Honda CB125 - Operation of Gear Shift; Transmission Assembly; Gear Shift Disassembly; After the Transmission and Crankshaft Are Coupled, the Lower Crankcase Should be Matched

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Contents3
Features of CB125 and 1605
Specifications6
Exterior Views - Front, Rear, Top and Side10
Product View11
Special Tools for CB125/16012
Engine13
Disassembling Engine14
Footrest Arm Bolts/Pinion14
All Wiring14
Air Cleaner Connecting Tube14
Clutch Cable Core15
Removing the Drive Chain Joint15
Removing the Starting Motor Cable15
Removing Carburetor15
Assembling Engine16
Cylinder Head and Cylinder Disassembly16
Engine Mounting Bolt16
Installation of Engine16
Caution Required During Disassembly and Assembly17
Cylinder Head Cover Nuts and Bolts17
Removing Cam Chain/Cylinder Head/Carbon17
Description of Cylinder Head Cover and Breather18
Cylinder Head and Cylinder Assembly18
Installing Cam Chain18
Handling Cam Tightener18
Breather and Breaker Disassembly/Assembly19
Principle of Breather19
Removal of Breaker Point Base Plate19
Disassembly of Spark Advance19
Description of Camshaft20
Camshaft Disassembly20
Names of Cam Parts20
Removing Rocker Arm/Camshaft20
Camshaft Assembly21
Description of Rocker Arm21
Rocker Arm Disassembly/Assembly21
Valve Rocker Arm21
Description of Valve22
Valve Disassembly/Installation/Seating22
Oiling the Valve Stem22
Dressing Valve Seat22
Description/Inspection of Cylinder23
Cylinder Disassembly/Assembly23
Valve Timing Models CB 125/16023
Coupling Piston to Cylinder23
Construction of Left Crankcase Cover24
Left Crankcase Cover Disassembly/Installation24
AC Generator24
Starter and Cable Fitted in Case Cover24
AC Generator Disassembly/Installation25
Operation of Starter Clutch25
Removing AC Generator Rotor/Generator Stator25
Example of Rotor Locating Key Set Operation25
Operation of Clutch Adjuster26
Disassembly and Installation of Clutch/Starter Sprocket26
Setting Operation of Starter Clutch Roller Spring26
Removing the Starting Sprocket Set Plate26
Description of the Right Crankcase Cover27
Disassembly and Assembly of Clutch Adjuster/Neutral Switch Rotor27
Right Crankcase Cover Disassembly/Screws27
Clutch28
Right Crankcase Cover Installation28
O Ring on Oil Filter Cover28
Description and Operation of Clutch29
Clutch Installed (Complete Vehicle)29
Sectional View of Clutch/Clutch Adjustment Thread29
Clutch Disassembly/Inspection30
Removing Set Ring30
Removing Outer Clutch and Pump Body30
Inspection Distortion of Clutch Plate30
Description of Oil Pump31
Clutch Assembly31
Fatigue of Clutch Spring31
Measurement of Clearance of the Outer Clutch Notch and the Clutch Friction Disc31
Lubrication Circuit32
Oil Pump32
Oil Pump Disassembly/Assembly33
Removing Pump Rod/Plunger33
Pump Parts33
Confirming Oil Circulation33
Operation of Oil Filter34
Oil Filter Disassembly34
Oil Filter Parts34
Removing the Oil Filter Cap34
Crankcase Description35
Operation of Oil Separator35
Oil Filter Assembly35
Cleaning Oil Filter35
Crankcase Disassembly/Assembly36
Disassembly and Installation of Starting Motor36
Crankcase Bolts36
Releasing Key from Shift Drum36
Description of Crankshaft37
Crankshaft Disassembly37
Crankshaft Lubricating Passage37
Crankcase Bolts and Nuts37
Description of Connecting Rods38
Crankshaft Inspection/Installation38
Measurement of Axial/Radial Clearance38
Matching Lower Crankcase38
Description of Pistons39
Connecting Rods Inspection39
Measurement of Maximum Deflection at the Piston End of Connecting Rod39
Measurement of Parallel Condition at the Piston End of the Connecting Rod39
Pistons Disassembly/Inspection40
Measurement of Outside Diameter of the Piston40
