2000-2006 Yamaha YFM400FWNP Big Bear 400 Service Manual

Field service reference for differential gear lash, drive train assemblies, and 2WD/4WD selector systems. Complete electrical diagnostics with wiring schematics, brake adjustment procedures, and ignition/starting system troubleshooting. Factory documentation LIT-11616-15-22.

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Document Details

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Document Number / Seller:
24718 / Kevin Thomas
File Size:
43.78 MB
File Type:
PDF
Language:
English
Printable:
Yes
Category:
ATV
Last updated / verified
May 30, 2025

Models Covered & Key Technical Specifications

Yamaha YFM400FWNP Big Bear 400 (LIT-11616-15-22) — 2001 Strategic Operational Reference | YFM400FWNP Unit.

  • Prescribed Cycle Rate: 1,450 ~ 1,550 r/min is rated at the engine idle speed Bounds.
  • Standard Rotation Data: For optimal combustion, 33.3 kPa (250 mmHg, 10 inHg) establishes the intake vacuum requirement Topology.
  • Core Installation Footprint: The steering geometry requires 4° caster angle setting Matrix.
  • Rated Threaded Fastener Data: Kingpin angle achieves 13° for front axle geometry Standards.
  • Calibrated Alignment Specs: Headlight bulb output is specified as 12 V 30 W × 2 configuration Margin.
  • Nominal Output Performance: Pickup coil resistance reaches 459 ~ 561 Ω (at 20 °C / 68 °F) Protocol.

Professional Workshop Service Manual & Technical Specifications

Comprehensive Troubleshooting Repair Manual: ATV Yamaha YFM400FWNP Big Bear 400 (2000-2006) - Definitive Maintenance & Repair Handbook Service-Portfolio

Diagnostic-Area: YFM400FWNP (2000–2006) Big Bear 400 // Asset-ID: ATV Service / Electrical Systems Logic // Diagnostic-Area: 435 pages, supplementary service data, comprehensive technical documentation.

Assessment-Parameter Technical-Path Validation-Data
Ignition & Starting Systems CDI magneto, rectifier/regulator, starter motor circuits Complete specifications provided
Electrical Lighting & Signals Headlight, tail/brake, indicator light assembly documentation See Chapters 5, 7, 8
Drive Train Components Constant velocity joints, differential gear assembly procedures Documented reference data

Service procedures are grouped by vehicle system and component, examining specifications, periodic checks and adjustments, drive train assembly, and electrical circuit diagnostics, detailing ignition system architecture, electric starting configuration, and lighting/signal system operation, addressing 2WD/4WD selecting system integration, cable routing requirements, and wiring diagram reference material.

Diagnostic Sequences

Adjustment procedures are detailed for brake lever free play, front brake hydraulic operation, and rear brake light switch timing correction. The manual includes circuit diagrams for the ignition system, covering CDI magneto pickup coil resistance verification, ignition coil primary and secondary winding measurements, and spark plug gap validation protocols. Engine idle speed, intake vacuum, and valve clearance reference specifications are documented for the YFM400FWNP engine framework.

Advanced Topology

Timing procedures are documented for ignition advance mapping at varying engine speeds—10 degrees at 1,000 r/min and 33 degrees at 5,000 r/min—with digital advancer type identification. The electric starting system architecture includes starter relay operation verification, main switch continuity testing, and gear position switch functional validation. Structured electrical troubleshooting sequences address no-spark conditions, starter motor inoperability, and indicator light failures through systematic component testing protocols.

Technical Sequences

Technical notes are provided for constant velocity joint assembly, differential gear lash measurement and adjustment procedures using specialized measurement tools, and shift fork sliding gear positioning. The document includes gear motor installation steps, oil filling requirements, and differential gear operation verification methodology. Cable routing diagrams illustrate placement of throttle cables, fuel tank breather hoses, rear brake lever switch leads, and handlebar switch connections throughout the vehicle frame structure.

Core Architecture

Quality checks are addressed for brake fluid condition assessment, spark arrester cleaning intervals, fuel line integrity inspection, and wheel bearing looseness detection protocols. Periodic maintenance lubrication intervals are specified for initial, routine, 3-month, 6-month, and annual service points. The wiring diagram encompasses all major electrical components: CDI unit, ignition coil, starter motor, battery connections, rectifier/regulator integration, fan motor control circuitry, and indicator light assemblies with complete lead color coding reference.

Structured Parameters

The manual documents torque specifications for engine mounting stays, differential gear case fasteners, and steering knuckle attachment points to ensure proper flange face sealing. Bulb wattage specifications, battery voltage requirements, and fuse amperage ratings for main circuit, headlight, ignition, carburetor warmer, and auxiliary DC jack protection are included. Detailed maintenance specifications cover cylinder bore dimensions, rocker arm bearing clearances, carburetor jet identification, and brake system adjustment parameters with metric and imperial unit conversions.

FAQ

What are the **proper** clearance measurements for rocker arm components? keyboard_arrow_down

0.009 ~ 0.037 mm (0.0004 ~ 0.0015 in) arm-to-shaft clearance is specified, with a wear limit threshold of 0.08 mm before replacement becomes necessary.

Specify the **standard** torque requirements for engine mounting bolts? keyboard_arrow_down

34 N·m (3.4 m·kg, 24 ft·lb) applies to M8 fasteners, 69 N·m (6.9 m·kg, 50 ft·lb) for M10 fasteners, and 30 N·m (3.0 m·kg, 22 ft·lb) for M12 steering knuckle bolts to ensure proper structural integrity.

What is the **necessary** differential gear lash specification for assembly? keyboard_arrow_down

0.09 ~ 0.47 mm (0.004 ~ 0.019 in) differential gear lash must be measured and adjusted at four positions with the shaft rotated 90° each time using the specified measurement tool P/N YM-01467 to ensure smooth operation.

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Reviews (2)

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This service manual is a must-have for anyone working on the Yamaha YFM400FWNP. The diagrams are incredibly helpful and the instructions are clear. Plus, the download was super quick after I made my purchase! Highly recommend!
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I found this manual very detailed and easy to use. The support team was also very prompt in sending the download link, making the whole process smooth. This has become my go-to reference for repairs!