Honda CM185T Twinstar 1978–1979 Service Manual

Honda’s December 1977 factory service manual covers the 1978–1979 CM185T Twinstar from frame number F/N 2000014 onward. The maintenance schedule refers to the separate Owner’s Manual for the pre-ride inspection.

PDF Navigation and Wiring Diagram Readability

Page bookmarks and text search: Bookmarks labeled with page image filenames link to individual pages. PDF text search is unavailable. Small wire and connector labels are easier to read when zoomed in on the clearer wiring diagram. Print showing through from the reverse side makes some labels harder to read on the other version.

The download contains one 207-page printable PDF in English. The opening motorcycle photo and the additional version of the full wiring diagram are included in the page count.

Engine Overhaul, Chassis Service, and Electrical Testing

The topics below are selected examples from the manual. It also covers oil screen cleaning and crankcase breather maintenance.

• Engine and cylinder head: Engine removal and installation, rocker arm and camshaft service, valve guide replacement, valve seat inspection and refacing, and cylinder and piston inspection.

• In-frame service: Clutch, oil pump, gearshift linkage, kickstarter, contact breaker, AC generator, starter clutch, and starter motor.

• Transmission and crankshaft: Crankcase separation, gearbox teardown, shift fork inspection and orientation, crankshaft and bearing work, balancer positioning, and reassembly.

• Carburetor: PD98A removal and disassembly, throttle valve and jet inspection, float and float valve service, and idle and high-altitude adjustments.

• Wheels, brakes, and suspension: Wheel bearings, drum brake panels and shoes, fork seals, steering stem, swingarm bushings, rear shocks, drive chain, sprockets, and brake pedal linkage.

• Electrical diagnostics: Charging tests, stator and rectifier checks, points ignition and starter tests, switch continuity tables, wiring diagrams, and symptom-based troubleshooting charts.

The manual suits mechanically qualified owners and service technicians with the measuring tools and special equipment needed for internal engine, suspension, and electrical work.

Engine and Transmission Inspection

Service tables pair standard dimensions with wear limits for the cylinder head, valves, camshaft, rocker arms, pistons, rings, connecting rods, clutch, oil pump, shift forks, shafts, gears, and bearings. Torque references, exploded views, and assembly illustrations accompany the procedures.

The manual distinguishes clutch and oil pump work that can be done with the engine in the frame from transmission and crankshaft work that requires splitting the crankcase. It shows how the shift forks and balancer are positioned during reassembly.

The lubrication diagram and assembly notes explain why the cylinder-head oil feed, O-rings, and dowels matter for camshaft lubrication. The crankcase section warns that an oil seal seated too deep at the countershaft can block its oil passage.

The tool chart includes the clutch outer holder (07923-1070001), valve guide reamer (07984-0980000), piston ring compressor (07954-4190000), and rear shock spring compressor (07959-3290001), along with pullers, drivers, pilots, and gauges.

Carburetor, Brakes, and Suspension

Carburetor coverage includes float level, idle speed, and pilot screw settings. The manual distinguishes routine idle adjustment from pilot screw adjustment after overhaul and includes a separate high-altitude setting. The emission-control label provides basic tune-up specifications for CM185Ts built after December 31, 1977.

The chassis chapters give inspection limits for the wheels, brakes, forks, swingarm, and rear shocks, with procedures for brake shoe replacement, fork seal replacement, and rear shock disassembly. They also specify how to support the CM185T securely for wheel removal, since it has only a side stand.

Wiring and Fault Diagnosis

The full wiring diagrams and cable routing layouts are supported by separate charging, ignition, and electric starter schematics. The clearer full diagram notes the headlight change on later models, which helps identify the applicable headlight specification before selecting a replacement.

The electrical chapters cover ignition coil and condenser checks, starter armature and field coil tests, and starter magnetic switch operation. The rectifier section specifies continuity testing and warns that a high-voltage insulation tester can damage the diodes.

Troubleshooting charts cover hard starting, loss of power, poor idle and high-speed performance, exhaust smoke, clutch and shifting faults, engine noise, pulling to one side, suspension faults, weak braking, and drive chain wear. Workshop cautions address fuel handling, battery charging, eye protection, and ventilation during engine-running checks.

Valve Clearance and Float Level Examples

The CM185T inspection section specifies 0.05 mm (0.002 in.) for both intake and exhaust valve clearance with the engine cold, below 95°F (35°C), and the cylinder being checked at top dead center on its compression stroke.

For the PD98A carburetor, the float adjustment section specifies a float level of 14.5 mm (0.57 in.) at the point where the float tip just contacts the float valve.