2005 Yamaha YZ250(T)/T1 Owner's Service Manual (P/N 1P8-28199-30)

This Yamaha factory Owner's Service Manual covers the 2005 YZ250 motocross machine in YZ250T1, YZ250 and YZ250T market versions. Publication 1P8-28199-30, first edition, May 2004, combines operating instructions, race maintenance, tuning and mechanical repair procedures.

• Engine repair: Cylinder-head, piston and power-valve service, engine removal, crankcase separation and crankshaft inspection.

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

• Fuel and cooling: Keihin PWK38S carburetor and reed-valve service, jetting charts, radiator testing and water-pump repair.

• Suspension and steering: Telescopic front-fork rebuilds, rear spring and bearing service, swingarm linkage inspection and steering-head adjustment.

• Brakes and wheels: Caliper and master-cylinder disassembly, hydraulic bleeding, pad replacement, wheel-bearing service and drive-chain checks.

• Electrical diagnosis: Ignition, solenoid-valve and TPS troubleshooting, with wiring diagrams, coil tests and sensor replacement and adjustment procedures.

Owners can use the operation and routine-maintenance sections; internal repairs suit mechanics with measuring equipment and the listed special tools. Yamaha recommends dealer maintenance for the front fork.

Engine, YPVS and Drivetrain Repair

Cylinder and piston matching charts distinguish the lettered size groups, helping you select a compatible replacement piston. The cylinder service section explicitly prohibits reboring.

YPVS coverage includes the governor, linkage, valve shaft and carbon-deposit inspection. The manual warns that push-rod work without the specified set pin can damage power-valve components.

Transmission inspection covers gear dogs, shift-fork grooves and bearings. Component torque tables include spark-plug, primary-drive and axle fasteners; exploded views, job instruction charts and sectional sketches support parts identification.

The special-tool list identifies crankcase separator YU-1135-A/90890-01135 and clutch holder YM-91042/90890-04086.

Carburetor Tuning and Cooling-System Service

European carburetors carry I.D. mark 1P82 10; the other listed markets use 1P81 00. Regional needle specifications let you check the correct market baseline before using the symptom-based jetting charts.

The tuning chapter relates mixture behavior to altitude, humidity, temperature and riding conditions. The carburetor's main nozzle is press-fitted and is not a replaceable tuning part.

Cooling coverage includes radiator and cap pressure checks, plus impeller, shaft, bearing and oil-seal inspection. Race maintenance also addresses air-filter cleaning, transmission-oil replacement and silencer-fiber replacement.

Fork, Rear Suspension and Brake Work

Front-fork instructions cover the damper assembly, base valve, seals and oil filling/air bleeding. A handling caution explains how a dropped damper assembly can damage the internal valve.

Rear-shock scope: The link-type Monocross section covers shock removal, spring replacement and mounting bearings. The nitrogen-filled shock cylinder and reservoir must not be disassembled; a leaking damper assembly is replaced.

Suspension symptom charts connect bottoming, harshness and poor grip with the relevant checks. Brake coverage extends to piston seals and cylinder cups, with leak and operating checks after bleeding.

Ignition, Solenoid and TPS Fault Finding

The ignition fault chart works through connections, the stop button, spark-plug cap, coils, magneto and CDI unit. Solenoid and TPS charts include connector test points, while the Cable Routing Diagram covers leads, control cables and brake hoses.

Engine-running tests require ventilation because the exhaust contains carbon monoxide. Reference only — always consult a certified technician before performing service on this equipment.

Examples of Engine Clearances and Ignition Test Data

These examples are a small selection of the manual's engine inspection and ignition specifications.

Cylinder head and piston fit: Combustion chamber capacity is 21.0 cm³ for USA, CDN, ZA, AUS and NZ versions, versus 21.5 cm³ for Europe. The piston-to-cylinder clearance limit is 0.1 mm.

Clutch and ignition checks: Standard clutch housing radial clearance is 0.030–0.055 mm. Source coil 1 resistance is 720–1,080 Ω at 20°C, with test-lead identification in the ignition-system section.

Searchable Text, Contents Bookmarks and PDF Details

Search and diagram detail: Main text is searchable, while lettering within the wiring diagram requires visual lookup. Embedded bookmarks open language-specific contents pages rather than individual repair sections. Small wiring and connector labels are readable when enlarged.

Supplied as one printable, 596-page PDF in English, French, German and Italian. The total already includes both cover pages, 24 pages of multilingual front matter, five memo pages and one blank page.