Market Segment:
Entry-level to intermediate dual-sport motorcycle, popular for trail riding, light off-roading, and commuting.
Competitors 1988:
Honda XL series, Kawasaki KLR250, Suzuki DR200/DR250.
Durability:
Yamaha's reputation for robust two-stroke engines and reliable chassis components.
Off Road Capability:
Designed with off-road prowess featuring long-travel suspension and durable construction.
Simplicity:
Relatively simple mechanical design for ease of maintenance and repair.
Coverage Summary:
Comprehensive factory service and repair for Yamaha DT125R 1988 model.
Estimated Pages:
Hundreds (specific count not provided, but described as complete).
Type:
Factory Service Repair Manual
Language:
English (assumed based on typical factory manuals for international markets).
Engine:
Complete engine disassembly, assembly, tuning, troubleshooting, and repair for the 125cc two-stroke engine.
Fuel System:
Carburetor (Mikuni VM series likely) disassembly, cleaning, adjustment, and troubleshooting; fuel tank and petcock inspection and repair.
Ignition System:
CDI ignition system, spark plug selection and gap, coil testing, timing procedures.
Transmission:
Six-speed gearbox overhaul, clutch adjustment and replacement, gearshift mechanism.
Suspension:
Front telescopic forks (likely KYB or similar) service, oil change, seal replacement, damping adjustment; rear Monoshock suspension (Monocross system) rebuild and adjustment.
Brakes:
Front and rear drum brakes (typical for this era and model) inspection, adjustment, and relining; hydraulic disc brake service if applicable to specific regional variants (though less likely for base 1988 R model).
Electrical System:
Wiring diagrams, lighting system, charging system (stator, regulator/rectifier), battery maintenance, starter motor (if electric start equipped), horn, indicators.
Cooling System:
Air-cooled engine specifications and maintenance.
Exhaust System:
Expansion chamber maintenance, mufflers, and performance tuning considerations.
Frame And Bodywork:
Chassis inspection, steering head bearing service, body panel removal and installation, seat maintenance.
Routine Maintenance:
Oil changes, filter replacements (air, spark plug), chain adjustment, lubrication points.
Troubleshooting:
Diagnostic procedures for common performance issues, starting problems, electrical faults.
Repair Procedures:
Step-by-step guides for major component overhauls and component replacements.
Specifications Charts:
Torque specifications, clearances, fluid capacities, electrical resistance values.
Wiring Diagrams:
Detailed, color-coded wiring diagrams for electrical system diagnostics and repair.
Special Tools:
Identification and usage of specialized tools required for certain procedures.
Depth:
Full factory level, covering everything from basic maintenance to complete engine and chassis rebuilds.
Format:
PDF (Portable Document Format)
Quality:
High-resolution scans of original factory documentation, allowing for clear printing of text and diagrams.
Binding:
N/A (Digital Download)
Paper Type:
N/A (Digital Download)
Text Search:
Likely text-searchable if OCR was applied during PDF creation, enhancing ease of navigation.
Printable:
Yes, pages can be printed individually or in full as needed.
Engine Type:
123cc liquid-cooled, 2-stroke, reed valve inducted, single-cylinder.
Bore X Stroke:
56.0 mm x 50.0 mm (typical for DT125R).
Compression Ratio:
Approx. 7.2:1 (varies with tuning).
Power Output Hp:
Approx. 22-25 HP @ 8000 RPM (typical for 1988 model, varies by region).
Torque Lb-Ft:
Approx. 15-17 lb-ft @ 7000 RPM (typical).
Top Speed Mph:
70-75 mph (estimated).
Carburetor Model:
Mikuni VM28SS (likely, standard fitment).
Fuel Type:
Unleaded gasoline, minimum 87 octane (Octane rating may vary based on regional fuel standards).
Fuel Mixture:
Pre-mix gasoline and 2-stroke oil (ratio typically 50:1 or 100:1 depending on oil quality and manufacturer recommendation).
Length:
Approx. 2170 mm (85.4 in).
Width:
Approx. 810 mm (31.9 in).
Height:
Approx. 1155 mm (45.5 in).
Wheelbase:
Approx. 1420 mm (55.9 in).
Dry Weight:
Approx. 115 kg (253.5 lbs).
Wet Weight:
Approx. 123 kg (271.2 lbs) (with fluids).
Fuel Capacity:
10.0 Liters (2.6 US gallons).
Crash Safety Rating:
N/A (Motorcycle safety ratings are not standardized like automotive).
Braking System:
Front drum brake, Rear drum brake. Manual will detail adjustment and maintenance.
Lighting:
Headlight, taillight, brake light, turn signals. Manual covers electrical diagnostics.
Frame Construction:
Steel backbone frame designed for durability and off-road resilience.
Tire Type:
Dual-purpose knobby tires suitable for on-road and off-road use. Manual will specify recommended sizes and pressures.
Features:
N/A (This is a 1988 model motorcycle, focusing on mechanical and electrical systems rather than modern infotainment).
Features:
N/A (No electronic driver assistance systems on this model).
Features:
N/A (No modern connectivity features).
Ypvs:
Yamaha Power Valve System (YPVS) for improved power delivery across the RPM range. Manual provides detailed information on its operation and maintenance.
Oil Change Engine:
Refer to manual; typically every 2,000-3,000 km for gearbox oil.
Spark Plug Check:
Recommended every 1,000-2,000 km, check gap and condition.
Air Filter Cleaning:
Recommended every 1,000 km or more frequently in dusty conditions.
Chain Adjustment:
Recommended every 500-1,000 km, check slack.
Engine Oil Type:
Yamaha's recommended 2-stroke synthetic oil (e.g., Yamalube 2) or equivalent meeting API TC, JASO FD specifications. Pre-mix ratio specified in manual.
Gearbox Oil Type:
Yamalube Gear Oil (e.g., Yamalube 10W-40) or equivalent SAE 80W API GL-4.
Fork Oil Type:
Yamaha's recommended fork oil (e.g., Yamalube 5W) or equivalent. Specific weight and quantity detailed in manual.
Power Valve Sticking:
Common in older two-strokes; manual will detail cleaning and lubrication procedures for the YPVS (Yamaha Power Valve System).
Carburetor Clogging:
Fuel deposits can clog jets; manual provides cleaning and tuning advice.
Worn Clutch Plates:
With high mileage, clutch plates can wear; manual details replacement procedure.
Comprehensive Schedule:
The manual contains a detailed maintenance schedule covering all intervals (e.g., 500km, 1000km, 3000km, 6000km, 12000km) for inspections, adjustments, and part replacements.
Yamaha Motorcycles:
Yamaha has a long and storied history in motorcycle manufacturing, particularly in off-road and racing categories with their durable and performance-oriented two-stroke engines.
Dt Series:
The DT series represents Yamaha's lineage of dual-sport motorcycles, evolving from earlier models to incorporate advancements like the Monocross rear suspension and liquid cooling in some variants. The DT125R was a significant model in this line for its sporty performance and off-road capability.
Production Period:
The DT125R was produced through various iterations from the mid-1980s into the 1990s, with the 1988 model being a well-recognized and sought-after example.
