Yingang YG125-23 Maintenance Manual
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Yingang YG125-23 Maintenance Manual

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YG125-23Maintenance ManualForeword
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!
Foreword
1

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Summary of Contents for Yingang YG125-23

  • Page 1 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.

  • Page 2: Table Of Contents

    YG125-23Maintenance ManualContents Contents 1-12 Overview 13-23 Lubrication system 24-39 Inspection and adjustment 40-45 Fuel system 46-50 Removal and installation of engine 51-67 Cylinder head, cylinder and piston 68-78 Clutch and Right crankcase cover 79-87 Magneto and starting system 88-104 Crankcase, crankshaft and Shift mechanism 105-109 Frame and exhaust system 110-121...
  • Page 3 YG125-23MaintenanceManual Overview 1、Overview Engine Number Position Bar Tool About Motorcycle Maintenance Maintenance Period Table Technical Data of Main Performance Symbol Descriptions Standard Torque Values Engine Number Position Photo of Complete Vehicle: Frame Number Position: Engine Number Position: Engine Number Frame Number...
  • Page 4 YG125-23MaintenanceManual Overview Maintenance Precautions To disassemble and assemble a motorcycle, Whenever reassembling after being disassembled, special service tools (SST) and general-purpose replace new washers, sealing members, etc. tools must be used in accordance with relevant regulations. While fastening bolts or nuts, proceed in diagonal crossing sequence to gradually screw down to the The specified or equivalent lubricating grease (oil) required torque for 2 to 3 tries.

  • Page 5: Overview

    YG125-23MaintenanceManual Overview The connector shall be fully inserted in place. For a connector with lock, confirm whether the lock is In case the fuse is blown, check for the causes and, completely fixed. after being repaired, replace corresponding fuse Make sure the harness is not falling off as per the specified capacity.
  • Page 6 YG125-23MaintenanceManual Overview 13. The clamp shall reliably bite the wire harness The wire harness shall not be slackened or be forcibly pulled. Do notpull! In case of a welded clamp, it shall not bite the wire If the wire harness has to contact the edge or sharp harness towards the weld mark corner parts, the contacting part shall be protected with hose or adhesive tape.
  • Page 7 YG125-23MaintenanceManual Overview 14. When wiring, note when turning it leftwards or 18. Do not forcibly twist or forcefully bend the cable. rightwards to the limit position, the wire harness Because a deformed or damaged cable is the shall not be tightened up or slackened, and make cause of bad operation and damage.
  • Page 8 YG125-23MaintenanceManual Overview Technical Data of Main Performance Item Data Length 1740mm Width 800mm Height 1010mm Wheelbase 1245mm Min. ground clearance 170mm Complete vehicle weight Non-loaded weight: 111.5kg, Curb weight: 118kg, Frame type Cradle type Rake angle 26° Front suspension device spring &...
  • Page 9 YG125-23MaintenanceManual Overview Clutch Wet clutch, coil clutch, paper friction wafer Clutch operating system Manual mechanical Variable speed gear 5-speed constant mesh Primary reduction ratio 3.35 Ⅰ 3.077 Transmission gear ratio Ⅱ 1.789 Ⅲ 1.304 Ⅳ 1.091 0.929 Final reduction ratio 3.466 Gear shifting mode Left foot operated to and back type...
  • Page 10 YG125-23MaintenanceManual Overview Standard Torque Values ENGINE Thread diameter Item Quantity Torque value (N.m) Thread locker (mm) Cylinder head cover connecting bolt 8～12 40～50 Cylinder bolt 8～12 Valve adjusting screw nut 8～12 Timing driven sprocket bolt 7～11 Rocker-arm shaft cover 24～28 Magneto flywheel fastening nut 38～45 LOCTITE 243...
  • Page 11 YG125-23MaintenanceManual Overview Name and dimensions Torque value (N.m) 4.5 ～6 5mm bolt & nut 8 ～12 6mm bolt & nut 18 ～25 8mm bolt & nut 30 ～40 10mm bolt & nut 50 ～60 12mm bolt & nut 3.5 ～5 5mm Screw 7 ～11 6mm Screw...
  • Page 12 YG125-23MaintenanceManual Overview Magnetic generator rotor puller: for dismantling Rubber hanner, Iron hammer, Copper hammer magnetic generator rotor Feeler gauge: to measure the clearance of piston, Micrometer: to measure the dimensions of piston, piston cylinder, valve, etc. pin, etc. Dial gauge: to measure the wheel bouncing, cylinder Cylinder barometer: to measure the cylinder pressure inner diameter, etc.
  • Page 13 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.
  • Page 14 YG125-23MaintenanceManual Overview YINGANG TECNOLOGY Service Station. Symbol Descriptions Meanings of various symbols in this manual: Explanation Measures to be prompted during operating, inspecting and maintaining. NOTICE: Special instructions or disposal measures given to prevent motorcycle from being damaged. WARNING: Special instructions or measures given to avoid serious damages or personal injuries.

