1987 Evinrude 100HP Service Manual

The 1987 Evinrude 100HP outboard motor is a V4, two-stroke powerhead featuring cross-flow scavenging, 99.6 cubic inch displacement, loop-charged induction system, 120° V-block configuration, thermostatically controlled cooling, CD ignition system, and single-lever remote control operation. This service manual covers maintenance procedures, troubleshooting, specifications, and repair guidelines for the 1987 model year E100 models. Below are key sections for safety, specifications, maintenance, troubleshooting, and service procedures.

1. Specifications 2. Safety Precautions 3. Maintenance Schedule 4. Fuel System 5. Ignition System 6. Cooling System 7. Lower Unit 8. Electrical System 9. Powerhead Service 10. Troubleshooting 11. Torque Specifications

Specifications

Technical specifications for the 1987 Evinrude 100HP outboard motor.

Specification	Value
Model Year	1987
Horsepower	100 HP @ 5000 RPM
Cylinders	4 (V4 configuration)
Displacement	99.6 cubic inches (1632 cc)
Bore x Stroke	3.50" x 2.60" (89mm x 66mm)
Ignition System	CD (Capacitor Discharge)
Fuel System	Dual carburetors with fixed jets
Fuel/Oil Ratio	50:1 with TC-W3 oil
Gear Ratio	1.85:1
Weight	Approx. 295 lbs (134 kg)
Starting System	Electric with manual backup
WOT RPM Range	4500-5500 RPM

Safety Precautions

Essential safety procedures for servicing the Evinrude 100HP outboard.

Disconnect battery cables before performing electrical work.
Use proper lifting equipment for powerhead removal.
Work in well-ventilated area when handling fuel.
Wear safety glasses during all service procedures.
Use marine-grade replacement parts only.
Properly support motor during lower unit service.

WARNING! Gasoline is highly flammable. No smoking or open flames near fuel system work. Always have fire extinguisher available.

Maintenance Schedule

Recommended maintenance intervals for optimal performance.

Every 100 hours or annually: Change gear lube, inspect spark plugs.
Every 200 hours: Replace water pump impeller, inspect thermostats.
Every 300 hours: Clean carburetors, inspect fuel lines.
Every 500 hours: Decarbonize powerhead, inspect reed valves.
Seasonal: Fog cylinders for storage, check battery charge.
Pre-season: Pressure test lower unit, check propeller hub.

CAUTION! Follow specified intervals to prevent premature wear and engine damage.

Fuel System

Dual carburetor system with fixed main jets and adjustable idle mixture.

Carburetor Type: Dual throat fixed-jet carburetors
Main Jet Size: #58D (standard)
Float Level: 1/2" ± 1/32"
Idle Mixture: 1-1/4 turns out from lightly seated
Fuel Pump: Diaphragm type, pulse-operated
Fuel Filter: In-line canister type

Synchronization procedure: Adjust throttle linkage so all butterflies open simultaneously. Set idle speed to 650-700 RPM in neutral.

Ignition System

CD ignition with power pack, trigger assembly, and charge coils.

Components: Power Pack, Stator, Timer Base, Charge Coils, Spark Plug Coils

Specifications: Spark plug gap: 0.030", Spark advance: 18° BTDC @ 4500 RPM, Minimum spark voltage: 25,000 volts

Testing procedures: Use DVA meter for output tests. Check stator output: 150+ volts AC. Check trigger resistance: 800-1100 ohms.

Cooling System

Thermostatically controlled pressureized cooling with tell-tale indicator.

Thermostat opens: 143°F (62°C)
Pressure relief valve: 15 psi
Water pump impeller: Replace every 2 years or 200 hours
Tell-tale flow: Strong, consistent stream indicates proper operation

Tip: Always run motor in test tank or with water supply during maintenance running.

Lower Unit

Gearcase service including water pump, propeller, and gear lubrication.

Drain and refill gear lube annually or every 100 hours.
Inspect propeller for damage and hub condition.
Check gear lube for water contamination (milky appearance).
Replace water pump impeller every 2 years.
Inspect drive shaft splines for wear.
Check shift rod height during reassembly.

WARNING! Use only recommended gear lube. Improper lubrication can cause gear failure.

Electrical System

12-volt DC system with alternator charging and electric start.

Component	Specification
Alternator Output	10 amps @ 5000 RPM
Battery	12V, minimum 450 CCA
Starter Motor	12V, 1.4 kW
Voltage Regulator	Solid state, 14.2V regulation
Fuse	20 amp in-line

Charging system test: 13.5-14.5 volts at 2000 RPM with battery connected.

Powerhead Service

Cylinder compression, decarbonizing, and major component service.

Compression test: All cylinders within 10% of each other (120-150 psi typical)
Decarbonize using approved combustion chamber cleaner
Inspect reed valves for proper seating and cracks
Check piston ring end gap: 0.010-0.020"
Main bearing clearance: 0.001-0.003"
Connecting rod side clearance: 0.008-0.012"

CAUTION! Measure carefully during reassembly. Improper clearances can cause engine failure.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Hard starting	Weak battery, fouled plugs	Check battery charge, replace spark plugs
Overheating	Water pump, thermostat	Replace impeller, test thermostat
Poor acceleration	Carburetion, timing	Clean carbs, check spark advance
No spark	Kill switch, ignition components	Check kill circuit, test power pack
Vibration	Propeller, motor mounts	Inspect prop, check mount bolts
Oil injection issues	Pump, lines, reservoir	Inspect oil lines, test pump operation

Diagnostic Tip: Use systematic approach: Compression > Spark > Fuel

Torque Specifications

Critical fastener torque values for proper assembly.

Component	Torque Value
Cylinder Head Bolts	240-250 in-lbs (20-21 ft-lbs)
Main Bearing Cap	300-320 in-lbs (25-27 ft-lbs)
Flywheel Nut	105-115 ft-lbs
Spark Plugs	180-200 in-lbs (15-17 ft-lbs)
Propeller Nut	55-60 ft-lbs
Gearcase Drain Screws	60-80 in-lbs (5-7 ft-lbs)

Note: Use calibrated torque wrench. Apply lubricant to threads where specified.