2002 Yamaha YZ125P / YZ125LC Owner's Service Manual PDF (P/N 5NY-9-30-0)

Yamaha's 2002 YZ125P Owner's Service Manual covers the YZ125P1 (USA), YZ125LC (Europe), and YZ125(P) (CDN, AUS, NZ, ZA) competition models. This OEM publication breaks down the 5NY-series into seven core sections, from general maintenance and engine overhaul to chassis upkeep, electrical diagnostics, and tuning.

Text search, bookmarks, and diagram detail: Service text supports keyword searches; the cover has no searchable text. Embedded bookmarks open all seven chapters and the wiring diagram. Small connector labels in the electrical test illustrations are best read with zoom.

• Engine repair: Cylinder-head, cylinder, and piston inspection, power-valve service, YPVS governor disassembly, crankcase separation, and crankshaft removal and installation.

• Clutch and transmission: Wet-clutch overhaul, primary-drive inspection, kickstarter and shift-shaft service, and five-speed transmission, shift-cam, and shift-fork repair.

• Fuel and cooling: Mikuni carburetor teardown, reed-valve inspection, fuel-level adjustment, radiator pressure tests, and water-pump servicing.

• Brakes and chassis: Caliper and master-cylinder overhaul, hydraulic brake bleeding, wheel-bearing replacement, steering-head adjustment, and swingarm linkage service.

• Suspension and tuning: Front-fork seal replacement, damper-rod service, rear-shock spring changes, and carburetor and suspension troubleshooting charts.

• Ignition diagnosis: CDI wiring diagram, ignition-timing checks, spark testing, coil-resistance measurements, and a fault-finding chart for a no-spark condition.

The repair sections are written for mechanics, with dedicated pullers, holding tools, and measuring equipment specified for overhaul work.

Top-End, Crankshaft, and Transmission Repair

The top-end section includes piston-to-cylinder matching by A–D identification marks and color-coded piston grades. That chart helps select a replacement piston for the cylinder fitted before ordering parts.

Crankshaft runout, connecting-rod play, clutch-plate wear, and transmission gear condition receive separate inspection coverage. Crankcase separation uses tool YU-1135-A / 90890-01135, while gearbox assembly identifies the different shift-fork positions.

Exploded and sectional views clarify part orientation. Torque tables, fluid-capacity data, wear limits, and lubrication notes support the repair procedures.

Mikuni Carburetor and Cooling-System Service

European jetting, jet-needle, and fuel-level specifications are distinguished from the other market versions. The throttle-opening chart and symptom-based carburetor tables connect running problems with the circuits involved. Atmospheric-condition guidance addresses temperature, humidity, and altitude, with test runs used to evaluate settings.

Carburetor disassembly has a specific limit: the venturi block and main nozzle are not intended for dismantling. The service procedures instead cover the float needle and seat, jets, throttle valve, and reed assembly.

Water-pump inspection covers the impeller shaft, bearings, and seals. The installation notes flag the risk of damaging the seal lip or displacing its spring when fitting the shaft; radiator-cap and cooling-system pressure tests are also documented.

Brake Repair and Chassis Inspection

Exploded caliper and master-cylinder views identify pistons, cups, seals, and hardware, with leak and operation checks following assembly. Wheel-runout inspection, steering-bearing replacement, and Monocross relay-arm and connecting-rod bearing service extend the chassis coverage.

Cable-routing diagrams show control cables, ignition leads, and breather hoses. Maintenance intervals for engine components, cooling systems, brake hydraulics, and suspension are mapped out in race-based schedules. Routine service also includes air-filter care, drive-chain inspection, and silencer packing replacement.

Fork Service and Track Setup

Front-fork procedures cover the base valve, damper rod, bushings, oil seals, bleeding, and oil-level setting. Yamaha recommends dealer servicing for the fork. Its assembly notes warn that a dropped damper rod can damage the internal valve.

Rear-shock work covers removal, spring changes, and bearing replacement. The cylinder and reservoir contain pressurized nitrogen; the manual warns against opening or tampering with them.

Tuning data distinguish equal-pitch and unequal-pitch springs and identify European spring and damping baselines. Spring-selection graphs, fork oil-level characteristic curves, and suspension-setting charts address bottoming, poor grip, and unstable response. Optional sprocket and spring tables include part numbers.

CDI Ignition Tests and Wiring

The electrical specifications distinguish the European 5NY-10 CDI unit from the 5NY-00 unit used elsewhere. The Wiring Diagram and Ignition System Inspection Steps chart cover the engine-stop button, ignition coil, pickup coil, and both source coils. Connector views show wire colors and tester connections alongside electrical test specifications.

English PDF and Included Pages

Supplied as one printable, English-language, 255-page PDF. That total comprises one cover, 11 introductory/index/contents pages, 241 technical pages, and two memo pages.