2004 Yamaha YZ450F(S) Owner's Service Manual (P/N 5XD-28199-80)

The 2004 Yamaha YZ450F(S) Owner's Service Manual, reference 5XD-28199-80, covers the 5XD-series USA, European, Canadian, Australian, New Zealand, and South African variants. It combines operating and maintenance information with engine repair, chassis service, electrical diagnosis, and race setup.

• Engine repair: Engine removal, camshaft timing, cylinder-head and valve service, piston inspection, crankcase separation, and crankshaft installation.

• Clutch and transmission: Wet-clutch disassembly and inspection, balancer alignment, kick-start mechanism service, and transmission, shift-cam, and shift-fork procedures.

• Fuel and cooling: FCR MX39 carburetor overhaul, accelerator-pump timing, radiator pressure checks, water-pump service, and oil-pump inspection.

• Chassis and brakes: Front-fork rebuilds, steering and swingarm bearing service, brake-caliper and master-cylinder repair, and hydraulic brake bleeding.

• Electrical diagnosis: Wiring and connector diagrams, ignition troubleshooting charts, map-controlled CDI operation, and throttle position sensor (TPS) testing and adjustment.

• Race preparation: Pre-operation checks, maintenance schedules, carburetor setting charts, sprocket selection, and front-fork and rear-suspension tuning.

Owners can use the operating and basic-maintenance sections; the internal repair procedures are suited to mechanics familiar with precision measurements and specialized tools.

Engine Repair and Workshop References

Valve-train coverage includes the pad selection table, cam-lobe measurements, camshaft-to-cap clearance checks, decompression-system inspection, and timing-chain installation. Cylinder and piston inspections distinguish standard dimensions from wear limits.

Exploded views and job instruction charts identify parts and the extent of removal for each assembly. Special-tool listings include the crankcase separating tool YU-1135-A / 90890-01135 and fork seal driver YM-01442 / 90890-01442, with country-specific part numbers.

The camshaft procedures warn that uneven cam-cap tightening can damage the cylinder head, caps, and camshafts.

Carburetor, Cooling, and Lubrication

FCR MX39 coverage extends to the float and needle valve, accelerator-pump diaphragm, hot-start plunger, and pump-timing adjustment. The tuning chapter separates US and other-market jet-needle options and relates mixture changes to throttle opening and atmospheric conditions.

The starting section explains accelerator-pump overfueling, spark-plug fouling, and kickback risks. It distinguishes cold starts, hot starts, and restarting after a fall.

Cooling procedures include radiator-cap and system pressure tests, radiator inspection, and water-pump shaft and seal service. Oil-pump checks cover rotor clearances, while lubrication diagrams and sectional views show the oil flow paths.

Ignition Fault Tracing and TPS Adjustment

The ignition inspection chart checks the stop switch, ignition coil, magneto source and pickup coils, and neutral switch before CDI-unit replacement. Together with the wiring diagram, cable routing diagrams, and connector views, it helps narrow a no-spark fault to the circuit or component under test.

TPS coverage links the sensor's signal to the map-controlled CDI's three-dimensional ignition timing, then documents resistance tests, input-voltage checks, and installation-angle adjustment with a digital voltmeter. Unnecessary loosening of the TPS mounting screws can reduce engine performance.

Suspension Service and Race Setup

Yamaha recommends dealer maintenance for the front fork; its assembly notes warn that a dropped damper rod can damage the internal valve. Fork procedures cover disassembly, seals, damper-rod installation, oil-level setting, and reassembly.

Swingarm and Monocross linkage instructions distinguish polylube bearing care from seal and collar lubrication. Suspension setting charts connect handling symptoms to damping and spring choices, with separate European baseline settings.

Rear-shock coverage includes removal, inspection, spring and bearing work, and external adjustments; it does not provide internal damper-cylinder or nitrogen-reservoir overhaul. The manual warns against opening those pressurized components.

Valve, Cylinder-Head, and Ignition Specification Samples

The valve-clearance section specifies an intake clearance of 0.10–0.15 mm with the engine cold, supported by the pad selection table. Cylinder-head inspection uses a warpage limit of 0.05 mm.

Electrical testing lists a pickup-coil resistance of 248–372 Ω at 20°C (68°F), with connector identification and meter connections shown in the ignition section.

Searchable PDF and Chapter Access

Text search and diagram detail: The PDF has searchable text and bookmarks for all seven chapters, plus the index and contents. Small wiring color codes and connector labels are clearest when enlarged.

The download contains one printable English 300-page PDF, including the cover and 11 pages of introductory material, index, and contents.