KYMCO ZX User manual

ZX / SCOUT
50
PREFACE
This Service Manual describes the technical feature.s and servicing
procedures for the KYMCO ZX / SCOUT 50.
In this manual, many illustrations and drawings are used to help
servicemen have better understanding.
Section 2 contains the service precautions for all operations and
troubleshooting stated in this manual. Read them carefully before starting
any operation.
Section 3 describes the inspection/adjustment procedures, safety rules and
service information for each part, starting from periodic maintenance.
Sections 4 through 16 give instructions for disassembly, assembly and
inspection of lubrication system, engine, fuel system and electrical
equipment.
Section 17 is the maintenance and inspection directions for the evaporative/
exhaust emission control system. Most sections start with an assembly or
system illustration and troubleshooting for the section. The subsequent
pages give detailed procedures for the section.
KWANG YANG MOTOR CO., LTD.
OVERSEAS SALES DEPARTMENT
OVERSEAS SERVICE SECTION
MARCH 2000

1. SPECIFICATIONS
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ZX / SCOUT
1TABLE OF CONTENTS
SPECIFICATIONS.................................................................................. 1
GENERAL INFORMATION .................................................................. 2
INSPECTION/ADJUSTMENT............................................................... 3
LUBRICATION SYSTEM....................................................................... 4
ENGINE REMOVAL/INSTALLATION................................................. 5
CYLINDER HEAD/CYLINDER/PISTON.............................................. 6
A.C. GENERATOR ................................................................................. 7
KICK STARTER/DRIVE PULLEY/CLUTCH/DRIVEN PULLEY....... 8
FINAL REDUCTION............................................................................... 9
CRANKCASE/CRANKSHAFT...............................................................10
CARBURETOR .......................................................................................11
FRAME COVERS....................................................................................12
STEERING HANDLEBAR/FRONT WHEEL/FRONT BRAKE/
FRONT SHOCK ABSORBER/FRONT FORK......................................13
REAR WHEEL/REAR BRAKE/REAR SHOCK ABSORBER..............14
ELECTRICAL EQUIPMENT.................................................................15
INSTRUMENT/SWITCHES/LIGHTS....................................................16
EVAPORATIVE/EXHAUST EMISSION CONTRAL SYSTEM...........17
1

1. SPECIFICATIONS
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ZX 50
SPECIFICATIONS
Name & Model SC10AS
Overall length (mm) 1792
Overall width (mm) 690
Overall height (mm) 1053
Wheel base (mm) 1225
Engine type Air cooled 2-stroke
Displacement (cc) 49.4 cc
Net weight (kg)
92.5
Seating capacity 2 riders (110kg)
Gross weight(kg)
150
Front wheel
120/70-12
Tires Rear wheel
120/70-12
Ground clearance (mm) 170
Braking distance (m)
(Initial speed Km/h) 7m (30km/h)
Min. turning radius (mm) 1940
Starting system Starting motor &
kick starter
Fuel type Gasoline, 2-stroke
motor oil
Cylinder arrangement Single cylinder, flat
Combustion chamber type Semi-sphere
Valve arrangement Reed valve & piston
Bore x stroke (mm) 39 x 41.4
Compression ratio 7.3 : 1
Compression pressure
(kg/cm²rpm) 11.5kg/cm²
Max. output (kw/rpm) 3.75/7000kw/rpm
Max. torque (kg-m/rpm) 4.5/6500 kg m/rpm
Open Automatic controlled
Intake Close Automatic controlled
Port Open 
timing Exhaust Close 
Open 
Scavenge
Close 
Idle speed (rpm)2100±100
Lubrication type Separate type
Oil pump type Plunger type
Oil filter type Full-flow filtration
Lubrication oil capacity (liter) 0.80
Air cleaner type & No. Wet, single
Fuel capacity (liter) 4.9
Type Plunger type
Carburetor Piston dia. (mm) 
Venturi dia. (mm) 14
Ignition system type CDI electromagnetic
Ignition
Ignition timing F mark 15.5°±2°BTDC/2000rpm
Spark NGK BR8HSA
plug ND
Spark plug gap (mm) 0.6 0.7
Battery capacity 12V3AH
Power to transmission gear Power-transmission
gear-clutch
Reduction ratio of power to
transmission 
Clutch type Dry multi-disc clutch
Transmission gear operation
type Automatic centrifugal
type
Transmission ratio 1 spe
ed

