Baotian BT49QT-28 Service Manual
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Baotian BT49QT-28 Service Manual

Baotian BT49QT-28 Service Manual

2-stroke scooter
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BT49QT-28 MODEL

SERVICE MANUAL

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Summary of Contents for Baotian BT49QT-28

  • Page 1: Service Manual

    BT49QT-28 MODEL SERVICE MANUAL...

  • Page 2: Table Of Contents

    CONTENTS CHAPTER ONE MAINTENANCE OF THE MOTORCYCLE Ⅰ. ITEMS OF MAINTENANCE Ⅱ. PERIODIC MAINTENANCE SCHEDULE AND MAINTENANCE LOCATIONS Ⅲ. MAINTENANCE SPECIFICATIONS Ⅳ. THROTTLE ACTUATION INSPECTION Ⅴ. AIR FILTER INSPECTION AND CLEANING Ⅵ. BRAKE BLOCKS INSPECTION Ⅶ. BRAKE SYSTEM INSPECTION, ADJUSTMENT AND REPLACEMENT Ⅷ.
  • Page 3 Ⅲ. FRONT SHOCK ABSORBER SERVICE Ⅳ. FRONT FORK SERVICE Ⅴ. HANDLEBAR SERVICE Ⅵ. REAR WHEEL SERVICE Ⅶ. REAR BRAKE SERVICE (DISK BRAKE) Ⅷ. REAR SHOCK ABSORBER SERVICE Ⅸ. COOLANT SYSTEM CHAPTER FIVE ELECTRIC PART TROUBLESHOOTING SECTION ONE ELECTRIC PART COMMON TROUBLES AND TROUBLE DETECTION SECTION TWO DETAILED DESCRIPTIONS OF ELECTRIC...
  • Page 4 This 2-stroke scooter BT49QT-28 is with low weight, enough power, low oil consumption and good operating performance. This manual is for maintenance men to repair and maintain BT49QT-28 and it is also useful when maintain other models. This manual holds the latest technical information. We reserve the right to amend the data, instructions and specifications without advice.

  • Page 5: Chapter One Maintenance Of The Motorcycle

    CHAPTER ONE MAINTENANCE OF THE MOTORCYCLE Ⅰ Ⅰ Ⅰ Ⅰ . ITEMS OF MAINTENANCE When the motorcycle is used, parts loose and mechanical wear inevitably occur to varied extents. Neglecting of timely maintenance not only reduces its mechanical function, economic performance, stability and durability, but also threatens the safety of the motorcycle and the rider.

  • Page 6: Maintenance Schedule

    1. Maintenance Schedule Maintenance Schedule time Mileage 1000km item 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 New R Engine oil 300km Engine oil strainer Gasoline strainer New R Gear oil Note 4 300km Throttle play Carburetor Note 3, Air filter...

  • Page 7: Ⅲ. Maintenance Specifications

    Ⅲ Ⅲ Ⅲ Ⅲ . MAINTENANCE SPECIFICATIONS The basic methods of motorcycle maintenance include inspection, adjustment, tightening, lubrication, cleaning, supplementing and replacement, which constitute the main elements of maintenance. 1. Inspection Inspection refers to basic inspecting operations in accordance with items and requirements specified in the user’s manual, including inspection with instruments or with eyes for abnormalities in machine parts, directly comparing related data and aligning with tools and gauges.

  • Page 8: Ⅳ. Throttle Actuation Inspection

    IV. THROTTLE ACTUATION INSPECTION Inspect throttle grip for easy and smooth movement. Inspect throttle free travel. Free travel: 2-6mm The main adjusting position is beside the carburetor. Remove rear store case inner cover. Adjust by loosening the fastening nut and turning the adjusting nut.

  • Page 9: Ⅴ. Air Filter Inspection And Cleaning

    Ⅴ Ⅴ Ⅴ Ⅴ . AIR FILTER INSPECTION AND CLEANING After a certain mileage, dust and impurities will gather in air filter case and strainer, which will clog strainer pores and reduce inlet of air and thus lead to excessive concentration of mixed gas and reduce the performance of engine.

  • Page 10: Ⅶ. Brake System Inspection, Adjustment And Replacement

    VII. BRAKE SYSTEM INSPECTION, ADJUSTMENT AND REPLACEMENT 1. Front brake (disk brake) Remove the bolts linking brake caliper and front shock absorber. Remove brake caliper. * Do not pull brake lever when brake caliper is removed so as to prevent jamming of brake blocks.

  • Page 11: Ⅷ. Front And Rear Shock Absorber Inspection

    2. Rear Brake (disk brake) Remove the exhaust muffler. Remove the black dust cover. Remove the rear wheel nut. Remove the three mounting bolts of the rear wheel mounting base. Remove the rear wheel. Remove the bolts linking rear brake caliper and engine.

