1985 GSX R400 GK71B Service Repair Manual

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Type: Motorcycle

Vendor:

Sku: 157446

Tags: 1985 GK71B GSX R400 GSX Series Motorcycle Motorcycles Suzuki

Product variants

Description

The Suzuki GSX-R400, model code GK71B, represents the first generation of Suzuki's renowned lightweight super-sport motorcycles, produced primarily in 1985. This sportbike was engineered with an emphasis on performance and handling, drawing inspiration from its larger GSX-R siblings. Featuring a liquid-cooled, 398cc inline-4 engine, a 6-speed transmission, and a steel twin-spar frame, it was designed to offer enthusiasts a potent combination of speed and agility. Its aerodynamic fairing and sporty suspension, including a telescopic front fork and a Monoshock rear, further cemented its status as a capable machine for both spirited riding and track-day enjoyment. This comprehensive factory service manual provides detailed guidance for the maintenance and repair of the Suzuki GSX-R400 (GK71B). It covers a wide array of systems, including in-depth engine diagnosis and overhaul, fuel system servicing with carburetor adjustments, lubrication, cooling, chassis, electrical components, braking, and wheel systems. The manual offers step-by-step instructions for periodic maintenance, tune-ups, engine rebuilds, and electrical diagnostics, along with troubleshooting charts for common issues. Designed for do-it-yourselfers and experienced mechanics alike, this English-language manual is an essential resource for preserving the performance and reliability of this classic sportbike.

🏷️ Basic Information

Identification

Make:

Suzuki

Model:

GSX-R400

Model Code:

GK71B

Year:

Generation

Generation Name:

First Generation GSX-R400

Generation Code:

GK71B

👋 Introduction

Market Position

Motorcycle Segment:

Lightweight Super-Sport / Sportbike

Target Demographic:

Enthusiasts seeking performance and handling in a smaller displacement package

Competitive Analysis

Key Competitors:

Honda CBR400, Yamaha FZR400, Kawasaki ZXR400 (later models)

Key Features

Motorcycle Design Philosophy:

Emphasis on lightweight construction, aerodynamic fairing, and sporty handling, inspired by larger GSX-R models

Manual Value Proposition:

Cost-effective solution for maintaining and repairing a classic Suzuki sportbike

📋 Manual Details

Coverage Areas

Primary Coverage:

Comprehensive Service and Repair

Intended Audience:

Do-it-yourselfers and experienced mechanics

Page Count

Estimated Pages:

Varies by specific printing, typically 300-500 pages

Manual Type

Type:

Factory Service Manual / Workshop Manual

Language

Language:

English

Format

Format:

📖 Manual Coverage

Systems Covered

Engine System:

Detailed diagnosis, repair, and overhaul procedures for the 400cc 4-cylinder engine

Fuel System:

Carburetor identification, adjustment, cleaning, and overhaul; fuel pump and lines

Lubrication System:

Oil pump, oil filter, oil passages, and oil change procedures

Cooling System:

Radiator, fan, water pump, thermostat, coolant flow, and flushing procedures

Chassis System:

Frame, swingarm, steering head bearings, front forks, rear shock absorber, and suspension adjustments

Electrical System:

Ignition system (CDI), lighting, charging system (alternator, rectifier/regulator), starter motor, battery, and wiring diagrams

Brake System:

Front and rear brake caliper servicing, master cylinders, brake fluid replacement, pad and disc inspection

Wheel And Tire:

Wheel bearing maintenance, tire pressure, and replacement

Procedures Included

Periodic Maintenance:

Scheduled maintenance, oil changes, filter replacements, spark plug service, chain adjustment

Tune Up:

Carburetor synchronization, ignition timing checks, valve clearance adjustments

Troubleshooting:

Diagnostic charts and symptom-based fault finding for various systems

Engine Rebuild:

Complete engine disassembly, inspection, component replacement, and reassembly with torque specifications

Suspension Service:

Fork oil replacement, seal replacement, and rear shock absorber servicing

Electrical Diagnostics:

Testing of electrical components, troubleshooting wiring issues using provided diagrams

Technical Depth

Depth:

Comprehensive, covering everything from basic maintenance to full engine and chassis overhauls

Diagram Quality:

High-quality, detailed diagrams and exploded views for clear instruction

Instruction Style:

