Yamaha YZ 250 1998 Service Repair Workshop Manual

Regular price: $16.99
Sale price: $16.99
Regular price
Unit price: per

🏷️ Basic Information Identification Make: Yamaha Model: YZ250 Year: 1998 Vehicle Type: Motocross Motorcycle Engine Type: 2-Stroke 👋 Introduction Market Position Motocross Segment: The YZ250 was a dominant force in...

23 people are viewing this right now

Type: Motorcycle

Vendor:

Sku: 492070

Tags: 1998 Motorcycle Motorcycles Yamaha YZ 250 YZ Models

Product variants

Description

🏷️ Basic Information

Identification

Make:

Yamaha

Model:

YZ250

Year:

Vehicle Type:

Motocross Motorcycle

Engine Type:

2-Stroke

👋 Introduction

Market Position

Motocross Segment:

The YZ250 was a dominant force in the 250cc open class motocross segment during the late 90s.

Competitors 1998:

Primarily competed against Honda CR250R, Suzuki RM250, and Kawasaki KX250.

Key Features

Engine Power:

Renowned for its potent 2-stroke power delivery and aggressive acceleration.

Suspension Performance:

Equipped with advanced Kayaba or Showa USD forks and a sophisticated Monocross rear suspension.

Handling Chassis:

Tuned for agility and stability on varied motocross tracks.

📋 Manual Details

Coverage Areas

Manual Type:

Service Repair Workshop Manual

Language:

English

Format:

Downloadable PDF

Page Count:

Estimated 300-400 pages (typical for this era/type of manual)

Manual Source:

Original Yamaha Documentation

📖 Manual Coverage

Systems Covered

Engine Overhaul:

Complete disassembly, inspection, and reassembly of the 2-stroke engine.

Top End Rebuild:

Piston, ring, cylinder, and cylinder head service procedures.

Bottom End Assembly:

Crankshaft, connecting rod, and bearing service.

Cooling System:

Radiator, hoses, and water pump maintenance and repair (if applicable).

Fuel System:

Carburetor (Mikuni VM series) disassembly, cleaning, adjustment, and tuning.

Ignition System:

CDI unit, ignition coil, spark plug, and timing checks.

Exhaust System:

Pipe and silencer inspection and maintenance.

Transmission Clutch:

Gearbox disassembly, inspection, lubrication, and clutch operation and service.

Suspension Front:

Upside-down fork (Kayaba/Showa) service, oil change, seal replacement, and adjustments.

Suspension Rear:

Monoshock (Pro-Link/Monocross) system, shock absorber service, linkage lubrication.

Braking System Front:

Hydraulic disc brake caliper, master cylinder, and hose service.

Braking System Rear:

Hydraulic disc brake caliper, master cylinder, and hose service.

Wheels Tires:

Spoke tensioning, rim maintenance, bearing service, and tire selection advice.

Electrical System:

Lighting (if applicable), wiring diagrams, fuse checks, and basic troubleshooting.

Chassis Frame:

Frame inspection, steering head bearing service, footpeg and control lever adjustments.

Bodywork Plastics:

Fairing, seat, tank cover removal and installation.

Procedures Included

Routine Maintenance:

Oil changes, filter cleaning/replacement, chain adjustment, lubrication points.

Troubleshooting Guides:

Diagnosing common starting, running, and performance issues with flowcharts.

Diagnostic Procedures:

Methods for checking ignition timing, compression, and carburetor circuits.

Rebuilding Procedures:

Step-by-step guides for major component overhauls.

Adjustment Specifications:

Carburetor jetting, suspension sag, chain slack, and cable free play.

Torque Specifications:

Critical bolt and nut tightening values for all major components.

Wiring Diagrams:

Detailed electrical schematics for troubleshooting and repairs.

Technical Depth

Diagnostic Level:

Intermediate to Advanced, covering component testing and symptom analysis.

Repair Scope:

From basic adjustments to complete engine and chassis rebuilds.

Special Tool Requirements:

Identification of required Yamaha specific tools and common aftermarket equivalents.

📊 Manual Specifications

File Format

Digital Format:

PDF (Portable Document Format)

Searchability:

Likely text-searchable if scanned optically with OCR.

Print Quality:

High-resolution scans allowing for clear printing of diagrams and text.

Illustrations:

Detailed, step-by-step diagrams and photographic illustrations.

