YINGANG YG125-23 Maintenance Manual

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YG125-23Maintenance ManualForeword

Foreword

With the ever increasing varieties of motorcycles, new structures and new techniques have increasingly been applied.

To help YINGANG TECHNOLOGY Co., Ltd users and maintenance personnel better understand the maintenance,

adjustment and repair techniques of YG125-23 motorcycle, we prepared this maintenance manual. This manual is

expected to facilitate the YINGANG TECHNOLOGY Co., Ltd users and maintenance personnel and provide technical

guidance for them.

The masterstroke of the manual is the YG125-23motorcycle , and the contents in Chapter 1-Chapter 3 are applicable to

the adjustment of various parts of the motorcycle. Chapter 4-18 describes various constituting parts of the motorcycle

respectively. Chapter 19 contains the electrical system diagram.

The standard maintenance procedures, maintenance precautions and general maintenance knowledge are not

covered in this manual. Any user or maintenance personnel who needs the above information may refer to the related

materials

All materials, charts and various data, as well as performance indices referenced herein, are for the latest model in our

product family at the date this manual is printed. YINGANG TECHNOLOGY Co., Ltd. shall have the right to, at any time,

amend this manual without prior notice. The copyright of all parts of this manual belongs to China YINGANG

TECHNOLOGY Co., Ltd. and no units or individuals are allowed to reprint it the without consent of our company.

We hope you will enjoy the comfort and pleasure it brings to you during your driving!

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YG125-23Maintenance ManualContents

1. Overview

1-12

2. Lubrication system

13-23

3. Inspection and adjustment

24-39

4. Fuel system

40-45

5. Removal and installation of engine

46-50

6. Cylinder head, cylinder and piston

51-67

7. Clutch and Right crankcase cover

68-78

8. Magneto and starting system

79-87

9. Crankcase, crankshaft and Shift mechanism

88-104

10. Frame and exhaust system

105-109

11. Front wheel, front overhang and steering stem

110-121

12. Rear wheel and rear overhang

122-127

13. General remarks of electrical system

128

14. Power supply system

129-131

15. Starting system

132-134

16. Illumination signal system

135-140

17. Electrical starting control system

141-144

18. Engine management system

145-156

19. Electrical System Diagram

157

Engine

Vehicle body

Electrical system

Overview

Contents

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YG125-23MaintenanceManual Overview

Engine Number Position

Bar Tool

About Motorcycle Maintenance

Maintenance Period Table

Technical Data of Main Performance

Symbol Descriptions

Standard Torque Values

Photo of Complete Vehicle:

Frame Number Position:

Engine Number Position:

Engine Number

Frame Number

1、Overview

Engine Number Position

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YG125-23MaintenanceManual Overview

Maintenance Precautions

1. Whenever reassembling after being disassembled,

replace new washers, sealing members, etc.

2. While fastening bolts or nuts, proceed in diagonal

crossing sequence to gradually screw down to the

required torque for 2 to 3 tries.

3. After being disassembled, the parts and

4. To disassemble and assemble a motorcycle,

special service tools (SST) and general-purpose

tools must be used in accordance with relevant

regulations.

5. The specified or equivalent lubricating grease (oil)

must be applied to or refilled into the specified

locations.

components should be cleaned before being

inspected and measured

To clean the spare parts, use only the cleaning

fluid that is incombustible or has high ignition point.

Before reassembling, apply the specified

lubricating oil to the sliding surface of the parts and

components.

After reassembling, check whether all the spare

parts are mounted properly by means of turning,

6. When 2 or more persons are carrying out the

operation, they shall work with each other and pay

attention to safety.

7. Before operating, always remove the negative (-)

end of the battery first and take care to prevent the

wrench or the like from touching the frame. After

operating, reconfirm all the connections, fixings

and junctions. If the battery is already removed,

connect the positive (+) end first.

moving and operating them.

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YG125-23MaintenanceManual Overview

Crackle

The connector shall be fully inserted in place.

8. In case the fuse is blown, check for the causes and,

after being repaired, replace corresponding fuse

as per the specified capacity.

9. The caps must be securely put on the terminals

after the operation is complete

For a connector with lock, confirm whether the lock is

completely fixed.

Make sure the harness is not falling off

Make sure the plastic jacket of the connector is securely

covering the connector without scaling off.

11. Before connecting a connector, make sure the

sleeve is not broken and the opening of the

intermediate terminal is not too large

The joint shall be fully inserted in place.

Make sure the plastic jacket is housing the terminal

10. While disassembling a connector joints with lock,

release the lock before proceeding with operation.

While disassembling a connector joints, hold the

connector body without pulling the wire harness.

Before connecting the connector, the terminals shall be

free from breaking or bending. Make sure the terminals

are not too long or are falling off.

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completely. The opening of the plastic jacket shall not

face up.

12. The harness fixing strap shall firmly button the

specified position on the frame.

YG125-23MaintenanceManual Overview

Do not touch!

Do notpull!

Pay attention not to press it.

13. The clamp shall reliably bite the wire harness

In case of a welded clamp, it shall not bite the wire

harness towards the weld mark

The wire harness shall be clamped at the position

without contacting a rotating part or a removing element.

The wire harness shall be clamped at the position

without contacting a part that generates high

temperature.

The wire harness shall not be slackened or be forcibly

pulled.

If the wire harness has to contact the edge or sharp

corner parts, the contacting part shall be protected with

hose or adhesive tape.

In case of a wire harness with garland, it shall be reliably

harnessed.

Do not damage the garnish of the wire harness.

Once the wire harness is damaged, repair it by coiling

with plastic adhesive tape.

The wire harness shall be clamped at the position

without contacting the edge or sharp corners of the

vehicle body.

The wire harness shall be incapable of passing through

the position contacting a bolt, a screw head or any front

part.

While mounting parts and components, do not press the

wire harness.

Do not mount wire harness with it twisted.

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YG125-23MaintenanceManual Overview

Rust must be eliminated!

Have you learned by heart the method

the instruction manual?

14. When wiring, note when turning it leftwards or

rightwards to the limit position, the wire harness

shall not be tightened up or slackened, and make

sure there is no significant bending, pressing,

intervening of marginal parts.

15. While using the test table, operate according to the

18. Do not forcibly twist or forcefully bend the cable.

Because a deformed or damaged cable is the

cause of bad operation and damage.

maintenance manual after understanding the

explanations in the instruction manual.

16. Do not drop or throw the parts and components.

of application? Are the measurement range and polarity in accordance with

17. In case of rust on the terminals, carry out

connection operation after disposing it with

abrasive paper, etc.

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YG125-23MaintenanceManual Overview

Item

Data

Dimension & Weight

Length Width Height Wheelbase Min. ground clearance Complete vehicle weight

1740mm 800mm 1010mm 1245mm 170mm Non-loaded weight: 111.5kg, Curb weight: 118kg,

Vehicle body

Frame type Rake angle Front suspension device Rear suspension device Front Tire size Rear Tire size Front wheel pressure Rear wheel pressure Front brake Rear brake Fuel tank volume Fuel grade

Cradle type 26° spring & hydraulic composite damping spring & hydraulic composite damping

120/70-12 120/70-12

Normally loaded: 225kPa, Normally loaded: 225kPa, Single disc type ModelΦ220 Single disc type ModelΦ190 9L 92#

Engine

Mode Cylinder bore × Stroke Cylinder displacement Compression ratio Max. power Max. torque Valve clearance (cold)

Valve driving gear Air filter Cooling method Lubrication method Engine oil grade Engine oil charge volume Engine oil filter element Electricmotor starting Idle speed Net weight of engine

Single-cylinder force air –cooling4-stroke engine

52.4mm ×57.9mm 125cc

9.0:1

6.8kw/7500rpm 9N.m/6500rpm IN: 0.06-0.08 EX: 0.06-0.08 Chain drive Oilpaper filter force air-cooling Please apply Shell 10W/40-SF engine oil in summer and 10W/30-SF in winte 1L Oilpaper filter Electric / foot start 1500±150r/min

28.5±1kg

Technical Data of Main Performance

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YG125-23MaintenanceManual Overview

Driving system

Clutch Clutch operating system Variable speed gear Primary reduction ratio Transmission gear ratio

Final reduction ratio Gear shifting mode

Wet clutch, coil clutch, paper friction wafer Manual mechanical 5-speed constant mesh

3.35

Ⅰ 3.077

Ⅱ 1.789

Ⅲ 1.304

Ⅳ 1.091

V 0.929

3.466 Left foot operated to and back type Sequence: I－N－Ⅱ－Ⅲ－Ⅳ-V

Electrical system

Electric generator Accumulator capacity Power supply system

Fusible cutout Spark plug Spark plug gap Ignition coil type Fuel supply mode Ignition mode Ignition advance angle Ignition timing Front lamp Turn lamp Stop / Rear-position lamp

permanent magnet DC magneto 12V7A.h DC power supply, and the electric generator is only used to recharge the accumulator 15A/10A CPR8EA-9

0.7-0.9mm Open magnetic circuit Electronically injection, ECU control EMS EMS EMS

13.5V/16.2/5.8W

Front: P1.5W 12V Rear: P1.5W 12V

13.5V 1.2/2W LED 0.8W 12V

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YG125-23MaintenanceManual Overview

Item

Quantity

Thread diameter

(mm)

Torque value (N.m)

Thread locker

Cylinder head cover connecting bolt

13 8 8～12

Cylinder bolt 4

40～50

2 6 8～12

Valve adjusting screw nut

8～12

Timing driven sprocket bolt

2 7 7～11

Rocker-arm shaft cover

24～28

Magneto flywheel fastening nut

38～45

LOCTITE 243

Clutch fastening nut

114～126

LOCTITE 243

Primary driving gear fastening nut

143～157

LOCTITE 243

Oil drain plug

28～32

Crankshaft, main-shaft bearing baffle screw

8～12

LOCTITE 648

Stud

8～12

Stud

40～50

Exhaust valve stud bolt

2 8 10～14

LOCTITE 243

Stator connecting bolt

3 6 8～12

LOCTITE 648

Stator leads pressure plate bolt

2 6 8～12

LOCTITE 648

Spark Plug

18～25

Pensioner plate fastening bolt

1 6 7～10

Item

Quantity

Thread diameter

(mm)

Torque value (N.m)

Thread locker

Front wheel spindle

50～60

Front vibration damper plate

30～40

Real wheel spindle nut

60～90

Rear fork shaft nut

50～60

Engine hanging bolt

30～40 4 8

20～30

Steering handle set bolt

4 8 20～30

Front fork vertical pipe cap nut

60～90

Lower connection plate set bolt

30～40

Upper connection plate set bolt

2 6 8～12

Rear sprocket nut

6 8 20～30

LOCTITE 243

Brake disc fastening nut

8 8 20～30

LOCTITE 243

Speed signal panel screw

4 8 20～30

LOCTITE 243

Front brake caliper screw

2 8 20～30

LOCTITE 243

Standard Torque Values

ENGINE

Vehicle body

In addition to the torque values of the important parts as listed above, the torque values for other standard fasteners are as follow:

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YG125-23MaintenanceManual Overview

Name and dimensions

Torque value (N.m)

5mm bolt & nut

4.5 ～6

6mm bolt & nut

8 ～12

8mm bolt & nut

18 ～25

10mm bolt & nut

30 ～40

12mm bolt & nut

50 ～60

5mm Screw

3.5 ～5

6mm Screw

7 ～11

6mm spool bolt & nut

10 ～14

8mm spool bolt & nut

20 ～30

10mm spool bolt & nut

30 ～40

Motorized gun: special power tool for mantling/ dismantling bolt and nut

Pawl socket: for mantling/dismantling oil filtering element nut and clutch nut

A and B bolt socket: for mantling/dismantling A and B bolt and exhaust muffler bolt Adaptor: electric special tool for cross,hexagon gun tip Valve adjusting socket: for valve clearance adjustment

Socket: for mantling/dismantling nuts andbolts

Cutting plier, Nipper plier, expansion plier: for mantling/ dismantling flexible retainer

T-socket wrench

Bar Tool

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YG125-23MaintenanceManual Overview

Magnetic generator rotor puller: for dismantling magnetic generator rotor

Rubber hanner, Iron hammer, Copper hammer

Feeler gauge: to measure the clearance of piston, cylinder, valve, etc.