  • Page 15: Lubrication System

    Lubrication system YG125-23Maintenance Manual 2、Lubrication system 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 Maintenance notice This section introduces the inspection and replacement method of engine lubricating oil as well as the cleaning method of...
  • Page 16 Lubrication system YG125-23Maintenance Manual Troubleshooting ● ● Lubricating oil contaminated Lubricating oil consumes too fast 1. Fail to replace lubricating oil according to the There is leakage with the engine; maintenance period table; The piston ring is worn. 2. The pouring orifice thread is damaged thus causing The inlet/exhaust valve guide is worn;...
  • Page 17 Lubrication system YG125-23Maintenance Manual Engine Lubrication System Diagram Camshaft oil through Cylinder head oil through Cylinder oil through Crankshaft oil through Oil filter Spindle oil through Oil pump Oil strainer Countershaft oil through...
  • Page 18 Lubrication system YG125-23Maintenance Manual Cylinder block, cylinder head, camshaft bearing seat and a Left crankcase body oil through camshaftoil through 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.
  • Page 19 Lubrication system YG125-23Maintenance Manual 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;...
  • Page 20 Lubrication system YG125-23Maintenance Manual 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.
  • Page 21 Lubrication system YG125-23Maintenance Manual 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；...
  • Page 22 Inspection and adjustment YG125-23 Maintenance Manual 3、Inspection 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...
  • Page 23 YG125-23 Maintenance Manual 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 ●...

  • Page 24: Inspection And Adjustment

    Inspection and adjustment YG125-23 Maintenance Manual Spark Plug Lubricating oil Remove the spark plug cap. Remove the spark plug with Park the motorcycle on a flat surface, let the engine stop a socket wrench. Visually check whether there is any...
  • Page 25 Inspection and adjustment YG125-23 Maintenance Manual Timing phase While aligning 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”...
  • Page 26 Inspection and adjustment YG125-23 Maintenance Manual The main reasons for insufficient cylinder pressure sealing washer and detach the old chain tensioner. Take include: care not let the sealing washer and so on fall into the Incorrect valve clearance adjusted ...
  • Page 27 Inspection and adjustment YG125-23 Maintenance Manual the top of the crankcase cover, and both intake and Valve clearance exhaust rock arms do not move but stop at their loosest Notice: position, which shows that the piston is in its top dead center position of the compressing stroke.
  • Page 28 Inspection and adjustment YG125-23 Maintenance Manual Idle speed Air filter Notice Cleaning and replacement of air filter  Remove the left side covers Handle it carefully to Check and adjust the idle speed after all other items avoid scraping. of the engine have been adjusted to the specified ...
  • Page 29 Inspection and adjustment YG125-23 Maintenance Manual 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.
  • Page 30 Inspection and adjustment YG125-23 Maintenance Manual bleed air from the deflating valve of the brake caliper with Actuate the front brake handle a vacuum pump, and then refill brake fluid into the cylinder. When the vacuum pump has fully exhausted the air Min.
  • Page 31 Inspection and adjustment YG125-23 Maintenance Manual touch to the side of the brake disc. It shows that the brake and also on the brake cam alignment, shows the brake shoe has touched the wear limit shoe has been touched the wear limit. Please change it.
  • Page 32 Inspection and adjustment YG125-23 Maintenance Manual Clutch control line specs Front tire Rear tire Clutch is the key part of transmitting power in motorcycle 120/70-12 120/70-12 transmission system，should adjust it according to the Cold tire air Front tire Front tire pressure following overhauling content．The content is the free...
  • Page 33 Inspection and adjustment YG125-23 Maintenance Manual remount it, and then mount the clutch control line, finally If the chain is too loose or too tight, make adjustment. adjust it to a satisfied free stroke according to the fine Adjusting methods: adjustment.
  • Page 34 Inspection and adjustment YG125-23 Maintenance Manual Cleaning and coating oil supply. Seriously corroded conductor connectors of the battery shall be replaced. Notice This model uses the oil seal chain, so the selected washing oil shall be in corrosive to the oil seal; while...
  • Page 35 Inspection and adjustment YG125-23 Maintenance Manual Replacement of Fuse cause serious hurt to skin and eyes by contact. Set the ignition switch to “OFF” position. The specified In case of contact with it, wash it off for 5 minutes and see a doctor immediately.
  • Page 36 Inspection and adjustment YG125-23 Maintenance Manual  Loose the screw to disassemble the headlight. Front and rear lamp bulb  If the headlights are not bright, only new headlights will be Loosen the screws, remove the Tail lights replaced. If the Tail lights are not bright, only new Tail lights will be 13.5V 16.2/5.8W...
  • Page 37 Inspection and adjustment YG125-23 Maintenance Manual Suspension system Bolts, nuts and fasteners Front suspension All the bolts, nuts and fasteners shall be screwed up as Make the front brake in braking state and press the front per the maintenance period table. And check all the cotter fork bracket for several times, and check the front pins, safety gripping gears, locks, etc.
  • Page 38 YG125-23Maintenance ManualFuel system 4、Fuel system...