Binding Type:

N/A (Digital Download)

Paper Type:

N/A (Digital Download)

⚙️ Engine Specifications

Primary Engine

Engine Type:

Liquid-cooled, 2-stroke, reed valve induction

Displacement:

249 cc

Bore X Stroke:

67.0 mm x 70.0 mm

Compression Ratio:

8.2:1 (typical for this model)

Carburetor:

Mikuni VM38SS (38mm) slide-valve, with dual jet system

Ignition:

CDI (Capacitor Discharge Ignition)

Spark Plug:

NGK BR9EG (typical specification)

Performance

Horsepower:

Approximately 45-50 HP (estimated at crankshaft)

Torque:

Not officially published, but significant mid-range torque

Fuel System

Fuel Type:

Unleaded gasoline (91 octane or higher recommended)

Fuel Oil Mixture:

50:1 ratio with high-quality 2-stroke premix oil

Fuel Tank Capacity:

Approx. 9.5 liters (2.5 US gal)

🔧 Transmission

Standard

Transmission Type:

5-speed constant mesh

Clutch Type:

Wet, multi-plate

Final Drive:

Chain drive (520 O-ring chain recommended)

Features

Gear Ratios:

1st: 2.615, 2nd: 1.867, 3rd: 1.400, 4th: 1.136, 5th: 0.917 (typical)

Transmission Oil Type:

Yamalube 10W-30 API SE or SF, or equivalent

Transmission Oil Capacity:

Approx. 0.8 liters (0.85 US qt)

📐 Dimensions

Exterior

Overall Length:

Approx. 2170 mm (85.4 in)

Overall Width:

Approx. 830 mm (32.7 in)

Overall Height:

Approx. 1250 mm (49.2 in)

Seat Height:

Approx. 970 mm (38.2 in)

Wheelbase:

Approx. 1475 mm (58.1 in)

Weights

Dry Weight:

Approx. 96 kg (211.6 lbs)

Wet Weight:

Approx. 105 kg (231.5 lbs) (estimated with fluids)

Ground Clearance:

Approx. 355 mm (14.0 in)

🛡️ Safety Features

Ratings

Safety Standards:

Designed for closed-course competition; not street legal.

Active Features

Braking System:

Powerful dual hydraulic disc brakes for effective stopping power.

Suspension Control:

Adjustable suspension components for optimized rider control and track conditions.

Passive Features

Frame Strength:

Durable steel frame designed to withstand rigorous off-road use.

Ergonomics:

Motocross-specific rider triangle for control and comfort.

💡 Technology Features

Infotainment

Features:

N/A (This is a competition motocross bike, not equipped with infotainment systems).

Driver Assistance

Features:

N/A (No electronic driver assistance systems).

Connectivity

Features:

N/A (No electronic connectivity features).

🔧 Maintenance

Service Intervals

Engine Oil Change:

Every 10-15 hours of operation or as recommended in manual for transmission oil.

Air Filter Cleaning:

Before or after every race/ride, depending on conditions.

Spark Plug Inspection:

Every 5-10 hours of operation.

Chain Lubrication:

Every ride or as needed, especially in dusty/wet conditions.

Fluid Specifications

Coolant:

Yamaha-specific coolant or a high-quality ethylene glycol-based coolant with distilled water (50:50 mix).

Fork Oil Type:

Yamalube Fork Oil G10 or equivalent (viscosity typically 10W)

Fork Oil Quantity:

Refer to manual for specific fork leg volumes (e.g., approx. 500-600cc per leg).

Known Issues

Clutch Wear:

Clutch plates can wear prematurely with aggressive riding; refer to manual for inspection.

Power Valve Sticking:

Carbon buildup can cause the powervalve mechanism to stick; requires regular cleaning.

Carburetor Jetting:

Requires careful jetting adjustments based on altitude, temperature, and riding conditions.

Suspension Seals:

Fork and shock seals can be prone to leaks with heavy use; regular inspection and maintenance are crucial.

📚 Vehicle History

Brand Heritage

Yamaha Motocross Legacy:

Yamaha has a long and successful history in professional motocross, dating back to the 1970s.

Model Evolution

Yz Series Development:

The YZ250 has undergone continuous development, with significant chassis and engine updates throughout the 90s.

1998 Updates:

The 1998 model often featured refinements in suspension, chassis geometry, and engine tuning based on racing feedback.

Production

Manufacturing Location:

Japan

🏆 Awards & Recognition

Recognitions

Motocross Magazine Reviews:

The 1998 YZ250 was generally well-received by motocross publications, praised for its strong engine and capable chassis.

Racing Performance:

YZ250 models have a history of success in professional motocross and supercross racing.