2006-2012 Yamaha YFM40FBW (Big Bear 400 4WD IRS) ATV Service Manual

2006–2012 Yamaha Big Bear 400 4WD IRS Service Reference

• Covers 2006–2012 Yamaha Big Bear 400 4WD IRS, documenting engine, chassis, and electrical parameters for the 4S11 and 4S14 model codes
• Official Yamaha publication P/N LIT-11616-20-45, first edition November 2006
• Contains 56 individual exploded-view diagrams, 16 comprehensive wiring schematics, and 3 detailed lubrication charts
• Delivered as a direct download the moment payment clears
• Indexed PDF search covers every chapter and appendix
• Laid out for standard letter and A4 printing
• This publication is the foundation for all technical service, providing the factory-spec values necessary for the 4S1-series build maintenance

Documented Maintenance Scope

The 2006–2012 Yamaha Big Bear 400 4WD IRS service documentation is segmented into nine distinct chapters addressing critical system checks and maintenance intervals. The text details engine management, starting from top-end valve clearance adjustments and camshaft inspections down to the crankcase, oil pump, and balancer gear internals. Chassis coverage includes steering system geometry, suspension travel specifications, and the maintenance of the unique wet multiple-disc brake system located within the final drive. Electrical system documentation includes circuit diagrams for the ignition, charging, and 2WD/4WD selecting mechanisms, alongside fuse ratings and bulb specifications.

Technical Data Highlights

This manual provides comprehensive engine specifications, including a 387.0 cm3 displacement and an 8.60:1 compression ratio for standard rebuilding. Cylinder head bolt torque values are documented in a multi-stage sequence, with specific assembly steps provided for the 4S11/4S14 chassis. Intake valve clearance is listed at 0.06–0.10 mm, and exhaust clearance is documented at 0.16–0.20 mm. Engine oil capacity is specified at 2.90 liters for a periodic change, while the differential gear case requires 0.23 liters of specific friction-modified lubricant. Spark plug gap settings are documented at 0.6–0.7 mm for the DR8EA/NGK standard plug.

Reference only — always consult a certified technician before performing service on this equipment.

An official 391-page Yamaha OEM workshop manual covering the 2006–2012 Yamaha Big Bear 400 4WD IRS, documenting engine, chassis, electrical, and drive train specifications for the 4S11 and 4S14 series builds.