🏷️ Basic Information

Make:

Yamaha

Model:

DT125R

Year:

1988

Vehicle Type:

Dual-Sport Motorcycle

👋 Introduction

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.

📋 Manual Details

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).

Format:

Downloadable PDF

📖 Manual Coverage

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.

📊 Manual Specifications

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 Specifications

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).

🔧 Transmission

Type:

Constant mesh, 6-speed sequential return.

Clutch Type:

Wet, multiple disc.

Gear Ratios:

Specific ratios available in the manual, crucial for performance tuning.

Final Drive:

O-ring sealed chain drive (specific sprocket sizes will be detailed).

📐 Dimensions

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).

🛡️ Safety Features

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.

💡 Technology Features

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.

🔧 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.

📚 Vehicle History

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.

🏆 Awards & Recognition

Model Awards:

Specific awards for the 1988 DT125R are not widely documented in general reviews, but the model was recognized for its performance and durability in its class.