2005–2006 Yamaha WR450F and WR450F(T) Service Manual (P/N 5TJ-28199-42)

• Exact model-code coverage: Covers the Yamaha WR450F(T), identified in the specifications as WR450FT for the USA, Canada, Australia, and New Zealand and WR450F for Europe and South Africa. Regional model codes are 5TJ8 (USA), 5TJ9 (Europe), and 5TJA (Canada, Australia, New Zealand, and South Africa).
• Major engine and drivetrain repair: Documents engine removal and installation; camshaft, cylinder-head, valve, piston, clutch, balancer, oil-pump, crankcase, and crankshaft service; plus internal transmission, shift-cam, and shift-fork inspection and assembly.
• Carburetor and induction procedures: Covers KEIHIN FCR MX39 removal, disassembly, inspection, float setting, accelerator-pump timing, and installation, together with air-induction valve testing and symptom-based jetting guidance.
• Chassis overhaul coverage: Includes wheel-bearing and brake service, caliper and master-cylinder disassembly, brake-system bleeding, front-fork oil-seal and damper-rod work, steering-bearing service, swingarm/linkage repair, and rear-shock removal and disassembly.
• Electrical diagnosis: Provides the full wiring diagram and fault-isolation charts for the map-controlled CDI ignition, electric starter and cut-off circuit, charging system, throttle-position-sensor testing and adjustment, and lighting system.
• OEM document and reference data: Official Yamaha Owner’s Service Manual number 5TJ-28199-42, first edition dated August 2004. The 758-page PDF contains English, French, German, and Spanish text, with torque tables, capacities, service limits, adjustment data, and electrical test specifications.

Model Match and Intended Use

This is a model-code-specific manual for the WR450F(T) competition machine, not a blanket reference for every WR450F. Yamaha identifies the motorcycle for closed-course competition use and specifies a liquid-cooled DOHC single, dry-sump lubrication, a constant-mesh five-speed transmission, and a semi-double-cradle frame. The procedures are expressly organized as a step-by-step reference for a mechanic, making this edition suited to technicians and experienced owners who can use precision measuring equipment and the specified service tools.

Repair Depth Beyond Routine Maintenance

The repair sections use exploded views, job charts, and “extent of removal” notes to show how far an assembly must be stripped. Engine work reaches valve-guide replacement and reaming, valve-seat inspection and lapping, decompression-system checks, crankcase separation, crankshaft installation, and transmission inspection. Separate lubrication-flow pages map the pressure-feed and scavenging routes through the dry-sump engine.

Chassis coverage goes well beyond pad changes and chain adjustment. It includes hydraulic brake repair and bleeding, fork base-valve and damper-rod service, steering and wheel bearings, swingarm relay-arm bearings, and rear-suspension setup. The chassis tables separate the standard rear-spring configurations for USA/Canada, Europe, and Australia/New Zealand/South Africa. The tuning chapter adds carburetor-setting tables by running symptom, optional jet and needle data, sprocket choices, fork spring and oil-level setup, rear spring selection, and front/rear damping charts tied to track behavior.

The electrical chapter explains the map-controlled ignition and separates the U.S. 5TJ-80 CDI unit from the 5TJ-90 unit used outside the USA. System-specific flowcharts guide repair checks for no-spark, starter-motor, no-charge, TPS, and lighting faults instead of leaving the wiring diagram as the only diagnostic aid.

Tools, Diagrams, and Factory Data

The special-tool list supplies both North American and 90890-series numbers. Examples include the crankcase separator YU-1135-A / 90890-01135, fork seal driver YM-01442 / 90890-01442, timing light YM-33277-A / 90890-03141, and vacuum/pressure pump gauge set YB-35956-A / 90890-06756. Reference tables cover component-specific torque values, fluid capacities, wear and runout limits, inspection clearances, suspension settings, carburetor data, and electrical resistance and output checks.

Notable visuals include the oil-lubrication flow diagrams, chassis cable-routing diagrams, complete electrical-component and wiring diagram, the CDI 3-D Image Map of Ignition Timing, carburetor exploded views, and symptom-based front-fork and rear-shock setup charts.

Cam Timing and Suspension Cautions

The camshaft section warns that turning the crankshaft during cam installation can cause damage or incorrect valve timing; uneven cam-cap tightening can damage the cylinder head, caps, and camshafts. Fork internals are highly contamination-sensitive and may retain air pressure, while the rear shock contains a high-pressure nitrogen reservoir. Yamaha recommends dealer servicing for the fork and reserves shock nitrogen discharge and disposal for Yamaha dealers; any suspension or hydraulic-brake repair requires secure machine support and the proper service equipment.