Reduction
Type Two-stage reduction
gear 1st reduction ratio 
2nd reduction ratio

Transmission gear type Non-stage transmission
Tire pressure
Front wheel
1.50
1.75
(kg/cm²)Rear wheel
1.75 2.25
Turning angle Right & left 45°
Brake system
Front wheel
Expanding/hydraulic
type Rear wheel
Expanding
Suspension
Front wheel
Telescope
type Rear wheel
Unit swing
Shock absorber
Front wheel
Telescope
type Rear wheel
Unit swing
Frame type Pipe under bone
CO 4.5%Exhaust
emission
concentration HC 7000ppm Max

2. GENERAL INFORMATION
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ZX / SCOUT
1
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
GENERAL INFORMATION
__________________________________________________________________________________
ENGINE SERIAL NUMBER/IDENTIFICATION............................2-1
SERVICE PRECAUTIONS ............................................................2-2
SERVICE INFORMATION............................................................2-6
TORQUE VALUES........................................................................2-8
SPECIAL TOOLS ..........................................................................2-9
LUBRICATION POINTS...............................................................2-11
WIRING DIAGRAM......................................................................2-12
CABLE & HARNESS ROUTING...................................................2-13
TROUBLESHOOTING ..................................................................2-17
2

2. GENERAL INFORMATION
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ZX / SCOUT
ENGINE SERIAL NUMBER/IDENTIFICATION
Location of Engine Serial Number

2. GENERAL INFORMATION
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ZX / SCOUT
SERVICE PRECAUTIONS
nMake sure to install new gaskets, O-rings,
circlips, cotter pins, etc. when reassembling.
nWhen tightening bolts or nuts, begin with
larger-diameter to smaller ones at several
times, and tighten to the specified torque
diagonally.
nUse genuine parts and lubricants.
nWhen servicing the motorcycle, be sure to use
special tools for removal and installation.
nAfter disassembly, clean removed parts.
Lubricate sliding surfaces with engine oil
before reassembly.
nApply or add designated greases and
lubricants to the specified lubrication points.
nAfter reassembly, check all parts for proper
tightening and operation.
nWhen two persons work together, pay
attention to the mutual working safety.
nDisconnect the battery negative (-) terminal
before operation.
nWhen using a spanner or other tools, make
sure not to damage the motorcycle surface.
nAfter operation, check all connecting points,
fasteners, and lines for proper connection and
installation.
nWhen connecting the battery, the positive (+)
terminal must be connected first.
nAfter connection, apply grease to the battery
terminals.
nTerminal caps shall be installed securely.
nIf the fuse is burned out, find the cause and
repair it. Replace it with a new one according

2. GENERAL INFORMATION
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ZX / SCOUT
to the specified capacity.
nAfter operation, terminal caps shall be installed
securely.
nWhen taking out the connector, the lock on
the connector shall be released before
operation.
nHold the connector body when connecting or
disconnecting it.
nDo not pull the connector wire.
nCheck if any connector terminal is bending,
protruding or loose.
nThe connector shall be inserted completely.
nIf the double connector has a lock, lock it
at the correct position.
nCheck if there is any loose wire.
nBefore connecting a terminal, check for
damaged terminal cover or loose negative
terminal.
nCheck the double connector cover for proper
coverage and installation.
nInsert the terminal completely.
nCheck the terminal cover for proper coverage.
nDo not make the terminal cover opening face
up.
nSecure wire harnesses to the frame with their
respective wire bands at the designated
locations.
Tighten the bands so that only the insulated
surfaces contact the wire harnesses.
nAfter clamping, check each wire to make sure
it is secure.
Easy confirm

