Yamaha 1984-92 15 HP Outboard Specs & Maintenance
Built between 1984 and 1992, this reliable 15 HP, 2-cylinder inline 2-stroke outboard remains a favorite among DIY boat mechanics and fishing enthusiasts. Packing a punch with its 246cc (15 cu. in.) displacement, it offers incredible power-to-weight performance for aluminum skiffs and Jon boats. Whether you’re troubleshooting ignition issues or doing routine servicing, our technical database provides the exact specs, spark plug gaps, and maintenance steps to keep this classic runner purring.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 15 |
| Year Range | 1984-92 |
| Engine Type | IL 2-stroke |
| Cylinders | 2 |
| Displacement | 15 cu-in (246 cc) |
| Bore x Stroke | 2.20 x 1.97 in (56 x 50 mm) |
| Compression Ratio | 7.0:1 |
| Full Throttle RPM | 4500-5500 |
| Idle Speed (Neutral) RPM | 700-800 |
| Idle Speed (Trolling) RPM | 600-700 |
| Spark Plug (NGK) | B7HS-10 |
| Spark Plug (Champion) | L82C |
| Spark Plug Gap | 0.035-0.039 in (0.9-1.0 mm) |
| Ignition System | CDI |
| Ignition Timing (Idle) | 4-6 |
| Ignition Timing (Carb Pickup) | 9-11 |
| Ignition Timing (Full Advance) | 29-31 |
| Fuel System | Carb |
| Starting System | Man or Man & Elec |
| Oil Injection System | Pre-Mix 100:1 |
| Injection Oil Ratio | Pre-Mix 100:1 |
| Gear Oil Capacity (mL/cc) | 185 |
| Gear Oil Capacity (Oz) | 6.3 |
| Approximate Weight | 83-87 lbs (38-40 kg) |
| Battery CCA / Reserve | 210 (40) |
| Battery Reserve | 59 minutes |
| Tach Pole Setting | 4 |
| Test Propeller Part Number | YB-1619 |
| Test Propeller New Engine RPM | 5000-5200 |
Maintenance Summary
Keep this classic 15 HP running strong with regular maintenance. Always inspect your cooling impeller, refresh lower unit gear lube, and mix fresh 2-stroke fuel. For peak ignition performance, install NGK B7HS-10 spark plugs correctly gapped between 0.035 and 0.039 inches (0.9–1.0 mm).
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Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only.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.
Spot an error or discrepancy in these specs? Please contact us with your engine details so we can update our database.
Non-Affiliation Notice: VintageMotorSpecs.com is an independent historical reference database and is not affiliated, associated, authorized, endorsed by, or in any way officially connected with Outboard Marine Corporation (OMC), Mercury Marine, Yamaha, Honda, or any of their subsidiaries or affiliates. All product names, trademarks, and registered trademarks are property of their respective owners.