 105 Ω
0-9Ω
- Repeat the operations in the reverse order for re-assembly.
(2) Pressure regulator:
- Remove the locking spring
- Extract the pressure regulator with sealing rings.
N.B.
INJEC - 41
Injection
Nexus 500 euro 3
TO OVERCOME THE RESISTANCE OF THE O-RINGS, LEVER WITH A SCREWDRIVER THROUGH
THE OPENINGS OBTAINED ON THE STOP INSERTION SIDE.
- Lubricate the O-rings and repeat the operations
in the reverse order for re-assembly.
(3) Fuel pump
- Note the position of the power supply wires on the support
pos 1 = positive (red)
pos 4 = negative (black)
- Disconnect the power supply cables
- Cut the delivery pipe mounting band on the support.
INJEC - 42
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Injection
- Remove the pump mounting washer
- Remove the filter coupling pipe
- Remove the pump with annular support and prefilter.
- If the pump requires replacement, remove the
pre-filter and the annular support.
- For re-assembly, perform the removal operations
in the reverse order using a new band for the delivery pipe and a new pump mounting washer.
N.B.
TO CLEAN THE PRE-FILTER, USE PETROL AND COMPRESSED AIR.
Orientate the pump properly.
INJEC - 43
Injection
Nexus 500 euro 3
(4) Fuel filter
The fuel filter is supplied already assembled with
the pump support.
To replace the support, move the level indicator,
the pressure regulator and the pump from the old
to the new support.
For these operations, follows the instructions given above.
Pump bracket installation
- Before reassembling, carefully check the tank
cleaning.
In case of dirt or water, remove the tank.
- Install the sealing gasket on the pump support.
- Introduce the pump into the tank being careful not
to deform the level indicator arm.
- Place the sealing gasket on the tank.
- Install the pump support onto the seat aligning
the connector with the scooter longitudinal axle.
N.B.
AN INCORRECT ORIENTATION MAY IMPAIR
THE LEVEL INDICATOR PERFORMANCE.
- Screw the mounting ring nut and tighten thoroughly.
Locking torques (N*m)
Electric pump locking ring nut 20
- Connect the feeding circuit pipes again and check the proper introduction by pulling and turning upwards.
- Reconnect the electric connector.
- Recharge the system with at least 4÷5 timings (key switch «OFF-ON»)
N.B.
DO NOT START THE PUMP BEFORE REFILLING THE TANK. FAILURE TO OBSERVE THIS RULE
CAN DAMAGE THE PUMP.
- Check that the feeding system quick couplings seal is efficient.
INJEC - 44
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Injection
Inspecting the injector circuit
KEY
11. Injection load remote control
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
56. Fuel pump / fuel level transmitter
58. Fuel injector
59. Spark plug
61. HV coil
64. Fuel injection electronic control unit
INJEC - 45
Injection
1 - Connect the diagnostic tester. Select the menu
on the "ACTIVE DIAGNOSIS" function.
Select the "INJECTOR" function.
YES go to 2
Specific tooling
020460Y Scooter diagnosis and tester
2 - Enable the function with continuous power supply on and engine off. The control unit controls the
fuel pump continuously and at the same time starts
the injector opening. The injector openings are repeated for a few seconds.
YES go to 3
3 - Acoustically check the injector openings and
wait for the tester results
YES go to 4 NO go to 5
4 - 5 injector openings detected. The injection tester displays "test successful".
YES go to 7
5 - No injector openings detected. The injection
tester displays "test failed".
YES go to 9 NO go to 6
6 - No injector openings detected. The injection
tester displays "test successful".
YES go to 8
7 - The injector control circuit is efficient. Perform
the injector hydraulic check.
8 - The injector control circuit is efficient. Repeat
the acoustic check and perform the injector hydraulic check for safety reasons.
9 - Select the menu on the "ERRORS" function.
Check whether the injector failure message only is
displayed.
YES go to 14 NO go to 10
INJEC - 46
Nexus 500 euro 3
Nexus 500 euro 3
Injection
10 - There are also fault messages for: pump relay
YES go to 13 NO go to 11
11 - There is also a fault message for the HV coil.
YES point 12
12 - Check the power supply circuit with the fuse 12 and the remote control switch. Common feeding
to the fuel pump.
13 - Check the pump relay control circuit
14 - Install the special tool between the injection system and the control unit.
YES go to 15
Specific tooling
020481Y Control unit interface wiring
15 - Arrange a multimeter with positive prod on pin
13 and negative prod on pin 23. Set the switch to
"ON" with switch to "RUN" and side stand raised.
Check the presence of battery voltage during the
fuel pump timing.
13 - 23 = battery voltage for 2 seconds.
YES go to 16 NO go to 17
16 - The injector electric circuit is steady Repeat
the checks. If the fault continues, check the control
unit connector. If necessary, replace the electronic
control unit.
17 - Repeat the test using the resistance multimeter. Check the resistance between pin 13 and pin
87 (black/green cable) of the pump remote control
switch.
13 - black/green = 14.5Ω ± 5% (resistance of the
injector)
YES go to 19 NO go to 18
INJEC - 47
Injection
Nexus 500 euro 3
18 - No continuity. Disconnect the connector and
repeat the resistive check directly at the injector
terminals.
Resistance = 14.5 Ω ± 2%
YES go to 21 NO go to 22
19 - Check the earth insulation of the injector negative line. Disconnected control unit and injector
connectors.
13 - 23 = Ω infinity
NO go to 20
20 - Repair or replace the cable harness.
21 - Check the continuity between the injector power supply connector (red - yellow) and pin 13. Restore
the continuity, if required, or replace the wiring
22 - Replace the injector.
Inspecting the injector hydraulics
To check the injector it is advisable to remove the
intake manifold along with throttle body and injector.
The injector should be removed from the manifold
only if necessary.
For these operations, see the "thermal unit and
timing system" chapter
1 - Connect the diagnostic tester. Use the socket
in the under-saddle compartment.
Install the fuel pressure check kit special tool.
In this case, the injector can be connected directly
to the tool quick couplings.
AHEAD go to 2
Specific tooling
020460Y Scooter diagnosis and tester
020480Y Petrol pressure check set
INJEC - 48
Nexus 500 euro 3
Injection
2 - Prepare a graduated container with minimum
capacity of 100 cm3 and a resolution of 10-20 cm3
Connect the injector to the wire supplied with the
injection tester. The wire is provided with alligator
clips for direct connection to the battery.
Prepare an auxiliary battery.
Set the switch to "ON" with switch to "RUN" and
stand raised.
Select the "active diagnosis" function.
Start the pump diagnosis.
During the first 30 seconds of pump diagnosis,
power the injector by the wire and the auxiliary
battery for 15 seconds.
Collect the fuel delivered by the injector into the
graduated container.
Power supply pressure = 300 KPa (3 BAR)
Quantity delivered = approx. 40 cm3
YES go to 3 NO go to 4
3 - Perform the injector sealing test.
Dry the injector outlet with a blast of compressed
air. Activate the fuel pump. Wait for one minute,
making sure there are no leaks coming from the
injector. Slight oozing is normal.
Value limit = 1 drop per minute
YES go to 5 NO go to 6
4 - Higher quantities are not expected.
For lower quantities, replace the injector (THERMAL UNIT AND TIMING SYSTEM).
5 - The injector is conforming.
6 - Repeat the test. If the fault continues, replace
the injector (THERMAL UNIT AND TIMING SYSTEM)
The injector atomisation cannot be checked by
simple methods. The injector is provided with 5
holes whose angulation forms a jet with a taper of
INJEC - 49
Nexus 500 euro 3
Injection
about 80°. The jet thus formed impinges both intake valves.
N.B.
- AN INJECTOR WITH LOW FLOW RATE AFFECTS THE MAXIMUM PERFORMANCE.
- AN INJECTOR WITH POOR SEAL AFFECTS
IDLING AND THE START-UP FEATURES AFTER A SHORT STOP WITH HOT ENGINE.
- IN CASE OF CLOGGING OF THE INJECTOR,
IT IS NECESSARY TO REPLACE IT, ALONG
WITH THE FUEL FILTER CONTAINED IN THE
TANK. CAREFULLY CLEAN THE SYSTEM AND
THE TANK.
Troubleshooting
1 - A failure of the EMS system is more likely to be due to the connections than to the components.
Before searching the EMS system for failures, perform the following checks:
SUGGESTION FOR TROUBLESHOOTING
1
Specification
1. Power supply
2
3
2. Chassis earth
3. Fuel supply
4
4. Ignition system
5
5. Intake circuit
6
6. Other
Desc./Quantity
- Battery voltage
- Burnt fuse
- Remote control switches
- Connectors
- Faulty fuel pump
- Dirty fuel filter
- Faulty spark plug
- Faulty coil
- Faulty screened cap
- Dirty air filter
- Dirty by-pass circuit
- Faulty stepper motor
- Wrong distribution timing
- Wrong idle speed carburetion
- Wrong reset of the throttle valve position
sensor
2 - Failures to the EMS system may depend on loosened connectors. Make sure that all connections
are properly implemented.
Check the connectors being careful of the following: 1. check that terminals are not bent. check that
connectors are properly engaged.
Check whether the failure changes if the connector is slightly vibrating.
3 - Before replacing the EMS control unit, check the whole system carefully.
If the fault is fixed by replacing the EMS control unit, install the original control unit again and check
whether the fault occurs again.
4 - For troubleshooting, use a multimeter with an internal resistance of more than 10KΩ/V.
Improper instruments may damage the EMS control unit.
INJEC - 50
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Injection
The instruments to be preferred have a definition of more than 0.1V and 0.5Ω and an accuracy of more
than ± 2%.
Immobiliser circuit
The EMS system is integrated with the immobiliser
antitheft device.
Its functions are:
- Start-up enabled by key recognition.
- Deterrent flashing.
System components
The system consists of:
-EMS system control unit
- Decoder
- Aerial
- Master key (red)
- Service key (black)
- Deterrent and diagnosis LED
Virgin circuit
When control unit (ECU) and decoder are not programmed, the following conditions occur:
- Key switch set to "OFF". Deterrent flashing inactive.
- Key switch set to "ON". Ignition and injection disabled and LED on with solid light.
When the key switch is set to "ON", the LED
switches on as shown in the figure.
The LED is turned on by the decoder.
The control unit data can be checked by the diagnostic tester.
Specific tooling
020460Y Scooter diagnosis and tester
INJEC - 51
Injection
Nexus 500 euro 3
To connect the diagnostic tester, open the spark
plug inspection port and pull out the EMS Diagnosis socket. Remove the protection cap and connect the tester terminal.
Power the diagnostic tester by connecting the terminals to the battery poles, or the specific connector to the socket inside the gloves compartment.
Set the switch to "ON" and select the diagnostic
tester menu to the immobiliser function.
Scroll the pages to display the control unit data.
N.B.
AN UNPROGRAMMED SYSTEM CANNOT BE DETECTED UPON FIRST FITTING, OR IN CASE
THE DECODER AND THE CONTROL UNIT ARE REPLACED CONCURRENTLY.
The information will be as follows:
Unprogrammed control unit «ON»
Start-up disabled «ON»
Key number Zero › 250
Setting the circuit
The electronic ignition system is controlled by the control unit with the integrated Immobilizer system.
The immobilizer is an anti-theft system that allows the scooter to be operated only when it is started
with coded keys recognised by the control unit. The code is integrated into a transponder inserted into
the body of the key. This permits transparent operation for the rider who has to do no more than the
normal turn of the key. The Immobilizer system consists of the following components:
INJEC - 52
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Injection
- Control unit
- Decoder
- Immobilizer aerial
- Master key with integrated transponder (brown key)
- Service key with integrated transponder (black key)
- H.V. coil
- Diagnostic LED
The diagnostic LED also control the function of the immobiliser lamp. This function is activated every
time the key switch is turned to position "OFF" or the emergency stop switch is turned to "OFF" and, in
order not to prejudice the battery charge, remains active for 48 hours. When the key switch is turned
to "ON", it interrupts the function of the immobiliser lamp and a start enable lamp comes "ON". The time
for which this lamp stays on depends on the programming of the control unit. In the event that the LED
goes out irrespective of the position of the key switch and/or the instrument panel is not initialised, check:
•
Battery voltage is "ON"
•
That none of fuses 1, 3, 7 or 8 has blown
•
Power supply to the control unit as specified below:
Disconnect the connector from the control unit. Check the following conditions:
With the key switch in position "OFF":
•
Battery voltage between terminals 17-23 and terminals 17-chassis ground (continuous power supply). In the event that there is no voltage, check that fuse 1 has not blown and check
the corresponding wiring.
With the key switch in position "ON" and the engine stop switch in "RUN":
•
Battery voltage between terminals 26-23 and terminals 26-chassis ground (continuous power supply). In the event that there is no voltage, check:
1. The condition of fuse No. 1 and the corresponding wiring.
2. The function of the engine stop remote control.
•
Check for voltage on the blue/grey cable at the exit from the engine stop remote control. In
the event that there is no voltage, check:
1. The contacts of the key switch.
2. The function of the engine stop switch, then for the presence of earth on the green/blue cable and
the engine stop switch with the stand raised and the engine stop switch in position RUN.
3. The function of the diode of the engine stop remote control.
If no fault is found, replace the control unit.
N.B.
AN ACCIDENTAL LOSS OF THE SERVICE KEY PROGRAMMING CAN ARISE FROM GENERAL
FAULTS OF THE IGNITION SYSTEM. IN THIS CASE, CHECK THE HV LINE SHIELDING.
In any case it is advisable to use resistive spark plugs.
INJEC - 53
Injection
LED signals
When the ignition system is not encrypted, any key
will start the engine but limited to 2000 rpm. The
keys can only be recognised when the decoder
has been correctly programmed. The procedure
for programming a new decoder requires the recognition of the "master" key as the first key to be
programmed: this is particularly important as it is
the only key that allows the decoder to be reset
and reprogrammed for programming the service
keys.
The master and service keys must be used to code
the system as follows:
- Insert the Master key, turn it to «ON» and keep
this position for two seconds (lower and upper limits 1 to 3 seconds).
- Insert the service key and turn it to "ON" for 2
seconds.
- If you have copies of the key, repeat the operation
with each key.
- Insert the MASTER key again and turn it to "ON"
for 2 seconds.
The maximum time to change keys is 10 seconds.
During a single data storage sequence a maximum of 7 service keys are allowed.
It is essential to adhere to the times and the procedure. If you do not, start again from the beginning. Once the system has been programmed,
master key transponder, decoder and control unit
are strictly matched. With this link established, it is
now possible to encode new service keys, in the
event of losses, replacements, etc. Each new programming deletes the previous one so, in order to
add or eliminate keys, you must repeat the procedure using all the keys you intend to keep using.
INJEC - 54
Nexus 500 euro 3
Nexus 500 euro 3
Injection
If a service key should become un-coded, the efficiency of the high voltage circuit shielding must
be thoroughly inspected: In any case it is advisable
to use resistive spark plugs.
Characteristic
MASTER key:
BROWN KEY
SERVICE key.
BLACK KEY
Checking master-box data
Connect the diagnostic tester.
Set to "ON" and select the immobilizer function.
Scroll the pages the find the data.
Specific tooling
020460Y Scooter diagnosis and tester
The information will be as follows:
- Blank control unit "OFF"
- Start-up disabled "OFF"
- Number of keys 2*
*The number denotes how many keys have been used for programming, master key included.
Resetting the circuit
1 Replacing the small cylinder
- Remove the original master key transponder and install it on the master key of the new cylinder.
- Program the system again as described above.
2 Decoder replacement
When the decoder is replaced it is necessary to program the system again.
Programming is indispensable for the engine start-up. (see System programming).
3 Control unit replacement
Programming is indispensable when the control unit is replaced to enable the engine start-up.
In this case it is sufficient to switch to "ON" using the master key.
N.B.
- THE SERVICE KEY (BLACK-COLOURED) IS NOT USED FOR PROGRAMMING.
INJEC - 55
Injection
Nexus 500 euro 3
- WHEN NOT PROGRAMMED, THE CONTROL UNIT ALLOWS NO FUNCTIONAL DIAGNOSIS ON
THE ENGINE.
4 Replacing or duplicating service keys
Keys can be duplicated using the blank keys and the original master key.
A copy may also be requested using the scooter CODE CARD.
Program the system again using the master key and all service keys (see System programming).
N.B.
THE CODE CARD CAN ONLY BE USED WHEN THE ORIGINAL MASTER KEY IS AVAILABLE.
Diagnostic codes
The immobiliser system is tested each time the ignition-key switch is turned from OFF to ON. During
this diagnostics phase a number of control unit
statuses can be seen and various light codes displayed. Regardless of the code transmitted, if at
the end of the diagnosis the led remains off permanently, the ignition is enabled. If, however, the
led remains on permanently, it means the ignition
is inhibited:
1. New decoder - key inserted: a single 2 second
flash is displayed, after which the LED remains off
permanently. The keys can be stored to memory,
the scooter can be started but with a limitation imposed on the number of revs.