2. GENERAL INFORMATION
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ZX / SCOUT
nDo not squeeze wires against the weld or its
clamp.
nAfter clamping, check each harness to make
sure that it is not interfering with any moving or
sliding parts.
nWhen fixing the wire harnesses, do not make it
contact the parts which will generate high heat.
nRoute wire harnesses to avoid sharp edges or
corners. Avoid the projected ends of bolts
and screws.
nRoute wire harnesses passing through the side
of bolts and screws. Avoid the projected
ends of bolts and screws.
nRoute harnesses so they are neither pulled
tight nor have excessive slack.
nProtect wires and harnesses with electrical
tape or tube if they contact a sharp edge or
corner.
nWhen rubber protecting cover is used to
protect the wire harnesses, it shall be installed
securely.
nDo not break the sheath of wire.
nIf a wire or harness is with a broken sheath,
repair by wrapping it with protective tape or
replace it.
nWhen installing other parts, do not press or
squeeze the wires.
nAfter routing, check that the wire harnesses
are not twisted or kinked.
Don’t touch

2. GENERAL INFORMATION
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ZX / SCOUT
nWire harnesses routed along with handlebar
should not be pulled tight, have excessive
slack or interfere with adjacent or surrounding
parts in all steering positions.
nWhen a testing device is used, make sure to
understand the operating methods thoroughly
and operate according to the operating
instructions.
nBe careful not to drop any parts.
nWhen rust is found on a terminal, remove the
rust with sand paper or equivalent before
connecting.
nSymbols:
The following symbols represent the servicing
methods and cautions included in this service
manual.
:Apply engine oil to the
specified points. (Use
designated engine oil for
lubrication.)
:Apply grease for lubrication.
:Use special tool.
:Caution
:Warning
(ð12-3) :Refer to page 12-3.
Engine Oil
Grease
Special
*
Remove the rest

2. GENERAL INFORMATION
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ZX / SCOUT
SERVICE INFORMATION
ENGINE
Standard (mm) Service Limit (mm)
Item SC10AS SC10AS
Cylinder head warpage 0.10
PistonO.D.(5mm from bottom of piston skirt) 38.955 38.970 38.90
Cylinder-to-piston clearance 0.10
Piston pin hole I.D. 12.002 12.008 12.03
Piston pin O.D. 11.994 12.0 11.98
Piston-to-piston pin clearance ←←
Piston ring end gap (top/second) 0.10 0.25 0.40
Connecting rod small end I.D. 17.005 17.017 17.03
Cylinder bore 39.039.025 39.05
Drive belt width 18 17
Drive pulley collar O.D. 20.01 20.025 ←
Movable drive face ID. 20.035 20.085 19.97
Weight roller O.D. 13.0 12.4
Clutch outer I.D. 107 107.2 107.5
Driven face spring free length 87.9 82.6
Driven face O.D. ←←
Movable driven face I.D. ←←
Connecting rod big end side clearance ←←
Connecting rod big end radial clearance ←←
Crankshaft runout A/B ←
CARBURETOR SC10AS
Venturi dia. 14mm
Identification number 014A
Float level 5.0mm
Main jet #80
Slow jet #35
Air screw opening 1 ±¼
Idle speed 2100±100rpm
Throttle grip free play 2 6mm
Jet needle clip notch 1st notch

2. GENERAL INFORMATION
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ZX / SCOUT
FRAME Standard (mm) Service Limit (mm)
Item SC10AS SC10AS
Axle shaft runout 0.2
Radial
Front wheel rim runout Axial
Front shock absorber spring free length 200.0 182.8
Rear wheel rim runout 2.0
Brake drum I.D. Front/rear 110 111
Brake lining thickness Front/rear 4.0/4.0 2.0/2.0
Brake disk runout Front/rear 0.30
Rear shock absorber spring free length 235.7 218.7
ELECTRICAL EQUIPMENT SC10AS
Capacity 12V3AH
Voltage13.0 13.2V
Charging
Standard 0.4A/5H
Battery
current Quick 4A/0.5H
Spark plug (NGK) BR8HSA
Spark plug gap 0.6 0.7mm
Primary coil 0.153 0.187Ω
Secondary coil
(with plug cap) 6.99 10.21KΩ
Ignition coil resistance Secondary coil
(without plug cap) 3.24 3.96KΩ
Pulser coil resistance (20 )80 160Ω
Ignition timing 15.5°±2°BTDC/2000rpm