  • Page 12: Ⅸ. Front Wheel And Rear Wheel Inspection

    2. Rear Shock Absorber Press rear shock absorber to inspect actuation. Inspect rear shock absorber to see if there is oil leakage and if there is damage or loosening in machine parts. Lift rear wheel, press rear wheel right and left to inspect if engine suspension lug buffer bush is loose.

  • Page 13: Ⅹ. Steering Stem Inspection

    Inspect tire pressure by means of a tire pressure gauge * Tire pressure should be inspected when the motorcycle is in a cold state. Specified pressure Unit: KPa Front tire Rear tire Tire Specifications: Front tire 130/60-13 Rear tire 130/60-13 Inspect if front wheel nut is loose.

  • Page 14: Chapter Two Maintenance Information

    CHAPTER TWO MAINTENANCE INFORMATION I. FRAME NUMBER AND ENGINE NUMBER LOCATION II. PRECAUTIONS IN OPERATION Removed washers, 0-rings, elastic retaining rings and split pins must be replaced with new ones. When mounting bolts, nuts and screws, proceed from trial tightening, from larger diameters to smaller diameters and inner ones to outer ones in a diagonally order.

  • Page 15: Ⅲ. Specified Torques

    Connectors must be inserted home. When connecting connectors with locks, confirm that their locks are fastened. Confirm that the wires are not loose. Confirm that connectors’ plastic sleeves completely cover the connectors without fail. Before connecting the connectors, confirm that their sleeves are free from breakage and their terminals are not oversized.
  • Page 16 Engine: Torsion Screw quadrature： Tighten part Number specification N·m Cyclinder head bolt A Cyclinder head boltB Oil filter cap M 30 Muffler flange fixing bolt Camshaft flange nut 16～18 Valve adjusting bolt Chain tensioner bolt 10～12 Leaking oil bolt M 10 Clutch outside wheel fixing bolt M 10 Magneto rotor fixing bolt...

  • Page 17: Ⅳ. Tools

    Standard Torques: Designations Torques: N·m Bolt, nut M5 Bolt, nut M6 Bolt, nutM8 21.5 Bolt, nut M10 Bolt, nut M12 Screw M5 Screw M6 Flange bolt, nut M6 Flange bolt, nut M8 Flange bolt, nut M10 Ⅳ Ⅳ Ⅳ Ⅳ . Tools Tools Number Flywheel disassemble ware...
  • Page 18 CHAPTER FOUR BODY TROUBLESHOOTING SECTION ONE BODY COMMON TROUBLES AND TROUBLE DETECTION Body part common troubles and possible causes are as follows: Details (reference) Troubles Causes Handlebar rotation Over tightening of handlebar not easy (strenuous adjusting nut Refer to “Front Fork Service”...
  • Page 19 Chart continued Troubles Causes Details (reference) Inadequate liquid Contaminated brake block and brake disc Bent or deformed brake disc Contaminated brake caliper Worn seal ring of brake caliper piston Feeble brake Viscous or worn lever brake caliper piston Inability of brake caliper normal sliding Worn main cylinder...
  • Page 20 Chart continued Details (reference) Troubles Causes Refer to “Front Fork Steering stem rotation not easy Service” Bent shock absorber Refer to “Front Shock Absorber Service” Shock absorber oil leakage Deviation of Bent front axle, incorrect wheel motorcycle direction mounting (inclining to roadside) Refer to “Front Wheel Roundness error of wheel rim Service”...
  • Page 21 SECTION TWO DETAILED DESCRIPTION OF BODY PARTS MALFUNCTION Precautions in Operation: Forced mounting or dismounting of body cover parts will cause damage to claws and slots of corresponding hoods. When mounting body cover parts, be sure to align the corresponding parts of hoods.
  • Page 22 Axle Bending Inspection Place axle on a V-seat and measure with a dial gauge. The dial gauge indicates a 1/2 bending value. Limit of use: Replace if >0.2mm. Wheel Rim Oscillation Inspection Measure oscillation value on a correcting bench. Limit of use: Replace if >2.0mm. Traverse direction: Replace if >2.0mm.
  • Page 23 Front Wheel Mounting Mount brake disc, tighten brake disc mounting bolts. Torque: 27N·m Spread front axle with a thin film of grease. Mount front axle from left side. Mount in order small bush, left front shock absorber, front axle bush, front wheel, transmission gearbox, right front shock absorber, front axle nut and fasten it.
  • Page 24 Connect a transparent hose to exhaust valve. Grip brake lever fast and open exhaust valve 1/2 turn to let out air and lock exhaust valve. Repeat this operation till no bubbles are exhausted from brake oil passage. ·Do not release brake lever before exhaust valve is closed.