2. New decoder - transponder missing or illegible: The LED is permanently ON; in this condition,
no operations are possible, including starting of
the scooter.
3. Decoder programmed - service key inserted
(normal operating condition): a single 0.7 second flash is displayed, after which the LED remains off permanently. The engine can be started.
4. Decoder programmed - master key inserted: a 0.7 sec. flash is displayed followed by the
LED remaining off for 2 sec. and then by short 0.46
sec. flashes the same number of times as there
are keys stored in the memory including the Master key. When the diagnosis has been completed,
INJEC - 56
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Injection
the LED remains permanently OFF. The engine
can be started.
5. Decoder programmed - fault detected: a light code is displayed according to the fault detected,
after which the LED remains on permanently. The engine cannot be started. The codes that can be
transmitted are:
•
Code 1 flash
•
2 flash code
•
3 flash code
Code 1
A one-flash code indicates a system where the serial line is not present or is not detected. Check the
Immobilizer aerial wiring and change it if necessary.
Code 2
Code 2 flashes signifies a system where the decoder does not recognise the transponder signal.
This might depend on the inefficiency of the immobiliser aerial or the transponder.
Turn the switch to ON using several keys: if the
code is repeated even with the Master key, check
the aerial wiring and change it if necessary. Otherwise replace the faults key and/or reprogram the
decoder. If the problem persists, replace the decoder.
INJEC - 57
Nexus 500 euro 3
Injection
Code 3
Code 3 flashes signifies a system where the decoder does not recognise the key. Turn the switch
to ON using several keys: If the error code is repeated even with the master key, replace the decoder. If this is not the case, perform a reprogramming.
Tachometer
Electric characteristic
TERMINAL: 7 - 12
CONDITIONS : Start up engine speed
STANDARD: approx. 0.8 - 4.5 V
CIRCUIT LAYOUT
1
2
Specification
electronic control unit
Engine rpm sensor
Desc./Quantity
The sensor allows the rotations and the angular position of the crankshaft to be recognised by reference
to the TDC. Since the wheel speed sensor is pivoted on the camshaft it is also possible to recognise
the 4-stroke cycle. Such solution allows controlling the injector and the spark plug every two revolutions
of the crankshaft.
INJEC - 58
Nexus 500 euro 3
Injection
The sensor is of the reluctance variation type and is therefore comparable to an alternate current alternator that powers the control unit.
The signal frequency is interrupted by the vacuum generated by the two missing teeth on the wheel
speed sensor.
The sensor signal is fundamental for obtaining starting of the engine.
The CPU autodiagnosis is enabled on this circuit in 2 different ways based on use conditions.
Right after turning to "ON" (Power under the panel present in the CPU), the continuity and isolation of
the sensor and related circuit are checked.
Any faults discovered in this phase are signalled via the injection light.
The fault continues to be signalled, but the circuit is only checked when turning to "ON". Therefore faults
which occur or disappear after turning to "ON" are not acknowledged.
During and after the start phase, the autodiagnosis checks the alternating current produced by the
sensor (synchronisation of the signal panel).
INJEC - 59
Injection
Nexus 500 euro 3
If a signal panel is detected which is not perfectly synchronised, corrective interventions are applied
used to reconstruct the cycle. In this case the autodiagnosis records the number of lost synchronisations
and signals the fault via the injection light.
The light remains on during the period the cycle is reconstructed.
If the revolution timing signal is completely missing due to mechanical faults or lack of magnetic activity,
it will be impossible to start the engine (or it will stop while driving) and the autodiagnosis will not be
able to record any faults.
To check the sensor and related circuit, proceed as follows:
1 - Connect the scooter tester.
Select the function "ERRORS" in the menu.
Check for any faults on the «Signal panel».
YES go to 2 NO go to 3
Specific tooling
020460Y Scooter diagnosis and tester
2 THE FAULT HAS BEEN RECORDED IN MEMORISED STATUS:
The signal panel may be synchronised with possibility of starting. The fault is probably occasional.
N.B.
A NON-CONFORMING SIGNAL PANEL FAULT MAY ALSO BE DETECTED IF THE ENGINE STOPS
AFTER A FAULT INVOLVING IDLING.
THE FAULT HAS BEEN RECORDED IN CURRENT STATUS:
The control circuit gave a negative result when
switching to "ON".
AHEAD go to 8
3 Select the "PARAMETERS" function on the
menu.
Check the number of «lost synchronisations»:
1 TOOTH and > 1 TOOTH
YES go to 4 NO go to 5
4 THE INDICATION INCREASES PROGRESSIVELY OVER TIME WITH THE ROTATION OF
THE ENGINE.
AHEAD go to 8
5 INDICATION = 1-3
THE RPM-TIMING CIRCUIT IS IN CONFORMANCE.
Make an attempt to start and use the parameters
function to check for the "rpm engine" indication.
INJEC - 60
Nexus 500 euro 3
Injection
YES go to 6 NO go to 7
6 The signal panel is in conformance.
7 CHECK THE AIR GAP AND MAGNETIC ACTIVITY OF THE SENSOR.
See engine mechanics.
8 Check the sensor and related connection circuit
with the control unit.
AHEAD go to 9
9 Install the connection wiring between the control
unit and injection system. Do not make the connection with the control unit.
CONTINUE at 10
Specific tooling
020481Y Control unit interface wiring
10 Install the connection connector between the rpm timing sensor and injection system.
Measure the sensor resistance by connecting a multimeter between the terminals marked + and - (see
the "Electrical system" chapter).
RESISTANCE OF THE REVOLUTION TIMING SENSOR: (AT 25°C)
1
2
Specification
Model with 1 clamp:
Model with 2 clamps:
Desc./Quantity
860 Ω ± 130 Ω
680 Ω ± 100 Ω
YES go to 11 NO go to 12
11 - Check the earth isolation between a pole and the shielding.
(see the "Electrical system" chapter).
Electric characteristic
S-+=
infinite (>MΩ)
INJEC - 61
Injection
Nexus 500 euro 3
YES go to 13 NO go to 12
12 - Replace the revolution sensor.
13 - Reconnect the revolution timing sensor connector.
Repeat the resistance check through the injection
wiring pin 7 pin 12.
Electric characteristic
7-12 =
680 Ω ± 100 Ω (Model with 2 clamps)
7-12 =
890 Ω ± 130 Ω (Model with 1 clamp)
The value should be very close to that detected directly by the sensor.
YES go to 17 NO go to 14
14 - Higher or infinite resistance.
YES go to 15 NO go to 16
15 - Check the connectors carefully. Disconnect and check the continuity between connector and pin
7-12
Electric characteristic
Connector - 7 =
Continuity
Connector - 12 =
Continuity
Fix the connectors or replace the cable harness.
16
Electric characteristic
Resistance
0
Repair or replace the injection wiring (short circuit)
17 - Check the earth insulation again.
Electric characteristic
INJEC - 62
Nexus 500 euro 3
Injection
7-23 =
infinite (>1MΩ)
YES go to 19 NO go to 18
18 - Check the sensor and control unit connectors.
Repair or replace the injection wiring
19 - Measure the alternated voltage between pins
7 and 12 with engine at start-up speed.
Electric characteristic
7-12 =
approx. 0.8 - 4.5 V eff
Revolution speed =
approx. 300-400 rpm
YES go to 20 NO go to 21
20 The sensor circuit is in conformance.
Use the parameter function to check if the engine rpm indication is present when trying to start.
If not, carefully check the CPU connection connector and replace it if necessary.
21 Check the air gap and magnetic activity of the sensor.
See the "Combustion unit and distribution" chapter.
If there is no magnetic activity replace the sensor.
N.B.
-THE SENSOR CABLE MUST BE PROPERLY INSTALLED FOR SERVICING.
-DO NOT FORCE THE CABLE.
-A POOR CABLE SHIELDING CAN IMPAIR THE ENGINE PERFORMANCE AT HIGH SPEED.
HT coil
This section describes the ignition system operation.
Circuit diagram
Electric characteristic
TERMINALS: 20 - 23
CONDITIONS : During the pump timing with engine off.
STANDARD: Battery voltage
INJEC - 63
Injection
KEY
11. Injection load remote control
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
56. Fuel pump / fuel level transmitter
58. Fuel injector
59. Spark plug
61. HV coil
64. Fuel injection electronic control unit
INJEC - 64
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Nexus 500 euro 3
Injection
The ignition system is integrated with the injection
and is of the inductive high efficiency type.
The control unit manages two important parameters:
- Ignition advance
This is optimised according to the engine rpm, to
the engine load, temperature and ambient pressure
With idle engine, it is optimised to obtain the stabilisation of the speed at 1450 ± 50 R/1'. - Magnetisation time
The coil magnetisation time is controlled by the
control unit. The ignition power is increased during
the engine start-up.
The injection system recognises the 4-stroke cycle
and therefore, ignition is only controlled during
compression.
To check the ignition circuit, proceed as follows:
1 - Connect the diagnostic tester. Select the menu
on the "ACTIVE DIAGNOSIS" function. Start the
HV coil check with switch set to "ON", switch to
"RUN" and side stand raised. Wait for the tester to
display: "TEST SUCCESSFUL"
YES go to 3 NO go to 2
Specific tooling
020460Y Scooter diagnosis and tester
2 - The tester displays: "TEST FAILED". Repeat the test and wait for the tester to display: "TEST SUCCESSFUL"
YES go to 3 NO go to 4
3 - Select the menu on the "ERRORS" function. Check the presence of current or stored errors relating
to the H.V. coil.
YES go to 6 NO go to 5
4 - Test failed
YES go to 6
5 - The coil control circuit is efficient.
Check the H.V. coil secondary, the cable and the screened cap
6 - Install the special tool between the injection system and the control unit.
INJEC - 65
Injection
Nexus 500 euro 3
Measure voltage between pins 20 and 23 of the specific
Specific during the timing phase of the fuel pump.
To start the timing, set the switch to "ON" with switch to "RUN" and side stand raised.
Electric characteristic
20-23 =
Battery voltage (coupled to the pump rotation -2 seconds).
If you want to increase the test time, enable the
"pump relay diagnosis" function
(30 seconds)
YES go to 7 NO go to 8
7 - The coil primary control circuit is efficient.
Carefully check the connectors to the control unit and to the coil.
Replace the control unit, if necessary.
8 - Disconnect the connector to the H.V. coil primary.
Repeat the voltage check between the black-green wire and earth.
Electric characteristic
Black-green-23 =
battery voltage
(coupled to the pump rotation-2 seconds).
YES go to 10 NO go to 9
9 - Check the black-green wire continuity.
Repair or replace the wiring.
N.B.
A FAILURE OF THE REMOTE CONTROL SWITCH WOULD CAUSE THE PUMP ROTATION FAILURE
10 - The positive power supply is conforming. Check the continuity between the pink-black wire of the
connector and pin 20.
INJEC - 66
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Injection
Electric characteristic
Pink-black-20 =
Continuity
YES go to 12 NO go to 11
11 - Check the continuity of the pink-black wire in the two systems.
Electric characteristic
Pink-black (coil connector)-20 =
Continuity
YES go to 12 NO go to 13
12 - Check the earth insulation of the negative line.
Electric characteristic
20-23 =
Ω infinite (>1MΩ)
YES go to 15 NO go to 14
13 - Repair or replace the faulty system. Repeat the check with the menu on "ACTIVE DIAGNOSIS".
INJEC - 67
Injection
Nexus 500 euro 3
14 - Repeat the earth insulation check in the two sections. Repair or replace the wiring. Repeat the
check with the menu on "ACTIVE DIAGNOSIS" H.V. coil control simulation. Delete the errors stored in
memory.
15 - Check the continuity of the H.V. coil primary. See figure.
Electric characteristic
Primary resistance =
0.5 ± 8%
YES go to 16 NO go to 19
16 - Check the earth insulation of the primary circuit
Measure between one of the primary terminals and earth.
Electric characteristic
Primary-earth =
Ω infinite (>1MΩ)
YES go to 17 NO go to 1 9
17 - Check the secondary resistance.
Measure the resistance between one of the primary terminals and the spark plug cable output
Electric characteristic
Primary HV cable output =
3.1 K ± 9%
INJEC - 68
Nexus 500 euro 3
Injection
YES go to 18 NO go to 19
18 - The coil is conforming.
19 - Replace the coil
Inspecting the spark plug shielded cap
Measure the shielded cap resistance.
Electric characteristic
Resistance:
5 KΩ
If different values are measured (<1; >20KΩ), replace the shielded cap.
N.B.
A SHIELDLESS CAP OR SPARK PLUG CAN ADVERSELY AFFECT THE INJECTION SYSTEM.
FOR INFORMATION ON THE SPARK PLUG, SEE THE «SPECIFICATIONS» AND «MAINTENANCE» CHAPTERS.
Spark advance
The ignition advance is determined electronically on the basis of parameters known by the control unit.
For this reason it is not possible to declare the reference values based on the engine rpm.
The ignition timing value is detectable any time using the diagnostic tester.
It is possible to check whether the ignition advance determined by the system does in fact correspond
with the value actually activated on the engine, by means of the stroboscopic light.
Specific tooling
020460Y Scooter diagnosis and tester
020330Y Stroboscopic light for timing control
INJEC - 69
Injection
Proceed as follows:
- Remove the transmission compartment cover as
described in the "automatic transmission" chapter.
- Remove the TDC reference inspection cap between flywheel and crankcase cover. See the "flywheel cover" chapter
- By the driving pulley, turn the engine to find the
alignment of the references to identify the TDC.
- Repeat for the reference between driving pulley
and engine crankcase.
INJEC - 70
Nexus 500 euro 3
Nexus 500 euro 3
Injection
- Replace the inspection cap on the flywheel side.
- Connect the diagnostic tester.
- Start the engine.
- Select the menu on the "parameter" function.
- Select the stroboscopic light command in the traditional four-stroke engine position (1 spark 2
revs).
- Check that the real values of rpm and ignition
advance match those measured using the diagnostic tester.
If the values do not match, check:
- distribution timing
- revolution-timing sensor
- Injection control unit
Coolant temperature sensor
Electric characteristic
TERMINALS: 4 - 22
CONDITIONS : coolant temperature
STANDARD:
With connected sensor:
20° = 2500 ± 100 Ω
80° = 308 ± 6 Ω
INJEC - 71
Injection
Nexus 500 euro 3
KEY
1 Central control unit
2 Valve position sensor
3 Air temperature sensor
4 Coolant temperature sensor
5 Digital display
The coolant temperature sensor is installed on the engine head and provides the indications for the
digital instrument and for the injection.
It is realised with two electrically different sections.
The injection section is realised with an NTC sensor connected to a 5V powered circuit. The resistance
variation causes a variation of the circuit voltage. Such voltage is combined with a temperature value.
By this value, the control unit can manage the engine operation, optimising it for all temperatures.
A failure of this circuit causes the switching on of the injection indicator and the tripping of the safeties
(among which the electric fan continuous start). In these conditions, the engine works, even though not
in an optimum way, always safeguarding the catalytic converter integrity.
A false temperature value that falls within the range of possible temperatures is a failure very difficult
to manage. This can cause a failure of the safeties and an improper management of the ignition. Such
failure is more easily detected upon the engine start-up.
To check the sensor and related circuit, proceed as follows:
1 - Connect the injection diagnostic tester and select the menu on the "errors" function.
INJEC - 72
Nexus 500 euro 3
Injection
Check whether faults have been recorded regarding the coolant temperature sensor.
YES go to 3 NO go to 2
Specific tooling
020460Y Scooter diagnosis and tester
2 - The EMS system has received no indications of temperatures out of the range of possible temperatures.
If you suspect a wrong temperature indication, proceed to perform the following check.
N.B.
A WRONG TEMPERATURE SIGNAL CAN BE DETECTED BY COUPLING THE ANALOGUE INSTRUMENT INDICATION WITH THE ELECTRIC FAN START.
IN ANY CASE, BEFORE CHECKING THE SENSOR, CHECK THE FILLING AND BLEEDING OF
THE COOLING SYSTEM
3 - Before checking the sensor and the relevant circuit, wait until the engine has cooled down and the
scooter has set to the working area temperature.
YES go to 4
4 - Set the switch to "ON" with switch to "RUN" and side stand raised. Select the menu on the "parameters" function. Do not start the engine.
YES go to 5
5 - Check the following values: coolant temperature sucked air temperature ambient temperature The
three indications are equal or they are slightly different (e.g. 1° C).
YES go to 6 NO go to 7
6 - The temperature sensor is providing probably correct information.
Check at approx. 80° C.