Micrometer: to measure the dimensions of piston, piston pin, etc.

Dial gauge: to measure the wheel bouncing, cylinder inner diameter, etc.

Cylinder barometer: to measure the cylinder pressure

Wrench: measure tighteness of ad bolt

Vernia caliper: measure size of rear wheel hub internal diameter

Tire barometer: to measure the tire pressure

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YG125-23MaintenanceManual Overview

Maintenance times

Maintenance Items

Period

Odometer km (Remark 2)

1000

k m

4,000

8,000

12,000

Remarks

* Fuel system passage

I I I

* Throttle operating system

I I I I

* Throttle valve body

I I I I Air filter element

Remark 1

C C

Replace every 12,000km driving

Spark Plug

Replace every 12000km driving

Engine lubricant oil

For a motorcycle, change every 1000km, and then change it every 2000km driving

Oil filter

Replace every 12,000km driving

* Tensioner

Remark 3

I I I

I both intake and exhaust

Remark 3 I Check every 4,000km driving

Clutch

I I I I

* Driving chain

Proceed with I and L for every 500km driving

** Front and rear brake system

I I I I

** Brake Pad

I I I I

** Brake fluid

Change every 2 years

* Front and rear brake lamp

switch

I I I

* Accumulator

Monthly

I I I

* Suspension system

I I I I

* Nut and bolt fastening

I I I I

** Wheel & tire

I I I I

** Steering column bearing

I I I I

** Steering backstay cable

Inspect every 5000km driving and replace every 10000km driving

Maintenance Period Table

Maintenance shall be carried out to the motorcycle in a specified period. The meanings of various symbols in the list are

as follows: I:Carry out inspection, cleaning, adjustment, lubrication or replacement.

C: Cleaning. R: Replacement. A: Adjustment. L: Lubrication.

* This item is subject to maintenance by persons from YINGANG TECNOLOGY Service Station. If the user has

special service tools, maintenance accessories or maintenance ability, it can repair it by itself.

** To ensure safety, this item is only subject to maintenance by persons from YINGANG TECNOLOGY Service

Station.

Remarks:

① While driving in a dusty area, it shall be cleaned more often.

② When the odometer reads more than the given maximum value, its maintenance period shall still repeat as per the

mile interval as stipulated in the table.

③ To ensure safety, the adjustment of timing chain and valve clearance shall only be carried out by persons from

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YG125-23MaintenanceManual Overview

Each time reassembled after being removed and disassembled, it must be replaced with a new

one.

Use special service tools (SST)

Use general-purpose tools.

Tightening torque of 50 N.m.

Use suggested engine oil.

Use the mixtures of engine oil and molybdenum disulfide

Use thread locker.

Use sealant.

Use lithium base grease.

Measures to be prompted during operating, inspecting and maintaining.

Special instructions or disposal measures given to prevent motorcycle from being damaged.

Special instructions or measures given to avoid serious damages or personal injuries.

Explanation

NOTICE:

WARNING:

YINGANG TECNOLOGY Service Station.

Symbol Descriptions

Meanings of various symbols in this manual:

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YG125-23Maintenance Manual

Maintenance notice

Inspection of lubricating oil

Troubleshooting

Replacement of lubricating oil

Lubricating Position of Complete Vehicle

Cleaning of Lubricating Oil Strainer

Lubrication of Control Lines

Cleaning and Replacement of Lubricating Oil Filter

Engine Lubrication System Diagram

Oil Pump

Selecting viscosity as per temperature conditions

Low temperatu re property

� Fuel economical efficienc y

� Lubricating property under h igh temperatu re

High temperat ure property

� Low temperature starting p roperty

� Noise reduction property und er high temper ature

WARNING:

Repeatedly contacting the engine lubricating oil

for a long period may cause skin cancer.

Although such possibility is small when you

deal with used engines oil every day, Care

must be taken to fully cleanse your hands with

soap and water after dealing with the used

engine oil. Children are strictly prohibited from

getting near to it.

Lubrication system

2、Lubrication system

Maintenance notice

This section introduces the inspection and replacement method of engine lubricating oil as well as the cleaning method of

lubricating oil strainer and lubricating oil filter. It also introduces various lubricating positions of the complete vehicle of this

model.

As an important factor that influences the engine’s performance and life span, the lubricating oil must be selected as per

regulations; ordinary engine oil, gear oil, vegetable oil, etc. are not allowed to be used instead of it. This engine was filled

with gasoline engine oil of 10W/40EG grade when leaving factory for sale. If you want to use other lubricating oil, its

quality scale must reach Grade SG, and its viscosity shall be selected according to the accompanying diagram depending

upon region and air temperature changes. While replacing lubricating oil, fully discharge the original lubricating oil in the

crankcase and clean it up with washing kerosene, and then refill fresh lubricating oil as per regulations.

The lubricating oil inside the engine must be fully discharged before inspection and cleaning.

Technical specifications: Lubricating oil charge volume:1L

Oil pump flow rate: 8L/min (when engine speed is at 4000 rpm).

Tightening torque of oil drain plug:28-32N.m

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YG125-23Maintenance Manual

● Lubricating oil contaminated

1. Fail to replace lubricating oil according to the maintenance period table;

2. The pouring orifice thread is damaged thus causing poor seal;

3. The piston ring is worn.

● Lubricating oil pressure low

1. The oil level is too low;

2. Oil through, orifice port or oil strainer is clogged;

3. Oil pumps failure.

● Lubricating oil consumes too fast

1. There is leakage with the engine;

2. The piston ring is worn.

3. The inlet/exhaust valve guide is worn;

4. The oil shield is worn or damaged.

Front wheel bearing

Rear wheel bearing

Engine lower hanging bolt

Rear fork shaft lever

Side stand shaft

Driving chain

Upper/lower retainers of vertical pipe

Lubrication system

Troubleshooting

Lubricating Position of Complete Vehicle

Among the positions shown in the above diagram, besides applying dedicated lubricating oil for chain to

the driving chain, apply lithium base grease to all other positions.

All lubricating oils not specified for use in this manual shall be ordinary common lubricating oil.

All sliding surfaces and cables not shown in this diagram shall be coated with lubricating oil or lubricating grease.

Lubrication of Control Lines

Regular lubrication shall be carried out to the clutch control line, throttle control line and steering cable. To do this, remove

the upper joining parts of all control lines, sufficiently lubricate and maintain their hoisting cables and all points of support with lithium base grease.

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YG125-23Maintenance Manual

Crankshaft oil through

Spindle oil Countershaft oil through

Camshaft oil through

Cylinder head oil through

Cylinder oil through

Oil filter

Oil pump

Oil strainer

Lubrication system

Engine Lubrication System Diagram

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Left crankcase body oil through

Cylinder block, cylinder head, camshaft bearing seat and a camshaftoil through

Waste engine oil flow into the oil collector Lubricating oil draining

YG125-23Maintenance Manual

Lubrication system

Replacement of lubricating oil

While replacing lubricating oil, it shall be carried out before the engine has cooled down. This will ensure quick and

complete discharge of the engine oil inside the crankcase.

When replacing, unscrew the oil drain plug and discharge the waste engine oil, and then clean the oil drain plug, engine oil

strainer, engine oil filter, etc. Finally, insert the oil drain plug. Unscrew the oil filter plug and slowly refill 1.0L new engine oil

of the specified trademark into the crankcase, then insert the oil filter plug.

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YG125-23Maintenance Manual

Flush the strainer with cleaning agent

Cleaning

Remove oil filter

Replacement of Filter

Cleaning of Strainer

Lubrication system

CAUTION

Application of engine oil of poor quality will have an impact on the functional performance and life span of the

motorcycle engine.

Cleaning of Lubricating Oil Strainer

It shall be carried out while replacing lubricating oil.

While cleaning, you should unscrew the oil drain plug to drain the waste engine oil, and flush the strainer with cleaning

agent; place the motorcycle side down to facilitate cleaning as required. Then insert the oil drain plug, and proceed with

the remaining steps according to the method of “Replacement of Lubricating Oil".

Cleaning and Replacement of Lubricating Oil Filter

Remove the engine oil filter cover to detach the engine oil filter element, clean the filter cover and filter element with cleaning agent, and then mount the clean engine oil element. Replace with a new one as required. Check for damage of the engine oil filter cover and its O-shaped sealing ring; replace with a new one as required. Mount the engine oil filter cover and screw up the bolt to the specified torque.

Notice

Before the crankcase is refilled with fresh engine oil, the engine oil filter must be cleaned.

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YG125-23Maintenance Manual

Remove the oil pump

Lubrication system

Oil Pump

In case of failure, the oil pump needs to be removed for repair or replacement.

This section includes the following contents:

Steps and illustration for oil pump removal;

Steps and illustration for oil pump installation;

Disassembly and assembly of oil pump, etc.

Steps for oil pump removal:

1. Remove the oil drain plug to drain the engine oil

inside the crankcase.

2. Loosen the right crankcase cover connecting bolts to

detach the right crankcase cover components.

4. Remove the oil pump。

3. Use the clutch push rod extractor to remove the clutch push rod assembly; use the fixing

tool to prevent the clutch and the primary driving gear from rotating; loosen the nut to remove

the clutch component,

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YG125-23Maintenance Manual

No. Procedures

Quantity

NOTICE

Removing order

Installation is in the reverse order of removal

Oil pump location pin

2 2

Oil pump sealing paper gasket

Replace it with a new one while assembling

Oil pump assembly

Coat it with engine oil; replace it when exceeding the wearing limit

Flange bolts M6*32

1 5

Flange bolts M6*50

1 6

Flange bolts M6*40

1 7

Oil pump rubber ring

Lubrication system

Steps for oil pump installation:

The installation procedures are the removal procedures in reverse order. Pay attention to the following points during the

installation:

1、 The spare parts shall be clean and intact；

2、 Install clutch assembly, and the retaining nut M18shall be coated with thread retaining adhesive LOCTITE243;

tightening torque:114N.m -126N.m；

3、Install clutch push rod assembly；

4、 After the right crankcase cover is mounted in place, the angle and position of the clutch operating lever may

possibly change; readjustment shall be carried out to accommodate the adjustment of clutch control line；

5、 The seal washer at the bolt under the oil pump, shall be replaced with new ones.；

6、Remember to refill engine oil after all these are completed.。

CAUTION

The clutch retaining nut must be screwed up to the specified tightening torque,must be applied to prevent the nut

from getting loose.

Disassembly and assembly of oil pump

Disassemble and assemble oil pump according to the following diagram.

While assembling, the rotor shall be coated with engine oil.

While assembling, check the clearances between the inner

and outer rotors of the oil pump; replace it if it exceeds the

wearing limit.

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YG125-23 Maintenance ManualInspection and adjustment

Maintenance notice

Brake system

Spark plug

Running system

Lubricating oil

Clutch control line

Oil output tank

Driving chain

Timing phase

Battery Checking

Cylinder pressure

Replacement of Fuse

Timing chain tension

Brake lamp adjustment

Valve clearance

Headlamp dimming

Air filter

Steering stem bearing

Idle speed

Suspension system

Throttle control

Bolts, nuts and fasteners

3、Inspection and adjustment

Maintenance notice

The parts that are washed should proceed thru relevant examination work．The purpose is to confirm that the part whether

it needs repair or replace．The examination method is divided into three methods include direct examination，testing

examination and detecting examination

Direct examination method

This method does not need instrument and other tools，it checks and determines the technologic state of part just

according to the sense organs of human being．The way is simple and easy to use，it is used wide in motorcycle

maintenance.

Testing examination method

This way is a way that test the size of part and change of geometric form with gauge and instrument，and make contrast to

the allowed limit with the data to confirm the technologic state of part．The accuracy of this way is high，but before test

should check the precision of gauge and instrument carefully and choose the testing position reasonably.

Detecting examination method

This way can test the invisible flaws of part．In motorcycle maintenance, generally adopt the best easy way--dipping oil to

beat by hammer，that means putting the parts into coal oil or diesel oil to soak several minutes then take out and wipe

the surface，spread talcum powder on the surface of parts uniformly，beat its nonworking sue face lightly by small

hammer. owing to beating will cause versatility of part, if part has crack，then the oil sludge that dipped into crack

originally will splash due to beating and versatility，then the talcum powder on surface will be dyed yellow，so one

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YG125-23 Maintenance ManualInspection and adjustment

yellow line will be revealed at the crack point.

