Target Audience:
Professional ATV technicians, experienced DIY mechanics, and owners seeking in-depth repair knowledge.
Value Proposition:
Provides essential technical data and procedures to maintain and repair the YFM400 Big Bear across its initial production years, crucial for cost-effective ownership.
Manual Utility:
Designed for efficient troubleshooting and accurate repair, minimizing guesswork and downtime.
Engine Overhaul:
Complete engine disassembly, inspection, repair, and reassembly procedures for the 385cc engine.
Fuel System Maintenance:
Carburetor cleaning, adjustment, fuel filter replacement, fuel pump (if applicable) diagnosis.
Cooling System:
Radiator, fan, coolant flushing, thermostat testing and replacement.
Transmission And Drivetrain:
Clutch adjustment, CVT (Continuously Variable Transmission) maintenance, gearbox inspection and repair, driveshaft and differential servicing.
Suspension System:
Front and rear suspension component inspection, lubrication, shock absorber adjustment and replacement, A-arm bushing service.
Braking System:
Brake pad replacement, caliper service, brake fluid bleeding and replacement, master cylinder inspection.
Electrical System:
Ignition system testing (spark plug, coil), charging system diagnosis (stator, regulator/rectifier), starter motor, battery maintenance, lighting and accessory wiring.
Steering System:
Tie rod end inspection, steering column adjustment, wheel alignment procedures.
Frame And Bodywork:
Chassis inspection, body panel removal and installation, fender and rack mounting.
Scheduled Maintenance:
Detailed service intervals for oil changes, filter replacements, spark plugs, and other routine checks.
Troubleshooting Guide:
Systematic diagnostic procedures for common and uncommon issues, including symptom-based troubleshooting.
Disassembly And Assembly:
Step-by-step instructions for component removal, reinstallation, and adjustment.
Torque Specifications:
Precise torque values for critical fasteners throughout the vehicle.
Wiring Diagrams:
Comprehensive electrical schematics for all systems.
Special Tool Requirements:
Identification of specific tools needed for certain repairs or adjustments.
Diagnostic Capabilities:
Covers basic to advanced diagnostics, including electrical system testing and component performance checks.
Repair Scope:
Encompasses routine maintenance, component replacement, and in-depth engine and transmission rebuilds.
Completeness:
A complete workshop manual, intended for professional mechanics, providing comprehensive information.
Searchability:
Typically searchable text within PDF documents of this nature, allowing for quick information retrieval.
Print Quality Recommendation:
High-quality print for clarity of diagrams and text.
Binding Type:
N/A (Digital PDF download)
Paper Type:
N/A (Digital PDF download)
Engine Type:
4-stroke, SOHC, 2-valve, single-cylinder
Displacement:
385cc (approximate, specific designation often in model name)
Bore X Stroke:
Specific dimensions available within the manual, crucial for rebuilds.
Cooling System:
Liquid-cooled
Compression Ratio:
Specific ratio detailed in the manual for engine diagnostics.
Horsepower:
Estimated 20-22 HP (typical for this class and era), precise figures in manual.
Torque:
Specific torque figures available in manual for performance tuning and diagnostics.
Carburetor Type:
Mikuni (likely BSR series), with specific model number provided in manual.
Fuel Delivery:
Gravity feed from fuel tank to carburetor, potentially with a fuel pump depending on configuration.
Fuel Type:
Unleaded gasoline, octane rating specified in manual.
Transmission Type:
Automatic, Continuously Variable Transmission (CVT) with high/low range and reverse.
Drive System:
Shaft drive to rear wheels, with selectable 4WD (4-Wheel Drive).
Clutch Type:
Wet, centrifugal clutch.
Gear Reduction:
Specific ratios for high, low, and reverse gears detailed in manual for drivetrain analysis.
Overall Length:
Specific dimensions are available in the manual, crucial for storage and trailering.
Overall Width:
Specific dimensions are available in the manual, important for trail legality and maneuverability.
Overall Height:
Specific dimensions are available in the manual.
Rack Capacity Front:
Typically rated around 120 lbs, specific rating in manual.
Rack Capacity Rear:
Typically rated around 240 lbs, specific rating in manual.
Dry Weight:
Approx. 562 lbs (134 kg), precise weight with fluids detailed in manual.
Ground Clearance:
Approx. 10.1 inches (257 mm), crucial for off-road capability.
Atv Safety Standards:
Compliant with ANSI/SVIA standards for ATVs, specific certifications detailed in manual.
Braking System Type:
Hydraulic disc brakes front and rear for reliable stopping power.
4Wd Engagement:
On-demand 4WD system for enhanced traction.
Lighting System:
Dual headlights and taillight for visibility.
Rollover Protection:
N/A (ATV design inherently lacks specific rollover protection structures like a roll cage).
Engine Oil Change Interval:
Every 1,000 km or 3 months (typical, verify in manual).
Air Filter Cleaning:
As needed, or every 6 months (typical, verify in manual).
Spark Plug Replacement:
Every 6,000 km or 2 years (typical, verify in manual).
Brake Fluid Flush:
Every 2 years (typical, verify in manual).
Engine Oil Type:
Yamalube 4 (or equivalent SAE 20W-40 API SG or higher) motorcycle oil. Specific viscosity for temperature ranges is detailed in manual.
Engine Oil Capacity:
Approximately 2.3 L (2.4 US qt) with filter change, specific amount in manual.
Coolant Type:
Ethylene glycol-based antifreeze coolant, specific mixture ratio and Yamaha recommended coolant type in manual.
Brake Fluid Type:
DOT 3 or DOT 4 hydraulic brake fluid, specified in manual.
Common Wear Items:
CVT belt wear, suspension bushings, wheel bearings, and brake pad wear are common maintenance items.
Carburetor Performance:
Carburetor can be prone to clogging with debris or water ingress, requiring regular cleaning and proper fuel storage.
Electrical Connections:
Corrosion or loose connections in electrical connectors can lead to intermittent faults, especially in wet environments.
Yamaha Atv Legacy:
Yamaha has a long-standing reputation for producing durable and reliable ATVs, with the Big Bear line being a cornerstone of their utility offerings.
Big Bear Lineage:
The Big Bear series has evolved over years, focusing on robust performance, comfort, and utility for work and recreation. The 400cc model introduced significant updates in power and technology.
Manufacturing Location:
Typically manufactured by Yamaha Motor Co., Ltd. in Japan or other global production facilities.
