2001 Yamaha YZ125(P)/LC Owner's Service Manual (P/N 5NY-28199-30)

Yamaha's Owner's Service Manual (document code 5NY-28199-30) covers the 2001 YZ125P1 (USA), YZ125(P) (CDN, AUS, NZ and ZA), and YZ125LC (Europe) competition models. It combines operating information, pre-operation checks, maintenance, repair and race setup.

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

• Clutch and transmission: Clutch-plate inspection, primary-drive service, and removal, inspection and assembly of the kick axle, shift shaft, shift cam and shift forks.

• Carburetor and intake: Carburetor disassembly, fuel-level measurement, reed-valve inspection, and separate European and non-European jet-needle settings.

• Cooling system: Radiator removal and inspection, radiator-cap and cooling-system pressure tests, and water-pump impeller, shaft, bearing and seal service.

• Brakes and wheels: Front and rear caliper and master-cylinder disassembly, brake-system air bleeding, wheel-bearing replacement, and brake-disc inspection limits.

• Suspension and steering: Front-fork disassembly, steering-bearing service, swingarm and linkage inspection, and rear-shock removal, spring service and adjustment.

• Ignition diagnosis: No-spark troubleshooting, ignition timing checks, spark-gap testing, ignition-coil and CDI magneto tests, and wiring diagrams.

Owners can use the operating and routine maintenance sections; internal repair work is suited to mechanics equipped for measurement and the specified special-tool procedures.

Engine Repair and Assembly References

Exploded diagrams are paired with job instruction charts that identify the extent of removal, helping you plan which assemblies need to come apart for a particular repair.

The piston-and-cylinder matching chart distinguishes cylinder grades and corresponding color-coded pistons. Crankshaft runout, connecting-rod clearances and transmission-gear inspection are covered alongside component-specific torque tables for engine covers, cylinder-head studs and suspension linkages.

The special-tool list identifies the crankcase separating tool as YU-1135-A for the USA and Canada, or 90890-01135 for other markets. Exhaust-pipe and silencer removal and silencer-fiber replacement are also documented.

Market-Specific Carburetor Settings and Cooling Checks

Model codes distinguish 5NY1 for USA/CDN/ZA, 5NY2 for Europe and 5NY4 for Australia/New Zealand. Carburetor identification marks 5NY1 00 and 5NY2 10 separate the regional settings.

The tuning chapter relates jet selection to throttle opening, atmospheric conditions and running symptoms, with jet-needle charts and setting-part numbers. The main nozzle is non-removable; needle selection is part of the documented tuning approach.

Cooling coverage extends to leak testing and water-pump inspection. The impeller-shaft installation notes identify the risk of damaging the seal lip or dislodging its spring.

Fork, Shock and Chassis Setup

Fork service covers oil seals, the damper rod and internal-pressure relief; Yamaha recommends dealer maintenance for the front fork. An assembly caution explains how a falling damper rod can damage the valve inside the fork tube.

Rear-shock coverage includes spring and bearing replacement, preload and damping adjustment. It does not provide an internal damper rebuild procedure: the manual prohibits disassembly of the cylinder and gas tank and calls for replacement of a leaking absorber assembly.

Suspension-setting charts relate handling symptoms to fork and shock adjustments, with regional spring options and identification marks. Maintenance interval charts, cable-routing diagrams and sectional views support the service work.

Follow the manual's precautions for carbon-monoxide exhaust and the rear shock's high-pressure nitrogen charge.

Ignition Fault Tracing

The ignition inspection flowchart links connection checks, the engine-stop button, ignition coil and CDI magneto tests to a no-spark complaint. Wiring diagrams show connector arrangements and wire-color codes, while the test illustrations identify meter connections.

CDI specifications distinguish the 5NY-10 unit for Europe from the 5NY-00 unit for other covered markets.

A Preview of Coolant, Reed-Valve and Ignition Data

These examples are a small selection of the specifications provided for the covered models.

Cooling and intake: Complete cooling-system capacity, including all routes, is 0.95 L. The reed-valve specification lists a standard thickness of 0.42 mm.

Ignition testing: Ignition-coil secondary winding resistance is 6.7–10.1 kΩ at 20°C (68°F), with the spark plug cap removed for the test.

PDF Navigation, Languages and Page Count

Search, navigation and diagram detail: Text search is available across the manual. Embedded bookmarks lead to language-specific contents pages; the English carburetor contents link opens the radiator section. Small wiring and connector labels are readable when enlarged.

One printable 561-page PDF contains English, French, German and Italian text. The stated total includes 22 introductory and contents pages, two covers and two memo pages.