This manual covers the Moto-4 (YFM100) model, specifically the first generation produced from 1987 to 1991. The Moto-4 is a practical and user-friendly All-Terrain Vehicle (ATV) designed for recreational riders and general utility tasks. Known for its reliable engine, compact size, and ease of operation, it offered a capable platform for light off-roading and farm use, competing with similar models from Honda, Suzuki, and Kawasaki during its production years. Its robust engineering ensures dependability for its intended applications. This comprehensive Service Repair Manual provides detailed, step-by-step instructions for the maintenance, repair, and troubleshooting of your Moto-4 YFM100. It covers all essential systems, including the engine, fuel system, transmission, drivetrain, suspension, steering, braking system, and electrical system. With clear illustrations and diagrams, this manual is an invaluable resource for professional technicians, mechanics, and DIY enthusiasts alike, ensuring the longevity and optimal performance of your vehicle through proper care and accurate repairs. 🏷️ Basic Information Identification Make: Yamaha Model: Moto-4 Model Code: YFM100 Production Years Covered: 1987, 1988, 1989, 1990, 1991 Generation Generation: First Generation 👋 Introduction Market Position Market Segment: Entry-level to mid-range ATV (All-Terrain Vehicle) Target User: Recreational riders, farm use, general utility Competitive Analysis Key Competitors Era: Honda FourTrax, Suzuki QuadRunner, Kawasaki Bayou (similar displacement categories) Key Features Key Features Vehicle: Compact size, user-friendly operation, reliable Yamaha engine, suitable for light off-roading and utility tasks Key Features Manual: Comprehensive coverage, detailed illustrations, troubleshooting guidance, DIY focus, instant download 📋 Manual Details Coverage Areas Covered Years: 1987-1991 Model Variants Covered: YFM100 Moto-4 Page Count Page Count: 238 Manual Type Manual Type: Service Repair Manual Manual Source: Original Manufacturer (implied) Language Language: English Format Format: Digital Download (PDF) File Delivery: Instant Download via Email/Checkout Page File Compression: May be zipped (.zip, .rar) Software Requirements: PDF Reader, Unzip Software (WinZip/WinRAR) Compatibility: Windows, Linux, Mac (all OS versions) Print Quality Print Quality: Printable Save Options: Can be saved to any device (computer, iPad, hard disk) 📖 Manual Coverage Systems Covered Engine Mechanical: Engine overhaul, cylinder, piston, crankshaft, connecting rod, valves, valve clearance, camshaft, lubrication, bore, stroke, compression ratio, ignition, magneto, stator, coil, spark plug Fuel System: Carburetor (Carburettor), pilot jet, main jet, mixture screw, fuel pump, fuel tank, fuel lines, fuel injection (implied mention of FI, though likely carbureted model) Transmission Drivetrain: Transmission, clutch, primary reduction gear, drive shaft, drive train, kickstart, starter, flywheel, gearshift Suspension Steering: Suspension, forks, triple tree, handlebars, steering, swingarm, struts Braking System: Brakes, brake pads, rotors, brake lever, hydraulic system (implied) Electrical System: Ignition system, lighting (lights), rectifier, regulator, battery, charging system, switches, electrical schematic Bodywork Chassis: Body, panels, plastic, fenders, seat, handle, bars, frame, tank Wheels Tires: Wheels, tires, tire size, wheel bolt pattern (implied) Procedures Included Maintenance: Preventative maintenance, oil change, coolant change, fluid specifications, lubrication, filter replacement (implied) Repair: Repairing all components, engine rebuild, carburetor rebuild, suspension repair, brake repair, electrical system repair Troubleshooting: Troubleshooting problems, diagnosing issues, 'no spark' issues, error codes Diagnostics: Diagnosing problems, fault finding Restoration: Restoring the motorcycle Installation: Component installation Adjustments: Idle adjustment, mixture screw adjustment, valve clearance adjustment Technical Depth Technical Depth: Comprehensive, detailed step-by-step instructions for repair, service, and maintenance Illustration Quality: Illustrated with clear step-by-step instructions, zoomable illustrations, exploded views, component breakdowns Target Audience: Professional technicians, mechanics, workshops, DIY individuals Content Scope: Complete step-by-step information for servicing, repairing, and preventative maintenance 📊 Manual Specifications File Format File Format: PDF File Size Consideration: Can be very large (up to 5 GB) File Type Examples: .pdf, .zip, .rar, .exe Print Quality Print Restriction: No restrictions on printing Binding Type Binding Type: Not applicable (Digital Download) Paper Type Paper Type: Not applicable (Digital Download) ⚙️ Engine Specifications Primary Engine Engine Type: Four-stroke, single-cylinder Displacement: 99.7 cc (cubic centimeters) Bore X Stroke: 52.0 mm x 45.0 mm (approximate, common for this engine family) Cooling System: Air-cooled Compression Ratio: Approximately 9.2:1 (typical for this era and displacement) Engine Family: Yamaha 100cc air-cooled 4-stroke Performance Horsepower: Estimated 7-8 HP (at ~6500 RPM, typical for a 100cc engine of this type) Torque: Estimated 5-6 lb-ft (at ~5000 RPM, typical) Fuel System Carburetor Type: Mikuni VM Series (e.g., VM17SH, common for Yamaha 100cc models) Fuel Type: Unleaded gasoline Fuel Tank Capacity: Approximately 2.5 Liters (typical for this size ATV) 🔧 Transmission Standard Transmission Type: Automatic with torque converter (CVT-like operation) Drive System: Shaft drive (2WD) Features Reverse: Yes Gear Selection: Forward, Neutral, Reverse 📐 Dimensions Exterior Length: Approx. 1700 mm (66.9 inches) Width: Approx. 970 mm (38.2 inches) Height: Approx. 1000 mm (39.4 inches) Weights Dry Weight: Approx. 110 kg (242 lbs) Curb Weight: Approx. 118 kg (260 lbs) 🛡️ Safety Features Ratings Safety Ratings: Not applicable (ATVs of this era typically did not have standardized crash ratings) Active Features Active Safety Features: Mechanical parking brake, front and rear drum brakes (standard) Passive Features Passive...