Measurement of the Ring Groove Clearance When a New Piston Ring Is Fitted40
Removing Piston Pin Retainer40
Description of Piston Rings41
Pistons Assembly41
Measurement of Piston Pin Hole41
Measurement of the Piston Outside Diameter41
Piston Rings Inspection/Replacing42
Measuring Piston Ring Gap/Tension42
Profile of Piston Ring Gap42
Operation of Cam Chain Tightener43
Cam Chain Tightener Disassembly43
Inspection Piston Ring by Rotating Around the Ring Groove43
Confirming Upper and Lower Surface of the Piston Ring43
Cam Chain Tightener Installation/Adjustment44
Cam Chain Guide Roller44
Tightener Push Bar Fully Inserted44
Adjusting a Cam Chain44
Transmission View45
Description of Transmission45
Transmission System46
Gears of Neutral Position46
Transmission of the First/Second/Third Speed46
Transmission Disassembly/Inspection47
Transmission of the Fourth Speed47
View of Transmission with Lower Crankcase Separated47
Measuring Clearance of the Transmission Unit Bearing47
Operation of Gear Shift48
Transmission Assembly48
Gear Shift Disassembly48
After the Transmission and Crankshaft Are Coupled, the Lower Crankcase Should be Matched48
Gear Shift Assembly49
Removing Shift Drum Limit49
Removing Gear Shift Spindle49
Division of Gear Shift Fork49
Operation of Kick Starter50
Kick Starter Disassembly and Assembly50
Gear Shift Drum Fork Limit50
Assembling Kick Starter Spring50
Description of Carburetor51
Main/Slow Speed System51
Sectional View of Carburetor51
Operation of Component Parts52
Float Chamber52
Choke52
Main/Air/Needle Jet52
Jet Needle53
Throttle Valve53
Slow Speed Jet53
Air Screw53
Adjustment at High Speed/MID-Throttle54
Replacing of Main Jet54
Changing Step of Jet Needle54
Adjutment at Low Speed55
Adjustment of Standard Fuel Level55
Adjusting Air Screw55
Measuring Standard Fuel Level55
Adjustment of the Throttle Opening of the Right and Left Carburetors56
Adjusting Throttle Valve Opening56
Construction of Handlebar57
Handlebar Disassembly57
Turning the Handlebar57
Tools Required for Disassembly and Assembly57
Handlebar Inspection/Assembly58
Removing Handlebar/Clutch/Brake Cable58
Adjustment of Throttle/Brake Cable Play58
Description/Disassembly of Front Cushion59
Adjustment of Clutch Wire Play59
Lead Wire Clamp59
Disassembling of Front Cushion59
Removing Front Wheel/Fender/Speedometer60
Front Cushion Inspection61
Measurement of the Front Cushion Spring/Fork Piston61
Measurement of the Outside Diameter and Bend of the Front Fork Pipe61
Sectional View of Steering61
Front Cushion Assembly62
Bend/Assembly of Front Fork Pipe62
Assembling/Installing Front Cushion62
Construction of the Steering Stem63
Steering Stem Disassembly63
Tools Required for Disassembly and Assembly of Steering Stem and Handlebar Lock63
Steering Stem Inspection/Assembly64
Measurement of Steering Stem Bending64
Fuel Tank64
Tools Required for Disassembly and Assembly of Fuel Tank64
Construction of Fuel Tank65
Fuel Tank Disassembly65
Remove the Tank by Using the Hose Clip65
Fuel Tank Inspection/Assembly66
Removing of Fuel Cock/Cock Body66
Installing Side Cover66
Sectional View of Side Cover Retaining Screw66
Construction of Frame Body67
Pushing Fuel Tank from the Rear Side67
Frame Body Disassembly/Inspection68
Tools Required for Disassembly and Assembly of Frame Body68
Removing/Driving in Ball Race68
Construction of Air Cleaner Case and Seat69
Frame Body Assembly69
Air Cleaner Case and Seat Disassembly/Inspection69
Tools Required for Disassembly and Assembly of Air Cleaner Case Seat69
Construction of Stand70
Air Cleaner Case and Seat Assembly70
Stand Disassembly/Inspection70
Inspecting of the Stand Spring70
Stand Assembly71
Construction of the Exhaust Pipe and Muffler71