  • Page 39: Fuel System

    YG125-23Maintenance ManualFuel system Fuel 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 Maintenance notice This section introduces the knowledge related to the fuel system. CAUTION ...
  • Page 40 YG125-23Maintenance ManualFuel system Installation steps Removal and installation of fuel tank Disassemble step The installation procedures are the removal procedures in Remove the seat reverse order. While installing, note that the wiring of the fuel pump control wire shall be in strict accordance with the wiring diagram.
  • Page 41 YG125-23Maintenance ManualFuel system Remove and installation of throttle body Installation steps： Disassemble step： The installation procedures are the removal procedures in reverse order. While installing, the locating slot must be Removal of rear wheel aligned with the locating lobe of throttle body Warning: Donot further disassemble the removed throttle body;...
  • Page 42 YG125-23Maintenance ManualFuel system Aintenance of Air Cleaner Component Damage form Trouble symptom ofmotorcycle Repair method description The engine is difficult to start．Insufficient engine output；Poor performance of engine C1ean the filtering Too much dust deposit during idle run．Excessive fuel element．c1ean on the filtering element． consumption．...
  • Page 43 YG125-23 Maintenance ManualRemoval and installation of engine 5、Removal and installation of engine...

  • Page 44: Removal And Installation Of Engine

    YG125-23 Maintenance ManualRemoval and installation of engine Removal and installation of engine Maintenance notice Installation of engine Removal 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.
  • Page 45 YG125-23 Maintenance ManualRemoval and installation of engine Removal of engine Remove muffler(front part). Open the seat cushion, Detach the earth wire from the negative pole of the battery. Remove bracket from left and right. Remove the magnet motor to connect the cable, Drive sprocket.
  • Page 46 YG125-23 Maintenance ManualRemoval and installation of engine  Move the engine slowly from the right. 10. remove the Intake pipe, temperature sensor. 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 11.
  • Page 47 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston 6、Cylinder head, cylinder and piston Cylinder head cover Cylinder head Cylinder...

  • Page 48: Cylinder Head, Cylinder And Piston

    YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Cylinder head, cylinder and piston Maintenance notice Cylinder head Troubleshooting Cylinder Cylinder head cover Piston Camshaft 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;...
  • Page 49 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Top planeness 0.05 φ52.37～φ52.39mm mm φ52.37mm Piston external diameter Fit clearance with 0.01mm～0.04mm 0.04mm cylinder Piston and piston φ12.995mm～φ13mm φ12.995mm Piston pin external diameter φ13.002mm～φ13.008mm φ13.008mm Piston pin hole inside diameter Fit clearance 0.002mm～0.013mm...
  • Page 50 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Troubleshooting  ●Excessive noise Low cylinder pressure Valve: Incorrect valve adjustment; Incorrect valve clearance adjusted; Valve jammed or valve spring broken; Valve ablated or bent; Camshaft worn or damaged; Valve sealing failure; Timing chain too long, worn or damaged;...
  • Page 51 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Cylinder head cover with a valve clearance adjusting tool as required. To remove the cylinder head cover: Mount the valve cover, etc Remove the lower / upper eyehole covers and turn the crankshaft so that the piston is at the upper dead point of the compression stroke.
  • Page 52 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Camshaft To remove the camshaft: Remove the lower / upper eyehole cover and turn the crankshaft so that the piston is at the upper dead point of the compression stroke. Strip the timing chain from the timing driven sprocket, and remove the timing driven sprocket.
  • Page 53 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston 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 Max.
  • Page 54 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Pull off the spark plug cap, Installation is in the reverse order of removal. Precautions for installation: Confirm the location pin; clean all parts and components, and check whether the cylinder head oil through is unobstructed, clean and free of leak.
  • Page 55 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston 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.
  • Page 56 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Cylinder head inspection Measure the width of the valve contacting surface. Maintenance limit: ≤1.7mm 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...
  • Page 57 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Cylinder inspection Check the cylinder for abrasion or damage, and check the cylinder wall for scratch. Whether the cylinder wall is scratched Notice: Do not drop the location pin into the crankcase. Do not bruise the cylinder wall.
  • Page 58 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Piston Mount the cylinder (See Installation of cylinder). To remove the piston: Mount the cylinder head (See Installation of cylinder Remove the cylinder head cover (See Removal of head); cylinder head cover) Mount the camshaft (See Installation of camshaft).
  • Page 59 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston 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). With side with marker face the top of...
  • Page 60 YG125-23 Maintenance ManualCylinder Head, Cylinder and Piston Piston inspection Measure the piston pin external diameter. Check the piston for abrasion or damage, cracks, etc. and Clearance gauge Maintenance limit: ≥φ12.98mm check the skirt section for scratch. Measure the piston external diameter at the position Work out the clearance between the cylinder and piston.

