Target Audience:
Farm, ranch and utility ATV users; DIY owners and technicians servicing the Big Bear 400
Competitive Advantage:
Simple, durable 400cc utility quad with shaft drive and selectable 4WD, easier to maintain than many rivals
Engine:
386cc air-cooled single-cylinder four-stroke
Drive:
Shaft drive with selectable 2WD / 4WD
Utility Focus:
Racks, towing capability and low-range gearing for work use
Engine:
Removal, disassembly, inspection, rebuild specifications and reassembly
Cylinder Head:
Valve service, timing, torque sequences
Fuel System:
Carburetor disassembly, tuning and fuel tank service
Lubrication:
Oil pump, oil strainer and lubrication circuits
Cooling:
Air-cooling shrouds and fin inspection
Transmission:
5-speed gearbox disassembly, gear inspection and countershaft service
Final Drive:
Shaft drive inspection and rear differential service
4WD System:
Front drive engagement and 2WD/4WD selector mechanism
Suspension:
Front and rear suspension, shocks and A-arm service
Steering:
Steering stem and handlebar service
Brakes:
Front and rear drum/disc brake service and pad replacement
Wheels & Tires:
Wheel removal, tire service and specifications
Electrical:
Wiring diagrams, CDI ignition, starter and charging system
Battery & Charging:
Battery testing, alternator/charging output checks
Frame & Body:
Frame inspection, fender, rack and body panel removal
Torque Specifications:
Complete torque tables for fasteners throughout the machine
Diagrams:
Exploded views, wiring schematics and detailed illustrations
Specifications:
Factory tolerances, clearances and wear limits
Troubleshooting:
Symptom-based fault finding for engine, drivetrain and electrical
Parts Data:
OEM part references and exploded diagrams for ordering
Fluid Capacities:
Oil and fluid capacity figures included
Fitment:
Covers all 2000-2006 Big Bear 400 variants
File Format:
PDF (searchable, bookmarked, zoomable)
Compatibility:
Windows, macOS, Linux, iOS, and Android — any device with a PDF reader
Requirements:
A PDF reader application (e.g. Adobe Acrobat Reader, free)
Searchability:
Fully text searchable for fast lookup of any topic
Print Quality:
High-resolution digital pages, printable at full clarity
Binding Type:
N/A — digital download, no physical binding
Paper Type:
N/A — digital download, no physical paper
Standard Transmission:
5-speed constant-mesh manual with automatic clutch
Optional Transmission:
Ultramatic-type automatic variation noted only where fitted - N/A for most 00-06 Big Bear models
Drive System:
Shaft drive to rear differential
4WD:
Select 2WD or 4WD via handlebar lever; limited-slip style front differential
Wheelbase:
Approximately 49.3 in (1,250 mm)
Length:
Approximately 78.5 in (1,995 mm)
Width:
Approximately 42.9 in (1,090 mm)
Seat Height:
Approximately 31.7 in (805 mm)
Curb Weight:
Approximately 550 lb (250 kg)
Ground Clearance:
Approximately 8.7 in (220 mm)
Towing Capacity:
Approximately 1,212 lb with optional hitch
Crash Test Rating:
N/A - ATVs are not crash tested by NHTSA or IIHS
Brakes:
Front dual drum and rear hydraulic disc (varies by year)
Lighting:
Dual headlights and taillight/brake light
Engine Braking:
Engine brake assist in low range
Parking Brake:
Locked parking brake mechanism
Owner Safety:
Requires helmet, eye protection and ATV rider training per manufacturer guidance
Audio System:
N/A - utility ATV, no factory audio system
Driver Assistance:
N/A - no electronic driver aids on this model
Ignition Technology:
CDI ignition with electric starter
Instrumentation:
Analog speedometer and indicator lights
Engine Oil:
Replace initially at 1 month / 200 miles, then every 6 months / 1,200 miles
Oil Filter:
Replace every other oil change
Air Filter:
Clean every ride in dusty conditions; replace as needed
Valve Clearance:
Check periodically per factory interval schedule
Differential & Final Gear Oil:
Inspect and replace per annual service schedule
Engine Oil Specification:
SAE 10W-40 API SE or higher 4-stroke motorcycle oil
Brake Fluid:
DOT 4 (where hydraulic disc fitted)
Common Wear Items:
Brake shoes/pads, drive shaft boots, CV joints, chain-free shaft U-joints, battery, spark plug, tires
Manufacturer:
Yamaha Motor Co., Ltd., Japan - established 1955, major powersports producer
Model Evolution:
Big Bear introduced as a 350 in 1987; grew to 386cc as the Big Bear 400 in 2000 with updated styling and selectable 4WD; produced through 2006
Production Location:
Yamaha powersports production facilities - Japan/USA assembly
Replacement:
Succeeded in the Yamaha utility ATV lineup by the Grizzly and Kodiak series