7 - Install the special tool.
WARNING
DO NOT CONNECT THE CONTROL UNIT CONNECTOR.
Specific tooling
020481Y Control unit interface wiring
YES go to 8
8 - Disconnect the coolant temperature sensor
connector. Measure the sensor resistance between the terminals shown in the figure.
Check that the resistance matches the values declared according to the temperature.
Electric characteristic
TEMPERATURE RESISTANCE
9.6KW -10° C
5.975KW. 0
3.81KW +10° C .
INJEC - 73
Injection
Nexus 500 euro 3
2.5KW +20° C
1.68KW +30° C
0.3KW +80° C
YES go to 10 NO go to 9
9 - Replace the sensor.
10 - Connect the sensor connector and repeat the resistive check at terminals 4 and 22;
Electric characteristic
4-22 =
Resistance equal to the value directly detected at the sensor.
YES go to 13 NO go to 11
11 - If slightly higher values are detected, check the connectors.
If infinite resistance is detected (>1MW), check the continuity between the two lines with disconnected
connectors.
Electric characteristic
Blue-white-4 =
0W (continuity)
Light blue/green-22 =
0 ohm. (Continuity)
YES point 12
12 - Repair or replace the cable harness.
YES go to 10
13 - Check that the sensor circuit is earth insulated.
Electric characteristic
4-23 =
INJEC - 74
Nexus 500 euro 3
Injection
ohm infinite (>1Mohm)
22-23 =
ohm infinite (>1Mohm)
YES go to 15 NO go to 14
14 - Repair or replace the wiring.
Check the air temperature lines and the throttle
valve position.
YES go to 13
15 - Connect the special tool to the control unit.
Set the switch to "ON" with switch to "RUN" and
side stand raised.
YES go to 16
Specific tooling
020481Y Control unit interface wiring
16 - Measure voltage at terminals 4 and 22;
TEMPERATURE VOLTAGE
1
2
3
4
5
6
Specification
XV
XV
XV
XV
XV
XV
Desc./Quantity
-10° C
0
+10° C
+20° C
+30° C
+80° C
YES go to 21 NO go to 17
17
INJEC - 75
Injection
Electric characteristic
Measured value =
5±0.2 V
Repeat the wiring and sensor continuity checks.
YES go to 18
18
Electric characteristic
Measured value =
0V
Repeat the sensor and circuit earth insulation
check.
YES go to 19 NO go to 20
19 - Check the control unit connector.
Check the control unit power supply.
Replace the control unit, if necessary.
20 - Repair or replace the cable harness.
21 - Start the engine and check that voltage decreases gradually according to the temperature
increase as per table.
YES go to 22 NO go to 23
22 - The temperature signal is conforming.
23 - Replace the temperature sensor.
N.B.
FOR A MORE ACCURATE CHECK OF THE
SENSOR, REMOVE IT FROM THE ENGINE AND
CHECK ITS RESISTANCE AT CONTROLLED
TEMPERATURE.
USING A SUITABLE CONTAINER, IMMERSE
THE METAL PORTION OF THE SENSOR IN
WATER, HEAT GRADUALLY AND READ THE
TEMPERATURE AND RESISTANCE VALUES.
CHECK THE MATCHING AS PER TABLE
Intake air temperature sensor
Electric characteristic
TERMINALS: 18 - 22
CONDITIONS: Sucked air temperature 20°
STANDARD: With connected sensor: 3750 ± 200 Ω
INJEC - 76
Nexus 500 euro 3
Nexus 500 euro 3
Injection
KEY
1 Central control unit
2 Valve position sensor
3 Air temperature sensor
4 Coolant temperature sensor
5 Digital display
The sucked air temperature sensor is installed in
the bottom side of the throttle body on the filter box
side.
The sensor is an NTC and has the same functional
layout as the coolant temperature sensor.
This signal is used to optimise the engine performance. Anyway, this data is less important than the
coolant temperature signal.
A failure of this circuit causes the control unit to
turn on the injection warning light and activate the
safety control, thereby ensuring the engine operation.
INJEC - 77
Nexus 500 euro 3
Injection
To check the sensor and related circuit, proceed
as follows:
1 - Connect the diagnostic tester.
Select the function "ERRORS" in the menu.
Check whether there are any indications regarding
the sucked air temperature sensor.
YES go to 3 NO go to 2
Specific tooling
020460Y Scooter diagnosis and tester
2 - The EMS system has received no indications of temperatures out of the range of possible values.
If you suspect a wrong temperature indication, proceed to perform the following check.
3 - Before checking the sensor and the relevant circuit, wait until the engine has cooled down and the
scooter has set to the working area temperature.
YES go to 4
4 - Set the switch to "ON" with switch to "RUN" and side stand raised. On the diagnostic tester, select
the «PARAMETERS» menu.
YES go to 5
5 - Check the following values:
coolant temperature
sucked air temperature
ambient temperature indicated by the digital instrument.
The three indications are equal or they are slightly different (e.g. 1° C).
YES go to 6 NO go to 7
6 - The sucked air temperature sensor is providing an incorrect information.
7 - Install the special tool. Do not connect the control unit connector.
YES go to 8
Specific tooling
020481Y Control unit interface wiring
8 - Disconnect the sucked air temperature sensor connector.
Measure the resistance between the sensor terminals. Check that the resistance matches the values
declared according to the temperature.
TEMPERATURE RESISTANCE
1
2
3
4
5
INJEC - 78
Specification
9.6 Kohm
5.975 Kohm
3.81 Kohm
2.5 Kohm
1.68 Kohm
Desc./Quantity
-10° C
0
+10° C
+20° C
+30° C
Nexus 500 euro 3
Injection
YES go to 10 NO go to 9
9 - Replace the sensor.
10 - Connect the sensor connector and repeat the resistive check at terminals 18 and 22.
Electric characteristic
18-22 =
Resistance equal to the value directly detected at the sensor.
YES go to 13 NO go to 11
11 - If slightly higher values are detected, check the connectors.
If infinite resistance is detected (>1Mohm) check the continuity between the two lines with disconnected
connectors.
Electric characteristic
Grey-white-18 =
0 ohm (continuity)
Light blue/green-22 =
0 ohm (continuity)
INJEC - 79
Injection
Nexus 500 euro 3
YES point 12
12 - Repair or replace the cable harness.
YES go to 10
13 - Check that the sensor circuit is earth insulated.
Electric characteristic
18-23 =
infinite (> 1 Mohm)
22-23 =
infinite (> 1 Mohm)
YES go to 15 NO go to 14
14 - Repair or replace the wiring. Check the valve position and the fluid temp. lines.
YES go to 13
15 - Connect the special tool to the control unit.
Set the switch to "ON" with switch in "RUN" and side stand raised.
YES go to 16
Specific tooling
020481Y Control unit interface wiring
16 - Measure voltage at terminals 18 and 22.
Electric characteristic
18-22 =
V as in the table.
INJEC - 80
Nexus 500 euro 3
Injection
TEMPERATURE VOLTAGE
1
2
3
4
5
6
Specification
XV
XV
XV
XV
XV
XV
Desc./Quantity
-10° C
0
+10° C
+20° C
+30° C
+80° C
YES go to 21 NO go to 17
17
Electric characteristic
Measured value =
5±0.2 V
Repeat the wiring and sensor continuity checks.
YES go to 18
18
Electric characteristic
Measured value =
0V
Repeat the sensor circuit earth insulation check.
YES go to 19 NO go to 20
19 - Check the control unit connector. Check the control unit power supply. Replace the control unit, if
necessary.
20 - Repair or replace the cable harness.
21 - Start the engine and check that voltage decreases gradually according to the air filter box temperature increase.
N.B.
WITH MILD WEATHER, 30° C CAN BE EASILY REACHED AFTER A FEW MINUTES OF STOP
WITH IDLE ENGINE.
INJEC - 81
Injection
Nexus 500 euro 3
Pressure sensor
This sensor does not have a system since it is directly installed into the control unit.
The sensor allows the control unit to optimise the
engine performance based on altimetric variations.
To check the sensor, proceed as follows:
1 - Connect the diagnostic tester.
Select the function "ERRORS" in the menu.
Check whether there are any indications regarding
the pressure sensor.
YES go to 2 NO go to 3
Specific tooling
020460Y Scooter diagnosis and tester
2 - Replace the injection control unit.
3 - Select the menu on the "PARAMETERS" function.
Check that the pressure value in mm/Hg matches that of another scooter or of an external barometer.
Electric characteristic
Max error:
± 20 mmHg
YES go to 4 NO go to 5
4 - The ambient pressure signal is correct.
5 - Replace the injection control unit.
Throttle valve opening sensor
Throttle position sensor (t.p.s.)
Electric characteristic
TERMINALS: 1 - 22
CONDITIONS: Switch set to "ON"
INJEC - 82
Nexus 500 euro 3
Injection
STANDARD: 5 V
TERMINALS: 11 - 22
CONDITIONS: Opening the throttle gradually
STANDARD: Volt= Progressive increase
CIRCUIT LAYOUT
1
2
3
4
Specification
electronic control unit
Valve position sensor
Air temperature sensor
Fluid temperature sensor
Desc./Quantity
The throttle valve position sensor is not removable
and is installed on the throttle body.
This sensor receives a 5-V power supply from the
control unit and transmit a gradually increasing
voltage to the same, with an increase of the throttle
valve opening. The control unit converts this voltage at an angular position of the valve.
The engine rpm and the throttle valve position are
the two basic signals for the engine management.
A failure of this circuit causes the switching on of
the injection indicator and the tripping of the safeties. In these conditions, the engine works, even
INJEC - 83
Injection
Nexus 500 euro 3
though not in an optimum way, always safeguarding the catalytic converter integrity.
The throttle valve position signal is especially important at the small valve openings. These areas
are also where the sensor works more frequently,
and therefore they require more frequent checks
after a high number of kilometres run.
To check the sensor and related circuit, proceed
as follows:
1 - Connect the diagnostic tester.
Set the switch to "ON" with switch to "RUN" and
side stand raised.
Select the tester menu on the «ERRORS» function.
Check whether the control unit has detected any
failures relating to the throttle valve position signal.
YES go to 6 NO go to 2
Specific tooling
020460Y Scooter diagnosis and tester
2 - Select the diagnostic tester menu on the "PARAMETERS" function.
Check whether the control unit recognises the extreme positions:
Throttle valve to minimum
Throttle valve to maximum
YES go to 4 NO go to 3
3 - Check the adjustment of the throttle valve control flexible transmissions. Fix or replace, if required.
YES go to 2
4 - Gradually open the throttle valve, check that the mV value increases progressively and proportionally
with the opening variation.
YES go to 5 NO go to 6
5 - The throttle valve position signal is conforming.
6 - Connect the special tool to the injection system.
Do not connect the tool to the control unit.
Disconnect the throttle valve position sensor connector.
Check the continuity between the connector's terminals and the relevant pins on the control unit.
INJEC - 84
Nexus 500 euro 3
Injection
Specific tooling
020481Y Control unit interface wiring
Electric characteristic
Light blue/green-22 =
0 Ω (continuity)
Brown-yellow-1 =
0 Ω (continuity)
Orange-light blue-11 =
0 Ω (continuity)
YES go to 8 NO go to 7
7 - Repair or replace the injection wiring.
YES go to 6
8 - Check the earth insulation of the three circuit lines.
Electric characteristic
22-23 =
Ω infinite (>1M)
1-23 =
Ω infinite (>1M)
11-23 =
Ω infinite (>1M)
YES go to 10 NO go to 9
9 - Repair or replace the injection wiring
YES go to 8
INJEC - 85
Injection
Nexus 500 euro 3
10 - Connect the special tool to the control unit.
Set the switch to "ON" with switch to "RUN" and side stand raised.
Measure voltage between terminals 1 and 22 of the special tool.
Specific tooling
020481Y Control unit interface wiring
Electric characteristic
1-22 =
5±0.2 V
YES go to 12 NO go to 11
11 - Check the control unit connector.
Replace the control unit, if necessary.
YES go to 10
12 - Connect the throttle valve position sensor connector.
Repeat the voltage measurement between terminals 1 and 22 of the special tool.
Electric characteristic
1-22 =
5±0.2 V
YES go to 13 NO go to 14
13 - Measure voltage between terminals 11 and 22. Gradually open the throttle valve and check that
the voltage value increases progressively.
N.B.
BY WAY OF AN INDICATION, VOLTAGE MAY VARY FROM APPROX. 700MV AT MINIMUM, AND
ABOVE 4V AT MAXIMUM.
Electric characteristic
INJEC - 86
Nexus 500 euro 3
Injection
11-22 =
V (progressive variation)
The possible variations of the limit values are
caused by the sensor installation tolerances.
YES go to 15 NO go to 14
14 - Replace the throttle body along with sensors
and stepper.
YES point 12
15 - Check that the voltage measured at pins 11
and 22 matches that indicated by the diagnostic
tester set to "PARAMETERS".
YES go to 16 NO go to 17
16 - The throttle valve position sensor and relevant circuit are conforming.
17 - Replace the control unit.
Zeroing the throttle
Resetting the throttle valve position signal (T.P.S. reset)
The throttle body is supplied with throttle valve position sensor and is pre-calibrated.
Pre-calibration entails regulating the minimum opening of the throttle valve to obtain a certain flow of
air under preset reference conditions.
Pre-calibration ensures optimal air flow for the control of the idling.
This regulation must not be tampered with in any way whatsoever.
The injection system will complete the management of the idling through the stepper and the variation
of the ignition advance.
The throttle body after the pre-calibration has an opened valve with angle that can vary depending on
the tolerances of the machining of the pipe and the valve itself.
The valve position sensor can also assume various fitting positions. For these reasons the mVs of the
sensor with the valve at minimum can vary from one throttle body to another.
To obtain the optimum fuel preparation, especially at small openings of the throttle valve, it is essential
to match the throttle body with the control unit following the procedure known as TPS resetting.
With this operation we inform the control unit, as the starting point, of the mV value corresponding to
the precalibrated position. The control unit will recognise such value as angle 5.24°.
To reset, proceed as follows:
INJEC - 87
Injection
Connect the diagnostic tester.
Set the switch to "ON" with switch in "RUN" and
side stand raised.
Select the functions of the diagnostic tester on
"TPS RESET".
Specific tooling
020460Y Scooter diagnosis and tester
Make sure that the throttle valve with the control is
supporting the stop screw.
Guaranteeing that this position will be kept, send
a confirmation for the TPS reset procedure.
Select the "PARAMETERS" function and check
that the TPS reset "YES" is displayed.
Reset should be performed in the following cases:
- on first fitting.
- in case of replacement of the throttle body
- if the injection control unit is replaced.
N.B.
INJEC - 88
Nexus 500 euro 3
Nexus 500 euro 3
Injection
THE TPS RESETTING PROCEDURE MUST NOT BE CARRIED OUT WITH A USED THROTTLE
BODY BECAUSE POSSIBLE VALVE WEAR AND STOP WEAR FOR THE MINIMUM OPENING
MAKE THE AIR FLOW DIFFERENTLY FROM THAT OF PRE-CALIBRATION.
Step motor
CIRCUIT LAYOUT
1
2
Specification
electronic control unit
Stepper motor
Desc./Quantity
Stepper motor
The throttle body is provided with an auxiliary air
circuit. This is enabled by a piston valve controlled
by a stepper motor.
The stepper is powered by the control unit only
when the opening must be changed.
The revolution is divided into portions called
"steps".
By changing the opening "steps" it is possible to
properly feed the engine to facilitate the start-up
procedure and adjust the air feeding with cold engine. When the engine reaches the working temperature, the stepper partly closes again.
INJEC - 89
Injection
Nexus 500 euro 3
To prevent wear of the adjustment piston, operation at full speed is obtained with a minimum opening of 43 - 45 "steps".
To recover possible adjustments, every switching
to "OFF" causes the piston to close up to end of
travel and to open up again by a fixed number of
steps (self-reset).
When the control unit changes the stepper opening "steps" it also changes the injection time to
ensure proper ignition.
The engine idle speed is practically stabilised at
1550-50 rpm. After a hot start-up step you can
perceive the first increase in the revolutions and
the subsequent closing of the stepper to stabilise
the speed.
In case of irregular speed, before carrying out
electric checks inspect the throttle valve and the
auxiliary air circuit cleaning.
To check the stepper and the relevant circuit, proceed as follows:
1 - Connect the diagnostic tester.
Set the switch to "ON" with switch to "RUN" and
side stand raised.
Lift the scooter on the central stand. Select the
function "ERRORS" in the menu.
Check whether the control unit has detected any
failures relating to the stepper circuit.
YES go to 8 NO go to 2
Specific tooling
020460Y Scooter diagnosis and tester
2 - Select the menu on the "PARAMETERS" function. Check the number of "steps" programmed by
the control unit to obtain start-up. This setting is a function of the engine temperature.