  • Page 61: Clutch And Right Crankcase Cover

    YG125-23 Maintenance ManualClutch and Right crankcase cover Clutch and Right crankcase cover Clutch Engine Right crankcase cove...
  • Page 62 YG125-23 Maintenance ManualClutch and Right crankcase cover Clutch and Right crankcase cover Maintenance notice Clutch Troubleshooting 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.
  • Page 63 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 Insufficient free stroke; Clutch disc abrasion;...
  • Page 64 YG125-23 Maintenance ManualClutch and Right crankcase cover Right crankcase cover To install the right crankcase cover: To remove the cylinder head cover: Confirm the location pin; clean up the residual Remove the oil drain plug to drain the engine oil sealing paper gaskets on the right crankcase and inside the crankcase.
  • Page 65 YG125-23 Maintenance ManualClutch and Right crankcase cover Adjust the direction of the clutch operating lever, Mount the clutch operating lever, rear brake return spring, cotter pin, rear brake lamp switch, etc. Refill engine oil. Notice: Do not scrape the crankshaft oil seal.
  • Page 66 YG125-23 Maintenance ManualClutch and Right crankcase cover Disassemble and assemble of right crankcase cover Procedure Quantity Remarks Removing order Installation is in the reverse order of removal Right crankcase cover Right crankcase cover sealing paper gasket Replace it with a new one while assembling...
  • Page 67 YG125-23 Maintenance ManualClutch and Right crankcase cover Clutch To install the clutch: To remove the clutch: Mount the clutch washer with the sabotage side Remove the right crankcase cover (See “Removal of facing the main shaft right bearing. right crankcase cover").
  • Page 68 YG125-23 Maintenance ManualClutch and Right crankcase cover Mount the clutch push rod with the clutch push rod assembler . Assemble the right crankcase cover by turning the clutch push rod until its rack side faces the crankshaft. (See “Installation of right crankcase cover").
  • Page 69 YG125-23 Maintenance ManualClutch and Right crankcase cover Removal / Installation of Clutch Procedure Quantity Remarks Removing order Installation is in the reverse order of removal Tightening torque 12N.m. clutch bush clutch assembly Nut M14*1 Flat washer Deepgroove Gum base, soaking oil while assembling...
  • Page 70 YG125-23 Maintenance ManualClutch and Right crankcase cover 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. Procedure Quantity Remarks Removing order Installation is in the reverse order of removal Tightening torque 12N.m.
  • Page 71 YG125-23 Maintenance ManualClutch and Right crankcase cover Clutch inspection Check whether the housing splice has scars or cuts Measure the free length of the clutch spring. Maintenance limit: ≥41.3mm. due to the collision of clutch disc. Inspection Clutch spring free length measurement...
  • Page 72 YG125-23Maintenance ManualMagneto and starting system 8、Magneto and starting system Double-linked gear cover Idle gear Left front cover Rotor assembly Double-linked Gear Disk gear Engine...

