Yamaha 1989-94 55 HP Outboard Specs & Maintenance
Looking to keep your 1989-1994 55 HP 2-stroke outboard running like new? This rugged 2-cylinder, 46 cubic inch (760cc) inline workhorse is a favorite among boating enthusiasts for its simplicity and reliable power. Whether you’re troubleshooting ignition issues or prepping for seasonal service, our comprehensive database provides the precise technical specifications and maintenance data you need to tackle any DIY marine repair project with confidence.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 55 |
| Year Range | 1989-94 |
| Engine Type | IL 2-stroke |
| Cylinders | 2 |
| Displacement | 46 cu-in (760 mm) |
| Bore x Stroke | 3.20 x 2.80 in (82 x 72 mm) |
| Compression Ratio | 6.5:1 |
| Full Throttle RPM | 4500-5500 |
| Idle Speed (Neutral) RPM | 1050-1150 |
| Idle Speed (Trolling) RPM | 750-850 |
| Spark Plug (NGK) | B8HS-10 |
| Spark Plug (Champion) | L78C |
| Spark Plug Gap | 0.035-0.039 in (0.9-1.0 mm) |
| Ignition System | CDI |
| Ignition Timing (Idle) | 4-6 ATDC |
| Ignition Timing (Carb Pickup) | 3-5 |
| Ignition Timing (Full Advance) | 25-27 |
| Fuel System | Carb |
| Starting System | Manual or Elec |
| Oil Injection System | Pre-Mix 50:1 |
| Injection Oil Ratio | Pre-Mix 50:1 |
| Gear Oil Capacity (mL/cc) | 500 |
| Gear Oil Capacity (Oz) | 16.9 |
| Approximate Weight | 192-218 lbs (87-99 kg) |
| Battery CCA / Reserve | 380 (70) |
| Battery Reserve | 124 minutes |
| Tach Pole Setting | 4 |
| Test Propeller Part Number | YB-1611 |
| Test Propeller New Engine RPM | 5300-5500 |
Maintenance Summary
Routine service keeps this 55 HP inline two-stroke firing smoothly. Maintain optimal combustion by installing fresh NGK B8HS-10 spark plugs gapped to 0.035–0.039 inches (0.9–1.0 mm). Always mix high-grade two-stroke oil, inspect the water pump impeller annually, and check lower unit gear lube regularly.
Disclaimer & Information Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only. Always verify data against an official OEM service manual prior to ordering parts or executing repairs. VintageMotorSpecs.com assumes no liability for repair errors, equipment damage, or personal injury resulting from the use of this data.
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