🏷️ Basic Information

Make:

Yamaha

Model:

YZ250

Model Variant:

YZ 250

Year:

1987

Product Name:

Yamaha YZ250 YZ 250 1987 87 Service Repair Workshop Manual

Chassis Code:

Likely 5X4

Engine Code:

Likely 5X4-00

👋 Introduction

Class:

High-performance motocross motorcycle, known for its potent two-stroke engine and agility.

Target Audience:

Motocross racers, off-road enthusiasts, and Yamaha YZ owners requiring detailed technical information.

Competitors 1987:

Honda CR250R, Suzuki RM250, Kawasaki KX250.

Engine Type:

Liquid-cooled, 249cc, 2-stroke, reed valve, single cylinder.

Suspension Front:

Telescopic forks (likely 43mm diameter) with adjustable compression and rebound damping.

Suspension Rear:

Monocross single shock with adjustable preload, compression, and rebound damping.

Brakes Front:

Hydraulic disc brake.

Brakes Rear:

Hydraulic disc brake.

Comprehensiveness:

A vital resource for maintaining and repairing the YZ250 to factory specifications.

Utility:

Enables owners to perform tasks ranging from routine checks to complete engine rebuilds, saving time and money on dealership service.

📋 Manual Details

Coverage:

Complete service, repair, and workshop information for the 1987 Yamaha YZ250.

Estimated Page Count:

Likely 300-500 pages (typical for a comprehensive service manual of this era).

Type:

Service Repair Workshop Manual

Language:

English

Format:

Digital (PDF assumed, as is common for online sales)

📖 Manual Coverage

Engine:

Full engine overhaul, disassembly, assembly, tuning, lubrication, cooling systems, and component diagnostics.

Transmission:

Clutch, gearbox, shift mechanism, lubrication, and troubleshooting.

Fuel System:

Carburetor (likely Mikuni VM series) disassembly, cleaning, adjustment, jetting, fuel pump (if applicable), fuel lines, and tank.

Ignition System:

CDI ignition, spark plug selection and gap, stator, coil, and troubleshooting.

Exhaust System:

Pipe and silencer maintenance and performance tuning considerations.

Suspension:

Front forks (likely conventional cartridge type) and rear monoshock (Monocross system) overhaul, fluid changes, seal replacement, and adjustment.

Brakes:

Front and rear hydraulic disc brake systems, caliper overhaul, master cylinder service, brake fluid type and bleeding procedures.

Electrical System:

Wiring diagrams, lighting, horn, battery maintenance, charging system, and component testing.

Cooling System:

Air-cooled engine, with emphasis on cylinder head fins and airflow.

Chassis And Frame:

Frame inspection, geometry, steering head bearing maintenance.

Wheels And Tires:

Tire pressure, sizes, spoke tension adjustment, wheel bearing service.

Controls:

Throttle, clutch, brake lever adjustments and cable maintenance.

Maintenance:

Regular scheduled maintenance, cleaning, lubrication, adjustments, and inspections.

Repair:

Component-level repairs, part replacements, and reassembly of all major systems.

Troubleshooting:

Diagnostic procedures for common and uncommon faults, guided by symptom analysis.

Rebuilds:

Detailed instructions for complete engine, transmission, and suspension rebuilds.

Disassembly Assembly:

Step-by-step guides for taking apart and putting together all motorcycle components.

Tuning:

Carburetor jetting, ignition timing adjustments (if applicable via CDI modifications), and suspension setup.

Depth:

Comprehensive, covering basic maintenance to full engine and chassis overhauls. Suitable for both home mechanics and professional technicians.

Diagnostics:

In-depth diagnostic flowcharts and symptom-to-cause analysis.

Specifications:

Includes all critical torque values, clearances, fluid capacities, and electrical resistances.

📊 Manual Specifications

Format:

PDF (Portable Document Format) - widely compatible, searchable, and printable.

Searchability:

Likely text-searchable, allowing for quick access to specific topics.

Quality:

High resolution, designed for clear reproduction of diagrams and text when printed.

Binding:

N/A (Digital format)

Paper:

N/A (Digital format)

⚙️ Engine Specifications

Type:

Liquid-cooled, 2-stroke, single cylinder

Displacement:

249 cc

Bore X Stroke:

68.0 mm x 68.5 mm (typical for this generation)

Compression Ratio:

7.4:1 (approximate, typical for performance tuning)

Reed Valve System:

Yes

Cooling Method:

Liquid-cooled

Horsepower Claimed:

Approximately 45-50 HP (unconfirmed, but typical for the era)

Torque Claimed:

Not readily available, but substantial for its displacement.