  • Page 73: Magneto And Starting System

    YG125-23Maintenance ManualMagneto and starting system Magneto and starting system Maintenance notice Rotor assembly Left front cover Starting motor and starting transmission 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，...
  • Page 74 YG125-23Maintenance ManualMagneto and starting system Left front cover To remove the left front cover: Remove the gear shift pedal and left rear cover, and separate the magneto lead connector with the main cable. Left rear pla Gear shift pedal Unscrew the oil drain plug to drain the engine lubricating oil inside the engine Draining engine oil Remove the double-linked gear cover connecting...
  • Page 75 YG125-23Maintenance ManualMagneto and starting system 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.
  • Page 76 YG125-23Maintenance ManualMagneto and starting system Rotor assembly Disk gear Disk gear washer To remove the clutch: Remove the left front cover (See Removal of left front cover). Remove the starting idle gear, double-linked gear, Notice: Double-linked Gear Do not let the semicircular key drop into the crankcase.
  • Page 77 YG125-23Maintenance ManualMagneto and starting system 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 Armature One-way device One-way device outer body M8×16...
  • Page 78 YG125-23Maintenance ManualMagneto and starting system Starting motor and starting Transmission system Mount the plain washer and apply thread retaining Remove the live wire and earth wire of the starting motor. adhesive LOCTITE648 to the fastening nut M12; use Remove the starting motor connecting bolt M6×25. the rotor fastening tool to fasten the rotor, and Push the motor towards the right and lift it, and then carefully take it out from the left side.
  • Page 79 YG125-23Maintenance ManualMagneto and starting system protection plate. Warning ⑹ Put on the oil drain plug and refill engine lubricating oil. Thread retaining adhesive LOCTITE243 must be applied to the rotor retaining nut M12 while Left front cover 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.
  • Page 80 YG125-23Maintenance ManualMagneto and starting system 6、Measure the disk gear diameter, the maintenance limit: ≥φ42.084mm Outside micrometer 7、Measure the washer thickness, the maintenance limit: ≥0.4mm Vernier calipers...
  • Page 81 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism 9、Crankcase, crankshaft and Shift mechanism Right hand crankcase body Gearshift drum Crankshaft Main shaft Counter shaft Left hand crankcase body...

  • Page 82: Crankcase, Crankshaft And Shift Mechanism

    YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Crankcase, crankshaft and Shift mechanism Maintenance notice Crankshaft and balance shaft Troubleshooting Variable transmission system Crankcase 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.
  • Page 83 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Troubleshooting  Noise from engine Crankshaft bearing worn; Connecting rod big end bearing worn; Driving/driven shaft bearings worn; Balance shaft supplementary tooth spring failure.  Driving/driven shaft gears engaged badly Shift fork bent or damaged; Shift fork shaft bent;...
  • Page 84 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Crankcase Notice To remove the crankcase: Do not pry the left/right hand crankcase body by Remove the engine from the frame (engine oil fully inserting such tools as screwdrivers into the mould drained) and put it on the assembly operating table. closing face.
  • Page 85 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism 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). Mount the assembled engine onto the frame, and engine oil to complete the assembly of the complete vehicle.
  • Page 86 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Removal and installation of crankcase Procedure Quantity Remarks Removing order Installation is in the reverse order of removal Right hand crankcase O-ring engine oil filter net Release oil bolt Left hand crankcase O-ring Double head bolt Main gear plate Bolt M6*16 Pin 10*14...
  • Page 87 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism 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.
  • Page 88 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism 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.
  • Page 89 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Crankshaft and balance shaft To remove the crankshaft and balance shaft: Remove the (left hand) crankcase (See “Removal of Use a high power electric drier to heat the right left hand crankcase"). crankcase body balance shaft bearing until the Remove the balance shaft.
  • Page 90 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Removal and installation of crankshaft and balance shaft Knock Procedure Quantity Remarks Removing order Installation is in the reverse order of removal Left hand crankcase Crankshaft Balance shaft Right hand crankcase...
  • Page 91 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism 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. Procedure Quantity Remarks...
  • Page 92 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Crankshaft and balance shaft inspection Clearance gauge 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 left hand crank journal. Measure the connecting rod small end bore diameter.
  • Page 93 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Variable transmission system Assemble the shift fork with To remove the variable transmission system: Mount the gearshift drum.。 Remove the (left hand) crankcase (See “Removal of Change the O-shaped sealing ring, mount the shift left hand crankcase").
  • Page 94 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism 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 Procedure Quantity Remarks...
  • Page 95 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism Check Shift mechanism Check the driving/driven shaft gears for serious abrasion To remove the shift mechanism Removal of left hand crankcase cover(See “Removal and pit corrosion; check whether the shift fork is bent and whether the gearshift drum guiding slot is damaged.
  • Page 96 YG125-23Maintenance ManualCrankcase, crankshaft and Shift mechanism 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 ").
  • Page 97 YG125-23Maintenance ManualFrame and exhaust system 10、Frame and exhaust system...

