2005–2007 Yamaha Majesty YP400 Service & Repair Manual (P/N LIT-11616-18-38, LIT-11626-20-31)

• 491-page PDF set — Yamaha YP400T Service Manual P/N LIT-11616-18-38 (389 pages; first edition, June 2004) plus the YP400W Owner’s Manual P/N LIT-11626-20-31 (102 pages; first edition, April 2006).
• The two factory publications have different model scope: repair procedures are identified for the YP400T, including model codes 5RU4 (USA) and 5RUC (Canada), while the companion owner’s manual is specifically for the YP400W.
• Covers engine removal and internal repair, including camshaft timing, cylinder head, valves and guides, piston and cylinder, crankshaft, balancer shaft, oil pump, crankcase bearings, and transmission.
• Details V-belt drive and clutch service, with primary and secondary sheave removal, controlled disassembly of the spring-loaded clutch, inspection, reassembly, belt installation, starter-clutch work, and generator service.
• Provides chassis repair procedures for wheels and brake discs, static balancing, brake pads, master cylinders and calipers, hydraulic bleeding, front fork, steering head, handlebar, rear shocks, and swingarm.
• Includes fuel-injection and electrical diagnosis through ECU self-diagnosis, fail-safe tables, diagnostic mode, fault-code troubleshooting, fuel-pressure and sensor tests, plus ignition, starting, charging, lighting, signaling, and cooling-system circuit checks.
• Supplies exploded views, job charts, cable-routing drawings, cooling-system diagrams, system circuit diagrams, and a color-coded YP400T wiring diagram, backed by torque tables, lubrication data, clearances, wear limits, fluid-capacity specifications, and electrical test values.

Operational and Maintenance Coverage

The 389-page service manual is built around Yamaha’s liquid-cooled, fuel-injected 395cc DOHC single-cylinder engine. Access procedures cover the seats, storage box, cowlings, footrest boards, front cowling, and air-filter cases. The scheduled-service chapters then address valve-clearance and exhaust-gas-volume adjustment, idle speed, throttle free play, spark-plug and ignition-timing checks, compression testing, engine and final-transmission oil service, air filters, the cooling system, and coolant replacement.

Chassis maintenance is equally specific. The manual documents rear brake lock lever cable adjustment, brake-pad and hose inspection, hydraulic brake bleeding, steering-head adjustment, fork checks, tire and wheel inspection, battery charging, fuse diagnosis, bulb replacement, and headlight aiming. Exploded assembly views and job charts show what must be removed and identify the seals, retainers, lubricants, replacement parts, and component-specific torque requirements tied to each repair area.

Major engine work is treated as workshop repair, not just inspection. Sections cover camshaft timing and decompression components, cylinder-head checks, valve-guide and valve-seat service, piston-ring and piston-pin inspection, crankshaft and connecting-rod measurement, balancer-shaft installation, crankcase bearing selection, oil-pump service, and internal transmission checks.

The CVT chapter is more than a belt-replacement note. It covers the V-belt, primary and secondary sheaves, sheave weights, clutch shoes, and spring-loaded clutch assembly. Removal, inspection, controlled disassembly, reassembly, and final installation are all documented, along with the starter clutch, generator rotor, stator, and related holding and puller tools.

Data and Reference Highlights

The FI chapter identifies the ECU, injector, fuel pump, throttle-position sensor, intake-air-pressure and temperature sensors, coolant-temperature sensor, crankshaft-position sensor, lean-angle cut-off switch, and ISC valve. It explains the ECU self-diagnostic function, fail-safe actions, diagnostic mode, and fault-by-fault troubleshooting. Fuel-hose and pump removal, injector inspection, throttle-body checks, fuel-pressure testing, TPS checks, and ISC operation are covered as factory procedures.

Electrical diagnosis is organized by system rather than left to one undifferentiated schematic. Useful examples include the fuel-injection wiring diagram, starting circuit cut-off diagram, charging-system circuit diagram, signaling-system circuit diagram, cooling-system circuit diagram, and the complete YP400T wiring diagram at the end of the manual. Connector checks, switch-continuity tests, bulb and socket inspection, starter-motor repair, and troubleshooting flowcharts support actual fault isolation.

The special-tool section lists Yamaha tool numbers alongside the corresponding 90890-series numbers. Examples include the YM-04134 sheave spring compressor with YM-04135 fixed block, the YU-03153 fuel-pressure gauge with YM-03181 adapter, and the YM-04146 plane-bearing installer/remover. These references help a shop judge whether a CVT, fuel-system, fork, valve-train, water-pump, or crankcase repair can be completed with the tools on hand.

The separate 102-page YP400W owner’s manual adds operating and minor-maintenance information: controls, pre-operation checks, starting and braking, break-in, maintenance charts, service access, scooter care, storage, specifications, and consumer information. Its instrument section explains the tachometer, multifunction display, fuel and coolant displays, oil and V-belt indicators, clock, ambient-temperature display, and two-digit self-diagnosis codes. Basic troubleshooting charts cover fuel, compression, ignition, battery condition, and overheating.

Important scope distinction: the YP400W file is an owner’s manual, not a YP400W service-manual supplement. Internal repair procedures in this set come from the YP400T service manual, so technicians should match the model label and applicable specifications before ordering parts or applying a repair procedure.

The publication also flags several repair traps. Turning the crankshaft during camshaft installation or tightening the camshaft caps unevenly can disturb timing and damage the cylinder head or camshafts. Grease contamination can ruin the V-belt and secondary-sheave surfaces, while uncontrolled clutch-spring disassembly creates a component and injury hazard. Excessive force during fork separation can damage the oil seal, bushing, or oil-flow stopper.

Fuel-system, brake-fluid, battery, and cooling-system work involves fire, pressure, chemical, and electrical hazards. The Yamaha procedures assume a properly ventilated shop, suitable personal protection, the specified service tools, and a technician or experienced owner with a working knowledge of scooter repair.