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

Yamaha’s Owner’s Service Manual (P/N 5NY-28199-30) covers the 2001 YZ125P1 (USA), YZ125(P) (Canada, Australia, New Zealand, and South Africa), and YZ125LC (Europe). It covers operation, pre-ride checks, scheduled maintenance, workshop repairs, and race setup.

PDF Search, Bookmarks, and Languages

Search and diagram navigation: Text search works across the manual. Chapter bookmarks lead to the relevant language’s contents pages. The English carburetor link opens the radiator section, and the small wire and connector labels are easiest to read when enlarged.

The download contains one printable 561-page PDF in English, French, German, and Italian. The total includes 22 introductory, index, and contents pages, two covers, and two memo pages.

Engine Teardown, Chassis Service, and Ignition Tests

The highlights below are a selection of workshop procedures. The manual also covers break-in and storage.

• Engine repair: Step-by-step instructions cover engine removal and crankcase separation, with procedures for cylinder head and piston inspection, power valve service, crankshaft checks, and YPVS governor disassembly and assembly.
• Clutch and transmission: Inspect the clutch plates and service the primary drive. Removal, inspection, and assembly procedures cover the kick axle, shift shaft, shift cam, and shift forks.
• Carburetor and intake: Disassemble the carburetor, measure fuel level, and inspect the reed valve. Jet needle settings are listed separately for European and other covered models.
• Cooling system: Remove and inspect the radiator, pressure-test the cap and cooling system, and service the water pump impeller, shaft, bearing, and seal.
• Brakes and wheels: Disassemble the front and rear calipers and master cylinders, bleed the hydraulic brakes, replace wheel bearings, and check the brake discs against service limits.
• Suspension and steering: Disassemble the front fork, service the steering bearings, inspect the swingarm and linkage, and remove, service, or adjust the rear shock within the documented limits.
• Ignition diagnosis: Trace a no-spark fault with the inspection flowchart and wiring diagram. Procedures cover ignition timing, spark gap, ignition coil resistance, and CDI magneto tests.

Owners can use the operating and routine maintenance sections. Internal repair procedures are intended for mechanics equipped to make the specified measurements and use the required special tools.

Engine Repair and Assembly References

Exploded diagrams are paired with job instruction charts that show which parts need to come off for each procedure. The piston and cylinder matching chart helps you select the corresponding color-coded piston by cylinder grade.

The manual gives inspection criteria for crankshaft runout, connecting rod clearance, and transmission gears. Torque tables cover engine covers, cylinder head studs, and suspension linkage fasteners.

The crankcase separating tool is listed as YU-1135-A for the USA and Canada and 90890-01135 for other markets. The manual also covers exhaust pipe and silencer removal and replacement of the silencer packing.

Carburetor Tuning and Cooling Checks

Carburetor ID marks 5NY1 00 and 5NY2 10 distinguish the non-European and European settings. The tuning chapter relates jet selection to throttle opening, atmospheric conditions, and running symptoms. It includes jet needle charts and setting part numbers, with needle selection used to tune the carburetor’s fixed main nozzle.

The water pump assembly notes explain how the impeller shaft can damage the seal lip or dislodge its spring during installation.

Fork, Rear Shock, and Race Setup

Fork service covers the oil seals, damper rod, and internal pressure relief. Yamaha recommends dealer service for the front fork and warns that a falling damper rod can damage the valve inside the inner tube during assembly.

Rear shock service covers spring and bearing replacement, preload, and damping adjustments. Yamaha prohibits disassembly of the pressurized cylinder and nitrogen reservoir and specifies replacement of the shock assembly if it leaks oil or gas.

Suspension charts match handling symptoms to fork and shock adjustments and identify regional spring options. Maintenance interval charts, cable-routing diagrams, and sectional views support the service procedures. The operating precautions also cover carbon monoxide exposure from exhaust.

Tracing a No-Spark Fault

The ignition flowchart takes you through the connections, engine stop switch, ignition coil, and CDI magneto. The wiring diagram shows connector layouts and wire color codes, and test illustrations identify meter connections. The CDI specifications list unit 5NY-10 for Europe and 5NY-00 for the other covered markets.

Selected Cooling, Carburetor, and Ignition Specs

The complete cooling system holds 0.95 L, including all coolant passages. Standard intake reed valve thickness is 0.42 mm.

Carburetor fuel level is measured above the float chamber mating surface. The specification is 11.5–12.5 mm for Europe and 9.5–10.5 mm for the other covered markets.

Ignition coil secondary resistance is 6.7–10.1 kΩ at 20°C (68°F), measured with the spark plug cap removed.