  • Page 98: Frame And Exhaust System

    YG125-23Maintenance ManualFrame and exhaust system Frame and exhaust system Maintenance notice Removal and installation of rear mudguard Troubleshooting Removal / installation of exhaust muffler Coverings, headlamp and meter Rear position lamp assembly Maintenance notice To carry out the maintenance stated herein, take special care of the scratches and damages to the coverings, meter and light fittings.
  • Page 99 YG125-23 Maintenance ManualFrame and exhaust system  Side cover and seat Remove the meter assembly (total of 3 connecting  The key opens the cushion lock， Remove the seat。 bolts). Remove 4 hole covers Seat cushion lock Remove the bracket ...
  • Page 100 YG125-23 Maintenance ManualFrame and exhaust system  Headlamp dimming Replace the new signal light（LED）, Do not remove Before driving, check the brightness, direction, etc. of the the replacement bulb.  headlamp. The order in which the signal light are installed is reversed.
  • Page 101 YG125-23 Maintenance ManualFrame and exhaust system  Remove the heat shield and suspension bolts on the muffler to check if it slides.. Connecting bolt  Dismantle muffler connecting nut, check whether the nut and bolt is sliding.  Dismantle the muffler, check whether the washer is damaged.
  • Page 102 YG125-23 Maintenance ManualFront wheel, front overhang and steering stem 11、Front wheel, front suspension device and steering stem...

  • Page 103: Front Wheel, Front Overhang And Steering Stem

    YG125-23 Maintenance ManualFront wheel, front overhang and steering stem Front wheel, front suspension device and steering stem Maintenance notice Front suspension device Troubleshooting Front brake Control subassembly Steering stem Front wheel Maintenance notice This section introduces the removal, installation and maintenance of the front wheel, front suspension device (front fork), front brake and steering stem.
  • Page 104 YG125-23 Maintenance ManualFront wheel, front overhang and steering stem Tire pressure insufficient Shift fork bent or damaged.  Insufficient suspension device rigidity Insufficient front fork spring Insufficient hydraulic oil refilled in the front fork  Poor brake performance The brake is not adjusted as per regulations...
  • Page 105 YG125-23 Maintenance ManualFront wheel, front overhang and steering stem 2mm) Gear is damaged． Speedometer Replace The indicator of the The gear drive speedometer gear speedometer fails to move gear box ring is damaged． Maintenance of Front Shock Absorber Component Damage form...
  • Page 106 YG125-23 Maintenance ManualFront wheel, front overhang and steering stem For the damage form, fault symptom and repair method of front brake Item Damage form Trouble symptom Trouble symptom of Repair method ofcomponent motorcycle brake 1iquid is brake liquid brake lose effect...
  • Page 107 YG125-23 Maintenance ManualFront wheel, front suspension device and steering stem  Control subassembly Remove the right brake cylinder body. 1、Remove the left/right balance weight. Remove the right brake cylinder body balance weight 2、Remove the right handle and right combination switch ...
  • Page 108 YG125-23 Maintenance ManualFront wheel, front suspension device and steering stem  Remove the clip and take out the grip tube Maintenance of wheel Bolt. To remove the front wheel Support the motorcycle with a jack to lift the front wheel above the ground.
  • Page 109 YG125-23 Maintenance ManualFront wheel, front suspension device and steering stem Disassembly and assembly of front wheel Dial Disassemble and assemble the front wheel according to indicator the following diagam. After the bearing is removed, replace with a new bearing along with dust seal.
  • Page 110 YG125-23 Maintenance ManualFront wheel, front suspension device and steering stem Unscrew the upper / lower connection plate bolt and. the Check Dismantle oil drain bolt and check bolt whether or direction of the tube bolt not is loose. Remove the front shock absorber Drain off absorber oil and check quality whether or not is turned.
  • Page 111 YG125-23 Maintenance ManualFront wheel, front suspension device and steering stem Dismantle circlip and return spring to check whether 10) Fill absorber oil per standard. or not there are elasticity Oiling quantity: 90 ± 2ml/, the brand is CN1# shock absorber oil, injected before the strict filtering, does not...
  • Page 112 YG125-23 Maintenance ManualFront wheel, front suspension device and steering stem To mount of steering stem Installation is in the reverse order of removal Removal of steering stem While installing the steering stem, adjust the adjusting nut and inspect it by turning it left and right and moving it up...
  • Page 113 YG125-23 Maintenance ManualFront wheel, front suspension device and steering stem Warning: When it is replaced with a new brake strip or brake disc, do not drive it immediately; instead, drive it after holding and releasing the front brake handle until the brake strip and the brake disc are well engaged.
  • Page 114 YG125-23 Maintenance ManualRear wheel and rear suspension device 12、Rear wheel and rear suspension device...
  • Page 115 YG125-23 Maintenance ManualRear wheel and rear suspension device 12、Rear wheel and rear suspension device Maintenance notice Rear fork Troubleshooting Rearshock absorber Rear wheel Maintenance notice This section introduces the removal, installation and maintenance of the rear wheel, rear brake, rear fork and rear damper .While repairing the rear wheel andrear damper, reliably stand the motorcycle from under the engine a jack or...
  • Page 116 YG125-23 Maintenance ManualRear wheel and rear suspension device For the damage form, fault symptom and repair method of rear wheels Component Damage form Trouble symptom Trouble symptom of Repair method description ofcomponent motorcycle Rear rim is twisted Rear rim is twisted and Off racking in running．rear...
  • Page 117 YG125-23 Maintenance ManualRear wheel and rear suspension device Rear wheel right scale lines of the chain adjuster are consistent, and then fasten the rear wheel spindle nut to the required To remove the rear wheel tightening torque of 60-90N.m Prop up the motorcycle with a maintenance Warning support,Leave the rear wheels off the ground.
  • Page 118 YG125-23 Maintenance ManualRear wheel and rear suspension device 3、Remove the rear damper and rear fork connecting bolt. Take out bush and dismantle bolt of rear driven chain Remove bolts and nuts. disc. On the left,Pull out the rear fork shaft.
  • Page 119 YG125-23 Maintenance ManualRear wheel and rear suspension device Rear fork bearing inspection Replace the inner shaft and coat of the bearing。face and apply lithium base grease on the bearing. After the installation is complete, check whether the bearing can rotate. Coordination clearance: 0~0.5mm.