  • Page 25: Ⅲ. Front Shock Absorber Service

    Inspection Inspect for wear or ageing of main and auxiliary cups on pistons. Inspect for scratches and other damages on main cylinder and piston. Measure main cylinder bore. Measure the outside diameter of piston at the end of auxiliary cup. Mounting Apply pure brake oil to piston, main cup and auxiliary cup.

  • Page 26: Ⅰ. Front Wheel Service

    absorber arm and if there is damage or loosening of any part. Mounting Mount front shock absorber on front fork and mount 2 bolts. Torque: upper bolt 40N·m. Mount bodycovering parts. Mount front wheel. Mount front fender and front brake caliper. Ⅳ...
  • Page 27 Inspection upper bearing top Inspect if there is slot or pit in bearing cup upper bear ing cup and bearing top. If there is, effect bottom bearing top replacemented. bottom bearing cup ball set Inspect for completeness of bearing balls and if there is, effect replacement with new ball set ones.

  • Page 28: Ⅴ. Handlebar Service

    Ⅴ Ⅴ Ⅴ Ⅴ . HANDLEBAR SERVICE Dismounting Remove covering parts of front part, rear part, upper cover and nether cover of handlebar. Remove the meter assy. Remove two bolts of rear brake main cylinder and remove brake main cylinder. Remove connectors of left handlebar switch.

  • Page 29: Ⅵ. Rear Wheel Service

    Mounting Mount nether cover of handlebar. Mount handlebar on steering stem guide tube, fit bush, setting bolt and nut. Torque: 45 N·m Mount upper cover of handlebar. Mount front and rear brake main cylinder. Mount left and right handlebar switch. Apply grease to throttle cable.

  • Page 30: Ⅶ. Rear Brake Service (Disk Brake)

    Rear Wheel Oscillation Inspection Measure oscillation value on a correcting bench by means of micrometers. Limit of use: Longitudinal >2.0 mm Traverse >2.0 mm Mounting Mount rear brake disc and fasten the bolts. Torque: 27N·m Mount rear wheel in an order reversed to that of dismounting. Torque: 120N·m Mount rear shock absorber and fasten lower mounting bolt.
  • Page 31 Inspection Inspect rear shock absorber oil seal for oil leakage, inspect buffer bar and spring for deformation and other parts for damage and loosening. Mounting Mount rear shock absorber. Torque: upper mounting bolt: 40N·m lower mounting bolt: 25N·m Mount motorcycle body covering parts.

  • Page 32: Chapter Five Electric Part Troubleshooting

    CHAPTER FIVE ELECTRIC PART TROUBLESHOOTING SECTION ONE ELECTRIC PART COMMON TROUBLES AND TROUBLE DETECTION Troubles Causes Details No electrolyte Whitened electrode plate Battery short circuit Battery discharge (overdischarging) No power Poor adjusting voltage rectifier Disconnection of battery wire Broken fuse Poor power switch (main switch) Refer to Poor battery charging...
  • Page 33 Details Troubles Causes Poor ignition coil Poor primary Poor contact of wire ignition loop or connector Poor main switch Poor ignition coil Refer to Generator running Poor secondary Poor contact of wire “Ignition not easy ignition loop or connector System Poor main switch Service’...

  • Page 34: Section Two

    SECTION TWO DETAILED DESCRIPTION OF ELECTRIC ASSEMBLIES AND PARTS SERVICE I. PRECAUTIONS IN ELECTRIC CIRCUIT SERVICE 1. Main switch must be set at position “OFF” before wires are connected or disconnected. 2. When connectors with locks are disconnected, locks must be pressed or lifted. 3.
  • Page 35 1. Storage Battery Precautions in Using Storage Battery ○, Do not effect the first starting of a new motorcycle by electric starter as a new storage battery has only 80% of full capacity. The difficulty in starting a new motorcycle often causes overdischarging of storage battery. ○, MF storage battery must not be replenished with the seal removed.
  • Page 36 In the following cases, effect replenishing charging of new storage battery Case for replenishing Replenishing method Charge for 2-3 hours at the charging current value (standard current) indicated 0 ℃ and below in winter on storage battery cover. Stored in high-temperature and high- Standard current (current indicated on humidity environment storage battery cover for charging)
  • Page 37 Charging current: Standard: 0.6A Quick: 6.0A Charging time: Standard: 5～10 hours Quick : 30 minutes At completion of charging: Open circuit: 12.8V and above 2 2 2 2 、 、 、 、 Charging System Inspection Electric Leakage Inspection Remove earthing wire from storage battery, connect voltmeter between storage battery negative terminal and earthing wire.
  • Page 38 3. Voltage Adjusting Rectifier Troubles Causes Inspection troubleshooting parameter method Burnt bulb in Damaged Start engine and Replace Voltage: 8- lighting system voltage measure lighting voltage adjusting part coil voltage. In adjusting of voltage case voltage rectifier adjusting rises with the rectifier rise of engine speed, trouble...
  • Page 39 Main Wire Terminal Loop Inspection Remove front cover. Remove voltage adjusting rectifier plug 4P and measure conductivity between main wire terminals. Item (wire color) judgment Between storage (red) and motorcycle earthing With storage battery voltage Between earthing wire (green) and motorcycle With conductivity earthing Between lighting wire (yellow) and motorcycle...

