Yamaha YFM40FB (Big Bear 400) Service Manual

Complete Yamaha Big Bear 400 YFM40FB service manual. Includes detailed instructions for engine, carburetor, drive train, chassis, electrical, and troubleshooting procedures. Part number: ACC-SHAFT-LU-00.

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Document Details

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Document Number / Seller:
27743 / Lisa Scott
File Size:
13.52 MB
File Type:
PDF
Language:
English
Pages:
388
Printable:
Yes
Category:
ATV
Last updated / verified
Sep 11, 2025

Models Covered & Key Technical Specifications

Yamaha YFM40FB (Big Bear 400) Service Manual: Yamaha Official Service & Repair Manual - Comprehensive Maintenance & Diagnostics System-Standards

Professional Reference Overview | Unit.

  • Prescribed Heat Tolerance: 15-30C represents the ideal environmental operating range for optimal performance.
  • Standard Output Performance: 25 ppm is the established maximum print output speed.
  • Core Mass Specs: The primary drive gear has a total mass of 0.53 kg for efficient operation.
  • Rated Output Density: The engine oil capacity is 3.5 L, ensuring adequate lubrication for all components.
  • Technical Capacity Limits: The fuel tank capacity is 15.0 L, providing ample range for extended use.
  • Advanced Operating Temps: The brake fluid type is DOT 4, suitable for standard operating temperatures.

Professional Workshop Service Manual & Technical Specifications

Yamaha YFM40FB (Big Bear 400) Service Manual: Yamaha Official Service & Repair Manual - Comprehensive Maintenance & Diagnostics System-Standards

Validation-Data: Yamaha YFM40FB (Big Bear 400) (ACC-SHAFT-LU-00) // Technical-Scope: ATV / Engine Logic // Operational-Scope: 388 pages. Full coverage for all maintenance and repair procedures.

TABLE HEADERS Integrated-Framework Operational-Logic Calibration-Standards
YFM40FB 4-Stroke, SOHC Air-Cooled
Engine Oil Capacity Fuel Tank Capacity Tire Pressure
12V DC CDI Ignition Wet, Multiple-Disc Brake Double Wishbone Suspension

Systematizing the service groups into distinct chapters, this manual covers:

Electrical system documentation covers wiring diagrams and troubleshooting for all electrical components, including the ignition, starting, charging, lighting, signaling, cooling, 2WD/4WD selecting, and carburetor warming systems.

Suspension service documentation covers the front and rear shock absorbers, steering system, front arms, rear knuckles, and stabilizer, detailing checks and adjustments for optimal performance.

Disassembly instructions are documented for engine removal, muffler and exhaust pipe, leads, cables and hoses, engine mounting bolts, and oil cooler.

Wear limits are specified for critical engine components such as the cylinder head, cylinder, camshaft, rocker arms and valves, piston, piston rings, crankshaft, and clutch.

System operation descriptions cover the drive train, including front and rear constant velocity joints, final drive gears, middle gears, and transmission checks and adjustments.

This manual documents torque specifications for various engine and chassis components to ensure proper thread engagement security.

FAQ

What procedures are **necessary** for adjusting the idle speed on a YFM40FB? keyboard_arrow_down

1,450 ~ 1,550 r/min is the specified engine idling speed range that requires adjustment by turning the throttle stop screw.

Determine the **recommended** calibration settings for the ignition timing on this ATV. keyboard_arrow_down

10°/1,500 r/min is the standard ignition timing (B.T.D.C.) specified for proper engine operation.

What specifications are **calibrated** for the camshaft lobe dimensions? keyboard_arrow_down

Intake measurements for the camshaft lobe are 40.620 ~ 40.720 mm (A) and 32.180 ~ 32.280 mm (B).

Check the **applicable** torque specifications for the cylinder head bolts. keyboard_arrow_down

40 Nm (4.0 m·kg, 29 ft·lb) is the specified torque for cylinder head bolts (ℓ = 245 mm) and cylinder head bolts (ℓ = 223 mm).

What does the **exact** starter plunger stroke distance specification indicate? keyboard_arrow_down

14.2 mm (0.56 in) is the specified starter plunger stroke distance that ensures proper starter cable adjustment.

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