Yamaha YZ250(R)/LC 2002 Owner's Service Manual (P/N 5UP-28199-30)

Yamaha's Owner's Service Manual (P/N 5UP-28199-30) covers operation, maintenance, tuning, and repair for the 2002 YZ250(R)/LC, with regional model names YZ250R, YZ250(R), and YZ250LC.

Searchable Text, Linked Contents, and Diagram Detail

Finding procedures and wiring details: Searchable PDF text is available throughout the technical chapters. Chapter bookmarks are grouped by language and lead to the contents pages; clickable contents entries open the individual sections. Small wire-color codes and connector details in the wiring diagram are best read with zoom.

Supplied as one printable 583-page PDF in English, French, German, and Italian. The total includes 23 front-matter pages containing the cover, introductory material, and contents, two memo pages, and the back cover.

Two-Stroke Engine Repair and Race Setup

The following selected contents summarize the main workshop areas rather than reproduce the full contents list. Further topics include starting and break-in procedures and silencer-fiber replacement.

• Engine and YPVS: Cylinder-head, piston, power-valve, and governor removal, inspection, and assembly.

• Clutch and transmission: Step-by-step procedures for clutch friction-plate replacement, crankcase splitting, crankshaft installation, and gearbox assembly.

• Carburetor and intake: Keihin PWK38S disassembly, float-height checks, reed-valve inspection, and jetting adjustments.

• Cooling system: Radiator-cap and cooling-system pressure tests, radiator service, and water-pump disassembly.

• Hydraulic brakes: Front and rear caliper and master-cylinder repair, pad replacement, and brake-system bleeding.

• Chassis and suspension: Telescopic-fork overhaul, steering-head and swingarm bearing service, plus rear-shock spring and mounting-bearing replacement.

• Electrical diagnosis: Wiring diagram and inspection charts for ignition, solenoid-valve, and throttle-position-sensor faults.

Owners can use the operating and routine-maintenance sections; internal repair work suits mechanics with measuring equipment and the specified special tools.

Engine Assembly and YPVS Service

Piston and cylinder selection is documented through matching marks and piston color codes. The cylinder inspection section explicitly rules out reboring.

The drivetrain coverage extends to the primary drive gear, kick-starter ratchet wheel, shift cam, and selector forks. Exploded views and job instruction charts identify parts and removal scope, helping mechanics plan how far an assembly needs to come apart for inspection or repair.

The tool list identifies the crankcase separating tool as YU-1135-A / 90890-01135 and distinguishes regional tool numbers. YPVS push-rod cautions explain how omitting the specified set pin can damage power-valve components.

PWK38S Jetting and Intake Checks

Carburetor tuning charts relate main-jet, power-jet, and needle settings to throttle opening, atmospheric conditions, and running symptoms. European needle-setting information is separated from the other listed markets, and the main nozzle is identified as press-fitted and nonreplaceable.

Cooling-System Inspection

Water-pump coverage includes the impeller shaft, housing cover, bearings, and oil seals. The inspection notes connect coolant loss, coolant discoloration, and milky transmission oil with reasons to investigate the pump.

Fork Overhaul and Rear-Shock Limits

The fork procedures cover oil seals, bushings, damper rods, oil-level measurement, and air bleeding. Yamaha recommends dealer maintenance for the front forks. An assembly caution warns that a falling damper rod can damage the internal valve.

Rear-shock coverage includes removal, inspection, spring and mounting-bearing replacement, and preload and damping adjustment. Internal shock-cylinder and nitrogen-tank rebuilding is excluded: the manual expressly warns against disassembling these components.

Suspension-setting charts connect handling symptoms with spring, oil-level, and damping changes. Cable-routing diagrams show hose and harness placement around the frame and controls.

Ignition, Solenoid, and TPS Testing

Electrical inspection charts work alongside coil tests, connector views, and TPS input/output-voltage checks. These references help distinguish wiring and component faults before the CDI unit is considered for replacement. Maintenance schedules and torque-check points cover engine mounts, frame joints, and control assemblies.

Examples of Fit, Torque, and Ignition Data

Standard piston-to-cylinder clearance is 0.045–0.050 mm; clutch-housing radial clearance is 0.030–0.055 mm. Cylinder-head nut data specify 25 Nm (18 ft-lb), with staged-tightening guidance in the assembly section.

Ignition reference data include 0.18 mm before TDC and source-coil 1 resistance of 720–1,080 ohms at 20°C (68°F), alongside the relevant test connections.

Note: Working on high-performance competition motorcycles involves handling pressurized systems and highly flammable fluids. Always review the pre-operation checks and general safety sections provided in the introductory chapters before beginning any teardown or chassis adjustment.