Electric characteristic
20° C =
approx. 135 - 140 steps
INJEC - 90
Nexus 500 euro 3
Injection
YES go to 3 NO go to 4
3 - Start the engine and let it warm up.
With a coolant temperature of more than 70°C, the
control unit must control the stepper with about 45
"steps".
YES go to 5 NO go to 4
4 - Check the coolant temperature sensor signal. Check the control unit, if necessary.
5 - Select the menu on the "ACTIVE DIAGNOSIS" function. Select "STEPPER" diagnosis. Start the
diagnosis with idle engine at the working temperature. Check whether the stepper controls some revolution variations and wait for the diagnostic tester response.
N.B.
THE CPU ENABLES THE DIAGNOSIS ONLY WHEN THE IDLE SPEED IS WITHIN THE SPECIFICATIONS.
YES go to 6 NO go to 8
6 - Test successful. Variations of revolutions perceived.
YES go to 7 NO go to 9
7 - Stepper and relevant circuit efficient.
8- Test failed. No change in the rpm, check the stepper circuit. Disconnect the stepper connector.
Check the resistance of the stepper circuits by connecting the tester as indicated in the figure. The two
measurements must have the same value.
Electric characteristic
INJEC - 91
Injection
Nexus 500 euro 3
Resistance =
approx. 51 Ω
YES go to 11 NO go to 10
9 - Test successful.
No variations of revolutions.
Remove the throttle body.
Check the auxiliary air circuit cleaning. Switch from
"ON" to "OFF" and again to "ON" and check whether the piston valve moves. If the valve does not
move, replace the throttle body.
10 - Replace the throttle body
11 - Connect the special tool.
For these checks, do not connect the special tool to the control unit. Check the continuity of the 4 power
supply lines of the stepper.
Specific tooling
020481Y Control unit interface wiring
Electric characteristic
A Light blue-red-14 =
0 Ω (continuity)
B Orange-blue-6 =
0 Ω (continuity)
C Light blue-yellow-21 =
0 Ω (continuity)
D Light blue-black-24 =
0 Ω (continuity)
INJEC - 92
Nexus 500 euro 3
Injection
YES go to 12 NO go to 13
12 - Check the earth insulation of the 4 stepper lines.
Electric characteristic
14-23 =
>1 MΩ (infinite)
6-23 =
>1 MΩ (infinite)
21-23 =
>1 MΩ (infinite)
24-23 =
>1 MΩ (infinite)
YES go to 14 NO go to 13
13 - Repair or replace the wiring.
YES go to 11
14 - Connect the stepper connector.
Repeat the continuity check with the tool pins.
Electric characteristic
14-24 =
approx. 51 Ω
6-21 =
approx. 51 Ω
INJEC - 93
Injection
Nexus 500 euro 3
YES go to 16 NO go to 15
15 - Check cable harness and connectors more carefully.
16 - Connect the control unit connector.
Set the switch to «ON» with switch to «RUN» and side stand raised. Repeat the "ON" "OFF" "ON"
switching.
Check the presence of voltage pulses on the stepper command lines.
Set-up for direct voltage measurements.
N.B.
PULSES ARE USED TO CHANGE THE STEPPER POSITION.
Electric characteristic
14-24 =
V (pulses for a few seconds)
6-21 =
V (pulses for a few seconds)
After reaching the optimum position, the power
supply voltage becomes null.
YES go to 17 NO go to 18
17 - The stepper circuit is efficient.
18 - Check the control unit connector. Replace the control unit, if necessary.
Lambda probe
SIGNAL CHECK
INJEC - 94
Nexus 500 euro 3
Injection
Install the electronic control unit interface wiring.
Start the engine and warm up until the electric fan
switches on.
Use an analogue multimeter with a direct voltage
scale measuring down to 2 V.
Connect the multimeter probes between pin 2 (-)
and pin 8 (+)
With the engine running at idle speed, check that
the voltage oscillates between 0V and 1V
With the throttle valve completely open, the voltage is approx. 1V.
During the closing phase, the voltage is approx.
0V.
If the voltage remains constant, the sensor may be
damaged. Remove the sensor and check that
there are no oil or carbon deposits inside it..
Impianto elettroventilatore
TERMINALS
5 - 23
CONDITIONS
Switch in position "ON"
STANDARD
Battery voltage
Switch on "RUN"
Side stand raised
Electric fan off
INJEC - 95
Injection
KEY:
4. Throttle valve position sensor
5. Ambient temperature sensor
7. Electric fan
8. Engine temperature sensor
9. Remote control for electric fan
12. Key switch
13. Fuse box A
14. Main fuse
15. Fuse box B
18. Engine stop remote control
19. Diode
20. Battery
25. Engine stop switch
26. Centre stand switch
54. Instrument panel
A. Instrument panel bulbs
B. Immobilizer LED
C. Speedometer
D. Digital display
INJEC - 96
Nexus 500 euro 3
Nexus 500 euro 3
Injection
E. Engine Warning indicator light
F. Low fuel warning light
G. Oil warning light
64. Fuel injection electronic control unit
The electric fan system is powered by a remote
control switch connected to the continuous power
supply controlled by the electronic control unit of
the injection system.
The electronic control unit of the injection system
controls the electric fan in relation to the measured
engine temperature.
If prolonged running of the electric fan is noticed,
check the following carefully before starting to
check the electrical system:
- Coolant level in the expansion tank - bleeding of
the inlet hose to the engine
- Bleeding of the outlet from the head
- Function of the thermostat
- Function of the pump
For these checks, see chapter "Cooling system".
To check the circuit, proceed as follows:
1 - Connect the diagnostic tester. Set the switch to
"ON" with switch to "RUN" and side stand raised.
Select the "ERRORS" function. Check whether the
control unit has detected any failures relating to the
electric fan control circuit.
YES go to 8 NO go to 2
2 - Select the menu on the "ACTIVE DIAGNOSIS"
function. Activate the electric fan diagnostic function. Check acoustically for rotation of the electric
fan. Wait for the exit from the diagnostic tester.
YES go to 3 NO go to 4
INJEC - 97
Injection
3 - Test successful. The fan is rotating.
YES go to 5
4- Test failed. The fan is not rotating.
YES go to 8 NO go to 6
5- The electric fan system is OK
6 - Test successful. The fan is not functioning
YES go to 7
7 - The remote control switch circuit is OK. Check
the connections to the electric fan, the function of
the contacts of the remote control switch, the positive lines, the negative line and the motor of the
electric fan.
8 - Disconnect the remote control unit of the electric fan. Check the continuity of the exciter coil.
85 - 86 = 100 ± 50Ω
YES go to 10 NO go to 9
9 - Replace the remote control switch
YES go to 8
10 - Connect the special tool between the control
unit and the system. Do not connect the electronic
control unit
YES go to 11
11 - Check for positive battery voltage at pin 85 of
the remote control switch connector.
85 (blue/grey) - 23 = Battery voltage with switch in
position "ON"
YES go to 13 NO go to12
12 - Repair or replace the wiring.
13 - Leaving the remote control switch disconnected, check for continuity between pin 86 of the
remote control switch connector and pin 5 of the
electronic control unit.
86 (green/white) - 5 = 0Ω (continuity)
YES go to 14 NO go to15
INJEC - 98
Nexus 500 euro 3
Nexus 500 euro 3
Injection
14 - Check the earth insulation.
5 - 23 >1 MΩ (infinite)
YES go to 16 NO go to 15
15 - Repair or replace the cable harness.
16 - Connect the remote control switch and check
for battery voltage between terminals 5 and 23 with
the key switch in position "ON".
5 - 23 = Battery voltage with panel in position "ON"
YES go to 17
17 - Repeat the check with the electronic control unit connected and the engine cold.
5 - 23 = Battery voltage with panel in position "ON"
If the fault continues, replace the electronic control unit.
INJEC - 99
Injection
INJEC - 100
Nexus 500 euro 3
INDEX OF TOPICS
SUSPENSIONS
SUSP
Suspensions
Nexus 500 euro 3
This section is devoted to operations that can be carried out on the suspension.
Front
Removing the front wheel
- Remove the fixing nut from the wheel axle on the
left side of the vehicle.
- Loosen the two screws fixing the wheel axle
clamp and remove the clamp.
Front wheel hub overhaul
Check that the wheel bearings do not show signs
of wear.
If you have to replace the wheel bearings, proceed
as follows:
- Remove the two bearings on the brake disc side
using pliers 14 and the special bell 9.
- Remove the internal spacer.
SUSP - 2
Nexus 500 euro 3
Suspensions
- Support the front wheel with two wooden shims
that make it possible to avoid scratching in the
case of contact with the rim.
- Insert the punch (consisting of adaptor handle,
24 mm adaptor and 15 mm guide) from the brake
disc side to permit the removal of the opposite side
bearing and the spacer bushing.
Specific tooling
020376Y Adaptor handle
020456Y Ø 24 mm adaptor
020412Y 15 mm guide
- Heat the bearing seat on the side opposite the
brake disc with the heat gun.
- Insert the bearing using the punch consisting of
adaptor handle, 40x37 mm adaptor and 15 mm
guide, and take it to the stop.
SUSP - 3
Suspensions
- Reinsert the spacer bushing on the brake disc
side using the appropriate tool and take it to the
stop.
Specific tooling
020376Y Adaptor handle
020359Y 42x47-mm adaptor
020412Y 15 mm guide
020201Y Spacer bushing driving tube
- Refit the cap and tighten the five fixing screws.
- Turn over the wheel and insert the internal spacer
with the part fitted with the seeger ring facing the
bearing on the brake disc side.
SUSP - 4
Nexus 500 euro 3
Nexus 500 euro 3
Suspensions
- Heat the bearing seat on the side the brake disc
with the heat gun.
2 - Insert the two bearings one at a time using the punch consisting of adaptor handle, 32x35 mm
adaptor and 15 mm guide, and take it to the stop.
Specific tooling
020376Y Adaptor handle
020357Y 32 x 35 mm adaptor
020412Y 15 mm guide
Refitting the front wheel
- When refitting, pay attention in repositioning the
odometer drive correctly.
Locking torques (N*m)
Wheel axle nut 45 ÷ 50 Wheel axle clamp
screws 6 - 7 Nm
Front fork
Removal
- Remove the front wheel.
- Remove the front mudguard
- Remove the front brake calliper
- Remove the front and rear handlebar cover.
- Remove the pin mounting the handlebar to the
steering tube.
- Remove the handlebar and rest it on the shield
back plate.
SUSP - 5
Suspensions
Nexus 500 euro 3
Using the special tool, loosen and remove the upper ring nut, the spacer washer and the counterring nut.
- Extract the fork.
N.B.
TAKE CARE TO SUPPORT THE FORK SO AS
TO PREVENT IT FROM COMING OFF ABRUPTLY
Specific tooling
020055Y Wrench for steering tube ring nut
Overhaul
Check pump unit
- Check that the oil holes on the pumping are free
from clogging.
- Check that the sealing snap ring is not damaged.
Check the spring length
- Check the length "A" of the spring.
Characteristic
Standard spring length:
291.6 mm
Servicing tapered bearing seats
- Check that the seats and the tapered bearings exhibit no scratches or wear.
N.B.
THE TAPERED BEARING SEATS SHOULD BE REMOVED ONLY IF STRICTLY NECESSARY.
SUSP - 6
Nexus 500 euro 3
Suspensions
In case of replacement, proceed as follows:
- Using a bearing removal punch, inserted from the
bottom, remove the top seat on the steering head.
Then, remove the bottom seat of the tapered bearing inserting the punch from the top of the headstock.
Specific tooling
020004Y Punch for removing fifth wheels from
headstock
Servicing fork stems
- Using an inside 17 mm hexagonal spanner, loosen the top stem closing cap.
- Loosen the stem support clamp and remove fork
leg and stem.
- Remove the spring.
- Drain the oil.
- Remove the screw with copper washer shown in
the figure. To prevent the pumping member rotation, insert an inside 22 mm hexagon spanner into
the stem.
- Remove the pumping member.
SUSP - 7
Suspensions
- Remove the dust guard ring using a screwdriver
as shown in the figure.
N.B.
BE CAREFUL NOT TO DAMAGE THE DUST
GUARD AND THE STEM.
- Remove the oil guard safety lock using a screwdriver.
- Repeatedly actuate the stem to remove it from
the fork leg.
- Extract the oil guard "D", the abutment washer
"C" and the top bushing "B".
- Widen and remove the bottom bushing "A".
Refitting
Installing stems on fork legs
Preassemble the stem as indicated:
- Install the bushing from the bottom of the stem
SUSP - 8
Nexus 500 euro 3
Nexus 500 euro 3
Suspensions
- Insert the following from the top of the stem:
1 Bushing "B"
2 Abutment washer "C"
3 Oil guard "D"
- Insert the pumping member guiding bushing at
the bottom end of the stem.
- Insert the stem into the casing being careful not to let the guiding bushing come out of the stem.
- Move the oil guard in abutment using a tube.
TUBE SIZE
Specification
Inside:
Outside:
Height:
Desc./Quantity
44 mm
51 mm
approx. 105 mm
SUSP - 9
Suspensions
- Insert the contrast spring into the pumping member.
- Insert the pumping member into the stem.
- Insert the stem into the fork leg being careful not
to let the guiding bushing come out of the stem.
- Insert and screw the pumping member screw with
a new copper washer and tighten to the prescribed
torque.
CAUTION
TO PREVENT THE PUMPING MEMBER ROTATION, INSERT AN INSIDE 22 MM HEXAGON
WRENCH INTO THE STEM.
Locking torques (N*m)
Pumping element fixing screw 25 - 35
- Pour recommended oil into the stem.
Recommended products
AGIP FORK 7,5W Oil for front fork
Hydraulic oil SAE 7,5W
Characteristic
Amount oil:
195 ± 3 cc
- Insert the spring with the thickest turns at the
bottom.
- Insert the stem into the fork clamp.
- Tighten the clamp to screw the top stem closing
cap.
- Check that the sealing ring on the cap is in good
working order, then tighten the cap on the stem to
the prescribed torque.
Locking torques (N*m)
Stem upper cap 35 - 55
SUSP - 10
Nexus 500 euro 3
Nexus 500 euro 3
Suspensions
- Loosen the fork clamp screws and move the stem
closing cap in abutment with the clamp.
- Tighten the clamp screws to the prescribed torque.
Locking torques (N*m)
Fork clamp screws 20 ÷ 25
- Grease the tapered bearing using the specified
product.
Recommended products
AGIP GREASE PV2 Grease for the steering
bearings, pin seats and swinging arm
White anhydrous-calcium based grease to protect
roller bearings; temperature range between -20 C
and +120 C; NLGI 2; ISO-L-XBCIB2.
- Insert the fork into the headstock.
- Insert the tapered bearing after applying the
specified product.
Recommended products
AGIP GREASE PV2 Grease for the steering
bearings, pin seats and swinging arm
White anhydrous-calcium based grease to protect
roller bearings; temperature range between -20 C
and +120 C; NLGI 2; ISO-L-XBCIB2.
- Using the special tool, tighten the first ring-nut on the steering tube to a holding torque, then tighten
completely.
Locking torques (N*m)
Holding torque of lower ring nut 20 ÷ 25
- Tighten to the prescribed torque.
Locking torques (N*m)
Lower steering ring nut 10 - 13 **
- Install the space washer.
- Using the special tool, tighten the second locking ring nut on the steering tube to the prescribed torque.
Locking torques (N*m)
Upper steering ring nut 36 - 39
SUSP - 11
Suspensions
Nexus 500 euro 3
- Install the handlebars on the steering tube, paying attention to the centring, aligning the recess on
the handlebar with that on the steering tube as
shown in the figure.
- Tighten the handlebar retaining screw on the steering tube to the prescribed torque.
- Install the front and rear handlebar covers as described in the section "Scooter body".
- Install the front mudguard
- Install the front wheel.
- Install the front brake callipers.
- Tighten the retaining screws of the brake calliper to the support.
Specific tooling
020055Y Wrench for steering tube ring nut
Locking torques (N*m)
Screw securing handlebar to steering tube 45 - 50 Holding torque of lower ring nut 20 ÷ 25 Upper
steering ring nut 36 - 39 Lower steering ring nut 10 - 13 ** Front brake calliper mounting on
fork 20 ÷ 25 Front brake disc mounting 11 ÷ 13 Plastic protection retaining screw 5 - 6
Steering bearing
Removal
Service of tapered bearing on fork
- Check that the tapered bearing on the fork exhibits no deformations or wear.
THE BEARING SHOULD BE REMOVED ONLY IF STRICTLY NECESSARY.
In case of replacement, proceed as follows:
- Support the fork in a vice.
