The MOTO 4 100 CHAMP (YFM100) is an All-Terrain Vehicle (ATV) produced from 1987 to 1991. Building on a strong legacy in powersports, this model was designed to offer reliability and ease of use for recreational riders and light utility tasks. Its engineering focuses on robust mechanical function, featuring a four-stroke, air-cooled 99cc engine paired with an automatic transmission and shaft drive. The MOTO 4 line was recognized for its value and dependable performance within the ATV market of its time, making it a popular choice for those seeking capable off-road mobility. This comprehensive service repair workshop manual provides in-depth information for the YFM100 MOTO 4 100 CHAMP ATVs manufactured between 1987 and 1991. It covers all essential aspects of maintenance, repair, and troubleshooting, including detailed procedures for engine service, clutch and transmission work, fuel and ignition systems, electrical components, brakes, steering, suspension, and frame. The manual is designed for DIY mechanics, enthusiasts, and professional technicians, offering professional-level guidance with clear instructions and illustrations to ensure proper upkeep and efficient repair of the vehicle. 🏷️ Basic Information Identification Make: Yamaha Model: MOTO 4 100 CHAMP Model Code: YFM100 Vehicle Type: All-Terrain Vehicle (ATV) Generation Production Years: 1987-1991 👋 Introduction Market Position Target User: DIY mechanics, ATV enthusiasts, professional repair shops Competitive Analysis Advantage: Provides professional-grade diagnostic and repair information typically only accessible to authorized service centers Key Features Accessibility: Instant download allows immediate access for timely repairs Completeness: Covers A-Z of repairs, ensuring all aspects of the ATV can be serviced 📋 Manual Details Coverage Areas Primary Coverage: Comprehensive service, repair, and maintenance for Yamaha YFM100 MOTO 4 100 CHAMP ATVs Scope: All models within the 1987-1991 production years Page Count Estimated Pages: Detailed, typically 200-400 pages (based on professional service manual standards for this era) Manual Type Type: Service Repair Workshop Manual Language Language: English Format Format: PDF Download 📖 Manual Coverage Systems Covered Engine Service: Engine disassembly, assembly, tuning, troubleshooting, internal component service Clutch Service: Clutch adjustment, replacement, and related component service Transmission Service: Gearbox inspection, repair, fluid changes, and component replacement Cooling System: Radiator, fan, thermostat, coolant, and associated plumbing Fuel System: Carburetor adjustment and overhaul, fuel tank, fuel lines, fuel filter service Exhaust System: Muffler, exhaust pipe inspection and replacement Ignition System: Spark plug, ignition coil, CDI unit, timing checks and service Electrical System: Battery, charging system (stator, regulator/rectifier), lighting, starting system Brakes: Brake caliper service, master cylinder, brake lines, brake pads, brake drums/discs (as applicable) Wheels Tires: Wheel bearing service, tire pressure checks, tire replacement guidelines Steering Suspension: Handlebar assembly, steering stem, ball joints, shocks, swingarm pivot Frame Bodywork: Frame inspection, body panel removal/installation, seat, fenders Wiring Diagrams: Comprehensive electrical schematics for fault diagnosis and component identification Procedures Included Routine Maintenance: Oil changes, filter replacements, lubrication points, general inspections Troubleshooting Diagnostics: Systematic fault finding for common and uncommon issues, symptom-based diagnosis Disassembly Assembly: Step-by-step guides for major component removal and reinstallation Rebuild Procedures: Detailed instructions for rebuilding key components like engines and carburetors Adjustments: Carburetor jetting, ignition timing, brake cable slack, clutch engagement Technical Depth Depth: Professional-level, covering from basic adjustments to complete engine and transmission overhauls Visuals: High-quality pictures and diagrams illustrating procedures and components 📊 Manual Specifications File Format Compatibility: Compatible with all major operating systems (Windows 95/98/2000/Me/XP/Vista/7+, macOS) Print Quality Clarity: Easy to read, professional quality information Binding Type Type: N/A (Digital Download) Paper Type Type: N/A (Digital Download) ⚙️ Engine Specifications Primary Engine Engine Type: Four-stroke, air-cooled, SOHC (Single Overhead Cam) Displacement: 99cc Bore X Stroke: Approx. 52.0 mm x 47.0 mm (typical for this displacement and era) Compression Ratio: Approx. 9.3:1 (typical for this era, manual will confirm specific value) Performance Horsepower: Approx. 7-9 HP (manual will provide exact figures) Torque: Specific torque figures not commonly published, but engine design emphasizes low-end grunt for off-road use. Fuel System Carburetor Model: Mikuni VM Series (e.g., VM17SH - manual will confirm specific model and jetting) Fuel Type: Unleaded Gasoline Fuel Tank Capacity: Approx. 2.5 - 3.0 Liters (manual will specify exact capacity) 🔧 Transmission Standard Transmission Type: Automatic with Torque Converter & 3-Speed Gearbox Optional Features: Forward, Neutral, Reverse Features Drive Type: Shaft Drive 📐 Dimensions Exterior Length: Approx. 1600-1700 mm (varies slightly by model year, manual will be precise) Width: Approx. 900-1000 mm Height: Approx. 950-1050 mm Weights Dry Weight: Approx. 110-120 kg (manual will provide exact dry weight) Payload Capacity: Typically around 70-100 kg (manual will list specific capacity) 🛡️ Safety Features Ratings Crash Safety: ATVs are not subject to the same standardized crash ratings as passenger vehicles. Safety is primarily rider-controlled. Active Features Braking System: Drum or disc brakes front and rear, with integrated rear braking system activated by thumb lever or foot pedal (specific configuration per manual) Passive Features Lighting: Headlight, taillight/stoplight for visibility and signaling Chassis Design:...