Step-by-step instructions designed for clarity and efficiency

📊 Manual Specifications

File Format

Compatibility:

All versions of Windows & Mac

Required Software:

Adobe PDF Reader & WinZip (for extraction if applicable)

Print Quality

Quality Assessment:

High-quality digital reproduction of original factory documentation

Binding Type

Binding:

N/A (Digital PDF)

Paper Type

Paper:

N/A (Digital PDF)

⚙️ Engine Specifications

Primary Engine

Engine Type:

4-stroke, Inline-4, DOHC, 16-valve

Displacement:

398 cc (24.3 cu in)

Bore X Stroke:

56.0 mm x 40.0 mm (approx.)

Compression Ratio:

11.0:1 (typical)

Performance

Horsepower Estimated:

59 PS (58 bhp; 43 kW) at 11,500 rpm (approx. manufacturer claimed)

Torque Estimated:

3.7 kgf·m (36 N·m; 27 lb·ft) at 10,000 rpm (approx.)

Fuel System

Fuel Delivery:

Mikuni VM22SS Carburetors (4x)

Fuel Type:

Unleaded gasoline

Cooling

Cooling Method:

Liquid-cooled

🔧 Transmission

Standard

Transmission Type:

Constant mesh 6-speed sequential

Optional

Optional Gearbox:

Features

Clutch Type:

Wet multi-plate

Final Drive:

Chain drive

📐 Dimensions

Exterior

Length:

Approx. 2,075 mm (81.7 in)

Width:

Approx. 700 mm (27.6 in)

Height:

Approx. 1,145 mm (45.1 in)

Weights

Dry Weight:

Approx. 156 kg (344 lbs)

Wet Weight:

Approx. 179 kg (395 lbs) (estimated)

Fuel Capacity:

16 L (4.2 US gal)

🛡️ Safety Features

Ratings

Safety Ratings:

N/A (Motorcycle safety standards from the 1980s)

Active Features

Braking System:

Dual front disc brakes, single rear disc brake

Suspension System:

Telescopic front forks, Monoshock rear suspension (Full Floater system)

Passive Features

Frame Construction:

Steel twin-spar frame

💡 Technology Features

Infotainment

Infotainment System:

N/A (Analog instruments: Speedometer, Tachometer, Fuel Gauge, Temperature Gauge)

Driver Assistance

Driver Assistance Features:

Connectivity

Connectivity Options:

Lighting

Headlight Type:

Halogen (12V 60/55W)

🔧 Maintenance

Service Intervals

Oil Change Interval:

Every 3,000-5,000 km (refer to manual for precise recommendations)

Valve Clearance Check:

Every 6,000-10,000 km (refer to manual)

Chain Lubrication Adjustment:

Every 500-1,000 km

Fluid Specifications

Engine Oil Type:

API SE/SF or SG, SAE 10W-40 or 20W-50 (refer to manual for exact specification)

Engine Oil Capacity:

Approx. 2.8 L (with filter change)

Coolant Type:

Ethylene glycol-based antifreeze coolant, 50/50 mix with distilled water

Brake Fluid Type:

DOT 3 or DOT 4

Fork Oil Type:

Approx. SAE 10W (refer to manual for precise grade and quantity)

Known Issues

Common Wear Items:

Carburetor float needles, cam chain, clutch plates, fork seals, swingarm bearings

Electrical Considerations:

Aging wiring harness, rectifier/regulator failure, starter motor solenoid issues

Engine Reliability:

Generally robust but requires diligent maintenance, especially valve clearances and carburetor synchronization

📚 Vehicle History

Brand Heritage

Manufacturer:

Suzuki Motor Corporation

Model Evolution

Gsx R Lineage:

Part of Suzuki's legendary GSX-R line, introduced to compete in the 400cc class, featuring race-derived technology

Gk71B Significance:

The first generation of the GSX-R400, establishing the lightweight, high-revving sportbike formula for Suzuki in this displacement

Production

Production Period:

1984-1987 (for GK71B chassis/engine variant)

Manufacturing Location:

Japan

🏆 Awards & Recognition

Recognitions

Motorcycle Awards:

While specific awards for the 1985 GSX-R400 are rare, the GSX-R lineage is highly regarded for its performance and handling characteristics in its era.