Segment:
Lightweight motorcycle, often used for commuting and entry-level riding.
Competitors Era:
Competed with other 250cc single-cylinder Japanese motorcycles of the early 1980s, such as Honda Rebel 250, Yamaha Virago 250 (later), and Kawasaki Eliminator 250 (later).
Gn250 Attributes:
Reliable single-cylinder engine, comfortable riding position, fuel efficiency, classic styling.
Target User:
Suzuki dealership technicians, independent repair shops, and experienced DIY motorcycle enthusiasts.
Primary Coverage:
Complete service and repair for 1982 and 1983 Suzuki GN250 motorcycle models.
Included Sections:
Engine, Chassis, Electrical System, Bodywork, Troubleshooting, Specifications, Maintenance Schedules.
Estimated Page Count:
300-400 pages (typical for this era and model)
Type:
Factory Service Manual / Repair Manual
Format:
Digital PDF (printable, searchable)
Engine Service:
Complete overhaul, including disassembly, inspection, assembly, valve adjustment, timing, carburation, and lubrication system.
Transmission And Clutch:
Gearbox inspection, repair, clutch operation, adjustments, and component replacement.
Fuel System:
Carburetor service (cleaning, adjustment, jetting), fuel tank, fuel pump, and fuel lines.
Electrical System:
Ignition system (spark plug, coil, CDI unit), lighting, charging system (stator, regulator/rectifier), battery, starter motor, and wiring diagrams.
Chassis And Suspension:
Front fork (oil change, seal replacement, spring), rear shock absorber, swingarm, bearings, and wheel service.
Brake System:
Front and rear brake caliper service, master cylinder, brake fluid replacement, bleeding procedures, and pad/shoe replacement.
Bodywork And Trim:
Fairings, fuel tank, seat, fenders, and other cosmetic components.
Routine Maintenance:
Oil changes, filter replacement, chain adjustment, spark plug replacement, air filter cleaning, and lubrication points.
Troubleshooting:
Diagnostic flowcharts and symptom-based problem solving for common issues.
Component Rebuild:
Detailed step-by-step instructions for rebuilding major components like the engine and carburetor.
Specifications And Data:
Torque values, clearances, fluid capacities, electrical specifications, and performance data.
Depth:
Comprehensive, covering everything from basic adjustments to complete engine and transmission overhauls.
Engine Type:
4-stroke, air-cooled, SOHC, single-cylinder
Bore X Stroke:
72.0 mm x 61.2 mm (approximate)
Displacement:
249 cc (249cc)
Compression Ratio:
9.5:1 (typical)
Horsepower:
Approximately 20-24 HP @ 7500 RPM (varies slightly by region/tuning)
Torque:
Approximately 14-16 lb-ft @ 6000 RPM (varies slightly by region/tuning)
Carburetor:
Mikuni VM34 (or similar 34mm constant velocity carburetor)
Fuel Type:
Unleaded gasoline (Octane rating as per Suzuki recommendation, typically 87-91)
Oil Type:
API SF or SG classification, SAE 10W-40 motorcycle specific oil
Oil Capacity With Filter:
Approximately 1.7 Liters (1.8 US qt)
Cooling Method:
Air-cooled
Ignition Type:
CDI (Capacitor Discharge Ignition)
Spark Plug Type:
NGK DPR8EA-9 or equivalent
Valve Clearance Intake Cold:
0.05-0.10 mm (0.002-0.004 in)
Valve Clearance Exhaust Cold:
0.10-0.15 mm (0.004-0.006 in)
Length:
Approx. 2140 mm (84.3 in)
Width:
Approx. 760 mm (29.9 in)
Height:
Approx. 1140 mm (44.9 in)
Wheelbase:
Approx. 1400 mm (55.1 in)
Ground Clearance:
Approx. 135 mm (5.3 in)
Dry Weight:
Approx. 148 kg (326 lbs)
Wet Weight:
Approx. 160 kg (353 lbs) (with fluids)
Gross Vehicle Weight Rating:
Not specified, but typically around 350-400 kg (770-880 lbs) for a motorcycle of this class.
Front Tire Size:
3.00-18 4PR
Rear Tire Size:
120/90-16 M/C 63P
Front Brake Type:
Disc brake
Rear Brake Type:
Drum brake
Wheel Type:
Spoked wheels
Fuel Tank Capacity:
16 Liters (4.2 US gal)
Safety Standards:
Meets applicable safety standards for motorcycles of its era (e.g., DOT, ECE if exported).
Braking Performance:
Adequate braking for its performance class, utilizing a single front disc and rear drum.
Frame Construction:
Steel cradle frame providing a stable platform.
Lighting:
Halogen headlight, taillight, and turn signals for visibility.
Oil Change Interval:
Every 3,000 km (2,000 miles) or 6 months, whichever comes first.
Air Filter Cleaning:
Every 4,000 km (2,500 miles)
Spark Plug Replacement:
Every 10,000 km (6,000 miles)
Valve Adjustment Interval:
Every 8,000 km (5,000 miles) or annually
Chain Adjustment Interval:
Every 1,000 km (600 miles) or as needed
Brake Fluid Type:
DOT 3 or DOT 4
Fork Oil Type:
SAE 10W fork oil
Fork Oil Capacity Per Leg:
Approximately 175-195 ml (varies by fork type and seal type)
Common Wear Items:
Carburetor jets clogging due to stale fuel, clutch wear, aging electrical connectors, and worn fork seals are common issues on older bikes.
Engine Performance Issues:
Hard starting or poor running can be attributed to carburetor issues, ignition timing problems, or compression loss.
Carburetor Cleaning Frequency:
Recommended annually or every 10,000 km to ensure optimal performance and fuel efficiency.
Suzuki Legacy:
Suzuki has a long history in motorcycle manufacturing, known for reliable engines and innovative designs across various displacement classes.
Gn Series Context:
The GN250 was part of Suzuki's range of versatile 250cc motorcycles, offering a blend of usability and classic motorcycle aesthetics. It preceded later models like the GN400 and the more modern TU250X.
Production Period:
The GN250 model line was produced from the early 1980s into the early 2000s, with the 1982-1983 models representing the initial iteration.
Manufacturing Locations:
Primarily manufactured in Japan by Suzuki Motor Corporation.
