Honda CB750 Nighthawk 1991–1999 Service Manual (P/N 61MW307)

This Honda model-specific service manual, P/N 61MW307, covers the carbureted CB750 Nighthawk for 1991-1993 and 1995-1999. It addresses the air-cooled inline-four, hydraulic-tappet valve train, four constant-vacuum carburetors, five-speed transmission, front hydraulic disc brake, and rear drum brake used in the covered U.S. and Canadian configurations.

Text Search, Chapter Bookmarks, and Wiring Detail

Search and diagram viewing: OCR text search is available through most text sections, with some recognition errors. Embedded bookmarks provide access to the service chapters. The full wiring diagram has no searchable text; its small labels require zooming, and the sideways diagram benefits from page rotation.

The RAR download contains one printable English PDF with 198 pages, including the front and back covers, four introductory pages, nine memo pages, and two blank pages.

Engine Overhaul, Carburetor Service, and Electrical Fault Finding

The following selected coverage highlights major workshop tasks. Other included topics include body-panel and exhaust-system removal, air-cleaner replacement, and tachometer inspection.

• Engine repair: Engine removal and installation, camshaft timing, cylinder-head disassembly, cylinder and piston service, hydraulic-tappet inspection and bleeding, oil-pump service, oil-pressure checks, and oil-cooler removal.

• Fuel system: Carburetor-rack removal, separation and recombination, vacuum- and float-chamber disassembly, U.S.-only idle-drop pilot-screw and high-altitude procedures, and California emissions plumbing.

• Internal drivetrain: Crankcase separation, transmission disassembly, shift-fork and shift-drum service, crankshaft and connecting-rod bearing selection, alternator-shaft overhaul, and starter-clutch disassembly.

• Chassis and suspension: Wheel service, fork disassembly and seal installation, steering-stem bearings, rear-shock spring removal, and swingarm pivot-bearing replacement.

• Brake repair: Front pad replacement, master-cylinder and caliper disassembly and assembly, rear drum-brake panel service, and brake-pedal linkage removal and installation.

• Electrical diagnosis: Charging, transistorized ignition, starter/interlock, and lighting/meter/switch systems, with fault-isolation flowcharts, system-location views, continuity tables, a full wiring diagram, and starter-motor disassembly.

Honda states that the book is written for readers with basic maintenance knowledge of Honda motorcycles; because standard workshop procedures are abbreviated, it is best suited to experienced owners and technicians who can also consult the Honda Common Service Manual.

Market Identification and Companion Manual Requirements

The manual identifies A (America), AC (California), and CM (Canada) types. Fuel specifications distinguish VE66B carburetors for A models, VE77C for California AC models, and VE66C for Canadian CM models. Identification illustrations show the frame and engine serial-number, VIN, color-code label, and carburetor-number locations.

Honda Common Service Manual: This separate publication is required alongside the model-specific book and is not included. Detailed carburetor synchronization, float-level inspection, valve-guide replacement, tubeless-tire work, wheel-bearing replacement, brake bleeding, battery testing and charging, and several general switch tests are cross-referenced there. The synchronization page here supplies adapter-plug and adjusting-screw locations plus model-specific specifications.

In-Frame Work and Internal Engine Repair

The manual separates jobs that can be completed with the engine in the frame from work requiring engine removal. The oil pump, cylinder head/cylinder/piston group, clutch and shift linkage, and alternator are serviceable in-frame. Transmission, shift-fork, shift-drum, crankshaft, connecting-rod, and starter-clutch work requires engine removal. This distinction supports planning the extent of a repair before disassembly.

Step-by-step instructions supplement the illustrated camshaft installation, hydraulic-tappet bleeding, and crankcase assembly procedures. Internal-engine coverage includes color-coded bearing-selection tables. The bearing-location cautions explain how a misplaced insert can block an oil feed and lead to engine seizure.

Carburetor service: The vacuum and float chambers can be serviced without separating the carburetors. Cleaning precautions address diaphragm damage from compressed air.

Diagnostic Charts and System Drawings

The electrical flowcharts isolate charging faults among the battery, wiring, regulator/rectifier, and alternator. Ignition diagnosis distinguishes no-spark conditions affecting all plugs, one ignition pair, or a single plug, alongside ICM, coil, pulse-generator, and side-stand/neutral-interlock checks. Ignition timing is inspected but is not adjustable.

Visual references include the Lubrication System Diagram, Cable & Harness Routing views, California Pulse Secondary Air Supply System and Evaporative Emission Control System diagrams, charging and ignition System Location views, and the Wiring Diagram with switch-continuity tables.

Reference material includes general and component-specific torque tables, fluid capacities, oil-pressure test data, wear limits, clearances, carburetor settings, and electrical test specifications.

Special Tools and Workshop Support

The tool lists identify the pilot-screw wrench 07908-4730001, hydraulic-tappet bleeder 07973-MJ00000, shock-absorber compressor 07GME-0010000, and flywheel puller 07933-2160000, along with valve, bearing, steering, and fork service tools.

Secure the motorcycle with a stable jack or hoist before engine, wheel, fork, shock, or swingarm repair, and follow the manual's fuel, brake dust, battery, and electrical-isolation precautions.

Sample Tappet and Ignition Test Data

Hydraulic-tappet inspection specifies a compression stroke of 0–0.2 mm (0–0.008 in) after priming in kerosene. These inspection data relate to the hydraulic lash-adjuster system, which eliminates routine manual valve adjustment.

For electrical diagnosis at 20°C (68°F), ignition-coil primary resistance is 2.6–3.2 Ω, and ignition pulse-generator resistance is 297–363 Ω. These values accompany component tests and ignition fault-isolation charts.