2002 Yamaha WR250F(R) Owner's Service Manual (P/N 5UM-28199-50)

• Yamaha document no. 5UM-28199-50, First Edition, November 2002. This 860-page PDF contains English, French, German, Italian, and Spanish text and covers WR250FR / 5UM1 (USA), WR250F / 5UM2 (Europe), and WR250F(R) / 5UM4 (Canada, Australia, New Zealand, and South Africa).
• Engine chapters cover FCR-MX37 carburetor removal and bench service, camshaft timing, cylinder-head and valve work, cylinder and piston inspection, and wet-clutch repair. Bottom-end procedures extend through the water and oil pumps, balancer, kick and shift shafts, AC magneto and starter clutch, engine removal, crankcase and crankshaft work, and the constant-mesh five-speed transmission.
• Chassis procedures include wheel and bearing service, brake-disc inspection, master-cylinder and caliper repair, brake bleeding, front-fork disassembly with seal and damper-rod work, steering service, swingarm and linkage inspection, and rear-shock spring and bearing service.
• Electrical coverage provides fault-isolation charts and test procedures for the map-controlled CDI ignition, electric starter and safety interlocks, charging circuit, throttle-position sensor, and lighting system, supported by component locations and a complete wiring diagram.
• Competition maintenance and tuning sections address pre-operation and race inspection, valve-clearance adjustment, oil-pressure verification, carburetor jetting by operating symptom and atmospheric condition, final-drive gearing, and front and rear suspension setup.
• Special-tool references cover crankcase separation and crankshaft installation, valve service, rotor removal, radiator pressure testing, fork repair, ignition timing, and electrical testing. The manual supplies both North American YM/YU tool numbers and 90890-series numbers used in other markets.

Match the 5UM Market Version

Yamaha identifies these motorcycles as closed-course competition machines, and the maintenance program is organized around break-in, pre-race inspection, race use, and condition-based service rather than ordinary street mileage. Fitment should be checked against the model and 5UM code mapping above instead of relying on the November 2002 publication date alone. Regional tables distinguish such items as tire and rim configurations, oil recommendations, carburetor settings, CDI units, suspension specifications, and optional gearing parts.

This Owner’s Service Manual is suited to experienced owners and professional technicians who can work from exploded assemblies, precision measurements, electrical test data, and special-tool callouts. Routine inspection sections are more approachable, but internal engine, brake, suspension, and electrical repair work assumes established shop skills and suitable measuring equipment.

From Routine Service to Engine Teardown

The manual covers control operation, starting, break-in, cleaning, storage, scheduled maintenance, and pre-operation checks, but its repair scope goes much further. Major sections begin with exploded removal-order drawings and parts tables, then proceed through removal points, inspection criteria, assembly, installation, and final operational checks. The engine material reaches full removal, crankcase separation, crankshaft installation, transmission inspection, and verification of shifting and rotating operation after assembly.

Reference tables provide component-specific torque specifications, fluid capacities, fits and clearances, wear limits, runout limits, valve-adjusting-pad selection, brake and suspension data, and electrical resistance, voltage, and output checks. Regional differences remain identified in the tables instead of being blended into one generic specification set.

Wiring, Fault Isolation, and Race Setup

Key visual references include the cable-routing diagram, complete wiring diagram, electrical-component location view, map-controlled CDI function illustration with its 3-D ignition-timing map, and exploded crankcase, transmission, fork, and rear-suspension assemblies. Electrical flowcharts isolate no-spark conditions, starter failures, charging faults, throttle-position-sensor problems, and lighting-system faults before individual components are condemned.

The tuning chapter relates carburetor changes to throttle position, temperature, humidity, altitude, spark-plug condition, and specific running symptoms. It also provides alternate jet and needle part numbers, sprocket choices, fork spring and oil-level data, rear spring selections, and symptom-based suspension adjustment charts.

Assembly Cautions and Rear-Shock Limits

Camshaft installation cautions warn against turning the crankshaft during assembly and require the cam caps to be tightened evenly; ignoring either point can upset valve timing or damage the cylinder head, caps, and camshafts. During fork reassembly, the inner tube must be held at an angle so the damper rod cannot fall into it and damage the internal valve.

Support the motorcycle securely before engine, wheel, or suspension removal. The rear shock contains high-pressure nitrogen: the manual covers removal, spring and bearing service, inspection, installation, and adjustment, but warns against opening the shock cylinder or reservoir and directs dealer handling for disposal.