Honda CT70, CT70H & ST50/ST70 Manual Set, 1969–1982 (P/N HC 37507)

Use the shop manuals for inspection and repair, the owner’s manuals for controls and routine maintenance, and the parts catalog to match illustrated components to model applications and production changes. The separate wiring sheets let you select a circuit diagram by model, market, or electrical system.

The parts catalog covers CT70, CT70H, CT70K1, and CT70HK1. Coverage of later CT70 versions comes from the shop-manual addenda, model-reference sheets, and applicable wiring diagrams. Some workshop sections also refer to the separate Honda 50/65 Shop Manual, which is sold separately from this set.

PDF Search, Bookmarks & Wiring Legibility

The parts catalog and the 130-page shop manual have searchable text on many pages. Use the PDF bookmarks to navigate both shop manuals, both owner’s manuals, and the model-reference sheets. The parts catalog also has bookmarks, though several group entries lead to its contents page. The standalone wiring sheets are image-based. Zoom in to follow wire colors and terminal labels, especially on the denser CT70 diagrams, where some small markings are difficult to read.

The ZIP contains 15 printable PDFs totaling 416 pages, including the additional cover copy in the parts catalog. The manuals are in English, with German and French/Dutch labels on the applicable market wiring sheets.

Engine Service, Chassis Work & Parts Identification

The topics below are a selection from the set. Other sections cover special service tools and specifications for tightening fasteners.

• Engine and lubrication: Engine removal and installation, cylinder and head work, cam-chain tensioner, oil pump, and piston and ring inspection.
• Fuel and drivetrain: Keihin Seiki carburetor assemblies and service, automatic and manual clutch layouts, gearshift mechanisms, transmissions, and kick starters.
• Steering, suspension, and brakes: Handlebar, fork, and cushion assemblies, plus inspection of wheels, hubs, brake shoes, and drive-chain components.
• Ignition and wiring: Generator and spark checks, contact-breaker adjustment, and circuit diagrams for selected CT70 and ST50/ST70 versions.
• Parts ordering: Numbered exploded views, Honda codes, replacement part numbers, and engine or frame serial breaks for identifying the correct part.
• Owner maintenance: Controls, starting and shifting, fuel and oil, scheduled maintenance, and routine adjustments.

Matching Parts to the Build

The catalog distinguishes Hitachi and Mitsubishi generator components, including points, condensers, flywheels, stators, and lighting coils. Its separate clutch, gearshift, and transmission plates help identify the corresponding components for CT70/CT70K1 and CT70H/CT70HK1.

Before ordering, use the application and remarks columns to match the part to the engine or frame number. The cylinder, gearshift fork, handle levers, and carburetor sets have production breaks. The catalog also lists standard and oversize piston and ring options, finish-specific chassis parts, superseded numbers, and unavailable items. Its thread-change notes distinguish wrench-size changes from changes in pitch that affect fastener interchangeability.

CT70 Ignition Specifications Preview

The CT70 owner’s manual specifies a spark plug gap of 0.024–0.028 in. (0.6–0.7 mm) for the standard NGK C-7HS or ND U-22FS plug. It lists a standard breaker-point gap of 0.012–0.016 in. (0.3–0.4 mm), measured at maximum point opening.