Suzuki GN400 1980–1982 Supplementary Service Manual (P/N SR-6600)

This Suzuki GN400 supplementary service manual, P/N SR-6600 (英) E-01, SUPPL. 2, was issued in September 1980. It documents GN400 features, service data, and procedures that differ from the SP400. The SP400 base service manual is needed for unchanged procedures and is not included in this download.

PDF Search, Diagram Detail, and Page Count

Search and diagram viewing: PDF text search and embedded bookmarks are not available. Small component labels and wire-color codes in the checked wiring diagrams are readable when enlarged; zooming is needed for dense circuit areas.

The download contains one printable English PDF with 47 pages, including the front cover, contents page, publication-details page, and back cover.

Front Brake and Steering Repair, Carburetor Details, and Electrical References

The following selected contents outline the main workshop coverage rather than reproduce the complete contents list. Additional illustrated references include the combination meter and its gear-position indicator assembly.

• Engine and drivetrain data: Specification tables for the valve train, camshaft, cylinder head, piston, rings, cylinder, crankshaft, oil pump, clutch, transmission, and drive chain.

• Mikuni BS36SS carburetor: Internal component identification, jetting and float specifications, pilot-circuit details, and an explanation of the transient-enrichment system.

• Front brake repair: Step-by-step procedures for hydraulic-circuit bleeding, pad replacement, master-cylinder and caliper disassembly and reassembly, plus disc inspection.

• Steering and chassis: Steering-stem removal, bearing and race replacement, reassembly, adjustment, and final play checks; wheel, fork, and rear-suspension assembly references.

• Electrical references: Wiring diagrams for E-01/E-24, E-02, E-04/E-34, E-21, E-22, E-25, and E-28, supported by routing drawings and electrical test specifications.

Used alongside the SP400 service manual, this supplement is suited to experienced DIY owners and professional technicians who are already comfortable with hydraulic brake and front-end repair work and have access to the specified measuring and service tools.

Front Brake Inspection and Component Service

The brake section covers fluid-level and pad-wear checks as well as internal inspection of the master-cylinder bore, piston, cups, and dust boot. Caliper coverage includes piston and seal inspection, assembly details, and the associated tightening specifications.

The illustrated master-cylinder and caliper assemblies support component identification during repair. Measuring-tool references include snap-ring pliers 09900-06108, micrometer 09900-20201, and dial gauge 09900-20606 for brake-disc runout inspection.

The brake chapter warns that mixing the specified glycol-based fluid with silicone- or petroleum-based fluid can seriously damage brake components. It also identifies excessive air pressure during caliper-piston removal as a cause of piston damage.

Brake and steering work should be performed with the motorcycle securely supported and with the factory hydraulic-system cautions observed.

Steering Bearings and Chassis Assemblies

Steering-stem instructions extend to outer-race installation, lower-bearing installation, lubrication, bearing seating, and the final check for free movement and play.

Special-tool drawings identify steering-stem nut wrench 09940-10122, bearing inner-race remover 09941-84510, steering race installer 09941-34511, and steering bearing installer 09941-74910.

The front and rear wheel, front fork, and rear suspension sections primarily supply exploded assemblies and tightening data. Complete overhaul instructions for unchanged components remain in the base manual.

Carburetor Operation and Market Differences

The BS36SS exploded view identifies the diaphragm, throttle valve, jets, needle valve, float, and related parts. A separate transient-enrichment circuit diagram explains how diaphragm-controlled pilot airflow changes when the throttle closes suddenly.

Market differences are identified within the relevant specifications. The E-02 version has separate entries for final gearing, chain length, wheel and tire fitment, fuel reserve, and fork oil level and capacity. Other distinctions cover dimensions, lamps, spark plugs, and electrical equipment.

Electrical Checks and Service-Limit Tables

The wiring diagrams show circuit connections, switch arrangements, and wire-color legends. Wire-routing and cable-routing drawings document harness placement and control-cable paths.

Electrical tables provide ignition-coil and magneto-coil resistance specifications, charging-rate checks, lighting-coil output, and battery data. These references connect the circuit drawings with the measurements used during electrical fault investigation.

The service-data tables distinguish standard dimensions from wear limits for many components, allowing measured parts to be evaluated during repair. They also cover fuel and oil requirements, tire pressures for different riding conditions, and market-specific lamp wattages.

A Preview of Valve, Ignition, and Fork Specifications

The valve table lists a cold clearance of 0.03–0.08 mm for both intake and exhaust valves. Electrical reference data specify approximately 40–54 ohms for each magneto pulser coil, with the corresponding wire pairs identified in the table.

The suspension table distinguishes a front-fork oil level of 170 mm for E-02 from 207 mm for the other listed markets. These separate entries show why the market designation matters when selecting service specifications.