2004 Yamaha Majesty 400 YP400T Factory Service Manual (P/N LIT-11616-18-38)

Factory service information for the 2004 Yamaha YP400T Majesty 400 maxi scooter, including the USA and Canadian variants. This is Yamaha’s first edition from June 2004, publication P/N LIT-11616-18-38.

• Maintenance: Emission-control and lubrication charts, valve-clearance adjustment, compression testing, and V-belt case air-filter service.

• Engine repair: Engine removal, cylinder-head work, valve-guide replacement, piston inspection, crankcase separation, and crankshaft bearing selection.

• Belt and final drive: CVT V-belt replacement, primary and secondary sheave service, centrifugal-clutch inspection, and transmission gear checks.

• Fuel injection: ECU self-diagnosis, fault-code tables, sensor and actuator tests, fuel-pressure measurement, and fuel-pump removal.

• Brakes and chassis: Brake-disc inspection, caliper and master-cylinder repair, hydraulic bleeding, front-fork overhaul, and steering-head service.

• Cooling system: Radiator pressure checks, thermostat testing, water-pump seal replacement, oil-cooler inspection, and cooling-system diagrams.

• Electrical troubleshooting: Wiring and circuit diagrams, ignition and charging tests, starter-motor overhaul, and lighting-system fault tracing.

Yamaha wrote this manual primarily for its dealers and qualified mechanics; it assumes basic mechanical knowledge and familiarity with vehicle repair techniques.

Maintenance and Internal Engine Repair

Periodic maintenance charts cover emissions, lubrication, and chassis checks. Valve-pad selection tables support clearance adjustment, while the engine documentation covers camshaft timing, automatic timing-chain tensioner inspection, and oil-pump rotor-clearance checks.

Internal repair extends to valve-seat lapping, cylinder and piston measurements, and crankshaft journal-bearing selection using the crankcase markings. The tightening tables distinguish cylinder-head nuts from cap nuts and specify staged tightening.

The camshaft chapter warns that uneven cap-bolt tightening can damage the cylinder head, camshaft cap, and camshafts.

CVT Sheaves, Clutch, and Transmission

Exploded views distinguish primary-sheave weights and sliders from secondary-sheave guide pins, seals, and clutch shoes. Separate inspection criteria address belt wear, clutch lining thickness, and transmission gears.

The clutch procedure specifies sheave spring compressor YM-04134 and fixed block YM-04135. Spring-loaded clutch assemblies and hydraulic brakes require the complete factory procedures and specified precautions.

The maintenance section also distinguishes the dry V-belt case air-filter element from the engine air-filter elements.

Fuel Injection Diagnosis and Throttle-Body Scope

The ECU’s self-diagnostic function and fault-code tables connect displayed faults with wiring checks, component tests, and reinstatement criteria. This helps distinguish a sensor fault from a connector or harness problem before replacement parts are selected.

Diagnostic mode covers sensor readings and actuator operation through the multifunction display. Detailed checks address the throttle-position sensor, intake-air pressure and temperature sensors, coolant-temperature sensor, lean-angle cut-off switch, and ISC valve.

Fuel-system procedures include pump removal, pressure-regulator testing, and injector inspection. Throttle-body scope: The assembly is not intended for complete disassembly, and the ISC valve unit must not be removed completely.

Brake, Suspension, and Cooling Work

The chassis sections cover front and rear brake-disc measurements, master-cylinder and caliper service, and hydraulic bleeding. The brake instructions warn that solvents can swell and distort piston seals.

Front-fork procedures include bushing and seal replacement, oil-level specifications, and assembly checks. Steering-head bearing inspection, rear shock-absorber checks, and swingarm removal are covered separately.

Cooling-system work includes radiator-cap testing, thermostat checks, and water-pump seal installation. Oil-cooler inspections and air-induction system diagrams supplement the main repair sections.

Electrical Circuits and Cable Routing

System-specific diagrams include the starting circuit cut-off system, charging circuit, and fuel-injection wiring. Cable-routing drawings show harness, hose, and control-cable placement; the final YP400T wiring diagram includes wire-color identification and a separate component key.

A Sample of Valve and Electrical Reference Data

These examples are a small selection of the adjustment and electrical specifications in the manual.

For cold-engine valve checks, intake clearance is 0.15–0.20 mm and exhaust clearance is 0.25–0.30 mm. The related adjustment section includes valve-pad selection tables.

The ignition reference specifies 5° BTDC at 1,400 r/min; ignition timing is not adjustable. For charging-system diagnosis, stator-coil resistance is 0.184–0.276 Ω at 20°C, measured between white leads.

Searchable PDF, Bookmarks, and Wiring Detail

Text access and diagram detail: Searchable text and 80 embedded bookmarks provide access to chapters, service sections, and the final wiring diagram. Small circuit labels and connector details require zooming.

One printable English PDF contains 387 pages total. This count already includes the 16 opening pages with the cover, publication information, usage notes, and contents, plus the final wiring diagram and component key and the back cover.