Yamaha GP800 WaveRunner GP Service Manual, 1998 (P/N LIT-18616-01-93)

Yamaha’s service manual for the 1998 GP800 WaveRunner GP, P/N LIT-18616-01-93, is the first edition published in February 1998. It covers maintenance, mechanical repair, electrical testing, and hull service for the 66E-powered model.

PDF Bookmarks and Wiring Detail

Navigation and diagram labels: Embedded bookmarks provide access to chapters and many individual service sections. PDF text search is not available. Small wire-color codes and connector labels in the wiring diagrams require zooming for comfortable reading.

One printable PDF contains 210 pages, including seven cover and introductory pages and one wide-format wiring-diagram page.

Power Unit, Jet Pump and Electrical Service

The following selected workshop topics outline the repair coverage rather than reproduce the full contents. Other subjects include seat-lock inspection and deck ventilation-system checks.

• Power unit repair: Engine removal, crankcase separation, cylinder and piston inspection, crankshaft checks, reed-valve service, and flywheel magneto removal and installation.

• Carburetors and fuel delivery: Dual Mikuni BN44 carburetor disassembly, diaphragm and needle-valve inspection, throttle-valve synchronization, and fuel-pump service.

• Oil injection: Oil-pump and filter inspection, pump-cable adjustment, delivery-hose checks, and oil-injection system air bleeding.

• Jet pump and intermediate housing: Impeller and drive-shaft removal, bearing and oil-seal replacement, nozzle service, and cooling and bilge-system inspection.

• Electrical diagnosis: Ignition, starting, and charging-system tests, YPVS servomotor checks, and multi-function meter, warning-system, and sensor testing.

• Hull and controls: Steering, throttle, choke, and trim-cable service, handlebar and hood disassembly, and procedures for hull scratches, cracks, and insert-nut repairs.

The manual was written primarily for Yamaha dealers and trained mechanics, and assumes a basic understanding of the mechanical and electrical concepts involved in the work.

Carburetor Setup and Lubrication

The carburetor sections distinguish cylinder-specific jetting and low-speed screw settings. Having these baseline settings allows you to compare the two carburetors against their respective specifications during diagnosis.

Fuel/oil mixing specifications, oil-pump cable alignment, and bleeding procedures accompany the fuel-system work. The Hose Routing and Cable Routing drawings show the relationships between fuel lines, water hoses, control cables, and electrical leads.

Engine Assembly and Pump Bearings

Exploded diagrams paired with removal and installation charts clarify assembly order and fastening specifications. Step-by-step procedures extend to intermediate-housing bearing replacement, with shaft and seal installation dimensions. Its Intermediate Housing exploded view identifies the shims, coupling, and bearing-housing components.

Engine inspection includes cylinder taper and out-of-round measurements, piston-ring clearances, and crankshaft deflection checks. Exhaust-chamber and muffler removal are documented alongside component-specific tightening sequences.

The Yamaha Power Valve System (YPVS) sections cover valve cleaning, cable adjustment, and actuator testing. The servomotor is a sealed replacement unit; internal servomotor repair is not covered. The manual also warns that sharp cleaning tools can scratch the YPVS valve surfaces.

Bearing-handling cautions explain that spinning bearings with compressed air can damage their surfaces.

Circuit Tests and Symptom Diagnosis

The Ignition System wiring diagram accompanies coil-resistance and switch-continuity tests. Starter-relay checks, rectifier/regulator test tables, starter-motor brush limits, and battery electrolyte specifications provide further diagnostic references.

The wide-format Wiring Diagram includes connector views and wire-color codes. The Trouble-Analysis Chart links symptoms such as starting trouble, overheating, poor charging, and increased bilge water to components and relevant chapters.

Working on marine propulsion systems involves flammable fuel vapors and high-voltage ignition components; follow the manual’s safety precautions.

Hull Repairs and Steering Controls

Control-system sections provide cable installation dimensions, free-play adjustments, and steering-column inspection criteria. Hull coverage includes scratch repair, fiberglass patching, insert nuts, and graphic replacement.

Crack, puncture, and insert-nut procedures refer to the separate Water Vehicle FRP Repair Manual, which is not included.

A Preview of Clearance and Ignition Test Values

The piston inspection section specifies a piston-to-cylinder clearance of 0.100–0.105 mm. Jet-pump inspection gives a maximum impeller-to-housing clearance of 0.6 mm, illustrating the dimensional checks used to assess wear.

For ignition diagnosis, the stator pulser coil specification is 445.5–544.5 ohms at 20°C (68°F), measured between the white/red and white/black leads. The electrical section pairs this value with the corresponding test illustration.