  • Page 40: Ⅲ. Ignition System Service

    III. IGNITION SYSTEM SERVICE Causes (Inspect and judge from ○ ○ ○ ○ , Troubles ○, Ignition coil voltage too Inner resistance too low, inspect with a specified circuit tester. ○, Crankshaft speed too low (storage battery voltage too low, or starting rod too feeble when tread ○, Circuit tester interfered (normal case: repeated measured voltgage readings stay above standard).
  • Page 41 ○, ignition and charging Poor ignition and charging coils coils Causes (Inspect and judge from ○ ○ ○ ○ , Troubles ○, Trigger coil voltage too Inner resistance too low, measuree with specified circuit tester. ○, Crankshaft speed too low (storage battery voltage too low or starting rod too feeble when tread on).
  • Page 42 Ignition Primary Coil Voltage Remove spark plug as illustrated and mount a faultless spark plug. Connect spark plug with engine earthling. Note: Effect correct connection of wires and their measurements。 Cylinder compression pressure measurement is effected in normal condition (measure with spark plug fitted on cylinder head). Remove middle cover.
  • Page 43 Ignition and Charging Coil Note: Mount spark plug on cylinder head, inspect at normal compression pressure. Remove CDI set connector 6P, connect distributor between ignition and charging coil at wire terminal (black/red terminal) and green terminal. Actuate starting motor or tread on starting rod, measure ignition and charging coil maximum voltage.
  • Page 44 3. 3. 3. 3. CDI Check CDI Check CDI Check CDI Check Troubles Causes 1. Poor contact 1. Damaged terminal, poor connecting 2. Absence of high-voltage or contact 3. Occasional misfire 2. punctured or damaged diode 4. Poor acceleration 3. punctured or damaged transistor 5.
  • Page 45 Primary Coil Inspection Measure resistance between primary terminals. Standard value: 0.21Ω±10% (20℃) Resistance within standard value indicates good state. Resistance “∞” (infinity) indicates open circuit of coil. Replace coil. Secondary Coil Inspection Measure primary coil resistance between terminals. Standard value: 7～12kΩ (20℃) Resistance value: “∞”indicates breakage of wire in coil.

  • Page 46: Ⅳ. Electric Starting System Service

    Ⅳ Ⅳ Ⅳ Ⅳ . ELECTRIC STARTING SYSTEM SERVICE Troubles Causes Electric starting failure with normal One-way clutch spring fatigue or circuit and normal starting motor rotation breakage Starting relay failure without closing Damaged brake switch sound when started but with other electric Burnt starting relay circuits normal Damaged starting switch...

  • Page 47: Ⅴ. Lighting And Signal System Service

    Starting Relay Earthing Loop Inspection Remove starting relay connector. Inspect conductivity between wire connector terminal yellow/red wire and motorcycle earthing. Conductivity between terminal yellow/red wire and motorcycle earthing when starting button is pressed. Inspect conductivity of starting button and wire. Connect starting relay with storage battery, connect starting motor terminal with three-in-one meter.
  • Page 48 1.Headlight Adjustment and Dismounting Loosen headlight fastening bolt and turn headlight to adjust headlight beam. Remove headlight fastening bolt. Remove headlight cover. Remove headlight bulb. Mounting is effected in an order reversed to that of dismounting. （If want to change healight bulb, the bulb should be 12V,18W）...
  • Page 49 Remove front head cover. Remove main switch wire connector. Inspect conductivity between connector terminals. 5. Horn Voltage Current Horn condition Location of Troubleshooting supplied supplied trouble No sound Horn Increase horn current, 10～ 0～2A turn out adjusting screw 14.5V counterclockwise at 1/6 turn a time No sound Horn...
  • Page 50 6.Handlebar Switch Remove handlebar switch connector. Inspect conductivity between connector terminals. Headlight Switch Starting Switch Horn Switch...
  • Page 51 Direction Light Switch Lighting Lamps Switching Switch Brake Switch Remove instrument hood. Remove brake switch wire. There should be conductivity between two wires while brake bar is gripped.

  • Page 52: Ⅵ. Circuit Diagram

    Ⅵ Ⅵ Ⅵ Ⅵ . Circuit Diagram...

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