  • Page 120: General Remarks Of Electrical System

    The development of electronics will especially influence the motorcycle’s electrical system significantly. YG125-23’s electrical system uses a lot of advanced vehicle electronics technologies that are much more complicated then the traditional motorcycle. It comprises the following sub-systems: •...
  • Page 121 Power supply system is the precondition for a complete vehicle to operate, capable of providing sufficient electric energy for other electrical systems. The main contents include recharging, charge storing and discharging. YG125-23 power supply features large power supply capacity as high as more than 250W. It comprises the following parts and components: •...
  • Page 122 YG125-23 Maintenance ManualPower supply system Maintenance of Charging System Check plate electrode whether is damaged Disassemble. assemble and check charging system Check socket whether contact well. Dismantle rectifier bolt and measure two yellow wire whether is short circuit or broken circuit by check connector socket of rectifier and measure millimeter.
  • Page 123 YG125-23 Maintenance ManualPower supply system Major faults diagnosis Phenomenon Possible causes Solutions    No electricity in the complete Main fuse is blown; Replace main fuse   vehicle: Main fuse circuits contact poorly; Re-plug.   Accumulator’s positive and ...
  • Page 124 When the engine starts to work, an exogenous action is needed to help it run, thus entering the ignition & fuel supply procedure to enable the internal combustion engine to combust repeatedly and work steadily. YG125-23 motorcycle is only equipped with electric controlled starting. First, release it from the protection of shift position switch, side stand switch and clutch switch;...
  • Page 125 YG125-23 Maintenance ManualStarting system Maintenance ofstarting system Disassemble, assemble and maintain Check relay whether is damaged Turn on ignition switch and flameout switch to check electrical start whether energize. Check magneto coil whether contact well. Check the closure of the circuit with the instrument.
  • Page 126 YG125-23 Maintenance ManualStarting system Major faults diagnosis Phenomenon Possible causes Solutions    Starting relay Accumulator voltage too low; Recharge the accumulator; doesn’t attract;   Corresponding fuse is not connected or is Connect the fuse or replace it;...
  • Page 127 YG125-23 Maintenance ManualIllumination signal system 16、Illumination signal system Overview Major parts and components Circuit schematic drawing Major faults diagnosis Overview Illumination signal system is an important guaranty for the safe driving of the vehicle. It includes the headlamp illumination system, signal lamp control system and horn system.
  • Page 128 YG125-23 Maintenance ManualIllumination signal system Circuit schematic drawing...
  • Page 129 YG125-23 Maintenance ManualIllumination signal system Maintenance of illumination system Take off headlamp switch socket to check whether there is current Turn on ignition switch and flameout switch to check electrical start whether energize. Remove the headlamp bolt, check the cable connection current.
  • Page 130 YG125-23 Maintenance ManualIllumination signal system 12. Dismantle afterbrake lamp switch to check it whether lose contact. Turn on signal indication switch left handle to check switch whether is rusted or lose contact. 13. Dismantle brake switch before to check it whether Check steering signal indication lamp socket whether lose lose contact.
  • Page 131 YG125-23 Maintenance ManualIllumination signal system Major parts and components...
  • Page 132 YG125-23 Maintenance ManualIllumination signal system Major faults diagnosis Phenomenon Possible causes Solutions    Headlamp does not Accumulator voltage too low; Recharge the accumulator;   illuminate; Corresponding fuse is not connected or is Connect the fuse or replace it;...