Exhaust Pipe and Muffler Disassembly71
Even Tightening of Muffler Steps71
Exhaust Pipe and Muffler Inspection/Assembly72
Muffler Mounting Bolt72
Removing Diffuser Pipe72
Removing Carbon with Wire Brush72
Construction of the Air Cleaner73
Air Cleaner Disassembly/Inspection/Assembly73
Tools Required for Disassembly and Assembly of Air Cleaner Tool Case73
Removing Tool Box from Frame73
Construction of the Rear Fork74
Rear Fork Disassembly/Inspection74
Measurement of the Rear Fork Center Collar74
Measurement of Rear Pivot Bushing Bore74
Rear Fork Assembly75
Measurement of Rear Fork Pivot Bolt75
Measurement of Twist of the Rear Fork75
Disassembly of Rear Fender75
Construction of the Rear Cushion76
Rear Cushion Disassembly/Inspection76
Measurement of the Rear Cushion Spring76
Tools Required for Disassembly and Assembly of Rear Cushion76
Front Wheel77
Rear Cushion Assembly77
Coupling Rear Cushion77
Description of the Front Wheel78
Front Wheel Disassembly/Inspection78
Measurement of Defiction and Eccentricity of the Rim78
Tools Required for Disassembly and Assembly of the Front Wheel78
Front Wheel Assembly79
Measurement of the Clearance in the Axial and Radial Directions of the 6302R Ball Bearings79
Measurement of Brake Shoe Spring79
Measurement of the Outside Diameter and Thickness of the Front Brake Shoe79
Insertion of Bearing80
Angle of Gear Box Installation80
Front Brake Wire Adjuster80
Play of Front Brake Lever80
Description of Rear Wheel81
Rear Wheel Disassembly81
Tools Required for Disassembly and Asssembly of Rear Wheel81
Removing Drive Chain81
Rear Wheel Inspection82
Measurement of Deflection and Eccentricity of the Rim82
Measurement of the Outside Diameter Bend of the Rear Wheel Axle82
Measurement of the Tooth Bottom Diameter of the Final Driven Sprocket82
Rear Wheel Assembly83
Measurement of Cam Unit Thickness of Rear Brake Cam83
Outside Diameter and Thickness Measurement of the Rear Brake Shoe83
Rear Brake Shoe Measurement83
Rear Brake Coupling84
Chain Tension84
Rear Brake Pedal Play84
General of Electrical Parts85
Electrical/Ignition System85
Construction/Performance of Ignition Coil86
Dual Side View of Ignition Coil86
Battery Operation Coil86
Ignition Coil Handling87
Spark Performance Graph87
Ignition Coil Specification/Measurement87
Terminal Unit Covering87
Capacitor Construction/Testing88
Breaker Points88
Parts of Breaker Point89
Breaker Arm and Spring89
Value for Maintenance and Replacement of Breaker Point89
Contact Point Cam90
Using Sandpaper90
Pointed File and Oilstone90
Correction by Oilstone90
Spark Advancer Maintenance and Replacement91
Graph of Spark Advancer91
Graph of Advanced Angle of Spark Advancer91
Spark Plug Requirements92
Construction of Spark Plug92
Electrode Construction92
Spark Plug/Insulator Construction93
Heat Characteristics of Spark Plugs93
Favorable Status of Plug93
Overheated/Smoke Plug93
Necessity of Spark Plugs with Different Heat Values94
Temperature Dissipation94
Sectional View of Plug Characteristics94
Plug Comparison94
Power Source Circuit95
AC Generator Construction95
Specifications of AC Generator95
AC Generator Installed on Engine95
Performance of AC Generator96
Silicon Rectifier96
Measurement of Timing96
Rectifying Operation96
Silicon Rectifying Element97
Rectifier of Silcon Wafer97
Feature Comparison of Silicon and Selenium Rectifiers98
Silicon Rectifier Mounting Section98
Connection98
Comparison of Silicon and Selenium Rectifiers98
Caution Concerning Wiring99
Specifications of the Silicon Rectifier99
Battery Construction100
Coupled Plate Group100
Separator100
Battery Charging, Discharging Ratio and Capacity101
Battery Components101
Graph of Specific Gravity and Electrical Capacity101