Explanation:

Unless expressly stated or indicated in the maintenance period table, check and adjust all parts of the YG125-23

motorcycle according to the contents hereof before using it.

Technical specifications

● Throttle bar free stroke：1-3mm

● Recommended spark plug：CPR8EA-9

● Spark plug gap： 0.7-0.9mm

● Valve clearance (cold) IN）0.06-0.08mm

● EX）0.06-0.08mm

● Idle speed：1500±150（rpm）

● Cylinder pressure： ≥0.8MPa(300rpm)

● Driving chain tension： 10～20mm

● Rear brake pedal free stroke 20～30mm

● Front brake operating handle free stroke 10～20mm

● Clutch operating handle free stroke10～20mm

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YG125-23 Maintenance ManualInspection and adjustment

Gap: 0.7-0.9mm

Upper scale line

Lower scale line

Check for gap, deposit and electrode corrosion

Check for the gasket sealing property

Spark Plug

Remove the spark plug cap. Remove the spark plug with

a socket wrench. Visually check whether there is any

damage with the spark plug insulator and ablation with the

electrodes. If yes, replace them.

Check the spark plug electrode gap with a plug gauge.

Spark plug electrode gap0.7 -0.9mm. Carefully adjust the

electrode gap. Then clear away the accumulated carbon

and contaminants with a spark plug cleaner or string wire.

Check that the spark plug sealing gasket is in good

condition.

To mount the spark plug, manually screw up the spark

plug first, and then tighten it with a socket wrench. Put on

the spark plug cap.

Lubricating oil

Park the motorcycle on a flat surface, let the engine stop

for 2-3 minutes, and check to see whither the oil level is in

between the upper and lower line the oil gauge. if the

engine oil level is under the lower scale line, refill the

recommended lubricating oil until the oil level reaches the

upper-middle limit。

Notice

The insufficiency or poor quality of the engine oil will lead to the premature wear-out of the engine.

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YG125-23 Maintenance ManualInspection and adjustment

The boss is in the center of the hole

While aligning

Timing phase

It shall be carried out when the vehicle is new or there is

any question about the timing phase.

Remove the cylinder head cover

Turn the crankshaft pulley Counterclockwise to align the

scale line “I” with the indication mark “ ” on the front-left

cover.

When the piston is at the upper dead point, the scale line

on the camshaft is at the same level with the.

Notice

At this point, the piston must be at the upper dead

point of the compression stroke other than that of the

exhaust stroke.

Adjustment of Ignition Time

That the ignition lead angle is not correct will cause a

series of problem that engine is difficult to start，power

decrease，oil consumption increase，engine overheats，

burning is not complete，emission exceed standard，use

life reduce and so on．So should adjust the ignition lead

angle at first

Need not adjust the ignition timing if engine without

contact ignition．If the ignition system is abnormal，should

check electronic ignition，high-voltage coil，charging on

the generator and trigger coil etc．

After properly timing, pull off the tensioner locking key and

coat the mixture of engine oil and molybdenum disulfide

Cylinder pressure

When the engine fails to start or is difficult to start, or

when questioning the cylinder pressure is abnormal after

other possible faults have been excluded, check the

cylinder pressure.

Cylinder pressure: ≥0.8MPa/300r/min.

While testing, remove the spark plug and mount

apressure gauge at the position where the spark plug

ismounted; fully open the throttle bar and electronically

start the engine, and then check all connecting points of

the pressure gauge for gas leak. Zero the pressure gauge

and restart the engine until the pressure gauge reading

stops rising. The maximum reading of the pressure gauge

on the tensioner to make it tensioned; mount the sprocket

retaining plate and retaining bolt.

can usually be reached after 1 or 2 startups. Such

maximum reading shall be the cylinder pressure. Upon

completion of testing, mount the spark plug to its original

position.

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YG125-23 Maintenance ManualInspection and adjustment

Test cylinder

Turn the key clockwise

Press engine’s start button

The main reasons for insufficient cylinder pressure

include:

 Incorrect valve clearance adjusted

 Valve leakage

 Cylinder head sealing gasket ablated

 Piston ring or cylinder worn

 Piston ring worn

The main reasons for excessive pressure include:

Presence of accumulated carbon inside

thecombustion chamber or on the piston top

Timing chain tension

Start the engine to run at idle speed.

Carefully listen to the sound given off by the running

engine: if the timing chain gives off ringing sound

“Dah-Dah”, it indicates insufficient tension of the chain

tensioner, replace it with a new one.

To replace the chain tensioner:

Unscrew the 2-M6×16 socket cap screw to remove the

sealing washer and detach the old chain tensioner. Take

care not let the sealing washer and so on fall into the

crankcase. Insert the tensioner 4locking key into the tail end of the newchain tensioner, turn and retract

the front end of the tensioner and lock it, then replace

with a new sealing washer, mount the new

chaintensioner and fasten.

Pull off the tensioner locking key to tension the timing

chain.

Replace with a new sealing washer and screw up the

bolts on the tail end of the chain tensioner.

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YG125-23 Maintenance ManualInspection and adjustment

Upper eyehole cover

Eyehole cover

Confirm the upper dead point

Valve clearance

the top of the crankcase cover, and both intake and

exhaust rock arms do not move but stop at their loosest

Notice:

While adjusting the valve clearance, the engine shall

be cold.

(Temperature ＜35℃)

Noise will stem from too big valve clearance. However if

there is too small gap or even no gap at all, closing of

the valve will be hindered, which will cause many

problems such as engine stall, power loss, etc. Therefore,

the valve clearance must be checked periodically.

The valve clearance should be inspected and adjusted on

a cold engine by the following procedures:

Remove the caps of the central hole and the ignition

timing observation hole on the left crankcase cover.

position, which shows that the piston is in its top dead

center position of the compressing stroke. If the “T” mark

is near its right position but rock arms will move

apparently when flywheel rotate a small angle, the

flywheel is not in the compressing stroke but

exhaust/intake stroke. In this case, continuously turn the

flywheelclockwise for 360 degrees to the top dead center

position of the compressing stroke, where the valve

clearance can be adjusted. Afterwards, check the valve

clearance by inserting a clearance gage into the gap

between adjusting screw and the end of the valve.

The specified valve clearance is : 0.06-0.08mm for intake

valve and 0.06-0.08mm for exhaust valve respectively.

Remove the caps of the two air valves on the cylinder

head.

Turn the nut of the flywheel clockwise until the engraved

“T” mark on the flywheel aligns with the engraved line on

If clearance adjustment is needed, loosen the locking nut

on the rock arm, turn the adjusting nut till a slight

resistance is felt on the inserted right clearance gage.

At the end of the adjustment, tighten the “Locking out ”to

prevent loosening and another check to make sure that

the valve clearance is OK before all those dismounted

caps are refitted on.

While adjusting, unscrew the retaining nut and then turn

the adjusting screw until you feel that the clearance

gauge is slightly pulled. Then secure the adjusting screw

using the valve adjusting tool , and then screw the retaining screw. And finally, check the valve clearance.

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YG125-23 Maintenance ManualInspection and adjustment

Air filter cover

Filter element

Air filter

Idle speed

Cleaning and replacement of air filter

 Remove the left side covers Handle it carefully to

avoid scraping.

 Remove 6 screws, remove Air filter cover

Description

1 Remove the filter element and check whether it is

in normal condition. This is a paper filter element,

of which the surface can be cleaned with

compressed air; if the filter element is too dirty,

broken or damaged, replace it;

2 While driving in a more dusty area, the time

period for cleaning and replacing air filter

element shall be shorter.

3 Keeping the cleanness of the air filter may

improve the engine’s operating efficiency and

prolong its life span.

Notice

Check and adjust the idle speed after all other items

of the engine have been adjusted to the specified

ranges.

For this model, the idle speed is controlled by an ECU.

Since the intake flow at idle speed has been properly

adjusted upon delivery, do not adjust the idle speed

adjusting screw as desired. In case the idle speed is

unsteady, zero or too high, find out the possible causes

with the troubleshooting method for the EMS system and

eliminate the trouble.

Under the monitoring of the maintaining and diagnostic

instrument, check whether the ignition advance angle is

between 0°-15°. If the ignition advance angle is more

than 15°, it indicates the throttle valve’s intake flow at

idle speed is insufficient, and at this point, the idle speed

is unstable or null; if the ignition advance angle is less

than 0°, it indicates the intake flow at idle speed is too

big, and at this point, the idle speed is often as high as

more than 1800 r/min. Only under the above two cases,

unscrew the retaining nut and adjust the idle speed

adjusting screw to let the intake flow reach the specified

flow.

Idle speed 1500r/min ±150 r/min.

After adjusting toe-in, remember to screw up the retaining nut.

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YG125-23 Maintenance ManualInspection and adjustment

10-20mm

Maintaining & diagnostic instrument

Retaining nut B

Retaining nut A

2-6m

Throttle control

First, check whether the throttle control line is deformed,

twisted or damaged.

Then, measure the throttle bar free stroke. Turn the bar to

throttle control line with throttle valve body and unscrew

the retaining nut B to make adjust the free stroke in a

larger range. Screw up the retaining but B after the

adjustment.

Check whether the throttle can turn smoothly from full

open to full close at any position. If there is clogging,

adjust or replace it.

lean it against one side of the free stroke, and draw a

straight line between the bar and the balance weight with

a mark pen, and then turn the bar to lean it against the

other side of the free stroke; measure the distance the

straight line staggers, i.e. the throttle bar free stroke.

Free stroke 2-6mm.

If the free stroke is insufficient or too big, make

adjustment.

Adjusting methods:

Fine adjustment: Pull open the rubber lagging, unscrew

the retaining nut A, and turn the adjusting solenoid to

adjust to a satisfied free stroke. And then screw up the

retaining nut A and mount the protective rubber lagging.

Coarse adjustment:

If the fine adjustment is not satisfying, separate the

Brake system

Check the front brake handle free stroke.

The brake handle free stroke 10-20mm.

Brake fluid level inspection:

Check the brake fluid level in the front brake cylinder: if

the level is too low but not emptied, directly refill brake

fluid (DOT 4 brake fluid).

If the brake fluid inside the cylinder is found cloudy,

impure or smelt, Drain and refill the brake fluid. Refer to

the brake fluid vacuum filling method in the next section.

I If the brake fluid in both the front cylinders is drained,

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YG125-23 Maintenance ManualInspection and adjustment

Actuate the front brake handle

Min. scale line

bleed air from the deflating valve of the brake caliper with

a vacuum pump, and then refill brake fluid into the

cylinder.

5. When the vacuum pump has fully exhausted the air

Brake fluid vacuum filling method:

This method is only applicable to refilling brake fluid for

new vehicles or when the brake fluid in the cylinder is

drained.

1. Bleed air from the deflating valve of the vacuum

pump’s caliper

2. Open the cover of brake cylinder cover and refill

brake fluid.

inside the brake caliper, after the brake fluid is

pumped out, firmly nip the handle or completely push

down quickly screw the deflating valve bolt, with the

torque being 7-9 N.m.

6. Mount the brake cylinder cover with the

sealinggasket flattened, and replace with new

sealing gasket as required.

7. After refilling, check the oil cup, hydraulic brake hose

and all connecting pieces for leakage.

Notice

1 The brake fluid shall be DOT 4 non-petroleum

base brake fluid.

The brake fluid can’t be mixed with other

3. Actuate the brake handle, exhaust the air in the dead

corner of the brake caliper.

2 Impurities; otherwise the braking performance

shall be reduced due to chemical change.

Caution

The brake fluid is strongly corrosive, never splash it

onto the surfaces of sprays painted or plastic pieces;

in case it splashes into the eyes or on the skin,

immediately flush with large amounts of fresh water

and see a doctor.

Brake piece checking

Operating brake, if the wears limit line of the brake shoe

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YG125-23 Maintenance ManualInspection and adjustment

20-30m

Adjustment nut.

touch to the side of the brake disc. It shows that the brake

shoe has touched the wear limit

Rear Brake

Pushing the brake pedal by hand, checking the resistance,

to confirm the move of the brake pedal whether is good. If

not, it could be adjusted by adjusting the rear brake

adjustment nut. Twirling the nut to adjust the pedal stroke.

Pushing the brake pedal by hand till feeling resistance .