2. GENERAL INFORMATION
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ZX / SCOUT
TORQUE VALUES
ENGINE
Item
Thread dia. (mm)
Torque (kg
-
m)
Remarks
Cylinder head bolt
Clutch drive plate nut
Clutch outer nut
Drive face nut
Oil check bolt
Engine mounting bolt
Engine hanger bracket bolt
Exhaust muffler joint lock nut
Exhaust muffler lock bolt
Spark plug
BF7x115
10
NH10
NH12
10
BF10x95
BF10x50
NC6mm
BF8x35
1.5 1.7
3.5 4.0
3.5 4.5
5.0 6.0
1.0 1.5
4.5 5.5
3.5 4.5
1.0 1.4
3.0 3.6
1.1 1.7
(cold)
(cold)
FRAME
Item
Thread dia. (mm)
Torque (kg
-
m)
Remarks
Handlebar lock nut
Steering stem lock nut
Steering top cone race
Front axle nut
Rear axle nut
Rear brake arm bolt
Front shock absorber:
upper mount bolt
lower mount bolt
hex bolt
Front damper nut
Front pivot arm bolt
Rear shock absorber:
upper mount bolt
lower mount bolt
lower joint nut
10
25.4
25.4
12
16
8
8
10
8
8
4.5 5.0
8.0 12.0
0.5 1.3
5.0 7.0
11.0 13.0
3.3
3.3
1.5 3.0
1.5 3.0
3.5 4.5
2.4 3.0
1.5 2.5
Flange bolt/U-nut
Flange U-nut
Flange U-nut
Flange nut
Flange bolt/U-nut
Cross head
Apply locking agent
Flange screw/U-nut
Flange nut
Torque specifications listed above are for important fasteners. Others should be tightened to standard
torque values below.
STANDARD TORQUE VALUES SH bolt: 8mm Flange 6mm bolt
Item
Torque (kg
-
m)
Item
Torque (kg
-
m)
5mm bolt, nut
6mm bolt, nut
8mm bolt, nut
10mm bolt, nut
12mm bolt, nut
0.45 0.6
0.8 1.2
1.8 2.5
3.0 4.0
5.0 6.0
5mm screw
6mm screw, SH bolt
6mm flange bolt, nut
8mm flange bolt, nut
10mm flange bolt, nut
0.35 0.5
0.7 1.1
1.0 1.4
2.4 3.0
3.5 4.5

2. GENERAL INFORMATION
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SPECIAL TOOLS
Tool Name Tool No. Remarks
Universal bearing puller E030 Crankshaft bearing removal
Lock nut socket wrench F001 Top cone race holding
Lock nut wrench, F002 Stem lock nut tightening
Crankcase puller E026 Crankcase disassembly
Bearing remover set, 12mm
(Spindle assy, 12mm)
(Remover weight)
E020 Drive shaft bearing removal/installation
Bearing remover set, 15mm
(Spindle assy, 15mm)
(Remover head, 15mm)
(Remover shaft, 15mm)
E018 Drive shaft bearing removal/installation
Bearing outer driver, 28x30mm E014 Bearing installation
Clutch spring compressor E027 Driven pulley disassembly/assembly
Crankcase assembly collar E023 Driven shaft, crankshaft & crankcase
assembly
Crankcase assembly tool E024 Crankshaft & crankcase assembly
Ball race remover F005 Steering stem bearing races
Rear shock absorber compressor F004 Rear shock absorber disassembly/assembly
Universal holder E017 Flywheel holding
Flywheel puller E001 Flywheel removal
Bearing outer driver, 32x35mm E014 Drive shaft bearing installation
Final shaft bearing installation
Bearing outer driver, 37x40mm E014 Drive shaft bearing installation Final shaft
bearing installation Crankshaft bearing
installation
Universal bearing puller E030 Crankshaft bearing removal
LUBRICATION POINTS

