Yamaha 1984-85 5 HP Outboard Specs & Maintenance
Looking to keep your 1984-1985 5 HP single-cylinder 2-stroke outboard running smoothly? This compact 6.3 cu in (103 cc) engine is a reliable workhorse for small tenders, Jon boats, and auxiliary power. Whether you are performing routine tune-ups or a full restoration, our technical database provides the exact factory specifications you need. Explore spark plug gaps, maintenance tips, and expert mechanical advice to keep this classic lightweight motor firing on the first pull.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 5 |
| Year Range | 1984-85 |
| Engine Type | CL 2-stroke |
| Cylinders | 1 |
| Displacement | 6.3 cu-in (103 cc) |
| Bore x Stroke | 2.13 x 1.77 in (54 x 45 mm) |
| Compression Ratio | 6.5:1 |
| Full Throttle RPM | 4500-5500 |
| Idle Speed (Neutral) RPM | 1100-1200 |
| Idle Speed (Trolling) RPM | 950-1050 |
| Spark Plug (NGK) | B7HS |
| Spark Plug (Champion) | L82C |
| Spark Plug Gap | 0.020-0.024 in (0.5-0.6 mm) |
| Ignition System | CDI |
| Ignition Timing (Idle) | 3-7 |
| Ignition Timing (Carb Pickup) | — |
| Ignition Timing (Full Advance) | 25-31 |
| Fuel System | Carb |
| Starting System | Manual |
| Oil Injection System | Pre-Mix 100:1 |
| Injection Oil Ratio | Pre-Mix 100:1 |
| Gear Oil Capacity (mL/cc) | 105 |
| Gear Oil Capacity (Oz) | 3.6 |
| Approximate Weight | 42-47 lbs (19-22 kg) |
| Battery CCA / Reserve | n/a |
| Battery Reserve | n/a |
| Tach Pole Setting | 4 |
| Test Propeller Part Number | YB-1630 |
| Test Propeller New Engine RPM | 4500-5500 |
Maintenance Summary
Routine maintenance for this 103 cc 2-stroke is simple and straightforward. Keep it running at peak performance by gapping an NGK B7HS spark plug to 0.020–0.024 inches (0.5–0.6 mm). Regularly inspect the cooling system, carburetor settings, and fuel mixture to ensure long-term reliability on the water.
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Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only.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.
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