Validation the pedal free stroke whether is in the scope of

regulations.

Brake pedal free stroke：20-30mm

and also on the brake cam alignment, shows the brake

shoe has been touched the wear limit. Please change it.

（2）If it needs to be changed. Please go to the

designated special maintenance station. And it is better to

use the parts from our company.

Caution

Please change the brake shoe in time if it has been

touched the wear limit. Otherwise it would cause

accidents by the lack of strength.

Substitution of the brake pads

Press the brake caliper towards the brake disc, and put

the brake piston back into its basic position. Remove the

clips and pull out the bolt. Clean up the brake caliper and

the support with compressed air. Check whether or not

the sleeves of guiding bolts in damaged or not, and

grease the bolts if necessary.

When installing the brake pads, be sure to check whether

The brake piece checking

（1）Pulling the rear brake, checking the wear and tear of

the brake shoe. If the mark "△" on the drum brake cover

or not the sliding metallic sheet is correctly set up on the

caliper support and in the spring.

Running system

Tire specifications and tire pressure

Check the tire pressure with a tire pressure gauge to see

whether the pressure conforms to the recommended

value.

Tire specifications and recommended tire pressure:

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YG125-23 Maintenance ManualInspection and adjustment

specs

Front tire

Rear tire

120/70-12

Cold tire air pressure

Front tire

225kPa

Spoke nut fastening tool

10-20mm

Adjusting Nut

Retaining nut

Clutch control line

Clutch is the key part of transmitting power in motorcycle

transmission system，should adjust it according to the

following overhauling content．The content is the free

If the tire pressure can’t reach the specified requirements,

check the tire for cuts, embeddediron nail or other sharp

articles.

Caution

The tire pressure measured when the tire is cooled

down shall be the correct tire pressure.

Spoke

Check whether the wheels are loose or wobbly. Tighten the loose bolt with the tool to make the torque: 20-30N.m. If it is wiggle or metal friction sound, check whether the bearing is damaged and replace the bearing..

stroke of clutch control handle(general is 10-20mm)，some

venial need adjust the adjusting screw of declutch

mechanism．

Check the clutch operating handle free stroke. Clutch

operating handle free stroke: 10-20mm.

Adjusting methods:

Fine adjustment: Pull open the rubber lagging, unscrew

the retaining nut, and turn the adjusting nut to adjust to a

satisfied free stroke. And then screw up the retaining nut

and mount the protective rubber lagging.

If a satisfactory free stroke can't be achieved by fine

adjustment, remove the clutch control line on the handle

end to adjust the engine end.

Adjusting methods:

Coarse adjustment:

Remove the clutch control line on the handle end, and

then remove the clutch operating arm on the engine end;

turn the clutch operating arm by a proper angle and

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YG125-23 Maintenance ManualInspection and adjustment

Retaining nut

Adjusting Nut

Unscrew the rear wheel spindle nut

Adjustment

Movement direction

Spring locking piece

remount it, and then mount the clutch control line, finally

adjust it to a satisfied free stroke according to the fine

adjustment.

protective rubber lagging

Notice:

Always ensure the clutch operating handle has

theproper free stroke! Being too loose will cause a

If the chain is too loose or too tight, make adjustment.

Adjusting methods:

Unscrew the rear wheel spindle nut and turn the adjusting

bolt on the chain adjuster until the specified tension is

achieved, and then fasten the rear wheel spindle nut, and

check the flexibility for free rotation of the rear wheel and

the consistency of the front and rear wheels.

failure of the clutch detachment, while being too tight

will cause poor clutch engagement thus damaging

the clutch

Driving chain

Driving chain tension inspection

Park the motorcycle on level ground with main stand, and

shift the transmission to the neutral position. Check the

driving chain tension. Press the chain with a finger up and

down to check the amount of movement of the lower

chain.

Driving chain tension: 10-20mm.

Warning:

The rear wheel spindle nut must be firmly screwed up

to the tightening torque of 60-90N.m.

Inspect the abrasion of major / minor sprocket. In case of

serious tooth abrasion, teeth missing or broken teeth,

replace it.

Inspect the abrasion of major / minor sprocket. In case of

serious tooth abrasion, teeth missing or broken teeth,

replace it.

Notice:

The scale lines of the chain adjuster on both sides must be consistent with each other.

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YG125-23 Maintenance ManualInspection and adjustment

Cleaning and coating oil

Notice

This model uses the oil seal chain, so the selected

washing oil shall be in corrosive to the oil seal; while

assembling the chain, the locking piece coupling

spindle shall be coated with appropriate amount of

chain-specific lubricating oil.

Warning:

supply.

Seriously corroded conductor connectors of the battery

shall be replaced.

Installation of accumulator

Installation is in the reverse order of removal. While

connecting the poles, connect the positive pole first.

While mounting the spring locking pieces, its opening

end shall be in the opposite direction with the normal

movement of the driving chain.

Battery Checking

Removal of accumulator

Open the left side cover.

Clean away dust and corrosive from the surface of the

battery.

Remove the negative, then the positive pole of the

accumulator; unscrew and remove the loosen battery

strap

Measure the voltage of the negative pole with a voltmeter;

if it is less than 12V, recharge it with a charge power

Warning:

1 In this model, both the startup and EMS system

are completely powered with accumulator.

Therefore, it is quite important to ensure

sufficient electric quantity of accumulator,

otherwise, startup is impossible.

2 Never fill in tap water, because this will shorten

the accumulator’s life span.

3 Todismantle battery,disconnect the

negative(-)electrode before the positive(+)one,

and vice versa in installation.Ensure against any

contact of the positive(+)electrode with the

vehicle body.

4 Never have the electrolyte level come over the

upper mark line when adding distilled

water.Otherwise overflow and corrosion will

occur.

5 The electrolyte contains sulfuric acid and will

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YG125-23 Maintenance ManualInspection and adjustment

Adjusting nut

Rear brake switch

Fuse

Adjusting bolt

cause serious hurt to skin and eyes by contact.

In case of contact with it, wash it off for 5

minutes and see a doctor immediately.

Brake lamp adjustment

If the rear breaks lamps abnormally light up and go

out, adjust it by turning the adjusting nut. If the rear

brake lamp switch is broken, replace it immediately.

Pull down the right side cover

Pull out and pull off the patch plug of the rear brake

lamp switch, and carefully pull out the rear brake

Replacement of Fuse

Set the ignition switch to “OFF” position. The specified

fuse tube of 15A/10A should be used for main fuse

replacement, and a 10A fuse tube for FAI injection nozzle.

Open the seat cushion, remove the fuse holder on the

side of the battery and replace the fuse tube.

If the new fuse tube is broken again as soon as it is fitted

on, it means that somewhere of the electric parts is

shorted unexpectedly.

lamp switch wire and remove the rear brake spring.

Replace with new rear brake lamp switch and mount

it in the reverse order.

While installing, the wiring of the rear brake lamp shall be

in strict accordance with the wiring diagram, and replace

the buckle strip

While installing, the rear brake spring shall be reliably

hooked with the pin hole on the rear brake lamp switch.

Caution

Do not use any fuse over 15A/10A

Be sure not to wash the battery when washing the

vehicle.

Headlamp dimming

Before driving, check the brightness, direction, etc. of the

headlamp.

The adjustment can be made to the headlamp in the left /

right and vertical directions.

After replacement, adjustment shall still be carried out to

the rear brake lamp switch.

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YG125-23 Maintenance ManualInspection and adjustment

Screw

Bulb

Screw

Headlamp UNIT

Socket

Bulb

Adjust the nut

 Loose the screw to disassemble the headlight.

If the headlights are not bright, only new headlights will be

replaced.

Headlight bulb 13.5V 16.2/5.8W

Position lampbulb

Front and rear lamp bulb

 Loosen the screws, remove the Tail lights

If the Tail lights are not bright, only new Tail lights will be

replaced.

Front and rear lamp bulb12V4W

Steering stem bearing

Lift the motorcycle with a jack or other support with the

front wheel being apart from the ground surface, and

Taillight、Taillight bulb

 Loosen the screws, remove the taillight lampshade

 Lightly rotate taillight seat, take out the seat and

bulb.

 Lightly press bulb, rotate in counter-clockwise.

 Install new bulb in opposite order as below.

Taillight bulb：13.5V/1.2/2W

check whether the steering handle can rotate freely; if the

steering handle cannot rotate in balance, or has axial

looseness or jamming, adjust the front fork stem adjusting

nut.

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YG125-23 Maintenance ManualInspection and adjustment

Front suspension inspection

Suspension system

Front suspension

Make the front brake in braking state and press the front

fork bracket for several times, and check the front

suspension for normal operation.

If abnormal noise or “Crack” sound is heard, check all the

fasteners and screw them up to the specified torques.

Bolts, nuts and fasteners

All the bolts, nuts and fasteners shall be screwed up as

per the maintenance period table. And check all the cotter

pins, safety gripping gears, locks, etc.

Rear suspension

Forcibly press the rear end of the seat cushion with the

rear suspension, and check the rear fork spindle sleeve

for abrasion or damage. If it is damaged, replace it. Check

whether the whole suspension assembly is mounted

securely, and whether it is damaged or deformed

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YG125-23Maintenance ManualFuel system

4、Fuel system

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YG125-23Maintenance ManualFuel system

Maintenance notice

Disassembly and assembly of fuel tank

Troubleshooting

Removal and installation of air filter

Removal and installation of fuel tank

Removal and installation of carburetor

Fuel system

Maintenance notice

This section introduces the knowledge related to the fuel system.

CAUTION

 Pay special attention to fire prevention while dealing with gasoline!

Take care of the mounting position of such sealing members as the O-ring while removing various parts of the fuel system.

While reassembling, always use new sealing members such as an O-ring.

Technical specifications

Throat opening diameter Φ16mmequivalent

Idle speed 1500r/min ±150 r/min

Throttle handle free stroke 1～3mm

Troubleshooting

 Engine ignition is ok, but it does not start

1 No fuel or insufficient fuel in the fuel tank

2 Too much fuel enters the cylinder;

3 Air filter is clogged;

4 Spark plug fails;

5 Fuel tube does not flow well;

6 Fuel quality problem (containing moisture);

7 Fuel is stored too long;

8 Fuel pump failure;

9 Injector failure (clogged)

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YG125-23Maintenance ManualFuel system

Removal and installation of fuel tank Disassemble step

1. Remove the seat

2. Unscrew one connecting bolts

3. Loosen the tube clamp and pull off the fuel tube

4. Pull off the fuel pump control wire patch plug.

Installation steps

The installation procedures are the removal procedures in

reverse order.

While installing, note that the wiring of the fuel pump

control wire shall be in strict accordance with the wiring

diagram. Avoid fuel line contamination.

Removal and installation of air filter

Refer to the section “Inspection and Adjustment—Air

Filter”,

It is unnecessary to remove the air cleaner assy from the

frame when performing maintenance on filter element;

take out the filter element for cleaning or replacement.

1. Remove covering parts

2. Remove Air cleaner cover, right

3. Take out the filter element for cleaning or

5. Remove the fuel tank.

To avoid fuel line contamination, clog the joint with

fireproof fabric after pulling off the fuel tube.

replacement.

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YG125-23Maintenance ManualFuel system

Remove and installation of throttle body Disassemble step：

1. Removal of rear wheel

2. Removal of seat

Removal of fuel tank

Installation steps：

The installation procedures are the removal procedures in

reverse order. While installing, the locating slot must be

aligned with the locating lobe of throttle body

Warning:

Donot further disassemble the removed throttle body;

in case several sensors on it need to be changed,

proceed under the instruction of an EMS system

technician.

4. Loosen inlet pipe clip;

5. Remove throttle body (including the fuel

injector).

