Yamaha Big Bear 350 YFM350FW ATV 1987–1999 OEM Service Manual (P/N 4WU-W0747-00-AD)

This 294-page official Yamaha OEM manual provides the complete reference data needed for servicing the 1987–1999 Big Bear 350 (YFM350FW). Whether you manage a busy powersports shop or handle your own routine maintenance, this digital PDF delivers the exact factory specifications for powertrain and chassis work across the 1YW and 4WU-series production builds.

• Publication Number: Official OEM P/N 4WU-W0747-00-AD.
• Visual Reference: Includes 47 exploded-view diagrams to simplify component identification and verify correct assembly order.
• Fastener Specifications: Features 35 torque-specification tables covering critical engine and chassis hardware.
• Model-Specific Data: Covers diagnostics tied strictly to the 1YW-000101 serial-number range for the 350-series engine.
• Comprehensive Coverage: Integrates ATV troubleshooting, 4x4 drivetrain teardowns, electrical system testing, and engine rebuilds.
• Essential Assemblies: Details factory procedures for the recoil starter, carburetion system, steering knuckle shafts, balancer drive, and middle gear.

Manual Layout & Technical Depth

The manual spans eight primary chapters, starting with machine identification and special tool requirements. It outlines the exact factory parameters for periodic inspections, including valve clearance adjustments, throttle linkage calibration, and ignition timing verification. By supplying factory-level step-by-step instructions for complex tasks like a full carburetor overhaul, steering system alignment, and primary clutch replacement, this resource directly helps you avoid expensive dealership labor rates. To support these jobs, the document provides detailed wiring diagrams, periodic inspection charts, cable routing views, electrical system schematics, wear limit charts, and valve seating drawings.

For deeper powertrain repair, the document covers complete engine overhaul protocols. You get clear component limits and clearance specs for disassembling and rebuilding the cylinder head, clutch assemblies, and transmission. A notorious pitfall on the YFM350FW platform is the middle driven gear nut backing off under heavy load, which can lead to catastrophic crankcase damage if not torqued and secured with the correct thread-locking agent. Having the exact factory torque sequence and gear lash measurements on the bench prevents you from making structural mistakes during this specific repair. For instance, the reference data specifies a 10 Nm torque rating for tappet covers and a 115 Nm requirement for the main bearing cap. Additional inspection data lists the oil gallery bolt at 7 Nm. You will also find precise tool callouts, such as the YM-01404 flywheel puller, ensuring you have the right gear on the bench before tearing down the block.

Always prioritize shop safety. The specifications and limits discussed here serve as a structural overview of the manual. Always verify torque figures and procedures directly against the full OEM documentation before applying force or running diagnostics to prevent equipment damage or personal injury.