2004 Yamaha Marine 160 Outboard Motor 6V, 8V Service Manual (P/N LIT-18616-01-64)

• 2004 application: Yamaha 8MLHC and 8MSHC, mapped in the model-year index to this 151-page PDF, P/N LIT-18616-01-64, with no supplement listed.
• The base 6V/8V manual also identifies 6CM, 6CEM, 8CM, and 8CEM worldwide models and the 6MH/8MH names used in the USA and Canada, with separate manual- and electric-start systems plus Europe-specific electrical coverage.
• Documents power-unit removal, flywheel-magneto service, cylinder/crankcase teardown, piston and crankshaft inspection, reed-valve and thermostat service, oil-seal replacement, reassembly, and recoil-starter repair.
• Details fuel-joint and strainer testing, carburetor and diaphragm fuel-pump disassembly, internal inspection and reassembly, plus idle, ignition-timing, throttle-link, and start-in-gear adjustments.
• Covers lower-unit removal and overhaul, water-pump service, gear and dog-clutch inspection, shaft/bearing/seal work, backlash measurement, shim selection, gearcase pressure testing, and bracket/steering-handle repair.
• Provides configuration-specific wiring diagrams, CDI and ignition diagnostics, charge/pulser/lighting-coil tests, rectifier/regulator checks, electric-start testing, starter-motor service, harness inspection, and system troubleshooting charts.

2004 Application and Manual Identity

The 2004 assignment uses an earlier Yamaha base publication. Its copyright page states first edition, July 1996; the rear Yamaha library label catalogs it as the 6V, 8V 1997 Service Manual, and the front cover carries the code 160. The earlier print date still fits: the model-year index assigns this base manual to the 2004 8MLHC and 8MSHC outboards.

The manual covers a two-cylinder, 165 cc 2-stroke platform. Its general specifications use engine model codes 6M8 for the 6 hp group and 6N0 for the 8 hp group. The identification chapter uses approved model code 6H6 for 6CM/6MH (starting at S 003802 or L 303150) and 6CEM (S 100101 or L 400101). Code 6G1 applies to 8CM/8MH (S 008601 or L 305566) and 8CEM (UL 700101, S 100101, or L 100101).

Engine and Fuel System Documentation

The powerhead chapter follows the assembly from the flywheel magneto and stator through the thermostat, exhaust and intake sections, reed valves, crankcase, cylinder body, crankshaft, pistons, rings, bearings, and oil-seal housings. Inspection data covers cylinder condition, piston-to-cylinder clearance, ring fit, crankshaft runout and axial play, thermostat operation, reed valves, and staged tightening sequences. Reassembly notes mark gasket-maker, locking-agent, oil, and marine-grease locations as well as required component orientation.

Fuel-system repair sections break down the fuel joint, strainer, carburetor, float chamber, jets and nozzle, needle valve, pilot screw, and diaphragm fuel pump. Factory procedures cover fuel-joint holding-pressure checks, leakage inspection, float setting, carburetor setup, idle-speed adjustment, ignition timing, throttle-link adjustment, and start-in-gear protection. Predelivery and periodic-service material adds gear-oil, spark-plug, anode, propeller, battery, lubrication, and control checks.

Lower Unit, Bracket, and Electrical References

Lower-unit repair is treated as an internal gearcase job, not merely an oil-change section. Procedures cover water-pump removal, gearcase disassembly, forward and reverse gears, pinion, dog clutch, shift shaft and plunger, propeller and drive shafts, bearings, bushings, seals, and reinstallation. The factory method for checking forward and reverse backlash is illustrated with the backlash indicator and dial gauge, followed by shim-selection guidance and a pressure-hold leakage test. Bracket chapters address the upper casing, bottom cowling, mounts, shift linkage, clamp/swivel and tilt hardware, pivot shaft, and tiller-handle throttle components.

Electrical content is divided by configuration. Manual-start diagrams show the CDI ignition and lighting system; the 6CEM/8CEM electric-start diagrams add the battery, fuse, starter relay, starter motor, starter switch, neutral switch, and rectifier circuit. Diagnostic sections provide resistance and continuity data, spark-gap and CDI tests, charging checks, starter-motor service, and harness fault tracing. Troubleshooting charts isolate no-start or rough-running complaints, power loss, misfire, impossible gear shifting, and a battery that is not charging.

Factory Tools, Illustrated References, and Repair Cautions

The special-tool section lists Yamaha numbers for tune-up, powerhead, and lower-unit work. Examples include the CDI tester YU-91022-B, flywheel puller YB-6117 / 90890-06521, flywheel holder YB-6139 / 90890-06522, Mity Vac YB-35956 / 90890-06756, and backlash indicator YB-6265 / 90890-06706. Factory data spans general and maintenance specifications, component torque callouts, a general torque chart, capacities, clearances, wear limits, ignition settings, shim data, and electrical test values.

Useful illustrations include the carburetor/fuel-pump breakdown, cylinder/piston/crankshaft exploded view, recoil-starter assembly, lower-unit gear train and backlash setup, manual- and electric-start wiring diagrams, and starter-motor breakdown.

The powerhead section warns that uneven or partially seated flywheel-puller bolts can damage the engine or the tool. It also keeps reused pistons, pins, and small-end bearings matched to their original cylinders and calls for protecting the lower-unit shim pack so the repair does not disturb the original gear setup. Yamaha also flags gasoline vapor, ignition-spark testing, recoil-spring tension, and battery isolation as workshop hazards.