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YG125-23Maintenance ManualFuel system

Component description

Damage form

Trouble symptom ofmotorcycle

Repair method

Air cleaner Too much dust deposit

on the filtering element．

The engine is difficult to start．Insufficient engine output；Poor performance of engine during idle run．Excessive fuel consumption．The exhaust muffler pipe fumes strongly (black)．

C1ean the filtering element．c1ean The filtering element is fractured or chipped

Engine air suction noise is toooud

Replace the filtering element．

Aintenance of Air Cleaner

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YG125-23 Maintenance ManualRemoval and installation of engine

5、Removal and installation of engine

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YG125-23 Maintenance ManualRemoval and installation of engine

Maintenance notice

Installation of engine

Removal of engine

Removal and installation of engine

Maintenance notice

It is only necessary to remove the engine from the frame when performing maintenance on the engine’s crankshaft,

balancing shaft, driving parts, etc. It is unnecessary to remove the engine from the frame when performing maintenance on other parts of the engine. Before removing the engine, park the motorcycle on level ground, and completely drain engine lubricating oil. To maintain the heat engine parts including cylinder head, cylinder body, piston, etc., it is necessary to remove the coverings, fuel tank, throttle body, air filter assembly, etc.

To remove the engine’s right crankcase cover for maintenance, it is necessary to remove the rear brake pedal To remove the engine’s left front cover for maintenance, it is necessary to remove the gear shift pedal, left rear cover, etc.

Installation is in the reverse order of removal. While reinstalling, all wirings shall be carried out in accordance with the wiring diagram, and replace the removed buckle strip

Specification

Net weight of engine 28.5±1kg Engine oil volume1L

Key torque values

Engine hanging bolt M8: 20-30N.m M10: 40-50N.m Rear fork shaft 55-65N.m

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YG125-23 Maintenance ManualRemoval and installation of engine

Removal of engine

1. Open the seat cushion, Detach the earth wire from

the negative pole of the battery.

2. Remove bracket from left and right.

3. Remove clutch cable

4. Remove the magnetic motor, gear display line and

hit the line wire

6. Remove muffler(front part).

7. Remove the magnet motor to connect the cable,

Drive sprocket.

8. Remove the gear shift pedal and left rear cover.

9. Remove the high voltage wire

5. Remove engine cycle tube

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YG125-23 Maintenance ManualRemoval and installation of engine

10. remove the Intake pipe, temperature sensor.

11. Remove the engine hanging plate,Front suspension.

 Remove the drive chain

 Move the engine slowly from the right.

Installation of engine

The installation of engine is in the reverse order of removal of engine. During installation, note that the wiring of cable shall be in strict accordance with the wiring diagram. Remove the 4 engine bracket and the frame connecting bolt Remove the 2 front suspension bolt Remove the 2 rear suspension bolt Remove the drive chain Move the engine slowly from the right.

 Remove the rear absorber and rear fork

connecting bolt;

 Unscrew the nut and take out the rear fork

shaft;

 Take out the rear fork backwards

 Loosen the nut and remove the lower hanging

bolt.

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Cylinder head cover Cylinder head

Cylinder

6、Cylinder head, cylinder and piston

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Maintenance notice

Cylinder head

Troubleshooting

Cylinder

Cylinder head cover

Piston

Camshaft

Item

Standard value

Maintenancelimit value

Camshaft Camshaft lift:IN

5.15mm

5.21mm

Camshaft lift:EX

5.0mm

5.06mm

Cylinder head

Planeness

0.03mm

0.05mm

Valve spring Internal spring free

length

36.5mm

36mm

External spring free length

36.5mm

36mm

Valve

IN Valve stem external diameter

φ5mm

φ4.975mm

Conduit inner diameter

φ5mm

φ5.012mm

EX Valve stem external diameter

φ5mm

φ4.955mm

Conduit inner diameter:

φ5mm

φ5.012mm

Valve clearance IN

0.06mm～0.08mm

Cylinder Internal diameter

φ52.4mm～φ52.41mm

φ52.41mm

Roundness

0.003

Cylindricity

0.004

Cylinder head, cylinder and piston

Maintenance notice

The lubrication of the camshaft and rocker arm is implemented by pumping oil by the oil pump through the oil troughs of

the cylinder, cylinder head and cylinder head cover; before assembling, please check whether the oil troughs are

unobstructed and clean them up properly.

Before assembling, clean all parts and components with cleaning agent and dry them with compressed air.

While assembling, coat engine oil and molybdenum disulfide lubricant on the protruding surface of the camshaft for

preliminary lubrication.

Be careful not to damage the cylinder wall and piston.

Technical specifications & maintenance benchmark

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Top planeness

0.05

Piston and piston pin

Piston external diameter

φ52.37～φ52.39mm mm

φ52.37mm

Fit clearance with cylinder

0.01mm～0.04mm

0.04mm

Piston pin external diameter

φ12.995mm～φ13mm

φ12.995mm

Piston pin hole inside diameter

φ13.002mm～φ13.008mm

φ13.008mm

Fit clearance

0.002mm～0.013mm

0.013mm

Connecting rod small end

Internal diameter

φ13.013mm～φ13.028mm

φ13.028mm

Clearance with piston pin

0.013mm～0.033mm

0.033mm

Piston ring

First ring gap clearance

0.015mm～0.05mm

0.05mm

Second ring gap clearance

0.015mm～0.05mm

0.05mm

First ring side clearance

0.002mm～0.013mm

0.013mm

Second ring side clearance

0.002mm～0.013mm

0.013mm

Oil ring side clearance

0.002mm～0.013mm

0.013mm

Key torque values

Cylinder head cover connecting bolt 8-12N.m

Cylinder bolt 40-50N.m

Timing driven sprocket bolt 8-12N.m

Spark plug 18-25N.m

Pensioner plate fastening bolt 8-12N.m

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Troubleshooting

 Low cylinder pressure

1. Valve:

-- Incorrect valve clearance adjusted;

-- Valve ablated or bent;

-- Valve sealing failure;

-- Incorrect valve timing;

-- Valve spring damaged.

2. Cylinder head:

-- Spark plug sealing failure;

-- Cylinder head gasket leaked or damaged;

●Excessive noise

1. Incorrect valve adjustment;

2. Valve jammed or valve spring broken;

3. Camshaft worn or damaged;

4. Timing chain too long, worn or damaged;

5. Timing chain tensioned failure;

6. Timing driven sprocket worn;

7. Cylinder / piston worn;

8. Rocker arm / Rocker-arm shaft worn;

9. Piston pin bore / piston pin worn.

-- Cylinder head cracked or blistered.

3. Cylinder and piston:

-- Piston ring clearance too big or cracked;

-- Piston cracked or damaged;

-- Cylinder / piston ring worn.

 Black smoke from exhaust

1. Valve guide worn;

2. Oil shield leaked or damaged;

3. Cylinder / piston / piston ring worn;

4. Piston ring clearance too big;

5. Piston ring incorrectly installed;

6. Piston or cylinder wall scratched or scuffed.

 Overheat / knocking (cylinder pressure too high)

1. Too much carbon deposited in combustion

chamber.

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Valve cover

Upper eyehole cover

Cylinder head cover

To remove the cylinder head cover:

1. Remove the lower / upper eyehole covers and turn

the crankshaft so that the piston is at the upper dead

point of the compression stroke.

2. Remove the valve cover, connecting bolt, etc.

3. Remove the cylinder head connecting bolt.

4. Remove the cylinder head cover.

Caution

Do not drop the location pin into the crankcase.

To mount the cylinder head cover:

1. Turn the crankshaft so that the piston is at the upper

dead point of the compression stroke.

2. Remember to confirm the location pin.

3. Mount the cylinder head cover and the sealing

gasket.

4. Mount the cylinder head connecting bolt. ; tightening

torque is 12N.m

5. Confirm the valve clearance, and make adjustment

with a valve clearance adjusting tool as required.

6. Mount the valve cover, etc

7. Connect the phase sensor and mount the eyehole

cover and upper eyehole cover in turn.

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Tensioner

Camshaft

To remove the camshaft:

1. Remove the lower / upper eyehole cover and turn

the crankshaft so that the piston is at the upper dead

point of the compression stroke.

2. Remove the cylinder head cover (See Removal of

cylinder head cover).

3. Remove the camshaft end cover, loosen the screw

and washer at the tail end of the tensioner; turn the

screw clockwise with the tensioner locking key

sothat the tensioner is loosened and locked.

4. Remove the timing driven sprocket bolt

5. Remove the camshaft retaining pins

6. Remove the camshaft bearings

7. Strip the timing chain from the timing driven sprocket,

and remove the timing driven sprocket.

8. Remove the camshaft

Caution

Do not drop the timing chain into the crankcase.

To mount the camshaft:

1. Turn the crankshaft so that the piston is at the upper

dead point of the compression stroke and the scale

line “I” on the rotor is aligned with the triangular

indication mark on the left front cover.

2. Clean all parts and components, coat the mixture of

engine oil and molybdenum disulfide on the

protruding surface of the camshaft, and coat oil

engine on the journal part.

3. Mount the camshaft retaining pins, camshaft ，

camshaft bearings and timing driven sprocket; let the

basic circle part of the camshaft facing up while

timing.

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Tensioner

Max. lift measurement

Outside micrometer

4. After properly timing, pull off the tensioner locking

key and coat the mixture of engine oil and

molybdenum disulfide on the tensioner to make it

tensioned; mount the sprocket retaining plate and

retaining bolt

5. Mount the bolt and washer at the tail end of the

tensioner.

6. Mount the cylinder head cover (See Installation of

cylinder head cover), and adjust the valve clearance

7. Connect the phase sensor and mount the eyehole

Camshaft inspection

Check the camshaft for abrasion, damage, oil through

jamming, etc. and check whether the decompressor flying

block can rotate and return smoothly.

Measure the maximum IN / EX lift.

Maintenance limit: IN≥≥5.5057mm, EX ≥5.515mm

Cylinder head

To remove the cylinder head:

1. Remove the muffler exhaust pipe

cover and upper eyehole cover in turn.

Caution

When the tensioner is not tensioned, never turn the crankshaft for fear of interlocking the teeth while timing.

2. Remove the engine cycle tube

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

3. Pull off the spark plug cap,

4. Unclamp the inlet pipe clip and remove the cylinder

head hanging bolt.

5. Remove the cylinder bolt and washer.

6. Remove the cylinder head and cylinder head gasket.

Caution

Do not drop the location pin into the crankcase.

To mount the cylinder head:

Installation is in the reverse order of removal. Precautions

for installation:

1. Confirm the location pin; clean all parts and

components, and check whether the cylinder head

oil through is unobstructed, clean and free of leak.

2. Replace new cylinder head gasket

3. The tightening torque of cylinder bolt is 45N.m.

Warning:

The cylinder head bolt must be fully screwed up to the

tightening torque of 45N.m, and carry out 100%

torque inspection.

Disassembly and assembly of cylinder head

Disassemble and assemble the cylinder head according to the following diagram.

Use the valve remover / replacerto remove and mount the intake valve and exhaust valve.

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

No.

Procedure

Quantity

Remarks

cylinder block

Cylinder head gasket

Coat the mixture of engine oil and molybdenum disulfide on the stem while assembling

Cylinder body gasket

Coat the mixture of engine oil and molybdenum disulfide on the stem while assembling

Dowel Pin

cylinder head

Assemble with sparse end facing up

spark plug

Assemble with sparse end facing up

Gas CAM shaft seat

Assemble with sparse end facing up

Bolt M6*105

Replace it with a new one as required

Cylinder head nut

flat washer

Replace it with a new one as required Tightening torque 18-25N.m.

flat washer

Use thread retaining adhesive while assembling Tightening torque 8-12N.m.

Muffler double head bolts

Gas CAM shaft baffle

Bolt M6*16

rectangular seals

The spark plug must be tightened to the specified tightening torque of 15～20N.m for fear of leak.

While mounting the intake / exhaust valve, coat the mixture of engine oil and molybdenum disulfide on valve stem for

preliminary lubrication.

While mounting the stud, please use specified thread retaining adhesive.

While mounting the valve spring, let the sparse end face up.

Notice:

Do not damage the oil shield lip while mounting.

The valve lock clamp must be mounted in place; dropout of the valve lock clamp is dangerous.

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Clearance gauge

Air gage

Outside micrometer

Vernier calipers

Chain slide

Cylinder head inspection

Check whether the cylinder head is unobstructed, clean

and free of leaks; check the cylinder head’s spark plug

hole and valve seat for cracks; insert the valve into the

valve guide bore and move it up and down to check its

movement; sway it back and forth and left and right to see

whether there is significant sloshing.

Check the cylinder head for deformation, and use the

edge ruler and clearance gauge to inspect the planeness

of the cylinder’s joining surface.

Maintenance limit: ≤0.05mm.

Measure the valve guide aperture.