2. GENERAL INFORMATION
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ENGINE
NO.
Lubrication Points Lubricant Remarks
1 Crankcase sliding & movable parts JASO-FC or API-TC
2 Cylinder movable parts JASO-FC or API-TC
3 Transmission gear (final gear) SAE-90#
4 Kick starter spindle bushing Grease
5 Drive pulley movable parts Grease
6 Starter pinion movable parts Grease
FRAME
Apply clean engine oil or grease to cables and movable parts not specified. This will avoid abnormal
noise and rise the durability of the motorcycle.
SC10AS WIRING DIAGRAM
Front/Rear Brake Lever
Seat Lock
Rear Wheel Bearing
Throttle Cable
Main Stand Pivot
Grease
Engine Oil
Grease
Engine Oil
Speedometer Gear/
Brake Cam/Front
Shock Absorber
Lower Mount
Bushings/Pivot
Grease
Grease
Grease
Grease
Engine Oil
Rear Brake Cable
Brake Cam/
Anchor Pin

2. GENERAL INFORMATION
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CABLE & HARNESS ROUTING

2. GENERAL INFORMATION
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Front Brake Reservoir
Rear Brake Cable
Throttle Cable
Ignition Switch
Regulator/Rectifier
Front Brake Fluid Tube
Resistor
Front Stop Switch Wire
Rear Stop Switch Wire
Speedometer Cable
Speedometer Cable
Front Brake Fluid Tube
Horn

2. GENERAL INFORMATION
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Ignition Coil
Fuel Unit
Wire Harness
Rear Brake Cable
Throttle Cable
Front Brake Fluid Tube
Speedometer Cable
Speedometer Cable
Front Brake Fluid Tube

2. GENERAL INFORMATION
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Fuel Filter
Oil Tank Cap
Starter Relay
CDI Unit
Battery
Wire Harness
Ignition Coil
Oil Tube

2. GENERAL INFORMATION
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TROUBLESHOOTING
Vacuum Tee
Oil Pump
Ignition Coil
Oil Tube
Fuel Unit
Fuel Tank Cap

2. GENERAL INFORMATION
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ENGINE WILL NOT START OR IS HARD TO START
•Empty fuel tank
‚Clogged float valve
ƒClogged fuel filter
„Faulty auto fuel valve
•Faulty spark plug
‚Fouled spark plug
ƒFaulty CDI unit
„Faulty A.C. generator
…Broken or shorted ignition coil
†Broken or shorted exciter coil
‡Faulty ignition switch
•Burned or worn cylinder
piston
‚Faulty reed valve
ƒBlown cylinder head gasket
„Leaking crankcase
…Faulty crankcase oil seal
•Incorrectly adjusted idle speed
‚Air leaking through intake
pipe
ƒIncorrect ignition timing
•Flooded carburetor
‚Throttle valve excessively
open
•Faulty auto bystarter
ENGINE STOPS IMMEDIATELY AFTER IT STARTS
Inspection/Adjustment Symptom Probable Cause
Check if fuel reaches
carburetor by loosening
drain screw.
Remove spark plug and
install it into spark plug
cap to test spark by
connecting it to engine
ground.
Inspection/Adjustment Symptom Probable Cause
Fuel reaches
carburetor
Spark jumps
Dry spark plug
Not clogged
Normal
compression
Engine does not
fire
Fuel does not
reach carburetor
Weak or no spark
Wet spark plug
Clogged
Low or no
compression
Engine fires but
does not start
Test cylinder
compression.
Remove spark plug and
inspect again.
Wait for
30 minutes and
then remove the
carbu-retor auto choke
circuit hose and blow
the hose with mouth.
Start engine by
follow-ing normal
starting procedure.