Vehicle Class:
Mini Sportbike / Pocketbike
Target Audience:
Enthusiasts, hobbyists, and young riders looking for a fun, approachable, and iconic mini sportbike.
Competitors:
Honda NSR50, Suzuki RG50 Gamma, Kawasaki AR50.
Unique Selling Points:
Aggressive sportbike styling in a miniature package, lightweight and agile handling, and Yamaha's reputation for reliability and performance.
Value For Buyers:
Provides the essential technical information that dealers use, enabling owners to perform maintenance, diagnostics, and repairs themselves, saving time and money. Crucial for preserving the unique character and functionality of this collectible model.
Engine:
Comprehensive coverage including general information, specifications, periodic checks and adjustments, and engine overhaul procedures.
Fuel System:
Detailed information on the fuel system, likely including carburetor settings, fuel lines, and fuel tank maintenance.
Chassis:
Coverage of chassis components, likely encompassing frame, suspension (front forks and rear shock absorber), steering, wheels, and brakes.
Electrical System:
Extensive details on the electrical system, including wiring diagrams, ignition system, lighting, battery maintenance, and component testing.
Suspension:
Front: Telescopic fork; Rear: Swingarm with mono-shock absorber. Manual covers inspection, adjustment, and overhaul.
Wheels Tires:
Front: 3.00-10; Rear: 3.50-10. Manual covers wheel bearing maintenance, tire inspection, and replacement guidance.
Maintenance:
Periodic checks, adjustments, fluid changes, lubrication schedules, and component inspections.
Repair:
Engine overhaul, transmission servicing (if applicable to YSR50's transmission type), brake system repairs, electrical component replacement, and chassis repairs.
Troubleshooting:
Diagnostic procedures and solutions for common problems, likely presented in a systematic, problem-and-solution format.
Engine Overhaul Details:
Piston removal/installation, cylinder head service, crankshaft and connecting rod inspection, oil seal replacement, and decarbonizing procedures.
Electrical Diagnostics:
Covers testing of the ignition system (CDI, ignition coil), charging system (if applicable), lighting circuits, and starter system (if electric start is present, though often kickstart only).
Depth:
Dealer-level technical information for in-depth diagnostics and repairs, suitable for both professional technicians and advanced enthusiasts.
Precision Specifications:
Includes precise torque values for critical fasteners, bearing clearances, ignition timing specifications, and detailed wiring diagrams with component identification.
Digital Format Details:
Likely a searchable PDF, allowing for quick access to information via keywords and hyperlinked table of contents. Printable pages.
Print Quality Description:
High-resolution scans or digital originals ensuring clarity of diagrams, illustrations, and text.
Binding Type Description:
N/A (for digital format). If physical, likely a comb or spiral binding for lay-flat use in a workshop.
Paper Type Description:
N/A (for digital format). If physical, typically durable, matte paper to reduce glare and withstand workshop conditions.
Engine Type:
Two-stroke, single-cylinder, reed valve induction, liquid-cooled (specific cooling method may vary, often fan-cooled for this class)
Bore X Stroke:
39.0 mm x 41.4 mm (typical specification)
Compression Ratio:
7.0:1 (typical specification)
Horsepower:
Approx. 7-8 HP (varies by market and tune)
Torque:
Approx. 5-6 Nm (varies by market and tune)
Carburetor:
Mikuni VM20 (typical specification), often with auto-choke.
Fuel Type:
Unleaded gasoline (minimum 87 octane recommended), mixed with 2-stroke oil (100:1 or 50:1 depending on Yamaha's recommendation for the specific model year).
Two Stroke Oil System:
Autolube system (automatic oil injection). Manual specifies oil type and ratio if pre-mix is used or as a backup.
Safety Standard:
As per Japanese domestic market (JDM) regulations for 50cc vehicles of the era.
Braking System Front:
Hydraulic disc brake (e.g., 200mm disc, 2-piston caliper typical)
Braking System Rear:
Drum brake (e.g., 110mm drum typical)
Lighting:
Halogen headlight, taillight, brake light, turn signals.
Frame Type:
Steel diamond frame.
Oil Change Frequency:
Refer to manual; typically every 3,000-5,000 km or annually for gearbox oil. 2-stroke oil injection system level checks are frequent.
Spark Plug Replacement:
Recommended every 6,000-10,000 km or as per manual, with specific gap settings (e.g., NGK BR9ES or equivalent).
Air Filter Cleaning:
Regular checks and cleaning/replacement as per manual, especially important for 2-stroke performance.
Engine Oil Type:
Yamaha's specific 2-stroke oil (e.g., Yamalube 2M or equivalent API TC, JASO FD certified oil).
Coolant:
If liquid-cooled: Mixture of permanent anti-freeze and distilled water (50/50 ratio). Capacity approx. 0.5L.
Brake Fluid:
DOT 3 or DOT 4 (for hydraulic disc brake system). Specifics will be in the manual.
Common Problems:
Carburetor clogging due to infrequent use or poor fuel quality, ignition system faults (coil, CDI), clutch wear, exhaust port carbon buildup, general wear and tear on rubber components (hoses, seals) due to age.
Preventative Maintenance Focus:
Regular fuel stabilizer use, proper 2-stroke oil mixing, keeping the fuel system clean, and periodic lubrication of moving parts.
Yamaha Motorcycle Division Founding:
1955
Ysr Series Introduction:
The YSR series, particularly the YSR50, was a significant model in the late 1980s and early 1990s, capitalizing on the pocketbike craze. It mimicked the styling of larger sportbikes like Yamaha's own YZF series.
Production Period:
1987-1992 (approximate, core generation).
Manufacturing Location:
Japan
