Yamaha 1984-94 50 HP Outboard Specs & Maintenance
Built between 1984 and 1994, this iconic 50 HP 3-cylinder inline 2-stroke outboard is legendary for its exceptional power-to-weight ratio and bulletproof reliability. Boasting a responsive 43 cubic inch (698cc) displacement, it remains a favorite among vintage boat restoration enthusiasts and DIY marine mechanics. Whether you’re troubleshooting ignition issues or conducting seasonal tune-ups, our comprehensive database provides the exact technical specs, guides, and service insights you need to keep your classic running smoothly.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 50 |
| Year Range | 1984-94 |
| Engine Type | IL 2-stroke |
| Cylinders | 3 |
| Displacement | 43 cu-in (698 cc) |
| Bore x Stroke | 2.64 x 2.60 in (67 x 66 mm) |
| Compression Ratio | 6.0:1 |
| Full Throttle RPM | 4500-5500 |
| Idle Speed (Neutral) RPM | 750-850 |
| Idle Speed (Trolling) RPM | 550-650 |
| 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) | 0-2 ATDC |
| Ignition Timing (Full Advance) | 24-26 |
| Fuel System | Carb |
| Starting System | Electric |
| Oil Injection System | PB or 50:1 PM |
| Injection Oil Ratio | PB or 50:1 PM |
| Gear Oil Capacity (mL/cc) | 430 |
| Gear Oil Capacity (Oz) | 14.5 |
| Approximate Weight | 164-200 lbs (75-91 kg) |
| Battery CCA / Reserve | 380 (70) |
| Battery Reserve | 124 minutes |
| Tach Pole Setting | 6 |
| Test Propeller Part Number | YB-1611 |
| Test Propeller New Engine RPM | 5250-5450 |
Maintenance Summary
Keep this 698cc inline-three firing on all cylinders with routine service. Ensure crisp ignition by gapping fresh NGK B8HS-10 spark plugs to 0.035–0.039 inches (0.9–1.0 mm). Inspect the water pump impeller annually, maintain proper oil-to-fuel ratios, and grease all lube points regularly for peak reliability.
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Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only.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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