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

This Yamaha Owner’s Service Manual (P/N 5UM-28199-50) is the first edition, published in November 2002. It covers the WR250FR (5UM1, USA), WR250F (5UM2, Europe), and WR250F(R) (5UM4, Canada, Australia, New Zealand, and South Africa).

PDF Search, Navigation, and Wiring Detail

Search and diagram detail: The manual text is searchable. Bookmarks lead to the cover and language-specific contents pages, where linked entries open the relevant sections. The small wire codes and connector labels on the main wiring diagram are readable when zoomed in.

The download is one printable, 860-page PDF in English, French, German, Italian, and Spanish. The total includes the front and back covers, two copyright and edition pages, nine numbered memo pages, and two blank pages.

Engine Overhaul, Chassis Service, and Electrical Diagnosis

These selected service topics show the range of procedures in the manual. Other examples include air filter cleaning and hot-start lever adjustment.

• Engine overhaul: Camshaft timing, cylinder head and valve service, piston and cylinder inspection, engine removal, crankcase separation, crankshaft installation, and transmission inspection.
• Fuel, cooling, and lubrication: Keihin FCR-MX37 carburetor removal and bench service, radiator cap testing, water and oil pump service, and oil flow verification at the pressure check bolt.
• Brakes and chassis: Wheel and bearing service, brake disc inspection, master cylinder and caliper repair, brake bleeding, front fork overhaul, steering service, and swingarm and linkage inspection.
• Electrical diagnosis: Fault-isolation charts and component tests for CDI ignition, electric starting, charging, the throttle position sensor, and lighting, with component locations and a complete wiring diagram.
• Competition setup: Break-in and pre-race checks, carburetor jetting, final-drive gearing, and front and rear suspension adjustments based on handling symptoms.

This manual is suited to experienced WR250F owners and professional technicians who can work from exploded drawings, take precision measurements, and use the specified service tools and electrical test equipment.

Market Specifications and Routine Service

Use the model code to match the manual’s market specifications for tires and rims, oil, carburetor settings, CDI units, suspension, and optional gearing. Yamaha specifies closed-course competition use and organizes the maintenance schedule around break-in, race use, and component condition. The general information also covers controls, starting, cleaning, and storage.

Engine Assembly and Special Tools

Exploded drawings and parts tables accompany removal, inspection, assembly, and installation. The engine chapter also covers the wet clutch, balancer, kickstarter and shift shafts, AC magneto, and starter clutch. After assembly, the manual includes checks for smooth rotation and shifting.

Reference tables cover component torques, fluid capacities, fits, wear and runout limits, valve shim selection, and brake and suspension specifications. Tool callouts identify equipment for splitting the crankcase, installing the crankshaft, servicing valves and forks, pulling the rotor, pressure-testing the radiator cap, and checking ignition timing. Yamaha lists YM-, YU-, and ACC-prefix numbers for the USA and Canada and 90890-series numbers for other markets.

Camshaft installation: The manual warns that crankshaft movement during camshaft installation can disturb valve timing. It also explains how uneven cap tightening can damage the cylinder head, caps, or camshafts.

Fork and Rear Shock Service

The fork chapter covers seals and damper rods, including how a dropped damper rod can damage the internal valve during assembly. The manual calls for secure support before engine, wheel, or suspension removal.

Rear shock coverage includes removal, inspection, spring and bearing service, installation, and adjustment. The cylinder and high-pressure nitrogen reservoir stay sealed during service. Yamaha assigns disposal to its dealers.

Wiring Tests and Race Tuning

The cable-routing drawings, wiring diagram, and 3-D ignition map support electrical diagnosis. For a no-crank complaint, the starting circuit diagram and test chart show how the clutch switch, neutral switch, and cut-off relay affect starter operation. The electrical chapter also lists resistance, voltage, and output checks for the relevant circuits.

The tuning chapter connects jet and needle choices to throttle position, temperature, humidity, altitude, spark plug condition, and running symptoms. It lists alternate jet and needle part numbers, sprocket options, fork springs and oil levels, and rear spring selections.

Valve and Piston Clearance Examples

For valve shim selection, Yamaha specifies cold clearances of 0.10–0.15 mm on the intake side and 0.17–0.22 mm on the exhaust side.

For cylinder and piston inspection, Yamaha gives a standard piston-to-cylinder clearance of 0.040–0.065 mm and a service limit of 0.10 mm.