Maintenance limit: ≤φ4.53mm

Measure the valve stem diameter.

Maintenance limit: IN≥φ5.15mm,

EX ≥φ5.15mm

Measure the width of the valve contacting surface.

Maintenance limit: ≤1.7mm

Measure the free length of the valve spring Maintenance limit: Internal spring≥35.00mm External spring ≥42.00mm. Calculate the clearance between the valve stem and valve guide Maintenance limit:IN≥0.09mm,

EX ≥0.10mm.

Cylinder

To remove the cylinder:

1. Remove the cylinder head cover (See Removal of

cylinder head cover)

2. Remove the camshaft (See Removal of camshaft);

3. Remove the cylinder head (See Removal of cylinder

head)

4. Remove the chain slide;

5. Remove cylinder connecting bolt

6. Remove the tensioner

7. Remove the cylinder; remove the cylinder gasket.

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Whether the cylinder wall is scratched

Clearance gauge

Edge ruler

Clearance gauge

Cylinder inspection

Check the cylinder for abrasion or damage, and check the

cylinder wall for scratch.

Notice:

Do not drop the location pin into the crankcase.

Do not bruise the cylinder wall.

To mount the cylinder :

Installation is in the reverse order of removal. Precautions

for installation:

1. Confirm the location pin; clean all parts and

components, and check whether the cylinder oil

through is unobstructed, clean and free of leak

2. Replace a new cylinder gasket, and confirm the

notch direction of the piston ring; mount the cylinder

after fastening the piston with the piston slide gage

seat

Check the cylinder wall for deformation, and use the edge

ruler and clearance gauge to inspect the planeness of the

cylinder’s joining surface.

Maintenance limit: ≤0.05mm.

Measure the cylinder internal diameter. The measurement

shall be made at three positions: top, middle and bottom,

measure in two crossing directions for each position, and

finally calculate their mean value.

Maintenance limit: ≤φ85.10mm

Work out the Cylinder’s grade slope.

Maintenance limit: ≤0.05mm

Work out the Cylinder’s roundness.

Maintenance limit: ≤0.05mm

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Piston

Piston pin

Piston pin retainer

Piston notch

Piston pin retainer gap

First ring

Second

Oil Ring

Piston

To remove the piston:

1. Remove the cylinder head cover (See Removal of

cylinder head cover)

2. Remove the camshaft (See Removal of camshaft).

3. Remove the cylinder head (SeeRemoval of cylinder

head).

4. Remove the cylinder (See Removal of cylinder)

5. Remove the piston pin retainer at one side, and pull

out the piston pin.

6. Take out the piston.

3. Mount the cylinder (See Installation of cylinder).

4. Mount the cylinder head (See Installation of cylinder

head);

5. Mount the camshaft (See Installation of camshaft).

6. Mount the cylinder head cover (See Installation of

cylinder head cover).

Notice:

Assemble the piston with the top side with the marker

“ ” facing exhaust side.

Do not drop the piston pin retainer into the crankcase.

Disassembly and assembly of piston:

Disassemble and assemble piston according to the

following diagram.

While assembling, let the side with marker face the top of

piston; if the marker can not be clearly

identified, judge according to the shape of the piston ring

(as shown in the figure below). Stagger the piston ring

gap by more than 120º

While assembling the oil ring, mount the corrugated ring

first, then mount the lip rings at both sides, with the

corrugated ring joint staggering with both lip rings by

Do not drop the piston pin retainer into the crankcase.

To mount the piston pin:

1. Coat engine oil on the piston pin surface and let the

2. Mount the new piston pin retainer, with the gap

Notice:

oil go through the piston and the small end bore of

the crankshaft link rod.

staggering the piston gap by more than 15°as

shown in the above.

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90 °, and with the two lip rings staggering with each

other by 180°

The piston pin retainer shall be replaced with new one

while assembling after disassembling, and stagger the

gap and the piston notch by more than 15°.

YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Procedure

Quantity

Remarks

Sequence of disassembling

Assembling is in the reverse order of disassembling.

Crank rod assembly

2 Piston

3 Piston ring

4 Piston pin

5 Piston pin circlip

With the side with marker face the top of

Notice: Do not damage the piston pin and piston ring. Do not reverse the mounting position of the first ring (ATG marker) and second ring (A marker).

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YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston

Piston inspection

Check the piston for abrasion or damage, cracks, etc. and

check the skirt section for scratch.

Measure the piston external diameter at the position

10mm above the piston skirt.

Maintenance limit: ≥φ52.39mm

Measure the piston pin hole inside diameter.

Maintenance limit: ≤φ20.05mm.

Measure the clearance between the piston ring and the

piston groove before removing the piston ring.

Maintenance limit: First ring / Second ring≤0.12mm, Oil

ring ≤0.40mm.

Mount the piston rings into the cylinder respectively and

measure the gap clearance. Maintenance limit: First ring

≤0.65mm, Second spring ≤0.7mm.

Measure the piston pin external diameter.

Clearance gauge

Maintenance limit: ≥φ12.98mm

Work out the clearance between the cylinder and piston.

Maintenance limit: ≤0.10mm.

Work out the clearance between the piston and piston pin.

Maintenance limit: ≤0.07mm.

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Clutch

Right crankcase cove

Engine

Clutch and Right crankcase cover

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Maintenance notice

Clutch

Troubleshooting

Right crankcase cover

Item

Standard value

Maintenance limit value

Clutch

Handle free stroke

10～20

Spring free length

39.74

38.7

Disc thickness

3.0

2.8

Disc planeness

Clutch plate thickness

1.4

Clutch plate planeness

0.10

0.20

Clutch and Right crankcase cover

Maintenance notice

To carry out the maintenance stated herein, it is unnecessary to detach the engine from the frame. However, the engine

lubricating oil must be discharged.

Remove the protecting shield, and loosen the rear brake cylinder body, rear brake lamp switch and spring and rear brake

return spring, and then pull out the rear brake pedal.

Before assembling, clean all parts and components with cleaning agent and dry them with compressed air.

To assemble the clutch, loosen the clutch spring and coat engine oil on the clutch disc; in case of replacing new clutch, the

clutch disc must be soaked in oil for over 24 hours before being assembled.

Be careful not to damage the crankshaft seal on the right crankcase cover.

Technical specifications & maintenance benchmark

Clutch retaining nut 114-126N.m

Primary driving gear fastening nut 143-157N.m

Clutch lift plate fastening nut 8-12N.m

Key torque values

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Troubleshooting

 Clutch

In case of clutch operation failure, a better correction may usually achieved by adjusting the clutch handle free stroke.

 Clutch slipping while accelerating

1) Insufficient free stroke;

2) Clutch disc abrasion;

3) Clutch plate deformed or bent;

4) Clutch spring failure.

 Excessive handle pressure

1) Clutch cable galling, damaged or dirty;

2) Clutch push rod damaged or jammed.

 Hard clutch operation

There is burr on clutch housing chute.

 Shift lever can’t return

1) Return spring cracked or slipped;

2) Transmission shaft plate convenes with crankcase or crankcase cover.

 Vehicle moves slowly upon firmly grabbing the handle

1) Excessive handle free stroke

2) Clutch plate deformed or bent.

 Hard shifting or impossible to shift

1) Locating plate bent;

2) Stopping plate assembly damaged or cracked;

3) Shifting yoke cracked or slipped;

4) Clutch improperly adjusted.

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Oil filter cover

Right crankcase cover

Clutch operating lever

Right crankcase cover

Waste engine oil flow into the oil

Clean up the seal surface

Right crankcase cover

To remove the cylinder head cover:

1. Remove the oil drain plug to drain the engine oil

inside the crankcase.

2. Separate the clutch control line with the clutch

operating lever

3. Remove the oil filter cover.

4. Remove the right crankcase cover connecting bolt

5. Take out the right crankcase cover component.

6. Take out the right crankcase cover sealing paper

gasket

To install the right crankcase cover:

1. Confirm the location pin; clean up the residual

sealing paper gaskets on the right crankcase and

right crankcase cover.

2. Replace with a new right crankcase cover sealing

paper gasket.

3. Mountthe right crankcase cover.

4. Mount the oil filter cover.

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YG125-23 Maintenance ManualClutch and Right crankcase cover

5. Adjust the direction of the clutch operating lever,

Mount the clutch operating lever, rear brake return

spring, cotter pin, rear brake lamp switch, etc.

6. Refill engine oil.

Notice:

Do not scrape the crankshaft oil seal. Assemble only when the rack side of the clutch push rod faces the crankshaft.

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

Right crankcase cover

1 2

Right crankcase cover sealing paper gasket

Replace it with a new one while assembling

clutch push rod

1 4

rubber ring

1 5

Oil Level Gauge

1 6

lever return spring

1 7

elastic cylindrical pin

1 8

clutch lever

1 9

Bolt M6*40

Replace it with a new one as required

Bolt M6*32

Bolt M6*35

Clutch zip plate

1 13

Right crankcase cover sealing paper gasket

Replace it with a new one while assembling

O-ring

Disassemble and assemble of right crankcase cover

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Clutch push rod

Nut

Washer

Clutch

Washer

Clutch

Washer

Fastening tool

Clutch

To remove the clutch:

1. Remove the right crankcase cover (See “Removal of

right crankcase cover").

2. Remove the clutch push rod with the clutch push rod

extractor.

To install the clutch:

1. Mount the clutch washer with the sabotage side

facing the main shaft right bearing.

2. Mount the clutch.

3. Mount the butterfly washer and retaining nut M18.

Note to assemble with the protruding side of the

butterfly nut washer facing outside.

3. Use the fastening tool to clamp the primary driving

and driven gear, and remove the nut M18 and

butterfly washer.

4. Remove the clutch.

5. Remove the clutch washer.

4. Use the fastening tool to clamp the primary driving

and driven gear, and screw up the retaining nut M18

to the tightening torque of 120N.m.

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Right crankcase cover

5. Mount the clutch push rod with the clutch push rod

assembler .

6. Assemble the right crankcase cover by turning the

clutch push rod until its rack side faces the

crankshaft. (See “Installation of right crankcase

cover").

Warning

Thread retaining adhesive LOCTITE243 must be

coated on the clutch retaining nut M18 while

assembling, with the tightening torque being

120N.m.

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

clutch bush

Tightening torque 12N.m.

clutch assembly

Nut M14*1

Flat washer

Deepgroove ballbearing

Gum base, soaking oil while assembling

Clutch out cover

Clutch lug washer

Clutch center bush

Clutchfriction plate

clutch driven plate

Assemble with the sub stage side facing inwards

Clutch platen

Clutch spring

Clutch plate

Bolt m6*25

Removal / Installation of Clutch

Disassemble and assemble of clutch

Disassemble and assemble the clutch according to the following diagram.

While removing the clutch lift plate, alternatively loosen the 6connecting bolts to avoid damage of cracking due to uneven

force of the clutch spring. While mounting the clutch lift plate, alternatively loosen the 6 connecting bolts to the specified torque. Assemble with

the protruding side of the butterfly washer facing the plain washer

While assembling, the clutch disc must be coated with lubricating oil; in case of replacing new clutch disc, it must be

soaked in oil for over 24 hours before being assembled. Do not further disassemble the clutch housing, otherwise

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YG125-23 Maintenance ManualClutch and Right crankcase cover

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

clutch bush

Tightening torque 12N.m.

clutch assembly

Nut M14*1

Flat washer

Deepgroove ballbearing

Gum base, soaking oil while assembling

Clutch out cover

Clutch lug washer

Clutch center bush

Clutchfriction plate

clutch driven plate

Assemble with the sub stage side facing inwards

Clutch platen

Clutch spring

Clutch plate

Bolt m6*25

damage will occur.

Explanation:

While unscrewing bolt, do it in a crossing way twice or thrice. Do in the same way for screwing up bolt.

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Edge ruler

Clearance

gauge

Clutch inspection

Clutch plate planners measurement

Clutch plate thickness measurement

Outside micrometer

Inspection

Are there scars or cuts?

Disc thickness measurement Outside micrometer

Clutch spring free length measurement

Vernier calipers

YG125-23 Maintenance ManualClutch and Right crankcase cover

1. Check whether the housing splice has scars or cuts

due to the collision of clutch disc.

2. Check the clutch disc. If there is a scratch or

depigment or a strong scorching smell, replace it.

