Honda CB250, CL250, CB350, CL350, SL350 Shop Manual (P/N 235802)

• 365 PDF pages total: a 146-page 1972 Honda CB/CL/SL 250-350 shop manual, plus a 219-page companion PDF containing a 191-page May 1968 CB/CL 250-350 base manual and a 28-page SL350 supplement.
• Model coverage centers on the CB250K4, CB350K4, CL350K4, and SL350K2, while retaining baseline CB250/350, CL250/350, and SL350 data. A principal-modification table compares CB/CL K-series changes and SL350 K1/K2 differences.
• Engine repair coverage takes the O.H.C. twin from removal and installation through cam case, valve train, pistons, cylinders, hydraulic cam-chain tensioner, crankshaft, connecting rods, oil pump, screen, and centrifugal oil-filter service.
• Drivetrain and fuel sections cover the wet multi-plate clutch, five-speed constant-mesh transmission, shift drum and forks, the CB/CL kick-starter and SL350 primary kick-starter arrangements, crankcases, Keihin carburetor inspection, float setting, and twin throttle-valve synchronization.
• Chassis procedures address the semi-double cradle frame, steering stem, telescopic front fork, fork seals, rear fork, rear cushions, wheels, drum brakes, controls, fuel tank, exhaust, seat, stands, and air cleaners through disassembly, inspection, repair, and reassembly.
• Electrical diagnosis spans battery-coil ignition, ignition timing, spark advancer and breaker points, AC generator, regulator/current limiter, selenium rectifier, battery, starter motor and one-way clutch, solenoid, lighting, switches, horn, meters, neutral circuit, and wire harness.
• Factory reference material provides maintenance schedules, tightening-torque standards, capacities, wear limits, clearances, electrical test values, fault-isolation charts, special-tool numbers, exploded/component views, and model- or market-specific wiring diagrams.

Honda presents these books as shop-personnel service literature, not entry-level owner instruction. They are best suited to motorcycle mechanics and experienced owners equipped for precision measurement, electrical testing, and engine or chassis disassembly.

The 1972 volume bears the Honda Motor Co., Ltd. copyright and a Printed in Japan imprint. The earlier base manual identifies Honda's Foreign Service Department as publisher.

O.H.C. Twin-Cylinder Engine and Drivetrain

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 service - from operations requiring engine removal. Internal repair data covers valve-seat and guide inspection, camshaft and rocker-arm measurement, piston and ring limits, cylinder wear, crankshaft runout, connecting-rod checks, oil-pump inspection, clutch-plate service, and transmission backlash and gear-to-shaft clearances.

One transmission change is identified by engine number. Units after CB/CL250E-1005974 or CB/CL350E-1042395 use added thrust- and lock-washer hardware between the C2 and C3 gears, changing how the shaft is dismantled. Honda points readers to Service Bulletin No. 012 for the CB/CL250 and 350, and Parts News No. 8034 for the CB250, for the related change details.

The carburetor material goes beyond jet specifications. It covers disassembly, component inspection, float-level setting, pilot adjustment, throttle-cable adjustment, and synchronization of the two throttle valves. The SL350 section clearly limits what is unique: its engine follows the CB/CL350 repair material except for engine removal and installation, carburetor settings, and the primary kick-start mechanism.

Chassis, Electrical Diagnosis, and Factory Views

Frame chapters document front-fork teardown and seal replacement, steering-stem inspection, rear-fork and wheel service, brake-shoe and drum checks, and rear-cushion disassembly where permitted. SL350-specific pages address its fork and steering arrangement, off-road wheel and tire details, frame, exhaust with spark arrester, air cleaners, and De Carbon rear suspension.

Electrical repair content covers static checks and operating diagnosis. It provides ignition-timing procedures using a timing light, AC-generator charging characteristics and winding-resistance data, rectifier testing, battery troubleshooting, and starter-system inspection. The earlier base manual also outlines the Jonan ST-4B4 Honda service tester for meter reading and continuity, resistance, insulation, voltage, current, coil, and condenser tests; full tester operation is left to the separate leaflet supplied with that instrument.

Named visual references include the Power Transmission System, Cam Chain Tensioner Mechanism, Oil Lubrication System, Cross Section of Oil Filter, Sectional View of Clutch, Gear Shift Mechanism, and numerous component layouts. 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 earlier base manual adds General, U.S.A., U.K., and Germany diagrams, while its SL350 supplement carries a separate SL350 circuit drawing.

Two assembly cautions are easy to miss. Honda calls out the drive-chain joint-clip direction and the clutch-release steel ball during engine installation; getting either wrong can allow chain separation or leave the clutch release inoperative. The SL350 De Carbon rear damper is identified as a sealed, pressurized, nonrepairable unit, so the damper cylinder must not be opened. Support the motorcycle securely before engine, wheel, fork, or suspension repair.