- Insert the contrast plate in the upper end of the
steering tube
SUSP - 12
Nexus 500 euro 3
Suspensions
- Insert the special tool as shown in the figure.
- Insert the retaining band of the two half-rings.
- Using a 19 mm hexagonal spanner, extract the
roller bearing.
Specific tooling
020458Y Puller for lower bearing on steering
tube
Refitting
Reassembly of tapered bearing in steering
tube
- Insert the a new plate and a new dust guard in
the steering tube
- Insert the a new tapered bearing in the steering
tube
- Using the special tool and a mallet to move the
dust guard and the bearing in abutment.
Specific tooling
006029Y Punch for fitting fifth wheel seat on
steering tube
SUSP - 13
Suspensions
Reassembly of steering tapered bearing seats
Using the special tool, reassemble the tapered
bearing housings on the head as described below:
- Place a new top housing on the head and a new
bearing seat on the bottom side.
- Insert the screw of the special tool set-up with the
adapters for inserting bearing and seat, into the
steering head, as shown in the figure.
- Using two 24 mm wrenches, tighten the screw to
move the two seats in abutment.
N.B.
ALWAYS USE A NEW BEARING AND A NEW
SEAT.
Specific tooling
001330Y Tool for fitting steering seats
Rear
A= Connection of rear shock absorber to support
connecting rod: 38 - 46
B = Strut upper connection: 56 - 70
C = Connection of front support strut and shock
absorber to frame: 73 - 80
A = Connection of rear support strut to hub cover:
20-25 N·m
B = Strut lower connection: 30 - 35 Nm*
* Lock using the recommended product
C = Rear support connection to crankcase: 11-13
Nm
D= Assembly plate mounting on strut support:
11-13 Nm
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
SUSP - 14
Nexus 500 euro 3
Nexus 500 euro 3
Suspensions
The scooter has a "Power Drive" progressive rear suspension system combined with the "Direct Link"
system of engine mounting on the frame that gives exceptional rigidity to the whole system.
The scooter has a special connecting strut between engine and frame that allows the travel gear to be
adjusted to 15 positions.
If is thus possible by turning the ring nut on the lower part of the strut to raise or lower the rear section
of the scooter.
It is possible to adjust the geometry of the rear end to the preference of the rider and thus to adjust the
road bolding of the scooter:
- Lowers the rear section for improved stability at
higher speeds.
- Preference for a higher rear section to improve
handling and reduced speeds.
Removing the rear wheel
- Remove the muffler assembly.
- Remove the plastic plug from the wheel locking
nut
SUSP - 15
Suspensions
- Remove the cotter pin, the cap, the wheel axle
fixing nut and the outer one of the two spacers.
- Remove the two screws fixing the mudguard to the bracket
- Remove the two screws fixing the bracket to the engine
- Undo the wheel axle bracket, using the heat gun
if necessary.
- Remove the 5 bolts of the wheel and remove
SUSP - 16
Nexus 500 euro 3
Nexus 500 euro 3
Suspensions
Refitting the rear wheel
To fit, follow the removal steps but in the reverse
sequence, being careful to fit the spacers on the
wheel axle as shown in the photograph.
Locking torques (N*m)
Muffler arm clamping screws 27 ÷ 30 Rear
wheel axle nut 104 ÷ 126 Shock absorbercrankcase attachment bracket 20 ÷ 25 Lower
shock absorber clamping screw 33 ÷ 41 Nm
Rear brake calliper fixing screws 25 ÷ 30 Nm
Swing-arm
The scooter has engine-chassis rigid fixing system
known as Direct-link.
The system consists of:
A= Left spacer
B= Right-side engine support bearing
C= Central spacer
D= Right spacer
E = Left side engine support bearing
F = Chassis
Removal
- Adequately hold the engine.
- Remove the engine to chassis fixing pin.
- Move the engine backwards so that spacers can
be removed
- Remove the left spacer shown in the figure.
SUSP - 17
Suspensions
Nexus 500 euro 3
- Remove the central and the right spacers.
- To refit perform the operation in reverse order
carefully respecting the locking torque and lubricate the area marked «A» for the right spacer on
the engine bearing to slide.
Locking torques (N*m)
Engine - chassis fixing pin 100 - 120
Two different types of fixing pins are fitted on the engine:
- 17 mm flanged head bolts.
- 22 mm head bolts and washer.
Shock absorbers
Removal
- To remove the rear shock absorber, remove the
two retaining screws shown in the figure.
Refitting
- To refit perform the operation in reverse order carefully respecting the locking torques.
Locking torques (N*m)
Rear shock absorber retainer to the chassis 38 - 46
SUSP - 18
Nexus 500 euro 3
Suspensions
Centre-stand
- Remove the two return springs from the centre
stand.
- Loosen the fastening nuts.
- Remove the centre stand.
- On refitting tighten the nut to the specified torque.
Locking torques (N*m)
Central stand retainers 25 - 30
Centre stand
We wish to inform you that from Chassis No. ZAPM3510000007012, a new centre stand has been
introduced to improve the function. The new stand differs from the old stand in having a 5 mm longer
stand arms, increasing the height of the scooter from the ground. The modification also requires the
introduction of a new stand stop buffer.
Side stand
- Unhook the springs.
- Loosen the nut.
- Pull out the screw.
Fitting
Carry out the previous operations in reverse order.
Locking torques (N*m)
Side stand clamp 15 ÷ 20
SUSP - 19
Suspensions
SUSP - 20
Nexus 500 euro 3
INDEX OF TOPICS
BRAKING SYSTEM
BRAK SYS
Braking system
Nexus 500 euro 3
Specifications
The scooter has an integral brake system.
This is obtained with the left-hand brake pump connected simultaneously to the rear brake calliper and
the front right calliper.
The connection to the rear calliper is direct.
The front calliper is connected via a pressure control valve with two thresholds.
The correct splitting of the braking force is also obtained via the dimensioning of the diameters of the
discs and of the plungers of the callipers.
The integral brake system is also designed to meet higher standards of safety. To this end, simple
deceleration is obtained only with the rear brake.
When the pump pressure exceeds 8 bar, front and rear brake operate simultaneously.
In this phase the increases in the pump pressure are detected by both the callipers.
When the front brake pressure reaches 23 bar, a new phase of limitation starts.
Any increments in the pump pressure will be detected in linear mode by the rear calliper.
The front calliper only detects slight increases, for example 80 bar rear corresponding to 31.7 bar front.
Any demands for excessive braking force will always result in a loss of rear wheel traction.
This condition helps to avoid dangerous locking of the front wheel.
When the traction conditions, load and speed permit the use of the full braking force, this is obtained
by combining the function of the integral brake with that of the single front brake.
BRAK SYS - 2
Nexus 500 euro 3
Braking system
[P]
Specification
A:
B:
Desc./Quantity
Rear brake pressure
Front brake pressure
Rear brake calliper
Removal
- Remove the rear wheel.
- Remove the snap ring of the pad retaining pin.
- Using a key, partially slide off the pad retaining
pin until the circlip is released.
- Remove the screws fixing the brake calliper to
the bracket, then remove the brake calliper complete with pipe.
- Complete the extraction of the pad retention pin, the spring and the pads.
N.B.
IF BRAKE CALLIPER REPLACEMENT OR SERVICE IS NEEDED, BEFORE REMOVING THE CALLIPER CLAMPS TO THE SUPPORT BRACKET, LOOSEN THE OIL JOINT FITTING.
BRAK SYS - 3
Braking system
Nexus 500 euro 3
Overhaul
- Remove the rear brake calliper
- Suitably support the brake calliper in a vice
- Remove the two calliper coupling screws as
shown in the photograph.
- Remove the two plungers from the calliper body
with the aid of short blasts of compressed air
through the brake fluid feed holes.
- Remove the dust ring and the O-ring of each half
calliper.
- Remove the two O-rings in the right half-calliper.
N.B.
WHEN REMOVING THE O-RINGS, BE CAREFUL NOT TO SCRATCH THE HALF CALLIPER
SEATS
- Check that the pistons and their seats show no
scratches.
- Wash and blow all the components carefully.
- Fit new sealing rings and dust guards.
- Refit the plungers in their seats being careful to
lubricate with brake fluid
- Couple the half-calliper and tighten the two screws to the prescribed torque.
N.B.
TO AVOID DAMAGING THE GASKETS, WASH THE PLIERS COMPONENTS ONLY WITH ALCOHOL. DO NOT USE FUEL OR DERIVATIVES.
Locking torques (N*m)
Brake calliper coupling 20 - 24
BRAK SYS - 4
Nexus 500 euro 3
Braking system
Refitting
- The rear break calliper can be recognised by its
Ø 34 mm plungers and the bleed screw as shown
in the figure.
- Insert the break pads in the pliers according to
the arrow that indicates the break disc direction of
rotation as shown in the photograph.
- Insert the pad fixing pin and the retention spring
being careful to position its ends pointing towards
the bleed screw as shown in the photograph.
- Insert the circlips on the pad fixing pin.
N.B.
FAILURE TO RESPECT THE PAD POSITIONING REQUIREMENTS WITH RESPECT TO THE DIRECTION OF ROTATION COULD INHIBIT PROPER BRAKE FUNCTION AND QUIETNESS.
- Keep the brake pads in contact with the plungers
and insert the calliper in the brake disc.
- Fix the calliper to the support with the two screws
with spring washer to the prescribed torque as
shown in the photograph.
- Fasten the brake pipe union to the calliper and tighten to the prescribed torque
BRAK SYS - 5
Braking system
Nexus 500 euro 3
- Bleed the system and replace the rear wheel
N.B.
IF THE REAR BREAK CALLIPER SUPPORT PLATE HAS BEEN REMOVED, UPON REFITTING IT
IS NECESSARY TO FOLD THE EDGES OF THE WASHER ON THE HEAD OF THE SCREWS FIXING
THE PLATE TO THE CRANKCASE.
Locking torques (N*m)
Pipe joint / brake calliper 20 ÷ 25 Rear calliper support clamp to crankcase 20 ÷ 25
Front brake calliper
Removal
- Check the good condition of the brake hoses, of
the seals and of the respective fittings. If any loss
of brake fluid is discovered at the brake callipers,
the callipers must be replaced.
- Remove the two retaining screws of the front
brake calliper at the fork as indicated in the photo.
N.B.
BEFORE STARTING TO SERVICE OR REPLACE THE CALLIPER, LOOSEN THE CONNECTION OF THE PRESSURE HOSE AT THE
BRAKE CALLIPER AFTER HAVING DEPRESSURISED THE CIRCUIT AS A WHOLE.
Overhaul
- Remove the front brake calliper and the corresponding pads.
BRAK SYS - 6
Nexus 500 euro 3
Braking system
- Remove the two pistons from the calliper body
with the aid of small blasts of compressed air
through the brake fluid feeding hole. A piece of
rubber pipe may be needed to seal with the compressor gun.
N.B.
PAY ATTENTION WHEN THE PISTONS COME
OUT AS THE STRONG BLASTS OF COMPRESSED AIR CAN MAKE THE PISTONS
COME OUT OF THE PUMP BODY VIOLENTLY
- Remove the dust-cover ring «A» and the sealing
ring «B» of each piston.
N.B.
DO NOT SCRATCH THE SEATS WHILE REMOVING THE RINGS.
- Check that the pistons and relevant seats exhibit
no scratches.
- Wash only with alcohol and blow all the components carefully.
- Fit new sealing rings and dust guards.
- Assembly the pistons into the appropriate seats
being careful to lubricate the sealing ring «B» with
brake fluid. The dust guard ring «A» has an internal groove with specific grease.
- Decouple the floating support of the calliper body
separating the 2 rubber dust-covers off their seats.
N.B.
TO EXTRACT THE LONG DUST-COVER PULL
IT BY ITS HEAD AND INTRODUCE THE BELLOWS ( LOCATED ON THE OTHER SIDE) INTO
THE CALLIPER HOLE. LUBRICATE THE SLIDING PINS WITH SPECIFIC GREASE (APPROPRIATE FOR RUBBER GASKETS).
- Once the cleaning and replacement operations have been performed, reassemble all the parts in the
reverse order followed during the removal.
N.B.
BRAK SYS - 7
Braking system
Nexus 500 euro 3
TO AVOID DAMAGING THE GASKETS, WASH THE PLIERS COMPONENTS ONLY WITH ALCOHOL. DO NOT USE FUEL OR DERIVATIVES.
Refitting
- Attach the sliding plate of the front brake calliper
to the fork using the two screws with lock washers
tightened to the specified torque.
- Connect the brake pipe to the calliper and tighten
it to the prescribed torque, turning the fitting towards the front and parallel to the scooter axis as
shown in the photo.
Locking torques (N*m)
Pipe joint / brake calliper 20 ÷ 25
Rear brake disc
Removal
- Remove the rear brake calliper
- Remove the brake disc with hub from the wheel
axle.
- To remove the brake disc from the hub, support
the unit in a vice and tighten the 5 fastening bolts
with self-locking nuts.
Refitting
- To reassemble the brake disc on the hub, carry
out the removal operations in the reverse order arranging the brake disc on the hub on the side
opposed the wheel keying
- Follow the direction of rotation shown by the arrow and tighten to the prescribed torque.
- Lubricate the seat of the wheel bearing shaft on
the manifold support with the recommended
grease.
N.B.
BRAK SYS - 8
Nexus 500 euro 3
Braking system
APPLYING AN EXCESSIVE QUANTITY OF
GREASE MAY IMPAIR THE BRAKE PERFORMANCE
Recommended products
AGIP GREASE PV2 Grease for the steering
bearings, pin seats and swinging arm
White anhydrous-calcium based grease to protect
roller bearings; temperature range between -20 C
and +120 C; NLGI 2; ISO-L-XBCIB2.
- Insert the hub - disc assembly in the wheel axle.
Locking torques (N*m)
Rear brake disc mounting 11 ÷ 13
Disc Inspection
- Remove the rear brake calliper.
- Using a micrometer check the disc thickness as
shown in the photograph.
Characteristic
Standard thickness:
5 +02-01mm
Minimum thickness allowed after use:
4 mm
- Repeat the measurement at no fewer than six
points on the disc.
- Check that the measurements do not show deviations higher than 0.1 mm
- Remove the front brake calliper.
- Position the magnetic base with dial gauge on the
brake calliper support bracket as shown in the
photograph.
- Suitably fix the flange to the wheel axle with the original nut and spacer and a Ø 17 mm bearing.
N.B.
SO AS NOT TO GET A DISTORTED READING, CAUSE THE DRIVEN PULLEY SHAFT TO TURN
IN ORDER TO ROTATE THE DISC.
Specific tooling
020335Y Magnetic support for dial gauge
Characteristic
Max. deviation allowed:
0.1 mm
BRAK SYS - 9
Braking system
Nexus 500 euro 3
- If you detect incorrect values, replace the disc. If the anomaly persists, replace the hub.
Front brake disc
Removal
- Remove the front wheel.
- Undo the five clamping screws shown in the photograph
Refitting
For the fitting, position the disc correctly using the arrow stamped on it as reference.
- Do up the screws to the prescribed torque and apply the recommended product
N.B.
THE ARROW STAMPED ON THE DISC INDICATING THE RUNNING DIRECTION MUST BE FITTED
TOWARDS THE OUTSIDE OF THE VEHICLE.
Recommended products
Loctite 243 Medium-strength threadlock
Loctite 243 medium-strength threadlock
Locking torques (N*m)
Brake disc fixing screw 5 ÷ 6.5
- Carry out the operations in the reverse order from
the removal being careful to respect the direction
of disc rotation shown by the arrow printed on it
- Tighten the six screws to the specified torque.
Locking torques (N*m)
Brake disc screws: 6 +0.5 -1 Nm
Disc Inspection
Checking the disc is important; it must be perfectly clean, with no sign of rust, oil or grease or other dirt
and must not show signs of deep scoring.
BRAK SYS - 10
Nexus 500 euro 3
Braking system
Characteristic
New rear disc thickness
4.0 mm
Disc thickness at wear limit (front)
3.5 mm
•
Using the appropriate tool, measure
how much the disc protrudes when the
wheel is fitted properly. The protrusion,
measured near the external edge of
the disc, must be less than 0.1 mm.
•
If a value is measured other than the
specified value, remove the front wheel
(Front/Rear Suspension chapter) and
check the protrusion of the disc. Maximum permissible out of true is 0.1 mm.
If the value measured is greater, replace the disc and repeat the check.
•
If the problem persists, check and replace the wheel hub if necessary.
Specific tooling
020335Y Magnetic support for dial gauge
Front brake pads
Removal
- Remove the front brake calliper unscrewing the
2 retainers but leaving the hoses connected.
- Disengage the upper part of the pad from the seat
located into the calliper body.
BRAK SYS - 11
Braking system
- Using a calliper, remove the 2 retaining pins of
the pad sliding pin.
