1971–1985 Honda CB100, CL100, SL100, CB125S, CD125S, SL125 & TL125 Service Manual (P/N 6210703)

Honda factory service information for the 1971–1985 CB100, CL100, SL100, CB125S, CD125S, SL125, and TL125. This shop manual combines the main engine, chassis, and electrical sections with an integrated TL125 supplement that refers back to shared procedures.

• Engine repair: Engine removal, cylinder-head and piston service, valve-guide replacement, valve-seat reconditioning, camshaft installation, and valve timing.

• Clutch and transmission: Wet-clutch disassembly, gear shift mechanism service, crankshaft inspection, transmission assembly, and primary kick starter repair.

• Maintenance and fuel system: Tappet, carburetor, ignition timing, clutch, and chain adjustments, plus oil-filter servicing, compression checks, and maintenance schedules.

• Brakes and chassis: Drum-brake inspection, wheel-bearing service, spoke adjustment and rim truing, steering-stem service, and front fork disassembly and oil-seal replacement.

• Electrical diagnosis: A.C. generator, selenium rectifier, ignition coil, condenser, and switch tests, supported by charging-circuit illustrations and model-specific wiring diagrams.

• TL125 differences: Dedicated clutch and transmission illustrations, front suspension procedures, control adjustments, cable routing, and flywheel-magneto ignition information.

Written for service technicians, the manual also identifies TL125 maintenance tasks suitable for mechanically proficient owners with the proper tools.

Engine Inspection and Internal Repair

The engine chapters distinguish work that can be performed with the engine installed from jobs requiring removal and crankcase separation. That distinction helps you plan access for oil-pump, clutch, or gear shift work before committing to a complete teardown.

Cylinder-bore and piston measurements, ring-clearance checks, valve-stem and guide inspection, and valve-seat reconditioning are accompanied by standard dimensions and service limits. Crankshaft runout checks and connecting-rod inspection extend the coverage beyond routine adjustments.

The lubrication-system illustration traces oil delivery through the centrifugal filter and passages serving the crankshaft, cylinder head, and transmission. Special-tool references include valve spring compressor 07031-10701 and dynamo rotor puller 07011-03001.

The crankshaft installation notes warn that forcing or hammering the assembly into the crankcase can damage its ball bearings.

Carburetor Setup and Fault Finding

Carburetor coverage includes idle-mixture adjustment, float-level setting, an exploded assembly view, and a setting table separating the main model groups. Fuel-system inspection also addresses tank ventilation, the fuel cock, and fuel lines.

Troubleshooting tables connect hard starting, stalling, poor performance, abnormal engine noise, clutch slip, and shifting faults with probable causes and corrective work. The compression-check section distinguishes leakage-related low readings from unusually high readings associated with carbon deposits.

Forks, Wheels, and Steering

Chassis procedures cover front and rear brake drums and linings, wheel-rim runout, bearing replacement, steering races, and rear-fork pivot inspection. Front suspension sections distinguish the fork constructions and related service specifications.

Rear suspension coverage includes spring removal, inspection, and assembly. The main manual specifies replacement of a defective shock absorber body; it does not provide internal damper repair.

For the TL125 fork, the cleaning notes specifically warn that gasoline can damage rubber parts.

Charging Circuits and TL125 Service Differences

The main electrical section covers the 6V battery system, with separate charging-test conditions and checks for the stator, selenium rectifier, ignition coil, and condenser. An A.C. generating specifications chart accompanies the circuit illustrations.

Model-specific wiring diagrams show switches, harness connections, and wire-color codes. The TL125 diagram instead details its magneto ignition circuit, keeping that arrangement distinct from the battery-equipped models.

The TL125 supplement illustrates its different clutch assembly and transmission gear arrangement. It directs readers to the main transmission chapter for shared procedures and adds front fork spring adjustment, pedal positioning, and an optional-parts table.

Follow the manual’s precautions around fuel, battery charging, and moving engine parts, and verify brake and control operation after service.

Examples of Compression, Tappet, and Condenser Data

The main compression-check section lists a normal pressure of 12 kg/cm² (170 psi), with the engine warm and the throttle fully open during kick-start testing. Cold tappet clearance is specified as 0.05 mm for both intake and exhaust in the main manual and TL125 supplement.

For the TL125 condenser, the electrical table lists insulation resistance of 10 MΩ measured with a 1,000 V Megger. This specification applies to the condenser, not a magneto pick-up coil.

Printable PDF with Wiring Diagrams and Printed Index

Search, navigation, and diagram detail: PDF text search and embedded bookmarks are unavailable; navigation relies on the printed contents and index. Small wire-color codes and switch-table labels in the detailed wiring diagrams require zooming.

One printable English PDF contains 101 pages: 4 opening pages comprising the cover, foreword, and contents; 74 pages of main service material; the 22-page TL125 supplement; and a 1-page index. All are included in the total.