Carburetor Type:

Mikuni VM34SS (typical)

Fuel Type:

Unleaded gasoline with 2-stroke oil mixture (e.g., 20:1 or 25:1 depending on oil and usage)

Fuel Capacity:

Approximately 2.5 Liters (0.7 Gallons)

🔧 Transmission

Type:

Constant-mesh, 6-speed sequential

Clutch Type:

Wet, multi-plate, cable-actuated

Gear Ratios:

Detailed in manual (specific ratios vary by model year and design).

Transmission Oil Type:

Yamaha Gear Oil or equivalent API GL-4, SAE 10W-30 or 20W-40 transmission oil (refer to manual for precise specification).

📐 Dimensions

Length:

Refer to manual (approx. 2100-2200 mm)

Width:

Refer to manual (approx. 800-850 mm)

Height:

Refer to manual (approx. 1250-1300 mm)

Dry Weight:

Approximately 97-100 kg (214-220 lbs)

Wet Weight:

Approximately 105-110 kg (231-243 lbs)

Front Tire Size:

80/100-21 (typical)

Rear Tire Size:

100/90-18 or 110/90-18 (typical)

Wheelbase:

Refer to manual (approx. 1450-1470 mm)

Ground Clearance:

Refer to manual (approx. 300-350 mm)

🛡️ Safety Features

Safety Classification:

Off-road competition motorcycle, not intended for street use. Safety relies on rider skill and proper maintenance.

Braking Performance:

Designed for strong stopping power with hydraulic disc brakes.

Frame Construction:

Robust steel frame designed to withstand off-road stresses.

Impact ABSorption:

Suspension system designed for absorbing impacts and maintaining control.

💡 Technology Features

Infotainment System:

N/A (Performance motocross bike, minimal electronics).

Power Valve:

Likely featured Yamaha Power Valve System (YPVS) for improved power delivery across the rev range.

Ignition Type:

CDI (Capacitor Discharge Ignition)

🔧 Maintenance

Oil Change Transmission:

Every 10-15 hours of operation or annually. Refer to manual for exact intervals.

Air Filter Cleaning:

After every few rides or as needed, depending on riding conditions.

Spark Plug Replacement:

Every 30-50 hours of operation or as per manual recommendations.

Top End Rebuild:

Typically every 50-100 hours for performance riding, or as indicated by compression loss.

Engine Oil Premix:

High-quality 2-stroke motorcycle oil (e.g., Yamalube 2M or equivalent) mixed with unleaded gasoline at a ratio specified in the manual (commonly 20:1 or 25:1).

Transmission Oil:

Yamaha Gear Oil or equivalent API GL-4, SAE 10W-30 or 20W-40 (verify specific viscosity with manual).

Brake Fluid:

DOT 3 or DOT 4 recommended (verify specific type with manual).

Coolant:

Not applicable (air-cooled engine).

Common Wear Items:

Clutch plates, piston rings, carburetor jets, fork seals, wheel bearings, chain and sprockets.

Typical Failures:

Carburetor issues (gumming, jet clogging), worn reed valves, premature piston/ring wear if not properly maintained, suspension seal leaks.

Carburetor Cleaning:

Regular cleaning and proper jetting are crucial for optimal performance and longevity.

2 Stroke Care:

Proper oil/fuel mixture and avoiding prolonged idling are key to preventing carbon buildup.

📚 Vehicle History

Yamaha Legacy:

Yamaha has a long and storied history in motorcycle racing and off-road performance, particularly with its two-stroke 'YZ' lineage dating back to the 1970s.

Yz250 Evolution:

The YZ250 has undergone continuous development, with the 1987 model representing a significant iteration of Yamaha's successful 250cc two-stroke motocross platform. Key updates in this era included advancements in suspension technology (Monocross), chassis design, and engine performance tuning.

Production Era:

The YZ250 model has been in continuous production since the mid-1970s, with the 1987 model being part of the third major generation of the YZ line.

Manufacturing Location:

Japan

🏆 Awards & Recognition

Motocross Awards:

While specific awards for the 1987 YZ250 are not readily documented, the YZ series has historically been a dominant force in motocross racing, frequently winning championships at various levels.

Performance Reviews:

Consistently reviewed as a potent and competitive machine in its class during its production era.