1999 Yamaha YZ250(L)/LC, YZ250L1 Owner's Service Manual (P/N 5CU-28199-30)

The 1999 Yamaha YZ250(L)/LC Owner's Service Manual (5CU-28199-30) covers the 5CU-series competition models YZ250LC (Europe), YZ250L1 (USA), and YZ250(L) (CDN, AUS, NZ, ZA). It combines race-based maintenance schedules and pre-operation checks with engine, transmission, chassis, and electrical repair procedures.

English PDF, Search and Chapter Bookmarks

Text search and diagram navigation: The body has an OCR text layer and chapter bookmarks. The cover is not searchable, and recognition errors can affect searches. Small wiring and connector labels are best read enlarged.

Supplied as one printable, English-language 252-page PDF: 238 technical pages, 11 introductory/index/contents pages, one multilingual cover, and two memo pages. These are all included in the total; there are no separate addenda.

Engine Rebuilds, Chassis Service and Race Setup

The selected topics below are part of a wider service reference that also covers silencer-fiber replacement and drive-chain wear inspection.

• Engine repair: Cylinder head, cylinder and piston inspection, YPVS governor service, crankcase separation, crankshaft removal and installation, and internal wear checks.

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

• Fuel and cooling: Keihin PWM38 carburetor disassembly, reed valve inspection, float-height checks, radiator pressure testing, and water pump seal replacement.

• Brakes and chassis: Front and rear caliper and master cylinder overhaul, brake system air bleeding, wheel-bearing replacement, steering inspection, and swingarm linkage service.

• Forks and race setup: Front fork rebuilds and oil seal replacement, rear shock spring and damping adjustments, and carburetor and suspension setting charts.

• Electrical diagnosis: Wiring diagrams, ignition and solenoid valve inspection flowcharts, spark-gap testing, coil resistance checks, and CDI magneto service.

The repair chapters suit mechanics and experienced owners with precision measuring equipment and the specified service tools; Yamaha recommends dealer maintenance for the front fork.

Engine Repair and Factory Inspection Data

The top-end section includes a piston/cylinder matching chart using A–D size marks and piston color codes. It helps identify the matching piston before parts are ordered, alongside bore, ring-gap, piston-clearance, and crankshaft inspection limits.

Power valve drawings and assembly notes cover the valve shaft, pulleys, and linkage. The manual warns that incorrect handling of the YPVS push-rod attachment can damage power valve components.

For crankcase separation and crankshaft installation, step-by-step instructions accompany exploded views and job instruction charts. Sectional views clarify circlip orientation.

Engine and chassis torque tables cover engine mounts, steering hardware, and brake components. Separate specifications include fluid capacities, spark-plug gaps, reduction ratios, and lubrication data.

The special-tool list includes crankcase separator YU-01135-A / 90890-01135 and fork seal driver YM-01442 / 90890-01442, with separate part-number conventions for the USA/Canada and other markets.

PWM38 Fuel System and Cooling

Regional carburetor data pair 5CU00 units with N3VF jet needles and the European 5CU10 specification with N4DE needles. Tuning coverage links throttle opening, weather, track conditions, and running symptoms with the relevant jetting charts.

The press-fitted main nozzle is not replaceable; needle selection is part of the documented tuning approach. Cooling coverage includes cap and system pressure checks plus impeller, shaft, bearing, and oil-seal inspection.

Fork, Suspension and Brake Service

Front fork coverage extends to the base valve, damper rod, bushings, oil-level setting, and bleeding. Assembly cautions identify the risk of damaging the internal valve if the damper rod drops into the tube.

Rear shock scope: Removal, spring replacement, mounting-bearing service, preload, and rebound/compression adjustments are included. Internal shock-cylinder and reservoir rebuilding are outside the documented scope; the manual warns against opening these nitrogen-pressurized components.

European suspension specifications and equal- and unequal-pitch spring tables distinguish the available setups. The air-spring/oil-level graph and suspension symptom charts connect setup changes with handling complaints.

Brake overhaul drawings cover piston and seal orientation; steering and swingarm pages include bearing inspection and installation.

Ignition and Solenoid Fault Finding

Separate inspection flowcharts cover ignition failure and solenoid valve operation. Connector views, wire-color codes, and electrical test specifications support fault isolation before CDI unit replacement.

The Wiring Diagram identifies the CDI unit, engine-stop button, ignition coil, solenoid valve, magneto, and spark plug. Cable Routing Diagrams show harness, control-cable, and hose paths.

A Preview of Float-Height and Ignition-Coil Test Data

The PWM38 carburetor section specifies a float height of 5.5–7.5 mm, measured with the carburetor inverted and the float arm resting on the needle valve without compressing it.

Ignition-coil inspection specifies primary winding resistance of 0.20–0.30 Ω and secondary winding resistance of 9.5–14.3 kΩ, both at 20°C (68°F). The secondary measurement excludes the spark plug cap.