Honda CB350F/CB400F Four 1975–78 Service & Repair Manual (P/N 623231)

• Combines the 1972-model CB350F base manual and CB400F supplement, with separate information for changed engine, frame, and electrical components.
• Covers engine removal, cylinder-head and piston teardown, valve timing, and cam-chain tensioner service, distinguishing on-vehicle work from engine-out repairs.
• Details wet multi-plate clutch inspection, primary drive chain and primary shaft disassembly, starter-clutch checks, and gear shift mechanism service.
• Provides vacuum-gauge carburetor synchronization, fast-idle and overtravel-stopper adjustments, plus throttle-cable setup.
• Front disc brake coverage includes master-cylinder and caliper repair, pad inspection, caliper adjustment, and hydraulic bleeding.
• Electrical diagnosis covers charging-system tests, ignition timing, starter operation, and switch continuity, supported by model-specific wiring diagrams.

The 113-page PDF set is divided into ten files: an 86-page base manual, a 26-page supplement, and one cover page.

Engine and Transmission Repair

For the 4-cylinder O.H.C. engine, the manual pairs disassembly procedures with inspection criteria and reassembly notes. Valve-seat contact checks, valve-guide replacement, and camshaft-bearing inspection extend the coverage beyond routine adjustment.

Bottom-end repair includes Plastigauge clearance checks and selective bearing fitting for the crankshaft and connecting rods. Identification tables connect journal measurements and rod codes with bearing grades. Separate instructions address matching connecting rods by weight.

The internal transmission teardown and exploded view use the CB350F five-speed assembly. The CB400F supplement provides six-speed specification data and gearshift-pedal linkage adjustment rather than a separate six-speed transmission teardown chapter.

Lubrication coverage addresses the double trochoid oil pump, relief-valve inspection, and two-stage oil filtration. The “Lubricating oil circuits” diagram traces pressure and splash lubrication through the engine and transmission.

Carburetors, Brakes, and Suspension

Carburetor teardown covers throttle valves and jet needles, float-valve service, jet inspection, and fuel-level adjustment. The supplement adds the CB400F carburetor setting table and Blow-by Gas Circulator, including breather-element cleaning and drain-tube service.

The frame section walks through wheel-bearing service and wheel balancing, steering stem adjustments, and rear drum brake inspection. Suspension work includes fork-seal replacement and rear-fork pivot-bushing checks; the supplement details the changed front-fork internals. Fuel-cock disassembly and muffler removal are covered there as well.

The brake chapter flags a specific repair hazard: careless installation can damage the master-cylinder primary cup.

Charging, Ignition, and Starting Systems

On the electrical side, the three-phase A-C generator section covers field- and stator-coil checks, silicon-rectifier testing, and charging measurements. The base text details the Tirrill-type voltage regulator and its contact adjustments. The CB400F supplement instead covers the charging circuit with a pointless regulator, along with its clutch-switch starting circuit.

Ignition diagnosis includes coil performance tests and spark-advancer checks. Starting motor characteristics, brush and armature inspection, and main switch continuity tests support fault isolation. The CB400F diode-testing notes warn that a high-voltage megger can damage the starting-circuit silicon diode.

The “Charging test circuit,” separate CB350F and CB400F wiring diagrams, and CB400F “Routing” drawings support circuit tracing and cable, hose, and harness placement. Exploded assembly views elsewhere identify internal components during teardown.

Service Data, Troubleshooting, and Special Tools

Component-specific torque tables, fluid-capacity data, assembly standards, service limits, and electrical test specifications accompany the repair coverage. Separate maintenance schedules organize recurring service work for each model.

Troubleshooting tables relate symptoms such as hard shifting, clutch slip, wheel wobble, and insufficient or excessive charging to probable causes and remedies. Special-tool lists identify the CB400F clutch lock nut wrench 07916-6390000 and carburetor synchronization wrench set 07908-3230200.

Because brake work and loaded suspension springs involve mechanical risks, always cross-check the applicable service data and ensure you have the proper technical background or professional supervision before starting any project.