- Unscrew the retaining pin and the pads too.
- Check that the thickness of the friction material
is more than 1.5 mm.
- Otherwise, replace it.
Refitting
- Assemble the brake pads into the calliper inserting the upper tip into the groove and pressing it
towards the thrust spring to facilitate inserting the
pin.
- Insert the pad fixing pin from the reaction plate
side, so that the pin head clicks in the seat in the
groove on that plate.
BRAK SYS - 12
Nexus 500 euro 3
Nexus 500 euro 3
Braking system
- Insert the 2 locking split pins of the pin orientating
the heads towards the calliper body as shown in
the figure.
Rear brake pads
Removal
- Remove the rear brake calliper
- Remove the brake pad and check there are no
faults or warping. If it does, replace it.
- Check that the thickness of the friction material
is over 1.5 mm. Otherwise, replace it.
Refitting
- Insert the brake pads according to the direction
of rotation of the brake disc, as indicated by the
arrow on the anti-vibration pad.
BRAK SYS - 13
Braking system
Nexus 500 euro 3
- Insert the pad mounting pin and the retaining
spring with its ends facing the bleed screw as
shown in the figure.
- Insert the retaining ring on the pin
- Fasten the rear brake calliper to the bracket and tighten the 2 screws to the prescribed torque.
Locking torques (N*m)
Pipe joint / brake calliper 20 ÷ 25
Fill
Rear - combined
To bleed the integral system, first bleed the rear
break calliper.
- Remove the rubber cap from the bleed screw and
insert a rubber pipe to recover the brake fluid.
- With the left-had brake lever, load the system and
bring it up to the required pressure.
- Keeping the left-hand brake lever pulled, loosen
the bleed screw to purge the air. Then tighten the
bleed screw.
BRAK SYS - 14
Nexus 500 euro 3
Braking system
- Repeat the operation until only brake fluid comes
out of the rubber pipe.
- Then repeat the bleed operations for both the
regulating valve and the front left calliper.
- To access the regulating valve, it is necessary to remove the front shield.
- Top up the brake fluid to the right level in the tank.
N.B.
DURING THE BLEEDING OPERATIONS, MAKE SURE THE BRAKE FLUID DOES NOT COME INTO
CONTACT WITH THE BODYWORK SO AS NOT TO DAMAGE IT. FURTHERMORE, DURING THE
BLEEDING OPERATIONS REGARDING THE BRAKE CALLIPERS, MAKE SURE THE BRAKE
FLUID DOES NOT COME INTO CONTACT WITH THE DISC BRAKES AND WITH THE BRAKE
PADS. FAILURE TO COMPLY WITH THIS NORM WILL ENDANGER THE PROPER WORKING AND
EFFICIENCY OF THE BRAKING SYSTEM
If necessary, bleeding can be done using a special vacuum pump
Specific tooling
020329Y MityVac vacuum-operated pump
Locking torques (N*m)
Circuit bleed calliper fitting 12 - 16
Front
- Remove the rubber hood from the bleed screw.
- Insert a rubber pipe in the bleed screw to permit
the brake fluid to be recovered.
- With the right-hand brake lever, load the system and bring it up to the required pressure.
- Keeping the right-hand brake lever pulled, loosen the bleed screw to purge the air. Then tighten the
bleed screw.
- Repeat the operation until only brake fluid comes out of the rubber pipe.
- Remove the fluid recovery pipe and refit the rubber hood over the bleed screw.
- Top up the brake fluid to the right level in the tank.
N.B.
DURING THE BLEEDING OPERATIONS, MAKE SURE THE BRAKE FLUID DOES NOT COME INTO
CONTACT WITH THE BODYWORK SO AS NOT TO DAMAGE IT. FURTHERMORE, DURING THE
BRAK SYS - 15
Nexus 500 euro 3
Braking system
BLEEDING OPERATIONS REGARDING THE BRAKE CALLIPERS, MAKE SURE THE BRAKE
FLUID DOES NOT COME INTO CONTACT WITH THE DISC BRAKES AND WITH THE BRAKE
PADS. FAILURE TO COMPLY WITH THIS NORM WILL ENDANGER THE PROPER WORKING AND
EFFICIENCY OF THE BRAKING SYSTEM
If necessary, bleeding can be done using a special vacuum pump
Specific tooling
020329Y MityVac vacuum-operated pump
Locking torques (N*m)
Circuit bleed calliper fitting 12 - 16
Front brake pump
Removal
- Remove the front handlebar cover.
- Empty the braking system corresponding to the
circuit being inspected.
- Remove the two screws fixing the brake pump to
the handlebar, indicated in the photograph.
- Remove the oil pipe fitting from the pump undoing
the screw indicated in the figure.
- Remove the stop light switch connector
BRAKE PUMP TECHNICAL DATA
Specification
Pump right piston diameter:
Left piston pump diameter:
Desc./Quantity
Ø 12
Ø 15
Refitting
To refit, carry out the removal operations but in reverse order, respecting the prescribed locking torques.
Locking torques (N*m)
Pipe joint / brake calliper 20 ÷ 25
BRAK SYS - 16
Nexus 500 euro 3
Braking system
Rear brake pump - combined
Removal
Replace the pressure distribution valve
If problems are discovered in the brake force distribution between the front left brake calliper and
the rear brake calliper (e.g. equal surface contact
and braking of both the wheels, the rear brake engages but the front brake does not operate or vice
versa, or the brakes function in completely different modes, or the distribution valve does not function correctly), proceed as described below:
- Bleed the brakes of the combined system.
- Remove the front knee guard.
- Loosen fitting 1 shown in the figure for the rear
brake calliper.
N.B.
INSERT A CLOTH UNDER THE DISTRIBUTION
VALVE TO AVOID BRAKE FLUID DRIPPING
ONTO THE PLASTIC OR OTHER COMPONENTS OF THE SCOOTER.
- Remove fitting 2 of the front brake calliper.
- Remove fluid inlet fitting 3 from the pump to the
valve.
- Remove the 2 TCEI socket head retaining screws
of the holding the valve to the frame in the 2 bores
shown in the figure.
- Remove the valve and replace with a new valve.
BRAK SYS - 17
Braking system
Refitting
To refit carry out the disassembly steps but in reverse order.
N.B.
USE NEW COPPER GASKETS ON THE
JOINTS.
- Tighten the screws fixing the valve to the chassis,
but above all tighten the brake piping to the prescribed locking torques.
- Fill and purge the braking system as described in
the relevant section.
Locking torques (N*m)
Coupling for oil on the integral braking system
pump 16 ÷ 20 Coupling on the integral braking
system device (from the pump) 20 ÷ 25 Front
brake calliper - integral braking system device
coupling 20 ÷ 25 Rear brake calliper - integral
braking system device coupling 20 ÷ 25
BRAK SYS - 18
Nexus 500 euro 3
INDEX OF TOPICS
COOLING SYSTEM
COOL SYS
Cooling system
Nexus 500 euro 3
Circuit diagram
The cooling system is of the forced circulation type, with continuous venting and air pressurisation.
Circulation takes places by a centrifugal pump driven by the countershaft.
The pump delivers the coolant to the thermal unit.
The two-way thermostat support is connected in output to the head. One way is connected to the pump
and the other to the radiator (of the horizontal circulation type).
The radiator output is directly connected to the pump.
The expansion tank is connected in parallel to the radiator.
The radiator hot box is connected to the upper side of the expansion tank (in air).
The radiator cold box is connected to the lower side of the expansion tank (in the fluid).
When the engine is cold, the thermostat output to the radiator is closed, even though there is still a little
flow for de-aeration obtained by a hole into the closing plate.
In this case, the circulation into the thermal unit is active to ensure an even heating.
Once the working temperature has been reached, the main circulation on radiator and expansion tank
starts.
With the small openings in the thermostat there is a flow overlapping (recirculation and main one).
When the temperature is higher, the thermostat allows excluding the recirculation to favour the main
circulation.
In this case, the flow is consistent in the expansion tank as well, and this ensures a continuous automatic
venting.
COOL SYS - 2
Nexus 500 euro 3
Cooling system
For the system venting during the circuit filling step, there is a special union at the top of the head (see
filling rules).
To ensure cooling in case of poor dynamic ventilation, there is an electric fan controlled by the injection
system.
TECHNICAL SPECIFICATIONS
Specification
Cooling system capacity
Prescribed fluid
Desc./Quantity
1.7 l
Mixture of 50% water and fluid for sealed circuits
(PARAFLU MOTO RIDER)
Cap calibrated at 0.9 bar
Sealing pressure
THERMOSTAT
Specification
Type
Starts opening
Desc./Quantity
Wax-type, with deviator
82 ± 2°C
ELECTRIC VENTILATION
Specification
Type
Electric ventilation start
Electric ventilation end
Desc./Quantity
With piston
107°C
103°C
WATER PUMP
Specification
Type
Control
Desc./Quantity
Centrifugal
Coaxial at the countershaft
RADIATOR
Specification
Type
Desc./Quantity
Aluminium, with horizontal circulation
EXPANSION TANK
Specification
Calibration
Desc./Quantity
Automatic bleeding, in parallel with the radiator
Electric fan check
- Connect the injection diagnostic tester and select
the menu on the "ERRORS" function.
- Check any failures in the electric fan control circuit (see "Injection" chapter)
Specific tooling
020460Y Scooter diagnosis and tester
COOL SYS - 3
Cooling system
Nexus 500 euro 3
- Select the menu on the "ACTIVE DIAGNOSIS"
function and start the electric fan operation simulation (see "Injection" chapter).
- If the electric fan is certainly efficient, check the
ventilation start and end temperature.
- Select the "PARAMETERS" function in the menu
to display the coolant temperature.
Electric fan starts: 107°C
Electric fan stops: 103°C
- If non-conforming values are detected, replace
the injection control unit (see «Injection» chapter).
- If the analogue instrument temperature is close
to the red zone, but the degrees indicated by the
diagnostic tester are below the electric fan start
temperature, check the temperature sensor on the
head and the relevant injection circuit (see «Injection» chapter);
N.B.
THE ELECTRIC FAN TEMPERATURE AT 107° C CAN ONLY BE MANAGED BY A SYSTEM SUPPLIED WITH A 50% MIXTURE AND PRESSURISED AT 0.9 BAR.
AVOID STARTING THE ENGINE WITHOUT PRESSURISATION SINCE IT MAY REACH THE BOILING TEMPERATURE BEFORE THE ELECTRIC FAN STARTS WORKING.
IN CASE OF AN INCREASE OF THE ELECTRIC FAN START TIME, CHECK THE THERMOSTAT
OPENING TEMPERATURE AND CHECK THAT THE COOLANT DENSITY IS CORRECT. THE OPTIMUM DENSITY IS OBTAINED WITH A 50% WATER AND 50% COOLING CIRCUIT FLUID
MIXTURE.
System sealing check
- Check the proper circuit sealing when it is in
pressure and at the temperature.
- For a more accurate check, wait until the system
has cooled down since small leaks may not be
visible due to evaporation
- The water pump is provided with a drainage hole
in case of leaks from the cooling system mechanical seal, or from the shaft sealing oil guard.
- If coolant or oil leaks are detected, inspect the pump (see Flywheel cover chapter).
COOL SYS - 4
Nexus 500 euro 3
Cooling system
N.B.
DO NOT USE OILS OR GREASES WHILE MOUNTING THE COOLING SYSTEM. FAILURE TO OBSERVE THIS REGULATION CAN CAUSE IRREVERSIBLE DEFORMATION TO THE SEALING
GASKETS.
Coolant replacement
System top-up rules
- Prepare the mixture of 50% water and coolant.
- Fill the system to reach a level ranging between
the MIX and MAX levels indicated in the expansion
tank filler.
- Do not close the expansion tank with the cap.
- Use a transparent hose to connect the venting
union with the expansion tank filler.
- Loosen the vent and start the engine.
- Keep it open until the air has been fully vented.
- Close the bleed screw.
- Stop the engine.
- Restore the level into the expansion tank and tighten the cap.
- Start the engine and let it warm up to reach the electric ventilation temperature.
- Stop the engine.
- Restore the level with cold engine.
CAUTION
ELECTRIC VENTILATION IS CONTROLLED BY THE TEMPERATURE MEASURED AT THE HEAD.
THE ELECTRIC VENTILATION START DOES NOT MEAN THAT THE VENTING HAS BEEN COMPLETED.
VENTING IS COMPLETE WHEN THE EXPANSION TANK TEMPERATURE RISES.
Water pump - overhaul
- Carefully position a new O-Ring, avoiding contact with grease or oil.
CAUTION
FAILURE TO OBSERVE THIS ADVICE CAN IRRETRIEVABLY DEFORM THE O-RING.
COOL SYS - 5
Cooling system
Nexus 500 euro 3
- Refit the water pump cover, tightening the 6 fixing
screws to the prescribed torque.
Locking torques (N*m)
Water pump cover screws 3 ÷ 4
Water pump ceramic seal
Our Leader, Quasar, and Master liquid cooled engines are equipped with water pumps fitted with the
ceramic seal in the subject. This component is intended to guarantee the leak tightness of the coolant
in relation to the pump shaft. The seal achieved via two special ceramics, a static one and a spinning
one, kept in contact by the thrust of a spring, coaxially mounted onto the pump shaft. The efficiency of
this system is guaranteed by the accurate machining and cleaning of the components as they are fitted;
in any case, ceramic seals are subjected to a running in period. During this period (1,000 ± 1,500 km),
there may be small leaks through draining holes, which remain visible on the aluminium crankcase.
This phenomenon is particularly visible there where the hole is more exposed (Quasar and Master). In
such cases we recommend cleaning the casing in order to be able to check again for leaks after a
distance of more than 1500 km. If leaks continue or in the event of real losses, the ceramic seal should
be replaced. For these operations, observe the tools and instructions given in the relevant service
station manuals.
Note: The ceramic seal may be overhauled according to the following couplings:
•
Coupling "A": seal ring no. 485084 with ceramic seal no. 486216
•
Coupling "B": seal ring no. 841329 with ceramic seal no. 841330
The couplings above may be selected according to their availability, as they are interchangeable.
- Check that the reed valve of blow-by circuit
closes adequately.
COOL SYS - 6
Nexus 500 euro 3
Cooling system
- Check that the water pump cover is not damaged
or deformed.
- Check that the sealing O-Ring is in good condition
- Check that the rotor does not show deformations
or dents.
- Check that the plastic rotor forms an integral unit
with the metal part.
- Check that the water pump shaft does not show
signs of wear and tear on the bearings in contact
with the crankcase, in the oil seal area and on the
motion sensor.
- Check that the ceramic seal surfaces are not
scratched or worn.
- Check that there are no damages or dents on the outside diameter of the bypass.
Characteristic
Outside diameter:
10.5 mm
COOL SYS - 7
Cooling system
- Check the free length of the spring.
Characteristic
Standard length:
65.2 mm
Length limit after use:
64.0 mm
Thermostat
Check
Before proceeding to disassembly, carry out a few
checks:
- Connect the diagnostic tester and select the «PARAMETERS» function (see Injection Chapter);
- Start the cold engine and let it warm up.
- Manually check when there is an abrupt increase
in temperature at the exit of the radiator cold housing.
N.B.
THERE SHOULD BE A SLIGHT AND GRADUAL
HEATING CAUSED BY A SMALL PASSAGE ON
THE THERMOSTAT TO THE OFF POSITION.
Specific tooling
020460Y Scooter diagnosis and tester
- Check the temperature read by the diagnostic
tester.
Thermostat opening start: ~ 80°C
- If opening occurs at different temperatures,
check the thermostat.
- Remove the thermostat as described in the flywheel cover paragraph.
COOL SYS - 8
Nexus 500 euro 3
Nexus 500 euro 3
Cooling system
- Visually check that the thermostat does not have
mechanical failures.
- Prepare a metal container with ~ 1 litre of water.
- Immerse the thermostat, and keep it in the middle
of the container.
- Immerse the multimeter thermometer probe
close to the thermostat.
- Warm up the container using the thermal gun.
- Heat the water and periodically pull the thermostat out until its opening becomes visible.
- Insert a thin copper wire between the seat and the thermostat closing plate.
- Keep the wire into position until locking up is perceived.
- Let water and thermostat cool down.
- Progressively heat the water keeping the thermostat immersed by the wire.
- Check the opening temperature when the thermostat releases from the wire.
Opening starting temperature ~ 82° C
Specific tooling
020331Y Digital multimeter
020151Y Air heater
- Warm up until the thermostat is completely open.
N.B.
HEATING SHOULD BE GRADUAL.
N.B.
AVOID CONTACT BETWEEN THERMOSTAT AND CONTAINER FOR A CORRECT TEST PERFORMANCE.
- If incorrect values are detected, replace the thermostat.