Measure the thickness of each clutch disc.

Maintenance limit: ≥2.8mm.

5. Measure the free length of the clutch spring.

Maintenance limit: ≥41.3mm.

3. Check the clutch plate for distortion, and check

the planners with a clearance gauge.

Maintenance limit: ≤0.20mm.

4. Measure the thickness of each clutch plate. The

thickness is 1.4mm.

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YG125-23Maintenance ManualMagneto and starting system

Engine

Double-linked Gear

Rotor assembly

Left front cover

Idle gear

Disk gear

Double-linked gear cover

8、Magneto and starting system

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YG125-23Maintenance ManualMagneto and starting system

Maintenance notice

Rotor assembly

Left front cover

Starting motor and starting transmission system

Item

Standard value

Maintenance limit value

Disk gear

Disk gear external diameter

φ51.67～φ51.7

φ51.57

One-way device outer

body

One-way device outer body internal

diameter

φ35～φ35.027

φ35.040

Disk gear washer

Washer thickness

5.65～5.75

5.6

Magneto and starting system

Maintenance notice

To carry out the maintenance stated herein, and the engine lubricating oil must be drained.。

Before assembling, clean all parts and components with cleaning agent and dry them with compressed air.

When mount， Mount the parts, coat the mixture of engine oil and molybdenum disulfide onto the left crank journal,as the

initial lubrication。

Do not dent the seal surface, and do not damage the stator coil.

Technical specifications & maintenance benchmark

Key torque values

Rotor fastening nut36～45N.m

Stator fastening bolt8-12N.m

Pressure plate fastening bolt7～10N.m

Starting clutch connecting screw8～12N.m

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YG125-23Maintenance ManualMagneto and starting system

Left front cover sealing paper gasket

Left front cover

Left rear pla

Gear shift pedal

Draining engine oil

Left front cover

To remove the left front cover:

1. Remove the gear shift pedal and left rear cover, and

separate the magneto lead connector with the main

cable.

2. Unscrew the oil drain plug to drain the engine

lubricating oil inside the engine

3. Remove the double-linked gear cover connecting

bolts

4. Remove the left front cover.

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YG125-23Maintenance ManualMagneto and starting system

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

stator module

1 2

Bolt M5*27

Replace it with a new one as required

Nut M14*1.25

1 4

rotor assembly

1 5

Bolt M6x16

Magneto clamp

1 7

lightened spring washer

1 8

flat washer

1 9

disc gear cutter

1 10

needle bearing

1 11

Bolt M6*12

Disassembly and assembly of left front cover

Disassemble and assemble the left front cover according to the following diagram.

Use the thread retaining adhesive LOCTITE 648 while assembling the pressure plate bolt.

Use the thread retaining adhesive LOCTITE 648 while assembling the magneto stator connecting bolt.

In case of O-ring aging, prolonging or deforming, replace it.

Notice:

Do not dent the seal surface, and do not damage the stator coil.

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YG125-23Maintenance ManualMagneto and starting system

Double-linked Gear

Rotor fastening tool

Rotor extracto

Disk gear

Disk gear washer

Rotor assembly

To remove the clutch:

1. Remove the left front cover (See Removal of left

front cover).

2. Remove the starting idle gear, double-linked gear,

etc

3. Use the rotor fastening tool to fasten the rotor, and

remove the fastening nut M12 and plain washer.

4. Use the rotor extractorto extract the rotor..

5. Remove the rotor assembly washer、 disk gear、

needle bearing、disk gear washer

Notice:

Do not let the semicircular key drop into the

crankcase.

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YG125-23Maintenance ManualMagneto and starting system

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

Screw M8×16

Use thread retaining adhesive LOCTITE 648 while assembling, with the tightening torque being 25N.m

One-way device outer body

3 One-way device

Be careful of the assembling direction

Armature

Disassembly and assembly of rotor assembly

Disassemble and assemble the rotor assembly according to the following diagram.

Use thread retaining adhesive LOCTITE 648 on the screw while assembling, with the tightening torque being 10-14N.m

M8×16

Armature

One-way device

One-way device outer body

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YG125-23Maintenance ManualMagneto and starting system

Take it out from the left Motor connecting bolt

Torque

Rotor fastening tool

molybdenum disulfide

Double-linked gear

Starting motor and starting

Transmission system

1. Remove the live wire and earth wire of the starting

motor.

2. Remove the starting motor connecting bolt M6×25.

3. Push the motor towards the right and lift it, and then

carefully take it out from the left side.

Installation is in the reverse order of removal

To mount the rotor assembly:

1. Mount the disk gear washer, coat the mixture of

engine oil and molybdenum disulfide onto the left

crank journal, and mount the disk gear and confirm

the semicircular key.

Apply the mixture of engine oil and

2. Mount the rotor assembly

3. Mount the plain washer and apply thread retaining

adhesive LOCTITE648 to the fastening nut M12; use

the rotor fastening tool to fasten the rotor, and

screw up the nut M12 to the torque of 45N.m

4. To install the double-linked gear:

The Washerand the double-linked gear is assembled into

the left crankcase

5. To install the left front cover:

⑴Clean the sealing paper gasket remaining on the left

crankcase and left front cover, replace with new left front

cover sealing paper gasket and confirm the location pin,

starting idle gear, double-linked gear, etc. are in correct

position.

⑵Mount the left front cover,

⑶Mount the left front cover bolt

⑷ Connect the magneto leads.

⑸ Mount the left rear cover, gear shift pedal and engine

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YG125-23Maintenance ManualMagneto and starting system

Edge ruler

Left front cover

Double-linked gear cover

Double-linked gear

Vernier calipers

protection plate.

⑹ Put on the oil drain plug and refill engine lubricating oil.

6. To install the double-linked gear cove:

⑴Clean up the left front cover and parts，mount the

starting idle gear, double-linked gear, etc.

⑵The O-ring into the double gear cover ，In case of

O-ring aging, prolonging or deforming, replace it.

⑶Mount the double-linked gear cove,

⑷screw up to the torque of 8-12N.m

Notice:

Never let adhere to the left crank conical surface and

rotor tapered surface.

The disk gear shall only be capable of rotating

clockwise flexibly relative to the rotor.

Use the thread retaining adhesive LOCTITE 648 while

assembling the pressure plate bolt.

Warning

Thread retaining adhesive LOCTITE243 must be

applied to the rotor retaining nut M12 while

assembling, with the tightening torque being 45N.m.

Check

1、Check the spline gear of output shaft of the starting

motor for defect, squeezing, deforming, etc.

2、Check the idle gear and double-linked gear for missing

teeth, etc.

3、Check the idle gear shaft and double-linked gear shaft

for bending.

4、Check the rotating flexibility and unidirectivity of the disk

gear (relative to clockwise rotor rotation).

5、Check the axial play of the disk gear, generally not less

than 0.4mm.

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YG125-23Maintenance ManualMagneto and starting system

Outside micrometer

Vernier calipers

6、Measure the disk gear diameter, the maintenance limit: ≥φ42.084mm

7、Measure the washer thickness, the maintenance limit:

≥0.4mm

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

Right hand crankcase body

Crankshaft

Gearshift drum

Counter shaft

Main shaft

Left hand crankcase body

9、Crankcase, crankshaft and Shift mechanism

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

Maintenance notice

Crankshaft and balance shaft

Troubleshooting

Variable transmission system

Crankcase

Item

Standard value

Maintenance limit value

Shift fork claw thickness

Gear shift fork

6.05～5.40

5.80

Crankshaft

Connecting rod small end bore diameter

Ф20.03～Ф20.038

Ф20.063

Disc planeness

0.028～0.042

0.06

Connecting rod big end radial clearance

0.30～0.60

0.80 Radial runout

0.03

0.10

Left crank journal

Ф29.959～Ф29.98

Ф29.87

Crankcase, crankshaft and Shift mechanism

Maintenance notice

To carry out the maintenance stated herein, the engine must be removed from the frame.

To repair the crankshaft, balance shaft or variable transmission system, the left hand crankcase and the right hand

crankcase must be separated, which is known as crankcase dissection. Before crankcase dissecting, the following parts

and components of the engine shall be removed:

1 Right hand crankcase, clutch, gear shifter

2 Cylinder head cover, camshaft, cylinder head, cylinder and piston (See “Cylinder head, cylinder and piston”);

3 Left front cover, rotor assembly, electrical starting transmission system (See “Magneto and electrical starting

system”);

4 Driving drive sprocket, shift switch.

Before assembling, clean all parts and components with cleaning agent and dry them with compressed air.

Technical specifications & maintenance benchmark

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

Troubleshooting

 Noise from engine

1. Crankshaft bearing worn;

2. Connecting rod big end bearing worn;

3. Driving/driven shaft bearings worn;

4. Balance shaft supplementary tooth spring failure.

 Driving/driven shaft gears engaged badly

1. Shift fork bent or damaged;

2. Shift fork shaft bent;

3. Gearshift drum badly machined or bearing shifted;

4. Driving/driven shaft bearings shifted.

 Gear shift trouble

1. Shift fork bent or damaged;

2. Shift fork shaft bent;

3. Gearshift drum guiding slot worn or damaged;

4. Clutch improperly adjusted.

5. Locking plate bend or fray；

6. Five star plate assy broken

7. Pin broken or slip off

 Gear shaft cannot return back

1. Sping broken or slip off

2. Variable-speed shaft plate interfere crankcase or crankcase cover

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

Balance shaft

Gearshift

Crankshaft box paper pad

Driving shaft

Counter shaft

Cranks-haft

Counter shaft oil seal

Gearshift drum oil seal

Shifting arm oil seal

Remove the mould closing bolt

Crankcase

To remove the crankcase:

1. Remove the engine from the frame (engine oil fully

drained) and put it on the assembly operating table.

2. Remove such parts and components as right hand

crankcase cover, clutch, gear shifter, cylinder head

cover, camshaft, cylinder head, cylinder, piston, left

front cover, rotor assembly, electrical starting

transmission system, driving drive sprocket, etc.

(Refer to the related sections).

Notice

Do not pry the left/right hand crankcase body by

inserting such tools as screwdrivers into the mould

closing face.

To mount the crankcase:

1. Place the right hand crankcase on the assembly

operating table, and assemble the internal parts and

components of the crankcase, including crankshaft,

balance shaft, driving/driven shaft, gearshift drum,

shift fork, etc

2. Clean up the left and right crankcase box surface,

put the new crankcase paper pad, confirm the

positioning pin.

3. Use a bakelite hammer or a nylon hammer to strike

the left hand crankcase gently to separate it with the

right hand crankcase.

4. Remove the driving/driven shaft, gearshift drum, shift

fork, etc.

5. Remove the cranks-haftand balance shaft。

3. Use the counter shaft oil seal guide to protect the

counter shaft oil seal, use the gearshift drum oil seal

guide to protect the gearshift drum oil seal, and

mount the left hand crankcase (closing).

4. Mount the mould closing bolt and fasten it.

5. Mount other parts and components of engine, mainly

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

Mount the mould closing bolt

include right hand crankcase cover, clutch, gear

shifter, cylinder head cover, camshaft, cylinder head,

cylinder, piston, left front cover, rotor assembly,

electrical starting transmission system, driving drive

sprocket, etc. (Refer to the related sections).

6. Mount the assembled engine onto the frame, and

engine oil to complete the assembly of the complete

vehicle.

Notice:

To close the crankcase, use your hand(s) to gently

press it in place, or use a Bakelite hammer to strike it

gently. Never strike it forcibly.

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

No.

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

Right hand crankcase

2 Pin

3 Pad

4 O-ring

engine oil filter net

6 Release oil bolt

7 Pad

8 Left hand crankcase

9 O-ring

Double head bolt

Main gear plate

Bolt M6*16

Pin 10*14

BOLT,FLGM6*40

BOLT,FLGM6*45

BOLT,FLGM6*70

Removal and installation of crankcase

Disassembly and assembly of left hand crankcase

Disassemble and assemble the left hand crankcase according to the following diagram.

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

No.

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

Left hand crankcase

Apply engine oil while assembling

Crankshaft bearing 6203

Apply engine oil while assembling

Driving shaft bearing 6006

Let the oil seal side face inward and apply engine oil while assembling

Balance shaft bearing 6301/13/C3

Apply engine oil while assembling

Crankshaft paper gasket -HK121610

Replace it with a new one while assembling

Arm stopper bolt M8x41

Do not remove it

Do not remove breather pipe joint, otherwise damage will be caused. Generally, do not remove the bearing; if it is

removed, coat engine oil on surfaces of spare parts while pressing it in; mount it with SST and confirm the press-in depth

of the bearing.

