Market Segment:
Compact, lightweight scooter designed for urban commuting and recreational use. Popular for its simplicity, fuel efficiency, and maneuverability.
Key Competitors:
Honda Aero 125, Honda Elite 125, Suzuki CV125, Kawasaki Invader 125.
Distinctive Features:
Reliable 125cc two-stroke engine, automatic CVT transmission, comfortable riding position, ample under-seat storage (model dependent), and durable construction.
Target Audience:
New riders, urban commuters seeking economical transport, and those looking for a fun, easy-to-ride scooter.
Systems Covered:
Engine, Fuel System, Lubrication, Cooling, Ignition, Electrical System, Transmission, Drive System, Brakes, Suspension, Steering, Frame, Bodywork, Maintenance, Troubleshooting, Specifications, Wiring Diagrams
Estimated Page Count:
200-300
Manual Type:
Service Manual / Repair Manual
Engine Mechanical:
Complete overhaul procedures for the 125cc two-stroke engine, including piston, rings, cylinder, crankshaft, connecting rod, bearings, and seals.
Fuel System:
Carburetor (Mikuni VM16SS) disassembly, cleaning, adjustment, jetting specifications, fuel pump operation, fuel filter replacement.
Lubrication System:
Oil injection system operation, oil pump adjustment, oil change intervals, and specifications.
Cooling System:
Air-cooling system analysis, cylinder fin maintenance, and heat dissipation considerations.
Ignition System:
CDI ignition system, spark plug specifications, ignition timing, and troubleshooting.
Electrical System:
Lighting system (headlight, taillight, turn signals), battery charging system (stator, regulator/rectifier), starter motor, and wiring harness diagrams.
Transmission Drive:
CVT (Continuously Variable Transmission) operation, drive belt inspection and replacement, clutch assembly, driven pulley, and final drive (gearbox) oil specifications and change intervals.
Brakes:
Front drum brake and rear drum brake inspection, adjustment, and component replacement. Brake shoe specifications.
Suspension Steering:
Front telescopic fork service, rear shock absorber inspection and replacement, steering assembly and bearing maintenance.
Frame Bodywork:
Frame inspection, seat and body panel removal/installation, and cosmetic component details.
Routine Maintenance:
Detailed steps for oil changes, air filter cleaning/replacement, spark plug replacement, transmission oil change, brake adjustment, and general inspection.
Troubleshooting:
Systematic diagnostic procedures for common issues such as hard starting, poor performance, electrical faults, and braking problems, often including fault code interpretation if applicable.
Engine Overhaul:
Step-by-step instructions for engine disassembly, component inspection, cleaning, measurement, and reassembly, including torque specifications for all critical fasteners.
Carburetor Rebuild:
Complete guide to disassembling, cleaning, replacing seals and jets, and reassembling the Mikuni carburetor for optimal performance.
Cvt Maintenance:
Instructions for drive belt inspection for wear and damage, clutch spring testing, and drive/driven pulley roller inspection.
Electrical Diagnostics:
Troubleshooting guides for lighting, charging, and starting systems, often with wiring diagrams and component testing procedures.
Suspension Service:
Fork seal replacement, oil level and type specifications for the front forks, and rear shock absorber mounting bolt torque.
Depth Of Coverage:
Comprehensive. Covers from basic rider maintenance to complete engine and transmission rebuilds. Includes detailed troubleshooting trees and diagnostic procedures.
Engine Type:
Air-cooled, 2-stroke, single-cylinder
Displacement:
121 cc (7.38 cu in)
Bore X Stroke:
52.0 mm x 57.8 mm (2.05 in x 2.28 in)
Power Output Hp:
Approx. 10-11 HP @ 6500 RPM (model/year dependent)
Torque Ft Lbs:
Approx. 9-10 lb-ft @ 6000 RPM (model/year dependent)
Top Speed Mph:
Approx. 55-60 mph
Carburetor Model:
Mikuni VM16SS
Fuel Tank Capacity:
Approx. 5.0 Liters (1.3 US gal)
Fuel Type:
Unleaded gasoline, 87 octane (minimum)
Oil Type 2 Stroke Injection:
API TD, JASO FB or FC grade 2-stroke engine oil (Yamalube 2 or equivalent)
Crankcase Oil Type:
Yamaha's specific gear oil for scooters or equivalent SAE 10W-30 API GL-III gear oil
Crash Test Data:
N/A - Scooters of this era were not subject to standardized crash testing in the same way as automobiles.
Braking System:
Dual drum brakes (front and rear) providing adequate stopping power for the scooter's performance envelope.
Lighting:
Standard headlight, taillight, and brake light for visibility. Turn signals for directional indication.
Frame Construction:
Steel tube frame provides structural integrity.
Rider Protection:
While not a safety feature in itself, the manual emphasizes the importance of proper riding gear (helmet, jacket, gloves, etc.) for rider safety.
Engine Oil Change:
Every 3,000 km (1,800 miles) or 6 months.
Transmission Oil Change:
Every 6,000 km (3,600 miles) or 12 months.
Air Filter Cleaning:
Every 1,500 km (900 miles) or 3 months (clean); replace every 6,000 km (3,600 miles).
Spark Plug Replacement:
Inspect every 3,000 km (1,800 miles); replace as needed.
Drive Belt Inspection:
Inspect every 6,000 km (3,600 miles); replace as needed based on wear.
Brake Adjustment:
Check and adjust every 3,000 km (1,800 miles).
Engine Oil Capacity:
N/A (2-stroke oil injected, no crankcase oil)
Transmission Oil Capacity:
Approx. 0.11 Liters (0.12 US qt)
Coolant Type:
N/A (Air-cooled)
Spark Plug Gap:
0.6 - 0.7 mm (0.024 - 0.028 in)
Spark Plug Type:
NGK BPR6HS-10 or equivalent
Common Wear Items:
Drive belt, brake shoes, carburetor jets, spark plug, air filter, piston rings, crank seals, and fork seals.
Potential Electrical Problems:
Issues with the stator or regulator/rectifier can affect battery charging and ignition system performance over time.
Carburetor Tuning:
Carburetors can become gummed up if the scooter sits for long periods, requiring cleaning and potential jetting adjustments.
Overheating Prevention:
Ensuring cooling fins are clean and free of debris is crucial for maintaining optimal engine temperature due to its air-cooled nature.
Yamaha Motors Legacy:
Yamaha Motor Company, established in 1955, has a rich heritage in motorcycles, musical instruments, and other recreational products. Known for innovation and performance.
Riva Lineup:
The RIVA series was Yamaha's foray into the scooter market, offering practical and stylish urban mobility. The 125/Z was a popular model within this lineup.
Key Design Philosophy:
Designed to be user-friendly, reliable, and affordable, catering to a broad demographic for daily transportation.
Manufacturing Origin:
Primarily manufactured in Japan.
Model Lifespan:
Successfully produced for over 15 years, indicating strong market acceptance and reliability.