- Repeat the filling and venting procedure.
diagnosis
Excessive system pressure
1 - Check the expansion tank cap efficiency.
N.B.
THE CAP IS EQUIPPED WITH A PRESSURE RELIEF VALVE CALIBRATED AT 0.9 BAR.
COOL SYS - 9
Cooling system
Nexus 500 euro 3
There is also a valve that must allow air inlet during the cooling step.
YES go to 2 NO go to 3
2 - Check the head gasket seal (see «Thermal group and timing system» chapter)
3 - Replace the cap.
Cooling fluid consumption
1 - Check the system outside seals as described above.
YES go to 2 NO go to 3
2 - Check the head gasket seal (see «Thermal unit and timing system» chapter)
- If water leaks are detected in the engine oil, inspect the pad on the head cooling circuit.
3 - Fix any damaged seals.
Oil in the fluid
1 - Oil into the coolant.
YES go to 2
2 - Check the head gasket seal (see «Thermal group and timing system» chapter)
COOL SYS - 10
INDEX OF TOPICS
CHASSIS
CHAS
Chassis
Nexus 500 euro 3
This section is devoted to the operations that can be carried out on the vehicle's bodywork.
CAUTION
NEVER CLEAN PAINTED PLASTIC PARTS WITH SOLVENTS CONTAINING PETROL OR ITS BYPRODUCTS.
Seat
- Remove the two clamping screws on the frame.
- Remove the control button of the undersaddle
light.
Rear handlebar cover
- Release the 3 locking tabs of the rear handlebar
cover shown in the figure using a screwdriver and
paying attention not to damage the paintwork.
- Remove the 5 mounting screws of the rear handlebar cover.
N.B.
WHEN INSTALLING, THE CENTRE SCREW IS
A METAL SCREW, THE OTHER 4 ARE PLASTIC.
CHAS - 2
Nexus 500 euro 3
Chassis
- Remove the frames of the brake pump on the left
and right secured with 2 locking tabs.
- Loosen the 4 retaining screws of the front handlebar cover with the handlebar proper.
Remove the 4 pressure indicator lights from the warning light group, pulling them downwards.
Instrument panel
- Remove the upper shield back plate.
- Loosen the 5 nuts of 10 mm holding the instrument panel.
CHAS - 3
Chassis
Headlight assy.
- Remove the centre cover of the shield.
- Remove the 4 front retainers of the front light assemblies.
- To remove the right-hand light assembly, remove
the screw located near the cover of the expansion
tank.
- To remove the left-hand light assembly, remove
the screw located in the left-hand storage compartment.
Remove the light, disconnecting the electric connector from the light and the complete lamp holder
of the position light.
N.B.
THE TWO REAR ADJUSTMENT SCREWS
SHOWN IN THE FIGURE ARE ADJUSTED DURING ASSEMBLY OF THE LIGHT AND MUST
NOT BE ALTERED.
CHAS - 4
Nexus 500 euro 3
Nexus 500 euro 3
Chassis
Frame central cover
- Remove the saddle.
- Remove the two screws in the battery compartment shown in the figure.
- Remove the fuel tank flap.
- Remove the 5 screws indicated in the figure.
CAUTION
PROVISIONALLY PROTECT THE NECK OF
THE FUEL TANK USING A CLEAN CLOTH TO
PREVENT ANY DIRT OR OBJECTS ACCIDENTALLY FALLING INTO THE TANK.
- Remove the lateral air conveyors and loosen the
two screws shown in the figure.
- Remove the cover, unscrewing it from its retainers.
- Remove the two screws indicated in the figure.
CHAS - 5
Chassis
Nexus 500 euro 3
- Remove the seven screws indicated in the figure.
- Remove the central cover from its retainers.
Legshield
- Remove the windscreen complete with support.
- Remove the front light assembly.
- Remove the upper shield back plate.
- Remove the lower shield back plate.
- Remove the front deflectors.
- Remove the 2 screws located under the front deflectors.
- Remove the centre screw (without slotted head)
located behind the front light.
- Remove the 4 screws (2 per side) accessible
from the footrest and located to the sides of the
radiator.
- Remove the front shield, disconnecting the wiring and the connectors of the headlights and lights.
- Remove the Gilera emblem.
- Remove the screw shown in the figure.
CHAS - 6
Nexus 500 euro 3
Chassis
- Paying attention not to damage the plastic parts,
release the 3 upper retainers of the windshield
support and the 4 side retainers of the front shield.
Knee-guard
- Remove the centre union.
- Remove the 4 lateral screws (2 on each side) indicated in the figure.
- Press the shield back plate forward to allow access to the socket on the frame of the key switch.
- Turn the frame in anticlockwise direction (it may
be necessary to use pliers), disengaging the locking teeth shown in the figure.
- Remove the front fuse holder, levering out using a flat screwdriver on the tab located on the side (on
the side of the key switch).
CHAS - 7
Chassis
Nexus 500 euro 3
- Remove the 2 screws located inside the storage
compartment and the coolant top-up compartment
(in order not to have to remove the front headlight).
- Unscrew the 4 screws indicated in the figure.
- Loosen the two upper screws on the front of the
scooter holding the plate.
- Remove the handlebar retaining bolt, unscrewing upwards and pushing towards the lower shield back
plate.
- Remove the cap of the expansion tank and the rubber gasket using a screwdriver or pliers.
- Disconnect the complete upper shield back plate from the lower section paying particular attention to
the tab located under the glove-box (left-hand side).
Once raised, remove the 3 connectors of the instrument panel and the connector on the wiring of the
instrument lighting.
CHAS - 8
Nexus 500 euro 3
Chassis
Removing the ignition key-switch when on *off*
- Remove the lower shield back plate.
- Unscrew the seat opening transmission from the
side.
- Remove in advance the ring of the immobiliser
antenna.
- Loosen the 2 hex. socket head screws and remove the complete switch.
- From the underside it is possible to loosen the 3
retaining screws and to release the 2 locking tabs
to raise the mounting plate of the steering lock
strut.
- The latter has a retaining tab with cylindrical teeth
that cannot be replaced.
Front wheel housing
- Remove the spoiler.
- Remove the front fork.
- Remove the plate supporting bracket for the horn
and voltage regulator by loosening the two retaining screws shown in the figure in order to release
the two lower retainer of the wheel housing.
- Remove the upper fixing screw of the wheel
housing to permit movement.
CHAS - 9
Chassis
Nexus 500 euro 3
- In order to remove the wheel housing it is necessary to remove the front brake hose to the tank and
combination with the splitter.
Taillight assy.
- Remove the side fairings.
- Remove the upper central screw.
- Using a wrench offset by 10 mm between the under-saddle compartment and the tubes of the frame,
loosen the 2 rear retaining bolts and then disconnect the retainers of the lights at the ends of the support.
- Remove the light and disconnect the bulb holder by turning it through 30° in anticlockwise direction.
Footrest
- Remove the centre union.
- Remove the side fairings.
- Remove the mat of the footrest.
- Remove the screws indicated in the figure.
CHAS - 10
Nexus 500 euro 3
Chassis
- Remove the complete footrest from the side fairing.
- Remove the screw shown in the figure to remove
the front footrest.
Side fairings
- Remove the rear central cover.
- Remove the passenger handles.
- Remove the lower cover.
CHAS - 11
Chassis
- Remove the lower side cover.
- Remove the eight screws shown in the figure
(four on each side).
- Pull out the fairing.
- Remove the three screws indicated in the figure.
CHAS - 12
Nexus 500 euro 3
Nexus 500 euro 3
Chassis
- Remove the 2 hex. socket head screws and then
the passenger handgrips on the left and right.
License plate holder
- Remove the lower cover.
- Remove the four retaining screws (2 per side)
and disconnect the electrical connectors.
- In order to access the licence plate bulb it is sufficient to remove the two retaining screws of the
rear cover from the support and to pull out the
complete bulb holder.
Air filter
- Remove the helmet compartment.
- Remove the straps of the oil vapour recovery
hose and the air bellows shown in the figure.
CHAS - 13
Chassis
- Loosen the two screws shown in the figure.
- Loosen the two retainers shown in the figure and
remove the complete air filter.
- Remove the general fuse.
- Disconnect the battery housing from its metallic
support and remove the complete filter housing.
Electric characteristic
Fuse
30A
Rear mudguard
- Remove the two clamps shown in the figure.
CHAS - 14
Nexus 500 euro 3
Nexus 500 euro 3
Chassis
- Remove the retainer of the mudguard/strut reinforcement plate to remove the complete mudguard.
Helmet bay
- Remove the side panels
- Remove the six upper clamping screws.
- Remove the 2 lateral retaining screws with the
central covers.
- Remove the 3 screws located inside the compartment in the rear part providing the mounting
for the electrical system of the saddle opening device and for the support of the transmission.
- Disconnect the connectors of the power socket and the under-saddle light.
- Remove in turn the complete power socket due to the interference with the frame.
- Remove the fuse holder assembly, disconnecting the lateral retaining tab.
CHAS - 15
Chassis
Nexus 500 euro 3
- Remove the complete underseat compartment.
Fuel tank
Fuel tank flap
- Open the fuel tank flap.
- Remove the hex. socket head screw shown in the
figure.
- Remove the 3 hex. socket head screws shown in
the figure.
N.B.
THE OTHER 3 SCREWS HAVE ONLY AN AESTHETIC FUNCTION
Remove the flap, the gasket, the second flap and the second gasket.
Fuel tank filler neck
- Remove the fuel tank flap.
- Remove the central chassis cover.
- Remove the 2 retaining straps of the filler neck to
the tank.
- Remove the 2 upper hoses (the left-hand hose
and the "too short" hose; the hose on the right is
the tank breather).
N.B.
THIS OPERATION SHOULD PREFERABLY BE PERFORMED WITH THE TANK EMPTY.
CHAS - 16
Nexus 500 euro 3
Chassis
- Remove the central chassis cover.
- Remove the lower cover.
- Remove the fuel tank cap.
- Remove the two upper tank retainers shown in
the figure.
- Remove the fuel pump retainers.
N.B.
PAY PARTICULAR ATTENTION WHEN UNSCREWING THE FUEL PIPES AS EXCESSIVE FORCE
COULD DAMAGE THE PLASTIC INSERTS ON THE PUMP BODY. IT IS NECESSARY, HOWEVER,
DURING REMOVAL TO PRESS LIGHTLY ONTO THE LINES AND TO PUSH THE CROWN TOWARDS THE PUMP, AND THEN TO MAINTAIN PRESSURE ON THE CROWN AND TO PULL THE
LINES UPWARDS.
- Remove the plate supporting bracket for the horn
and voltage regulator by loosening the two retaining screws shown in the figure in order to release
the two lower retainers of the wheel housing.
- Remove the tank through the front lower part of the scooter.
- For reassembly, perform the previous operations in the reverse order.
Rear central cover
- Raise the saddle.
- Remove the two fixing screws shown in the figure.
CHAS - 17
Chassis
Front mudguard
- Remove the 4 retaining screws and pull the mudguard towards the front of the scooter.
- Pay attention during assembly to the correct positioning of the retaining straps of the hoses.
Radiator fan
- Remove the spoiler.
- Remove the front fork.
- Remove the plate supporting bracket for the horn
and voltage regulator by loosening the two fixing
screws shown in the figure in order to release the
two lower retainers of the wheel housing.
- Remove the upper fixing screw of the wheel
housing to permit movement.
- Prepare a container to collect the coolant.
- Remove the feed and return hoses from the expansion tank.
- Remove the coolant feed and return hoses from
the radiator.
- Remove the retaining screws of the radiator to
the frame shown in the figure.
- Disengage the complete radiator and the electric
fan.
CHAS - 18
Nexus 500 euro 3
Nexus 500 euro 3
Chassis
Flyscreen
- Remove the 3 hex. socket head screws (when
reassembling, pay attention to insert the longest
screw in the middle position) then remove the
windshield complete from the rubber lips.
- Remove the plugs and remove the seals on the
2 lateral windshield support arms.
- Remove the plastic cover from the windshield
support, loosening the 5 screws shown in the figure.
- Disengage the 7 retaining tabs (3 with the shield
back plate, 4 with the shield).
Once the 4 lateral tabs have been released it is
sufficient to separate the upper part from the lower
part and to pull it carefully upwards.
CHAS - 19
Chassis
Pilot lights kit
- Remove the handlebar cover.
- Remove the three screws shown in the figure,
then pull the complete group from the front handlebar cover.
Battery
- Remove the elastic strap and the battery cover.
Lower cover
- Remove the two screws of the lower spoiler (long
type).
- Remove the 2 screws located under the footrests.
CHAS - 20
Nexus 500 euro 3
Nexus 500 euro 3
Chassis
- Remove the 4 union screws with the front wheel
housing cover.
- Pull the spoiler from the lower part of the scooter.
CHAS - 21
Chassis
CHAS - 22
Nexus 500 euro 3
INDEX OF TOPICS
PRE-DELIVERY
PRE DE
Nexus 500 euro 3
Pre-delivery
Carry out the listed tests before delivering the scooter.
WARNING
BE VERY CAREFUL WHEN HANDLING FUEL.
Aesthetic inspection
Appearance check:
- Paintwork
- Fitting of plastics
- Scratches
- Dirt
Tightening torques inspection
Lock check
- Safety locks
SAFETY LOCKS:
Name
Rear shock absorber retainer to the chassis
Front wheel shaft
Rear wheel axle
Rear brake disc mounting
Engine - chassis fixing pin
Screw securing handlebar to steering tube
Upper steering ring nut
Lower steering ring nut
Torque in Nm
38 - 46
45 ÷ 50
104 ÷ 126
11 ÷ 13
100 - 120
45 - 50
36 - 39
10 - 13 **
** tighten and loosen by 90°
- Cover retaining screws
Electrical system
Electric System:
- Main switch
- Headlamps: high beams, low beams, side/taillights (front and rear) and relevant warning lights
- Adjusting the headlights according to the regulations currently in force
- Front and rear brake light buttons and relevant bulb - Turn indicators and relevant bulbs
- Instrument lighting
- Instrument panel: fuel and temperature indicator
- Instrument panel warning lights
- Horn
- Electric start-up
- Engine stop by emergency stop switch and side stand
- Saddle electric opening button
PRE DE - 2
Nexus 500 euro 3
Pre-delivery
CAUTION
TO ENSURE MAXIMUM PERFORMANCE, THE BATTERY MUST BE CHARGED BEFORE USE.
INADEQUATE CHARGING OF THE BATTERY WITH A LOW LEVEL OF ELECTROLYTE BEFORE
IT IS FIRST USED SHORTENS THE LIFE OF THE BATTERY.
CAUTION
WHEN INSTALLING THE BATTERY, CONNECT THE POSITIVE CABLE BEFORE CONNECTING
THE NEGATIVE ONE, AND PERFORM THE REVERSE OPERATION UPON REMOVAL.
WARNING
BATTERY ELECTROLYTE IS TOXIC AND IT MAY CAUSE SERIOUS BURNS. IT CONTAINS SULPHURIC ACID. AVOID CONTACT WITH EYES, SKIN AND CLOTHING.
IN CASE OF CONTACT WITH EYES OR SKIN, RINSE WITH ABUNDANT WATER FOR ABOUT 15
MINUTES AND SEEK MEDICAL ATTENTION AT ONCE.
IF IT IS SWALLOWED, IMMEDIATELY DRINK LARGE QUANTITIES OF WATER OR VEGETABLE
OIL. SEEK IMMEDIATE MEDICAL ATTENTION.
THE BATTERIES PRODUCE EXPLOSIVE GAS; KEEP THEM AWAY FROM NAKED FLAMES,
SPARKS AND CIGARETTES. IF THE BATTERY IS CHARGED IN A CLOSED PLACE, TAKE CARE
TO ENSURE ADEQUATE VENTILATION. ALWAYS PROTECT YOUR EYES WHEN WORKING
CLOSE TO BATTERIES.
KEEP OUT OF THE REACH OF CHILDREN
CAUTION
NEVER USE FUSES WITH A CAPACITY HIGHER THAN THE RECOMMENDED CAPACITY. USING
A FUSE OF UNSUITABLE RATING MAY SERIOUSLY DAMAGE THE VEHICLE OR EVEN CAUSE
A FIRE.
Levels check
Level check:
- Hydraulic brake system liquid level.
- Rear hub oil level
- Engine coolant level
- Engine oil level
Road test
Test ride
- Cold start
- Instrument operations
- Response to the throttle control
- Stability on acceleration and braking
- Rear and front brake efficiency
- Rear and front suspension efficiency
- Abnormal noise
Static test
Static test after test ride:
- Restarting when warmed up
PRE DE - 3
Pre-delivery
Nexus 500 euro 3
- Starter operation
- Minimum hold (turning the handlebar)
- Uniform turning of the steering
- Possible leaks
- Operation of the radiator electric fan
Functional inspection
Operating test:
- Hydraulic brake system
- Lever travel
- Clutch - Check for correct operation
- Engine - Check for correct general operation and make sure there is no unusual noise
- Other
- Check documents:
Check chassis No. and engine No.