Assemble the driving shaft bearing with the with oil seal facing inwards. Disassembling the needle bearing may damage it;

in case it is damaged, always change a new one. Replace oil seal with a new one after being removed.

Notice:

Do not dent the sealing surface, and assemble the driving shaft bearing with the side with oil seal facing inwards.

Disassembly and assembly of right hand crankcase

Generally, do not remove the bearing; if it is removed, coat engine oil on surfaces of spare parts while pressing it in; mount

it with SST and confirm the press-in depth of the bearing. Assemble the driven shaft bearing with the with oil seal facing

inwards.

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

No.

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

Right hand crankcase

2 Balance shaft bearing 6302

Apply engine oil while assembling

Driving shaft bearing 62/22/C3

Let the oil seal side face inward and apply engine oil while assembling

Gear shift shaft oil seal 18x34x5

Apply engine oil while assembling

Driven shaft bearing 60/18RLYAB

Let the oil seal side face inward and apply engine oil while assembling

Driving shaft bearing pressure plate

Stud bolt M6×16

Use thread retaining adhesive LOCTITE 648 while assembling

Disassembling the needle bearing may damage it; in case it is damaged, always change a new one.

Replace washer with new ones after being removed.

Apply the thread retaining adhesive LOCTITE 648 while assembling the stud bolt.

Notice:

Do not the sealing surface, and assemble the driven shaft bearing with the side with oil seal facing inwards.

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

Crank-shaft

Balance shaft

Electric drier

Balance shaft

Crank-shaft

Aligning the markers

Crankshaft and balance shaft

To remove the crankshaft and balance shaft:

1. Remove the (left hand) crankcase (See “Removal of

left hand crankcase").

2. Remove the balance shaft.

3. Remove the crankshaft.

Notice:

2. Use a high power electric drier to heat the right

crankcase body balance shaft bearing until the

temperature at the inner circle of the bearing

reaches 106℃, and then assemble the balance shaft.

Remember to align the markers on the driving and

driven gears.

3. Mount the left hand crankcase (See “Installation of

crankcase").

While removing, you may strike the balance shaft and

crankshaft gently; however, always avoid damaging

them.

To mount the crankshaft and balance shaft:

1. Place the right hand crankcase assembled with

variable transmission system (driving/driven shaft,

etc.) on the assembly operating table, and use a

high power electric drier to heat the right crankcase

body crankshaft bearing until the temperature at the

inner circle of the bearing reaches 106℃, and then

assemble the crankshaft.

Notice:

Only assemble when the temperature reaches 106℃,

otherwise it can’t be assembled. Never savagely

strike it!

The markers on the driving and driven gears must be

aligned.

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

No.

Procedure

Quantity

Remarks

Removing order

Installation is in the reverse order of removal

Left hand crankcase

2 Crankshaft

3 Balance shaft

4 Right hand crankcase

3 2 1

Knock

Removal and installation of crankshaft and balance shaft

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

No.

Procedure

Quantity

Remarks

Sequence of disassembling

Assembling is in the reverse order of disassembling.

Balance shaft

Apply engine oil while assembling

Driving gear

Apply engine oil while assembling

Pad

Apply engine oil while assembling

Driven plate

Buffer rubber

Apply engine oil while assembling

Driven gear

Apply engine oil while assembling

Spring

Apply engine oil while assembling

WASHER

Apply engine oil while assembling

WASHER

Apply engine oil while assembling

WASHER

Apply engine oil while assembling

RACE

Apply engine oil while assembling

Pad

Apply engine oil while assembling

Nut M14*1.25

bear

Apply engine oil while assembling

Disassembly and assembly of crankshaft and balance shaft

Do not further disassemble the crankshaft, otherwise the spar parts may be damaged.

Disassemble and assemble the balance shaft according to the following diagram.

Notice:

Always align the markers while assembling the balance shaft.

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

100

Inside micrometer

105

Radial

Dial gauge

Suppor

Outside

Clearance gauge

Crankshaft and balance shaft inspection

1. Check whether the crankshaft journals are

abnormally worn, whether the connecting rod can

rotate flexibly and whether there is significant noise

while rotating.

Measure the connecting rod small end bore diameter.

Maintenance limit: ≤Ф20.063mm.

5. Measure the left hand crank journal.

Maintenance limit: ≥Ф29.87mm.

2. Measure the crankshaft radial run out.

Maintenance limit: ≤0.10mm.

3. Measure the connecting rod big end radial

clearance.

Maintenance limit: ≤0.06mm.

4. Measure the connecting rod large end side

clearance, the maintenance limit: ≤0.80mm.

6. Check whether the balance shaft supplementary

tooth spring fails and whether the balance shaft

supplementary tooth can return.

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

101

Driving shaft

Counter shaft

Gearshift drum

Driving shaft

Counter shaft

Gearshift drum

Shift arm

Variable transmission system

To remove the variable transmission system:

1. Remove the (left hand) crankcase (See “Removal of

left hand crankcase").

2. Remove the shift fork shaft.

3. Remove the gearshift drum.

4. Remove the shift fork.

5. Remove the driving/driven shaft

To mount the variable transmission system:

1. Place the right hand crankcase assembled with

crankshaft and balance shaft on the assembly

operating table, and the driving/driven shaft and

assemble the them together.

2. Assemble the shift fork with

3. Mount the gearshift drum.。

4. Change the O-shaped sealing ring, mount the shift

fork, and check whether the driving/driven shaft can

rotate freely

5. Mount the shift arm

6. Replace it with a new paper pad assembly one while

assembling ，mount the left hand crankcase(See

“Installation of crankcase")

Notice:

Only assemble when the temperature reaches 106℃,

otherwise it can’t be assembled. Never forcefully

strike it!

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

No.

Procedure

Quantity

Remarks

Sequence of disassembling

Assembling is in the reverse order of disassembling.

Shift shaft

Apply engine oil while assembling

Pad 6*14*1

3 Bolt M6*28

4 Shift show

5 Shift show trigger

6 Shift fork

Apply engine oil while assembling

Shift fork(right)

Apply engine oil while assembling

driving shaft

Apply engine oil while assembling

driven shaft

Apply engine oil while assembling

Warping spring

Bolt M8*28

gearshift drum

Apply engine oil while assembling

Shift plant assm.

Apply engine oil while assembling

Shift fork

Apply engine oil while assembling

Bolt M6*25

Bolt

Replace it with a new one while assembling

Apply engine oil while assembling

O-ring

Apply engine oil while assembling

Removal and installation of driving shaft and driven shaft and gearshift drumand shifting shaft

Attention: the washer, retainer, etc. must be assembled in place at the correct positions, the spare parts 8apply lubricating

oil.while assembling

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

104

Driving/driven shaft inspection

Gearshift drum inspection

Shift fork shaft inspection

Outsidemicrometer

Pull out the shift arm combination

Mount the left crankcase assembly

Check

Check the driving/driven shaft gears for serious abrasion

and pit corrosion; check whether the shift fork is bent and

whether the gearshift drum guiding slot is damaged.

Measure the shift fork claw thickness.

Maintenance limit: ≥5.80mm.

Shift mechanism

To remove the shift mechanism

1. Removal of left hand crankcase cover(See “Removal

of left hand crankcase cover ").

2. Remove the unloaded rotor assembly, left crankcase

assembly(See “Removal of left hand crankcase

cover ").

3. If only remove unloading gear arm, is not required to

remove unloading gear drum assembly can be

directly drawn outward shift arm combination.

To mount the shift mechanism

1、Mount the gearshift arm combination

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YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism

105

2、Mount the left crankcase body combination（Use oil seal

guide to protect oil seal）

3、Mount the rotor assembly(See “Mount of left hand

crankcase cover ").

4、Mount the left hand crankcase cover(See “Mount of

right crankcase cover ").

Warning

Thread retaining adhesive LOCTITE243 must be

applied to the rotor retaining nut M12 while

assembling, with the tightening torque being 45N.m.

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YG125-23Maintenance ManualFrame and exhaust system

106

10、Frame and exhaust system

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YG125-23Maintenance ManualFrame and exhaust system

107

Maintenance notice

Removal and installation of rear mudguard

Troubleshooting

Removal / installation of exhaust muffler

Coverings, headlamp and meter

Rear position lamp assembly

Component description

Damage form

Trouble symptom of component

Trouble symptom of motorcycle

Repair method

Frame

The frame is deformed or broken.

Running off-tracking

Calibrate or replace frame

Main stand Deformation or fractured

Deformation or fractured

Effect of parking

Replace the main

stand

Return spring is fractured

Main stand impossible

to return

Effect of parking

Replace the return

spring

Covering parts

Broken

Effect the appearance

Replace or repair

Covering parts

Fender

Damaged

Broken

Effects of fender effect

Replace the fender

Seat

Broken

Decrease of the

comfortable

Replace the seat

Footrest

Broken and deformation

Replace the footrest

Component

description

Damage form

Trouble symptom

ofcomponent

Trouble symptom of

motorcycle

Repair method

Exhaust

pipegasket

The gasket is broken．

Exhaust pipe leakage．

Engine exhaust noise is

too loud．

Replace the exhaust

pipe gasket．

Exhaust

muffler

The muffler case is broken．

The muffler case is

broken．

Engine suction noise is too

loud．

Replace the exhaust

muffler．

Frame and exhaust system

Maintenance notice

To carry out the maintenance stated herein, take special care of the scratches and damages to the coverings, meter and light fittings. Removing or repairing the parts and components before the exhaust system is cooled down may cause serious burn injury.

This section mainly includes the removal and installation of the complete vehicle’s coverings, rear mudguard, exhaust

muffler, radiator and lamps.

Troubleshooting

 Excessive exhaust noise

 Remove the engine cycle tube

 Abnormal operation

 Remove the engine cycle tube

Maintenance of Frame

Maintenance of Exhaust Muffler

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YG125-23 Maintenance ManualFrame and exhaust system

107

assembly bolt

side cover

lamp connecting wire

Remove the bracket

Remove 4 hole covers

Remove the 3 connection nuts.

Remove turn the connecting wire.

Side cover and seat

 The key opens the cushion lock，Remove the seat。

 Remove the left/right side cover assembly. Handle it

carefully in order to prevent scratching the exterior

decorating surface.

 Remove the meter assembly (total of 3 connecting

bolts).

 Remove the 3 connecting bolts in the headlamp

bracket.

 Pull off the headlamp patch plug to remove the

headlamp.

To mount the coverings, headlamp and meter:

The installation of the coverings, headlamp and meter is

in the reverse order of removal. During installation, do not

scratch the coverings or damage the bulb.

Notice

During removal and installation, do not scratch the

outer surface of coverings or break the

bucklemortise.

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YG125-23 Maintenance ManualFrame and exhaust system

108

Adjusting

BULB

Bulb

Taillight lampshade

nut

Headlamp dimming

Before driving, check the brightness, direction, etc. of the

headlamp.

The adjustment can be made to the headlamp in the left /

right and vertical directions.

 Loosen bolts and screws.  Move the headlights back and forth, Adjust the

lighting height to the desired location.

 Lock bolts and screws.

Headlight bulb 13.5V16.2/5.8W(LED), Do not remove

the replacement bulb.

 Replace the new signal light（LED）, Do not remove

the replacement bulb.

 The order in which the signal light are installed is

reversed.

Front and rear lamp bulb12V1.5W(LED)

Taillight、Taillight bulb

 Loosen the screws, Remove the rear lights.

 Replace the new taillights（LED）, Do not remove the

replacement bulb.

 The order in which the tail lights are installed is

reversed.

Taillight bulb：13.5V 1.2/2W(LED)

Position lampbulb

Replace the steering signal light.

 Loosen the nut,Remove turn the connecting wire，

Remove the signal lights.

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Removal / installation of exhaust muffler

To remove the exhaust muffler:

 Park the motorcycle on the plane ground with main

stand; pull off the oxygen sensor patch plug.

YINGANG YG125-23 Maintenance Manual

Specifications and Main Features

Frequently Asked Questions

User Manual