2009 Yamaha YZ250Y Owner's Service Manual (P/N LIT-11626-22-55)

• Exact 2009 application: Covers the YZ250Y sold in the USA, Canada, Australia, and New Zealand, plus the YZ250 designation used in Europe and South Africa. Yamaha identifies the market builds as 1P8H, 1P8J, and 1P8L. This is a 244-page PDF, 1st Edition, April 2008, Yamaha literature number LIT-11626-22-55; the cover also carries code 1P8-28199-14.
• Engine teardown and repair: Details engine removal, cylinder-head and cylinder service, piston and ring inspection, YPVS power-valve work, crankcase separation, crankshaft installation, wet clutch service, kick and shift shafts, and the constant-mesh 5-speed transmission.
• Fuel, intake, and cooling systems: Includes PWK38S carburetor and reed-valve disassembly, inspection, and setup; radiator and cap pressure testing; water-pump service; region-specific base jetting; and race-tuning charts for atmospheric conditions and running symptoms.
• Chassis and brake repair: Maps front and rear wheel service, bearing and brake-disc inspection, caliper and master-cylinder overhaul, brake-hose installation, hydraulic bleeding, steering-head work, and swingarm, relay-arm, and connecting-rod bearing service.
• Suspension service and setup: Breaks down front-fork removal, full disassembly and assembly, damper and base-valve inspection, seal replacement, oil filling, and compression/rebound tuning. Rear coverage addresses removal, spring and bearing work, preload, and external damping setup rather than internal shock rebuilding.
• Electrical diagnosis and factory reference: Provides a color-coded wiring diagram, regional cable-routing diagrams, and fault-isolation charts for the CDI ignition, solenoid valve, and throttle position sensor. Component-specific torque tables, capacities, wear limits, clearance data, and electrical test specifications support the covered repair work.

Built for the Carbureted Competition YZ250

This Yamaha Owner's Service Manual is specific to the carbureted, liquid-cooled 250cc 2-stroke motocross machine described above. It is not a generic multi-year YZ manual, and the motorcycle is identified as a closed-course competition model. Because Yamaha states that the electrical chapter assumes basic Yamaha motorcycle service knowledge, the manual is best suited to mechanics and experienced owners who already understand inspection and assembly work and have the specified meters and special tools.

Market differences are documented instead of being folded into a single specification. The tables separate USA/Canada, Europe, and Australia/New Zealand/South Africa carburetor calibrations, while also flagging differences in compression specification, chassis geometry, rear-shock fitting length, and neutral-switch wiring. The neutral switch and its circuit are excluded from USA and Canadian builds.

Engine, Drivetrain, and Race Setup

The engine sections supply the required data for a complete teardown and inspection. Coverage includes A-through-D piston and cylinder matching, top-end wear limits, reed-valve condition, crankshaft runout and connecting-rod play, clutch plate and spring limits, and transmission-shaft checks. Sequential job charts and exploded illustrations accompany removal and disassembly sections, keeping the repair scope tied to the correct part order and fastener data.

This is also a competition service reference. Its maintenance schedule is keyed to break-in and race use, while the tuning chapter relates the main jet, power jet, pilot circuit, and jet needle to throttle opening, air temperature, humidity, altitude, and observed engine behavior. Tables identify optional jets, needles, sprockets, fork springs, and rear springs by Yamaha part number. Suspension symptom charts connect track behavior with the relevant spring, oil-volume, preload, and damping categories without turning the manual into a generic setup guide.

Tools, Diagrams, and Repair Cautions

Yamaha lists separate special-tool numbers for USA/Canada and other markets. Representative callouts include the crankcase separating tool YU-1135-A / 90890-01135, fork seal driver YM-A0948 / 90890-01502, pocket tester YU-3112-C / 90890-03112, and dynamic spark tester YM-34487 or ignition checker 90890-06754. Fastener specifications are presented in Nm, m-kg, and ft-lb.

The repair notes identify two easy-to-miss damage points. The supplied set pin is required when the YPVS push rod is removed or installed; omitting it can damage the power-valve components. Yamaha also warns against hammering the crankshaft or forcing uneven crankcase separation, which can harm the case mating surface and related bearing or seal interfaces.

Rear-shock coverage intentionally stops at removal and installation, spring and bearing service, inspection, and external setup. The nitrogen-charged cylinder and reservoir are not covered as internal rebuild procedures, and Yamaha directs disposal of a damaged unit to a dealer. Brake hydraulic work, cooling-system pressure tests, and engine repair should be carried out with suitable shop equipment, with clearances and fastener integrity checked against the factory data before the motorcycle returns to the track.