- Check tool kit
- License plate assembly
- Check locks
- Check tyre pressures
- Installation of mirrors and any accessories
CAUTION
NEVER EXCEED THE RECOMMENDED INFLATION PRESSURES OR TYRES MAY BURST.
CAUTION
CHECK AND ADJUST TYRE PRESSURE WITH TYRES AT AMBIENT TEMPERATURE.
PRE DE - 4
INDEX OF TOPICS
TIME
TIME
Nexus 500 euro 3
Time
This section is devoted to the time necessary to carry out repairs.
For each operation, the description, code and time envisages are specified.
Engine
ENGINE
1
TIME - 2
Code
001001
Action
Engine to chassis - Replacement
Duration
Nexus 500 euro 3
Time
Crankcase
CRANKCASE
1
Code
001100
2
001133
3
001153
Action
Oil seal, clutch side - Replacement
Engine crankcase- Replacement
Crankcase half gasket - Replacement
Duration
TIME - 3
Nexus 500 euro 3
Time
Crankshaft
CRANKSHAFT
1
2
TIME - 4
Code
001117
001098
Action
Crankshaft - Replacement
Countershaft - Replacement
Duration
Nexus 500 euro 3
Time
Cylinder assy.
CYLINDER GROUP
1
Code
001002
2
001154
3
001129
Action
Cylinder piston - Replacement
Pin-ring-piston assembly Service
Chain tensioner - Service and
Replacement
Duration
TIME - 5
Nexus 500 euro 3
Time
Cylinder head assy.
HEAD UNIT
1
2
3
4
5
6
Code
001045
001049
001056
001126
001083
005116
7
007012
TIME - 6
Action
Valves - Replacement
Valves - Adjustments
Head gasket - Replacement
Head - Replacement
Thermistor - Replacement
revolution timing sensor - Replacement
Coolant bleed valve - Replacement
Duration
Nexus 500 euro 3
Time
Rocker arms support assy.
ROCKING LEVER SUPPORT UNIT
1
2
Code
001044
001148
Action
Camshaft - Replacement
Rocking lever valve - Replacement
Duration
TIME - 7
Nexus 500 euro 3
Time
Cylinder head cover
HEAD COVER
1
2
3
TIME - 8
Code
001089
001093
001088
Action
Head cover - Replacement
Spark plug - Replacement
Head cover gasket - Replacement
Duration
Nexus 500 euro 3
Time
Flywheel cover
FLYWHEEL COVER
1
2
3
4
5
6
Code
001087
001113
001123
001124
001057
001062
7
001150
8
001160
9
007011
Action
Flywheel cover - replace
Water pump - Replacement
Oil filter -Replacement
By-pass valve - Replacement
Thermostat - Replacement
Water pump command shaft Replacement
Flywheel cover gasket - Replacement
Minimum oil pressure sensor
- Replacement
By-pass manifold - thermostat - drain valve - Replacement
Duration
TIME - 9
Nexus 500 euro 3
Time
Driven pulley
DRIVEN PULLEY
1
2
3
4
TIME - 10
Code
001022
001012
001110
001155
Action
Clutch - Replacement
Driven pulley - Overhaul
Driven pulley - Replacement
Clutch bell housing - Replacement
Duration
Nexus 500 euro 3
Time
Oil pump
OIL PUMP
1
2
Code
001042
001051
3
4
5
001112
001125
001071
6
7
001020
001102
8
003064
Action
Oil pump - overhaul
Belt/ Timing chain - Replacement
Oil pump - change
Chain guide pads - change
Start-up pinion - Replacement
Starter motor - Replacement
Net oil filter - Replacement /
Cleaning
Engine oil - change
Duration
TIME - 11
Nexus 500 euro 3
Time
Final gear assy.
FINAL REDUCTION GEAR ASSEMBLY
1
Code
001010
2
001156
3
4
003065
004125
TIME - 12
Action
Geared reduction unit - Service
Gear reduction unit cover Replacement
Gear box oil - Replacement
Rear gear shaft - Replacement
Duration
Nexus 500 euro 3
Time
Driving pulley
DRIVING PULLEY
1
Code
001086
2
3
4
001011
001006
001141
5
001066
Action
Driving half-pulley - Replacement
Driving belt - Replacement
Driving pulley - Service
Belt anti-flapping roller - Replacement
driving pulley - Replacement
Duration
TIME - 13
Nexus 500 euro 3
Time
Transmission cover
TRANSMISSION COVER
1
Code
001065
2
001096
3
001131
4
001135
5
001170
TIME - 14
Action
Internal transmission cover Replacement
External transmission cover Replacement
Transmission air intake - Replacement
Transmission cover bearing Replacement
Air manifold - replacement
Duration
Nexus 500 euro 3
Time
Flywheel magneto
MAGNETO FLYWHEEL
1
2
3
4
Code
001173
001067
001058
001104
5
001151
Action
Rotor - replace
Stator - Replacement
Flywheel - Replacement
Start-up freewheel - Replacement
Start-up driven gearing - Replacement
Duration
TIME - 15
Nexus 500 euro 3
Time
Butterfly valve
THROTTLE BODY
1
2
3
4
Code
001013
001047
001166
004122
5
001171
TIME - 16
Action
Intake manifold - change
Injector - Replacement
Throttle body - Replacement
Cleaner / Throttle body union
- Replacement
Throttle body - Service/cleaning
Duration
Nexus 500 euro 3
Time
Exhaust pipe
MUFFLER
1
2
Code
001009
001092
3
4
5
001095
004169
005138
Action
Muffler - Replacement
Exhaust manifold - Replacement
Muffler guard - Replacement
Muffler guard - Replacement
Lambda probe - Replacement
Duration
TIME - 17
Nexus 500 euro 3
Time
Air cleaner
AIR CLEANER
1
2
Code
001015
001014
3
001074
TIME - 18
Action
Air filter box - change
Air filter - Replacement/
Cleaning
Oil vapour recovery pipe - Replacement
Duration
Nexus 500 euro 3
Time
Frame
FRAME
1
2
3
Code
004001
004146
001032
Action
Frame - replace
Front frame - Replacement
Engine support pin - Replacement
Duration
TIME - 19
Nexus 500 euro 3
Time
Centre-stand
SIDE/CENTRAL STAND
1
2
3
Code
004004
004102
005079
4
004171
TIME - 20
Action
Stand - Replacement
Side stand - Replacement
Side stand switch - Replacement
Stand support plate - Replacement
Duration
Nexus 500 euro 3
Time
Legshield spoiler
FRONT SHIELD - SPOILER
1
Code
004066
2
005091
3
005067
4
5
004064
004149
6
004065
7
005080
Action
Rear-view mirror - Replacement
Turn indicator glass - Replacement
Front direction indicator bulb
- Replacement
Front shield - Replacement
Shield central cover - Replacement
Shield back plate - Replacement
Front fuse-holder - Replacement
Duration
TIME - 21
Nexus 500 euro 3
Time
Central cover
CENTRAL FRAME COVER
1
Code
004011
2
004104
3
004105
4
5
004079
004143
TIME - 22
Action
Central chassis cover - Replacement
Left side cover - Replacement
Right side cover - Replacement
Rear footrest - Replacement
Footrest support - replace
Duration
Nexus 500 euro 3
Time
Mudguard
MUDGUARDS
1
2
Code
004167
004009
3
4
004002
003087
Action
Grill / radiator cover - replace
Rear mudguard - Replacement
Front mudguard - change
Wheel housing - Replacement
Duration
TIME - 23
Nexus 500 euro 3
Time
Fuel tank
FUEL TANK
1
2
Code
004005
004170
3
4
004168
004109
TIME - 24
Action
Fuel tank - replace
Tank filler neck - Replacement
Fuel filler flap - Replacement
Fuel tank breather - replace
Duration
Nexus 500 euro 3
Time
Handlebar covers
HANDLEBAR COVERS
1
Code
004018
2
004019
3
005129
4
004156
5
005038
Action
Handlebar front section - Replacement
Handlebar rear section - Replacement
Warning light group - Replacement
Glove-box flap - Replacement
Instrument panel warning
light bulbs - Replacement
Duration
TIME - 25
Nexus 500 euro 3
Time
Handlebar components
HANDLEBAR COMPONENTS
1
2
3
Code
003001
005017
002037
4
002060
5
002059
6
003059
7
002063
8
003061
9
10
11
002024
002071
002088
TIME - 26
Action
Handlebar - Replacement
Stop switch - Replacement
Brake or clutch lever - Replacement
Complete gas command Replacement
Right hand grip - Replacement
Counterweight - Replacement
Throttle control transmission
- Replacement
Accelerator transmission Adjustment
Front brake pump - replace
Left hand grip - Replacement
Integral brake pump - Replacement
Duration
Nexus 500 euro 3
Time
Seat
SADDLE
1
2
Code
004003
004150
Action
Saddle - Replacement
Saddle shock absorber - Replacement
Duration
TIME - 27
Nexus 500 euro 3
Time
Locks
LOCKS
1
2
Code
004010
005099
3
002083
4
002092
5
004054
6
005072
7
005126
TIME - 28
Action
Antitheft lock - Replacement
Electric saddle opening device - Replacement
Saddle opening transmission
- Replacement
Seat locking transmission replacement
Saddle lock catch - Replacement
Immobilizer antenna - replacement
Saddle opener receiver - replacement
Duration
Nexus 500 euro 3
Time
Turn signal lights
REAR LIGHTS
1
2
Code
005005
005022
3
005068
4
005091
5
005031
6
004136
7
005030
8
005048
9
005032
10
005028
11
005066
Action
Taillight - change
Rear turn indicators - Replacement
Rear turn indicator bulb- Replacement
Turn indicator glass - Replacement
Licence plate light bulb - Replacement
License plate holder support Replacement
Rear headlight cable unitReplacement
Licence plate holder - Replacement
Transparent licence plate
cover - replace
Rear light assembly glass Replacement
Rear light bulbs - Replacement
Duration
TIME - 29
Nexus 500 euro 3
Time
FRONT LIGHTS
1
2
Code
005002
005008
3
005044
TIME - 30
Action
Front headlamp - replace
Front headlamp bulbs - replace
Front lights cable unit - replace
Duration
Nexus 500 euro 3
Time
Front wheel
FRONT WHEEL
1
2
Code
005089
002041
3
003037
4
003038
5
003040
6
7
8
003047
003063
004123
Action
Tone wheel - Replacement
Front brake disc - Replacement
Front wheel rim- Replacement
Front wheel axle - Replacement
Front wheel bearings - Replacement
Front tyre - replace
Tyre pressure - check
Front wheel - Replacement
Duration
Grease tone wheel or drive
Please take note that the code has been introduced:
900001 - Tone wheel / drive greasing - 15'.
Never mistake the codes 002011 (movement sensor replacement) and 005089 (tone wheel replacement) in the event of noise of the indicated
components. The grease recommended is TUTE-
TIME - 31
Nexus 500 euro 3
Time
LA MRM 2 (soap-based lithium grease with Molybdenum disulphide).
In the following points we indicate with an arrow
the area to be greased (1 - Drive, 2 - Tone wheel)
Rear wheel
REAR WHEEL
1
2
3
Code
001016
001017
002070
4
5
003063
003077
6
004126
7
002028
8
004052
TIME - 32
Action
Rear wheel - Replacement
Rear wheel rim - replace
Rear brake disc - Replacement
Tyre pressure - Check
Muffler / rear shock absorber
support arm - Service
Rear wheel tyre - Replacement
Rear wheel hub - Replacement
Bumper - Replacement
Duration
Nexus 500 euro 3
Time
Fuel pump
FUEL PUMP
1
2
Code
004073
004137
Action
Fuel pump - Replacement
Injector pump pipe - Replacement
Duration
TIME - 33
Nexus 500 euro 3
Time
Electric devices
HANDLEBAR ELECTRICAL COMPONENTS
1
Code
004035
2
005014
3
005083
4
003074
5
003075
6
005082
TIME - 34
Action
Instrument panel - Replacement
Odometer assembly - replacement
Board computer - replacement
Handlebar right control - Replacement
Handlebar left control - Replacement
Instrument unit wiring - replacement
Duration
Nexus 500 euro 3
Time
ELECTRIC DEVICES
1
Code
005127
2
3
4
5
001069
005007
005046
005073
6
005011
7
8
005128
001094
9
005024
Action
Overturn sensor - replacement
H.V. coil - Replacement
Battery - change
Battery cover - change
Immobilizer decoder - Replacement
Start-up remote control
switch - Replacement
Diode group - replacement
Spark plug cap - Replacement
Main fuse - replacement
Duration
TIME - 35
Nexus 500 euro 3
Time
ELECTRIC DEVICES
1
Code
001023
2
005009
3
005117
4
005088
5
005096
6
005003
TIME - 36
Action
Injection control unit - Replacement
Voltage regulator - Replacement
Electrical fan remote control Replacement
Emergency stop remote control - Replacement
Injection components remote
control - Replacement
Horn - Replacement
Duration
Nexus 500 euro 3
Time
ELECTRIC DEVICES
1
Code
005001
2
3
4
5
005054
005052
005114
005130
Action
Electrical system - Replacement
Fuse holder - Replacement
Fuse (1) - Replacement
Electrical system - Service
Electric control management
device - Replacement
Duration
TIME - 37
Nexus 500 euro 3
Time
Helmet bay
HELMET COMPARTMENT
1
Code
004016
2
005033
3
005026
4
5
004142
005027
TIME - 38
Action
Helmet compartment - replace
Glove-box light switch - Replacement
Helmet compartment light Replacement
Plug socket - Replacement
Helmet compartment bulb
support - Replacement
Duration
Nexus 500 euro 3
Time
Rear side fairings
REAR COVERS
1
2
3
Code
004053
004085
004068
4
004159
5
004036
6
004012
7
8
9
004075
004015
004056
Action
Spoiler - Replacement
Rear fairing - Replacement
Passenger handgrip - Replacement
Plates / Stickers - Replacement
Lower chassis cover - Replacement
Rear side panels (2) - Replacement
Mat - Replacement
Footrest - Replacement
Upper rear light cover - Replacement
Duration
TIME - 39
Nexus 500 euro 3
Time
Front suspension
FRONT SUSPENSION
1
2
3
4
5
6
7
8
TIME - 40
Code
003051
003010
003076
003079
003048
003073
003002
004119
Action
Complete fork - replace
Front suspension - service
Fork housing - replacement
Fork stem - Replacement
Fork oil seal - Replacement
Steering clearance - Adjust
Steering fifth wheels - change
Upper steering bearing - replacement
Duration
Nexus 500 euro 3
Time
Rear suspension
REAR SUSPENSION
1
Code
003085
2
003007
3
004120
4
003086
Action
Suspension strut - Replacement
Rear shock absorber - Replacement
Rear suspension linkage Replacement
Suspension strut support - replacement
Duration
TIME - 41
Nexus 500 euro 3
Time
Cooling system
COOLING SYSTEM
1
Code
007002
2
007016
3
007001
4
007024
5
007019
6
007013
7
001052
8
007022
TIME - 42
Action
Water cooling radiator - Replacement
Fan with support - Replacement
Expansion tank - Replacement
Expansion tank cap - Replacement
Coolant return pipe - replacement
Expansion tank / radiator
connecting hose - Replacement
Coolant and air bleed - replacement
Coolant delivery pipe - Replacement
Duration
Nexus 500 euro 3
Time
Braking system
BRAKE SYSTEM
1
Code
002021
2
002047
3
002020
4
002087
5
002084
6
7
002085
002089
8
002090
9
002039
10
11
12
002040
002007
003070
13
14
002002
003071
15
002048
Action
Front brake piping - Replacement
Front brake fluid and air
bleeding system - replace
Rear brake disc piping - Replacement
Rear integral braking system
rigid hose - Replacement
Integral break pump pipe, device - Replacement
Integral front brake pipes
Integral breaking device - Replacement
Integral brake fluid and bleeding system - Replacement
Front brake calliper - Replacement
Front brake calliper - Service
Front brake pads - replace
Front brake pads - Wear and
tear check
Rear brake pads - replace
Rear brake pads - Wear and
tear check
Rear brake calliper - Replacement
Duration
TIME - 43
Nexus 500 euro 3
Time
16
Code
002068
Action
Rear calliper - Service
Duration
Windscreen
WINDSHIELD
1
Code
004028
2
3
004101
004117
TIME - 44
Action
Windshield glass - Replacement
Windscreen - Replacement
Top fairing - Replacement
Duration
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