  • Page 133: Electrical Starting Control System

    YG125-23 Maintenance ManualElectrical starting control system 17、Electrical starting control system Overview Major parts and components Circuit schematic drawing Major faults diagnosis Overview The information display system displays the dynamic and static information of the complete vehicle on the instrument panel for the driver’s safe operation.
  • Page 134 YG125-23 Maintenance ManualElectrical starting control system Major parts and components ○ Combination meter Outline drawing Line color function corresponding table COLOUR FUNCTION COLOUR FUNCTION Black Power Supply(+) Green/Red Neutral indicator The rotational speed signal green Power Supply(-) Black/ Yellow Fuel oil signal...
  • Page 135 YG125-23 Maintenance ManualElectrical starting control system Maintenance of electrical starting control system Turn on ignition switch and flameout switch to check electrical start whether energize. Check fuse whether is burned. Dismantle headlamp holder to check holder whether there is current.
  • Page 136 YG125-23 Maintenance ManualElectrical starting control system Major faults diagnosis Phenomenon Possible causes Solutions    Winker indicator is out of The winker indicator filament is burnt Replace winker indicator bulb work    Meter dial illuminator is out...
  • Page 137 YG125-23 Maintenance ManualEngine management system 18、Engine management system System Overview Tools Major parts and components Maintenance depending on the malfcode Maintenance depending on the performance Circuit schematic drawing Maintenance of Engine management system System Overview Components of system and Operating principle...
  • Page 138 YG125-23 Maintenance ManualEngine management system Major parts and components...
  • Page 139 YG125-23 Maintenance ManualEngine management system...
  • Page 140 YG125-23 Maintenance ManualEngine management system ITEM PIN No. DESCRIBE ITEM PIN No. DESCRIBE J1-1 IACAHi J2-1 COILA J1-2 MAGNETO CUT RELAY J2-2 J1-3 J2-3 KW2000 J1-4 J2-4 CRANK HI J1-5 J2-5 INJA J1-6 TACH J2-6 J1-7 CANLo J2-7 O2AHTR J1-8...
  • Page 141 YG125-23 Maintenance ManualEngine management system Maintenance depending on the malfcode. Description If the issure cannot repeat, the issure analysis may be wrong. The multimeter below means the digital type. Pointer-type is forbidden. If the malfcode shows the voltage is low, it means maybe the wire is short to ground. If the malfcode shows the voltage is high, it means maybe the wire is short to battery.
  • Page 142 YG125-23 Maintenance ManualEngine management system Malfcode：P0107 Information：MAP Circuit Low Voltage or Open ITEM OPERATION RESULT NEXT STEP Connect the diagnostic tool, and ignition on. Next Check the data of ‘BARO’. Make sure whether it is about 100kPa Step 5 Next...
  • Page 143 YG125-23 Maintenance ManualEngine management system Malfcode：P0113 Information：IAT Circuit High Voltage ITEM OPERATION RESULT NEXT STEP Connect the diagnostic tool, and ignition on. Next check whether the data of ‘intake air temperature’ equals to the real intake Setp 5 air temperature.
  • Page 144 YG125-23 Maintenance ManualEngine management system Malfcode：P0122 Information：TPS Circuit Low Voltage or Open ITEM OPERATION RESULT NEXT STEP Connect the diagnostic tool, and ignition on. Next Step 5 Check whether the data of ‘Throttle opening’ is bettwen 0%-1%. Next Open the throttle to 100% slowly, check whether the data of ‘throttle Step 5 opening’...
  • Page 145 YG125-23 Maintenance ManualEngine management system Malfcode：P0201 Information：Injector 1 Circuit Malfunction ITEM OPERATION RESULT NEXT STEP Connect the diagnostic tool, and ignition on. Next Step 4 Remove the conneter of injecor 1, use multimeter to check whether the voltage of Pin A is about 12V.
  • Page 146 YG125-23 Maintenance ManualEngine management system Maintenance depending on the performance. Before issue analysis, please check: The MIL works well. Clear the history malfcode. When the malfcode comes again, note the condictions. Check the appearance Whether there is leakage of the fuel pipe or not.
  • Page 147 YG125-23 Maintenance ManualEngine management system Next Check wether the fuel pump pressure is about 250kPa at idle. Check the pump. Next Pull out the spark plug, check whether the sparkover is normal. Check the ignition system Check the engine Remove the connector of the engine temperature sensor, and temperature sensor check whether the enigne start well.
  • Page 148 YG125-23 Maintenance ManualEngine management system engine works well Change the sensor Check whether the air filter is blocked and whether the intake Intake system maintenance pipe leaks. Next Next Check whethe the fuel pressure is about 250kPa. Check the pump dry the plug and combustion chamber.

  • Page 149: Electrical System Diagram

    YG125-23Maintenance ManualElectrical System Diagram 19、Electrical System Diagram...

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