2001 Yamaha YZ80(N)/LC and YZ80LW(N) Owner's Service Manual (P/N 4ES-28199-88)

This 2001 Yamaha YZ80(N)/LC and YZ80LW(N) Owner's Service Manual, publication 4ES-28199-88, covers operation, maintenance, repair, electrical troubleshooting, and race setup.

• Engine repair: Engine removal, cylinder-head and piston service, crankcase separation, crankshaft inspection, and cylinder-to-piston matching charts.

• Clutch and transmission: Wet-clutch disassembly, primary-drive inspection, kick axle and shift shaft service, and transmission, shift cam, and shift fork assembly.

• Fuel and cooling: Mikuni VM26SS carburetor and reed-valve service, float-height inspection, radiator-cap pressure testing, and water-pump inspection and assembly.

• Brakes and chassis: Brake-system air bleeding, caliper and master-cylinder repair, wheel-bearing replacement, steering-head adjustment, and swingarm linkage inspection.

• Suspension service: Front-fork disassembly and oil-seal replacement, plus Monocross rear-shock removal, spring replacement, preload adjustment, and damping settings.

• Ignition diagnosis: CDI wiring diagram, spark-gap testing, engine-stop switch checks, and ignition-coil, pickup-coil, and source-coil tests.

• Race setup: Weather and track-condition carburetor charts, spark-plug heat-range selection, sprocket gearing, and symptom-based suspension setting charts.

The operating and basic-maintenance sections address owners; the repair procedures are organized for mechanics using the specified measuring equipment and special tools.

Engine and Transmission Repair

The engine chapter covers internal inspection through crankshaft removal and transmission reassembly. Cylinder and piston identification charts distinguish the A–D size groups, helping match replacement components before top-end assembly.

Clutch instructions distinguish friction-plate patterns, clutch-plate types, and assembly positions. Transmission inspection covers gear dogs, shift-fork grooves, bearings, and guide bars, with checks for smooth shifting after assembly.

Exploded views, job instruction charts, and sectional sketches support the procedures. Torque-check charts and component-specific tables distinguish cylinder-head nuts from studs and right from left crankcase covers. Listed tools include crankcase separator YU-1135-A/90890-01135 and clutch holder YM-91042/90890-04086.

Carburetor, Cooling, and Track Settings

Carburetor inspection covers the needle valve and seat, float height, throttle valve, and reed-valve limits. The tuning charts relate throttle opening and running symptoms to the main jet, pilot jet, air screw, jet needle, and main nozzle, with examples for changing weather and track conditions.

Cooling coverage includes coolant replacement and capacity data, radiator-cap testing, system leak checks, and water-pump service. The impeller-shaft installation notes identify oil-seal lip damage and displacement of the seal spring as repair hazards.

Review the factory safety precautions before teardown, particularly those concerning hot pressurized coolant and brake-system work.

Brake, Fork, and Rear-Suspension Work

Brake procedures extend to caliper pistons, seals, and master-cylinder cups. Routine chassis work includes drive-chain inspection and adjustment, silencer fiber replacement, and front-fork oil-seal and dust-seal cleaning.

Separate YZ80 and YZ80LW tables identify differences in wheel sizes, final-drive gearing, fork position, and spring selection. Rear-shock settings also distinguish European specifications from other markets. Suspension charts connect handling symptoms with the relevant adjustment areas.

The fork assembly notes explain how careless damper-rod installation can damage the internal valve. Rear-shock coverage includes removal, inspection, spring replacement, and external adjustments; the manual expressly prohibits opening the nitrogen-charged damper cylinder or reservoir.

Ignition Tests and Wiring References

The ignition fault chart links spark testing, wiring connections, the engine-stop switch, coils, and CDI-unit checks. Electrical specifications identify the Mitsubishi F4T807 magneto and 4ES-20 CDI unit.

Spark-plug inspection covers the NGK BR10EG, electrode-gap specifications, and plug condition. The ignition schematic includes wire-color codes, while cable-routing diagrams show lead and hose placement around the steering head, frame, and engine.

A Preview of Piston-Clearance and CDI Test Data

These examples are a small selection of the engine inspection and electrical test specifications in the manual.

For both covered models, standard piston-to-cylinder clearance is 0.040–0.045 mm, with a service limit of 0.1 mm. The inspection section relates this measurement to cylinder bore and piston diameter.

CDI magneto source-coil resistance is 257–314 ohms between the brown and black leads. Pickup-coil resistance is 15.8–19.4 ohms between the white/green and white/red leads. Both ranges apply at 20°C (68°F).

PDF Navigation, Languages, and Page Count

Text search and diagram detail: PDF text search is unavailable. Eleven embedded bookmarks provide access to introductory material and all seven main chapters. Small wire-color labels on the ignition schematic are readable when zoomed in.

Supplied as one printable 534-page PDF containing English, French, and German. The total includes one cover page, seven chapter-divider pages, and 12 memo pages; these are already included in the stated page count.