Reversible Reaction101
Discharge/Charge Rate102
Initial Charge102
Caution Required During Starting102
Battery Without Electrolyte102
Caution Required During Use103
Supplementary Charge of Battery103
Specific Gravity103
Indication of Electrolyte Level103
Battery Trouble/Repair104
Anode/Negative Plate104
Separators104
Caution in Battery Use104
Self-Starter105
Starting Circuit105
Motor Performance105
Situation Caused Prolby Onged Discharge105
Starter Reduction106
Starting Motor106
Parts of Starting Motor Reduction Mechanism106
Starting Motor Mounted on Engine106
Removing/Maintenance Starting Motor107
Removing the Carbon Brush107
Commutator107
Starting Clutch107
When the Starting Motor Rotates108
When the Engine Starts108
Lubrication108
Caution Required During Maintenance108
Starter Solenoid109
Principles of Operation109
Caution109
Disassembly of Solenoid109
Safety Parts110
Circuit110
Horn110
Parts of Main Safety Units110
Tail/Stop/Neutral Pilot Lamp111
Horn Adjustment111
Composition Lamp for Tail Lamp111
Neutral Lamp111
Speedometer112
Components of the Neutral Lamp112
Neutral Switch112
Speedometer Assembly/Scale112
Gear Box113
Standard for Operating Safety113
Principle of Speedometer113
Replacement Values for Speedometer Repair113
Head Lamp114
Construction of Head Lamp114
Principle of the Head Lamp114
Automotive Vehicle Bulbs115
Test Voltage115
Inspection of Lamp Distribution115
Combination Switches116
Stop Switch116
Switch Disassembly/Assembly116
Operation and Connection of Combinatin Switch116
Wire Harness117
Horn Button and Dimmer Switch117
Tips of Wires in Wire Harness117
Fuse Box Incalled on Wire Harness117
Maintenance118
Engine Adjustment118
Compression118
Maintenance Shop118
Tappet Adjustment119
Correct Compression Pressure119
Troolsequired for Tappet Clearance Adjustment119
Alignment of the Stator119
Ignition Timing120
Checking Clearance with a Thickness Gauge120
Tools Required for Adjusting the Spark Timing120
Adjustment of Points120
Adjusting the Spark Plugs121
Spark Advance Arm121
Tools Required for Spark Plug Adjustment121
Cleaning the Spark Plugs121
Fuel Supply122
Carburetor Cleaning and Adjustment122
Tools Required to Inspect the Fuel System122
ON and RES Positions of Fuel Tank Pet Cock122
Air Cleaner123
Inspecting the Throttle Valve Openings with a Mirror123
Cable Adjuster123
Tools Required for Cleaning the Air Cleaner123
Clutch Adjustment124
Tools Required for Adjustment of Clutch124
Clutch Lever Play124
Clutch Cable Adjuster124
Drive Chain Adjustment125
Front Brake Adjustment125
Tools Required for Drive Chain Adjuster/Adjustment of Front Brake125
Drive Chain Slack125
Rear Brake Adjustment126
Play of the Front Brake Lever/Rear Brake Pedal126
Adjustment of Play of Front Brake Lever126
Tools Required for Adjusting Rear Brake126
Battery Inspection127
Engine Oil127
Adjustment of Play of Rear Brake Pedal127
Lifting the Battery from the Frame127
Grease128
Drain Plug128
Oil Gauge128
Grease Fitting on Left128
Oiling the Drive Chain129
Critical Connections129
After Greasing, Replace Bearings in Hub129
Tools for Chain Lubrication129
Wheel Spokes130
Daily Inspection130
Left/Right Side Connections130
Tightening the Spokes130
Periodical Inspection and Repair131
Right Side of the Vehicle131
Honda Models CB125 and CB160 Maintenance Specifications132
CB125 and 160 Exploded View136
Honda Motorcycle Parts and Accessories137

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Honda CB125 - Operation of Gear Shift; Transmission Assembly; Gear Shift Disassembly; After the Transmission and Crankshaft Are Coupled, the Lower Crankcase Should be Matched

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