Honda CB125, CB160 Shop Manual (P/N 622161)

• 1972 Honda factory shop manual for the CB125 and CB160, issued by Honda Motor Co., Ltd., Service Department, Foreign Sales Division; a 139-page PDF reproduced from 300-dpi scans, with Honda document code 622161.
• Defines the shared 360-degree, air-cooled OHC parallel-twin layout with dual carburetors, battery ignition, electric and kick starting, a wet multiplate clutch, and a four-speed constant-mesh transmission; separate factory columns distinguish CB125 and CB160 specifications.
• Covers engine removal and installation, cylinder-head and camshaft service, valve and seat work, cam-chain timing, crankcase separation, crankshaft/rod/piston inspection, transmission and gearshift repair, clutch and starter-clutch service, lubrication-system checks, and twin-carburetor adjustment.
• Follows chassis repair through the front cushion/fork, steering stem and handlebar lock, fuel tank, frame, seat and air cleaner, stand, exhaust, rear fork and cushion, wheels, bearings, drum brakes, drive chain, spokes, and wheel alignment.
• Explains inspection and testing of the ignition coil, breaker points, condenser, spark advancer, AC generator, silicon rectifier, battery, starter motor and solenoid, horn, neutral switch, speedometer, headlamp, switches, and wire harness, supported by circuit drawings and performance charts.
• Supplies a dedicated CB125/160 special-tool plate, model-specific maintenance tables, torque references, capacities, standard values, correction limits, periodic inspection schedules, and a full-width engine exploded view.

Engine and Drivetrain Repair

Honda organizes the publication around the common 360-degree parallel-twin architecture rather than treating the two displacements as unrelated motorcycles. Procedures are shared where the construction is the same, while the specifications and maintenance tables keep the CB125 and CB160 in separate columns. That lets a technician follow one factory repair sequence while checking the correct model-specific dimensions, carburetor data, performance references, and service limits.

The engine chapters go well beyond tune-up work. They document cylinder-head removal, camshaft and rocker-arm service, valve removal and seat dressing, cylinder and piston inspection, crankcase separation, crankshaft and connecting-rod checks, transmission and shift-mechanism inspection, kick-starter work, and wet multiplate clutch repair. Assembly references include cam timing, cylinder-head tightening order, bearing and oil-passage alignment, gasket and O-ring inspection, and the factory standard-versus-correction-limit tables used to decide whether parts remain serviceable.

Lubrication is treated as a complete system: plunger oil-pump operation, wire-mesh and centrifugal filtration, the oil separator, internal passages, and diagnostic checks for poor circulation. The carburetor section explains the main, midrange, and slow-speed circuits before covering cleaning, jet and needle selection, float-height inspection, idle setting, full-throttle travel, and matching the right and left throttle openings. That is the repair depth needed when a twin runs unevenly after fuel-system work.

Frame, Brakes, and Electrical Systems

The chassis chapters cover removal, inspection, and assembly of the telescopic front cushion, steering stem bearings and damper, tank and petcock, frame body, center stand, mufflers, swingarm, rear cushion, and both wheel assemblies. Honda includes inspection criteria for brake shoes and cams, hubs, bearings, spokes, rims, axles, tire and tube installation, speedometer-drive alignment, chain tension, and front and rear brake adjustment.

Electrical coverage combines operating theory with practical testing. It addresses simultaneous ignition on the 360-degree twin, point and condenser condition, centrifugal spark advance, spark-plug diagnosis, AC-generator charging performance, rectifier checks, battery service, planetary starter reduction, starter clutch, solenoid, lighting, horn, neutral indicator, combination switch, and harness color identification. The manual also describes the AC-generator emergency-start circuit used with the kick starter.

Diagrams, Scope, and Repair Cautions

Representative references include the cam-chain installation and cylinder-head tightening sequence, clutch sectional view and lubrication circuit, front-fork and steering-stem section views, ignition-coil spark-performance graph, AC-generator charging curve and rectifier circuit, and the large CB125/160 engine exploded view. The special-tool plate identifies equipment such as the drive-sprocket holder, valve lifter, rotor puller, piston ring tool and slider, bearing puller, steering-stem socket, and fork/rear-cushion fixtures.

Several factory cautions address mistakes that can cause immediate trouble. Reversing the marked piston can bring the piston crown into contact with the valves. Incorrect rectifier wiring or operating the generator with the battery disconnected can destroy the silicon rectifying layer, while misplaced starter-clutch parts near the magnetic rotor can disable AC generation.

Coverage is limited to motorcycles identified in the publication as CB125 and CB160. The manual contains no serial-number breakouts or suffix-specific chapters, so matching the engine, starter, charging, brake, and chassis layout remains important. Fuel, battery, brake, wheel, and running-engine tests require secure support, electrical isolation, and proper fire precautions.