Yamaha 1984-96 8 HP Outboard Specs & Maintenance
Built between 1984 and 1996, this reliable 8 HP 2-cylinder 2-stroke outboard motor remains a favorite for small boats and skiffs. Packing a 10 cu in (165 cc) displacement, it offers an exceptional power-to-weight ratio and straightforward mechanical design. Whether you are restoring a classic portable outboard or troubleshooting a mid-season misfire, our comprehensive database provides the technical specs, maintenance guides, and spark plug requirements you need to keep your vintage 8 HP running smooth.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 8 |
| Year Range | 1984-96 |
| Engine Type | CL 2-stroke |
| Cylinders | 2 |
| Displacement | 10 cu-in (165 cc) |
| Bore x Stroke | 1.97 x 1.65 in (50 x 42 mm) |
| Compression Ratio | 7.0:1 |
| Full Throttle RPM | 4500-5500 |
| Idle Speed (Neutral) RPM | 850-950 |
| Idle Speed (Trolling) RPM | 750-850 |
| 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) | 3-5 |
| Ignition Timing (Carb Pickup) | — |
| Ignition Timing (Full Advance) | 34-36 |
| 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) | 160 |
| Gear Oil Capacity (Oz) | 5.4 |
| Approximate Weight | 57-65 lbs (26-30 kg) |
| Battery CCA / Reserve | 210 (40) |
| Battery Reserve | 59 minutes |
| Tach Pole Setting | 4 |
| Test Propeller Part Number | YB-1625 |
| Test Propeller New Engine RPM | 5300-5500 |
Maintenance Summary
Routine maintenance keeps this 165 cc two-stroke performing reliably. For peak ignition, run fresh fuel mix and replace your spark plugs with NGK B7HS-10, gapped precisely between 0.035 and 0.039 inches (0.9–1.0 mm). Always inspect lower unit gear lube and water pump impellers seasonally.
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Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only.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.