Honda C50/C65/S50/S65 & C70/CL70 Service Manual Set, 1965–1969

The supplement uses the CL70 as its base model and refers readers to the 50/65 shop manual for detailed fundamentals. Its C70/C70M engine-removal instructions, carburetor adjustment information, and chassis inspection procedures rely on the base material where indicated.

PDF Search, Page Bookmarks and Wiring Detail

Search and diagram navigation: PDF text search is not available. Embedded bookmarks provide individual-page access using image-file labels rather than descriptive chapter names. Wiring diagrams are sideways; rotate the page and zoom in to read small wire-color codes and switch-terminal labels.

ZIP download containing one printable, English-language PDF with 156 pages. The base-manual total includes five front-matter pages and three memo pages; the supplement occupies printed pages 122–151.

O.H.C. Engine, Drivetrain and Electrical Service

The following selected content highlights show the main workshop coverage. Other included topics range from muffler diffuser cleaning to speedometer fault diagnosis.

• Engine repair: Step-by-step engine removal and installation, cylinder-head and valve-seat repair, cylinder and piston inspection, crankshaft service, and trochoid oil-pump work.

• Clutch and transmission: Wet-clutch disassembly, inspection, adjustment, and reassembly, plus transmission, gear-shift mechanism, and kick-starter service.

• Chassis service: Steering-head and front-fork work, front and rear cushion inspection, wheel bearings and axles, drum brakes, rear-fork bushings, and drive-chain adjustment.

• Fuel-system diagnosis: Model-specific carburetor settings, float-level measurement, mixture adjustment, and fault tables for overflow, hard starting, poor idling, and weak acceleration.

• Electrical testing: Starting and charging checks, ignition-coil and condenser tests, spark-advancer inspection, battery service, and selenium-rectifier diagnosis.

• Workshop reference: Numbered special-tool references, torque and wear-limit tables, performance curves, dimensional drawings, sectional and exploded views, and model-specific wiring diagrams.

Honda presents this as a maintenance and servicing guide for servicemen, with system background also useful to sales staff. Internal repair work calls for experience with pullers, precision gauges, and electrical test equipment.

Engine Internals and Drivetrain Differences

The engine material follows the O.H.C. unit from its power-transmission layout and pressure-lubrication routes into internal inspection and reassembly. Detailed coverage reaches valve-guide replacement and reaming, valve-seat contact checks, camshaft inspection and timing, piston-ring measurements, centrifugal filtration, and crankshaft and connecting-rod checks.

The right crankcase cover, crankcase breather, and hydraulic/spring cam-chain tensioner receive separate treatment. Drawings include the power-transmission diagram, trochoid oil-pump operating view, cam-chain tensioner detail, clutch oil-passage layout, and transmission construction views.

Clutch configurations: The main specifications distinguish the automatic centrifugal clutches on C50/C50M/C65/C65M from the manually operated S50/S65 clutches. The supplement likewise separates the manually clutched CL70 from the automatic C70/C70M arrangements. These distinctions help readers select the appropriate clutch checks and adjustment information before working on a particular model.

Uneven cylinder-head tightening can crack or warp the head, causing sealing and compression loss. The manual addresses head inspection and assembly precautions alongside the related service measurements.

Carburetor Settings and Fuel-System Faults

The carburetor setting table separates the 1000-series carburetors used on C50/C50M/C65/C65M from the S65’s PW16FA6 or PW16FA10 and the S50’s PW16FA11. Its data identifies throttle and venturi bores, main and air jets, bleed arrangements, needle and clip settings, throttle cutaway, slow-speed components, valve seats, pilot outlets, and fuel levels.

Separate adjustment material covers high-, intermediate-, slow-speed, and idle operation. Symptom-based tables connect overflow, flat spots, poor speed transition, and loss of high-speed performance with likely fuel-system causes, supporting diagnosis beyond simply changing carburetor settings.

The supplement supplies a separate carburetor specification table. Its chassis chapter primarily gives inspection specifications for suspension, axles, brakes, and rear-fork bushings, with the base manual supplying the referenced procedures.

Electrical Circuits, Troubleshooting and Tools

Starting and charging: Electrical coverage distinguishes the electric-start C50M/C65M circuits from the other 50/65 arrangements. Generator performance charts, ignition-coil checks, condenser tests, spark-advance information, battery charging instructions, and rectifier tests support fault isolation.

Full wiring diagrams cover C50/C65, C50M/C65M, and S50/S65. Separate diagrams cover CL70, C70, C70M General Export Type, and C70M USA Type, including their switch arrangements and wire-color legends.

The troubleshooting tables also address engine noise, steering pull or shimmy, clutch slip or drag, missed shifts and gear jump-out, suspension faults, brake performance, and drive-chain wear.

Special-tool references: The chart lists 21 tools, including valve-guide reamer 07984-0980000, clutch assembly tool 07960-0110000, flywheel puller 07933-0010000, and rear-cushion disassembly tool 07959-3290000. The supplement identifies Tool Set No. 07900-1180000 as the shared C65/S65 kit.

Operating the engine with the battery or electrical load disconnected can damage the selenium rectifier through excessive reverse current. Fuel handling, battery-electrolyte service, ignition testing, brake repair, and drive-chain work call for suitable workshop precautions and properly calibrated equipment.

Oil-Pump and Clutch Inspection Examples

For CL70/C70/C70M oil-pump inspection, the supplement lists an outer-rotor-to-body clearance of 0.10–0.15 mm as standard, with replacement specified above 0.20 mm. The illustrated measurement distinguishes housing clearance from the separate rotor end-clearance check.

The same supplement gives clutch friction-disc thickness as 3.50 mm standard, with replacement below 3.10 mm. These component-specific measurements illustrate the distinction between normal dimensions and service limits used in its inspection tables.