Honda CB250/350, CL250/350 & SL350 Shop Manual Set, 1972 (P/N 6228602)

The SL350 supplement is used with the base manual for shared procedures. The later volume incorporates SL350-specific chapters and a principal-modification table comparing CB/CL K-series and SL350 K1/K2 changes.

Match the SL350 information to the configuration being serviced: the companion supplement documents the earlier electric-start, CV-carburetor layout, while the later volume includes primary-kick-starter procedures and Keihin PW24 carburetor data.

Printable PDFs and Wiring Diagram Detail

Search, bookmarks and diagram labels: PDF text search is unavailable in both files. The companion PDF has bookmarks for the main chapters and SL350 supplement; the 1972 volume has no embedded bookmarks. Small wiring labels require enlargement.

The ZIP download contains two printable English PDFs: a 146-page volume and a 219-page companion, totaling 365 pages. Covers, introductory material, publication pages, memo sheets and blank pages are included in these totals. The 1972 volume carries Honda’s copyright and a Printed in Japan imprint; the earlier base manual identifies Honda’s Foreign Service Department as publisher.

O.H.C. Twin Repair, Chassis Service and Electrical Diagnosis

The following highlights are a selection of the contents, rather than a complete table of contents. Other topics include fuel-strainer inspection and stoplight-switch adjustment.

• Engine repair: Step-by-step procedures for engine removal, cylinder-head and valve-train disassembly, piston and cylinder inspection, cam-chain-tensioner service, and reassembly.

• Clutch and transmission: Wet multi-plate clutch service, crankcase separation, transmission inspection, shift-drum and fork checks, and CB/CL kick-starter repair.

• Carburetor service: Keihin carburetor removal and cleaning, float-level checks, pilot adjustment, throttle-cable adjustment, and synchronization of the two throttle valves.

• Chassis and brakes: Telescopic-fork teardown, fork-seal replacement, steering-stem and rear-fork service, wheel inspection, drum-brake checks, and rear-cushion spring service.

• Electrical diagnosis: Battery-coil ignition tests, breaker-point and spark-advancer inspection, charging-system checks, starter-system service, and model- or market-specific wiring diagrams.

• Factory reference material: Maintenance schedules, tightening-torque standards, capacities, wear limits, clearances, electrical test values, fault-isolation charts, special-tool numbers, and component views.

Honda prepared these books for shop personnel performing service and repair with precision measuring equipment, electrical testers, and the tools needed for engine or chassis disassembly.

Engine Inspection and In-Frame Service

The engine chapters separate work that can be performed in the frame—including clutch, oil-pump, oil-filter, AC-generator, neutral-switch, and cam-chain-tensioner-holder service—from operations requiring engine removal. That distinction helps plan the scope of engine work before disassembly.

Internal inspection covers valve seats and guides, camshaft and rocker-arm measurements, piston and ring limits, cylinder wear, crankshaft runout, and connecting-rod checks. Lubrication sections explain the plunger oil pump, screen strainer, and centrifugal oil filter.

Transmission Changes and Carburetor Circuits

Engine-number-specific transmission notes identify added thrust- and lock-washer hardware between the C2 and C3 gears. These distinctions help determine which shaft-disassembly notes apply; Honda also references Service Bulletin No. 012 for CB/CL250 and 350 and Parts News No. 8034 for CB250.

Transmission inspection includes gear backlash and gear-to-shaft clearances. The later SL350 section separately describes the primary kick-start mechanism, which differs from the CB/CL arrangement.

The earlier carburetor chapter explains airflow, fuel flow, and the slow, primary, and secondary circuits through different throttle openings. Its sectional views provide context for the adjustment and synchronization procedures.

Frame, Suspension and SL350 Differences

Chassis material addresses the semi-double cradle frame, controls, fuel tank, exhaust, seat, stands, and air cleaners through removal, inspection, and reassembly. SL350 sections add configuration-specific fork and steering details, frame construction, off-road wheels and tires, bead spacers, and the exhaust spark arrester.

Rear-cushion spring removal is distinguished from damper repair. The SL350 De Carbon damper is a sealed, pressurized, nonrepairable unit; its cylinder must not be opened. Support the motorcycle securely before engine, wheel, fork, or suspension repair.

Engine-installation notes also flag drive-chain joint-clip orientation and the clutch-release steel ball. Incorrect assembly can allow chain separation or leave the clutch release inoperative.

Charging Tests, Starter Service and Factory Views

Electrical sections pair AC-generator charging characteristics and winding-resistance data with regulator/current-limiter checks, selenium-rectifier testing, and battery troubleshooting. Starter coverage includes the motor, one-way starting clutch, and solenoid; lighting, switches, horn, meters, the neutral circuit, and wire harness are also addressed.

The earlier manual outlines the Jonan ST-4B4 Honda service tester for meter reading and continuity, resistance, insulation, voltage, current, coil, and condenser tests. Detailed instrument operation refers to the separate leaflet supplied with the tester.

System illustrations include the Power Transmission System, Cam Chain Tensioner Mechanism, and Oil Lubrication System. Component references include the Cross Section of Oil Filter, Sectional View of Clutch, and Gear Shift Mechanism.

The 1972 volume supplies six wiring diagrams: CB250K4 U.K.; CB350K4 U.S.A. and General; CL350K4 U.S.A. and General; and SL350K2 U.S.A. The companion base manual adds General, U.S.A., U.K., and Germany diagrams, followed by a separate SL350 circuit drawing in the supplement.

Selected Tappet and Breaker-Point Specifications

The 1972 volume’s CB/CL engine-inspection section specifies cold tappet clearances of 0.05 mm at the inlet and 0.10 mm at the exhaust.

Its breaker-point section gives a maximum-opening gap of 0.3–0.4 mm for both left- and right-cylinder points, alongside the corresponding ignition-timing procedures.